JP5110854B2 - Wheel bearing device with in-wheel motor built-in sensor - Google Patents

Description

  The present invention relates to an in-wheel motor-equipped wheel bearing device in which an electric motor for traveling is arranged on the inner peripheral portion of a wheel rim, and more particularly, to a device provided with a sensor for detecting a force acting on a contact point between a wheel and a road surface. .

  As a wheel bearing device for a vehicle such as an electric vehicle, an in-wheel type motor-equipped wheel bearing device in which a bearing and an electric motor are combined has attracted attention. When this in-wheel type motor-equipped wheel bearing device is used as a driving wheel of an electric vehicle, each driving wheel can be individually driven to rotate, so that a large-scale power transmission mechanism such as a propeller shaft and a differential is not required. Can be made lighter and more compact. In particular, when the electric motor is disposed on the inner peripheral portion of the wheel, the wheel bearing device can be prevented from protruding inward in the axial direction of the wheel, and can be made more compact (for example, Patent Document 1).

In general wheel bearings used in engine-driven automobiles, suspension control, ABS (anti-lock brake system) control, and the like are used as control techniques for ensuring the running stability of the vehicle body. Further, various states of the vehicle are measured by various sensors attached to the vehicle body, and the engine, brake, steering, and the like are controlled based on the measurement results.
JP 2006-57732 A Special table 2003-530565 gazette

  Since the motor drive has a faster torque response than the engine drive, when the suspension control or ABS control is introduced into a motor-driven vehicle, the running stability of the vehicle is higher than when it is introduced into an engine-driven vehicle. Sex can be secured. In order to improve the accuracy of suspension control and ABS control, it is necessary to accurately measure the force acting on the vehicle and perform control based on the measurement result.

  The force acting on the vehicle is mainly generated between the wheel and the road surface. The acting force acting on the contact point between the wheel and the road surface includes the force in the vertical direction (the normal direction of the wheel at the contact point), the force in the left and right direction (the wheel axial direction), and the force in the front and rear direction (traveling direction). is there. In addition to the force generated between the wheel and the road surface, there are also air resistance that depends on travel speed and aerodynamic force due to natural winds, but these are usually very small. Therefore, for the control for ensuring the running stability of the vehicle, it is only necessary to detect the forces in the three axial directions acting between the wheels and the road surface with good responsiveness.

  However, measuring the force acting on the vehicle with a sensor attached to the vehicle body as in the prior art means measuring vibration transmitted to the vehicle body via the suspension or chassis, resulting in a time lag in the measurement result. Therefore, when the measurement result is used for control, there is a problem that the response of the control becomes slow.

  The object of the present invention is to detect the force acting on the ground contact point between the wheel and the road surface with a load detecting sensor that is compactly installed on the wheel bearing device, and to control for ensuring the running stability of the vehicle body. It is an object to provide a wheel bearing device with a sensor with a built-in in-wheel motor that can be accurately performed.

The in-wheel motor-equipped sensor-equipped wheel bearing device according to the present invention includes a double row rolling element interposed between an inner member and an outer member, a knuckle of a suspension device attached to the inner member, and the outer member square member mounting a wheel on said provided electric motor stator inwardly member, the wheel bearing apparatus provided respectively b over data of the electric motor to the outer member, detecting the distortion of the inner member by, act on the grounding point of the wheel and the road surface, setting a sensor for measuring at least one force of the vertical direction, the lateral direction, and the longitudinal direction of the three axial directions forces perpendicular to each other, This sensor is fixed to the inner periphery of the inner member .

  When an external force acts on the contact point between the wheel and the road surface as the vehicle travels, a load is applied to the outer member. This load is transmitted from the outer member to the inner member via the rolling elements, causing distortion of the inner member. A sensor detects the distortion of the inner member. If the relationship between the strain and the external force is obtained in advance by experiment or simulation, the force acting on the wheel and the ground contact point of the road surface can be detected from the output of the sensor. The force acting on the contact point between the wheel and the road surface is a combination of the forces in the vertical direction, the horizontal direction, and the front-rear direction at the contact point in the three axial directions. Detect a force in at least one direction. This detected force can be used for control such as suspension control and ABS control.

As one of the sensors for measuring the force in the three axial directions, a radial strain measuring sensor for measuring the radial strain of the inner member is provided, and the contact between the wheel and the road surface is determined from the output of the radial strain measuring sensor. It is preferable to provide estimation means for estimating the vertical force and the horizontal force acting on the point.
Since the magnitude of the radial distortion of the inner member differs depending on the magnitude of the vertical force and the horizontal force acting on the contact point between the wheel and the road surface, the vertical force and the horizontal force and radial distortion are determined in advance. , The magnitude of the vertical force and the horizontal force can be calculated. The estimation means determines the wheel and the road surface by the output of the radial strain measurement sensor based on the relationship between the vertical force and the horizontal force and the radial strain that have been previously determined through experiments and simulations. The vertical force and the horizontal force acting on the ground contact point are calculated. By obtaining the vertical force and the horizontal force by this method, the vertical force and the horizontal force can be detected with high sensitivity.

The radial strain measurement sensor is a strain sensor that is attached to the inner member via a sensor attachment member and measures the strain of the sensor attachment member, and the sensor attachment member is at least relative to the inner member. It has two contact fixing parts separated in the circumferential direction, and has at least one notch part between adjacent contact fixing parts, and the radial strain measurement sensor is arranged in this notch part. Is preferred.
The sensor mounting member has at least two contact fixing portions separated from each other in the circumferential direction with respect to the inner member, and has at least one notch portion between adjacent contact fixing portions. Since the radial strain measuring sensor is disposed on the sensor mounting member, the radial strain measuring sensor is disposed at a location where the sensor mounting member has a larger strain than the inner member due to a decrease in rigidity. Thereby, the distortion of the inner member can be detected with high sensitivity.
In addition, since the radial strain measuring sensor is attached to the inner member via the sensor mounting member, the radial strain measuring sensor can be compactly installed in the wheel bearing device. Since the sensor mounting member is a simple part that can be mounted on the inner member, by attaching a radial strain measuring sensor to the sensor mounting member, the sensor mounting member can be excellent in mass productivity, and the cost can be reduced.

As one of the sensors for measuring the force in the three axial directions, a radial strain measuring sensor for measuring the radial strain of the inner member is provided, and the contact between the wheel and the road surface is determined from the output of the radial strain measuring sensor. It is preferable to provide estimation means for estimating the vertical force acting on the point.
Since the magnitude of the radial distortion of the inner member differs depending on the magnitude of the vertical force acting on the contact point between the wheel and the road surface, the relationship between the vertical force and radial distortion is obtained in advance through experiments and simulations. Thus, the magnitude of the vertical force can be calculated. The estimation means acts on the contact point between the wheel and the road surface by the output of the sensor for measuring the radial strain based on the relationship between the vertical force and the radial strain previously obtained and set through experiments and simulations. Calculate the vertical force. By obtaining the vertical force by this method, the vertical force can be detected with high sensitivity.

As one of the sensors for measuring the force in the three axial directions, an axial strain measuring sensor for measuring the axial strain of the inner member is provided, and the wheel and the road surface are connected from the output of the axial strain measuring sensor. It is preferable to provide an estimation means for estimating the lateral force acting on the point.
Since the change in the axial strain of the inner member differs depending on the magnitude of the lateral force acting on the contact point between the wheel and the road surface, the relationship between the lateral force and the axial strain is obtained in advance through experiments and simulations. By setting it, the magnitude of the force in the left-right direction can be calculated. The estimation means acts on the ground contact point between the wheel and the road surface by the output of the sensor for measuring the axial strain based on the relationship between the lateral force and the axial strain previously obtained and set by experiments and simulations. Calculate the left-right force. By obtaining the lateral force by this method, the lateral force can be detected with high accuracy.

The inner member and the outer member may be provided with brake wheels and brake pads, respectively. In that case, as one of the sensors for measuring the force in the three axial directions, a current sensor for measuring the current amount of the electric motor and a brake force sensor for measuring the braking force acting on the brake are provided, and these currents are provided. It is preferable to provide estimation means for estimating the longitudinal force acting on the contact points between the wheels and the road surface from the outputs of the sensor and the brake force sensor.
The amount of current flowing through the electric motor differs depending on the magnitude of the longitudinal force acting on the ground contact point between the wheel and the road surface when the vehicle is traveling. Similarly, the braking force of the brake varies depending on the magnitude of the force in the front-rear direction. Therefore, if the relationship between the longitudinal force and the electric motor current and the braking force of the brake is obtained in advance through experiments and simulations, the longitudinal force can be determined by measuring the electric motor current and the braking force of the brake. Can be estimated. It is possible to estimate the force in the front-rear direction even from a single measurement result of the electric motor current amount or the braking force of the brake, but by comparing and contrasting both, it is possible to accurately estimate the force in the front-rear direction. it can.

The in-wheel motor-equipped sensor-equipped wheel bearing device according to the present invention includes a double row rolling element interposed between an inner member and an outer member, a knuckle of a suspension device attached to the inner member, and the outer member square member mounting a wheel on said provided electric motor stator inwardly member, the wheel bearing apparatus provided respectively b over data of the electric motor to the outer member, detecting the distortion of the inner member by, act on the grounding point of the wheel and the road surface, setting a sensor for measuring at least one force of the vertical direction, the lateral direction, and the longitudinal direction of the three axial directions forces perpendicular to each other, Since this sensor is fixed to the inner circumference of the inner member, the force acting on the ground contact point between the wheel and the road surface can be detected with high sensitivity by the load detection sensor installed compactly on the wheel bearing device. Ensure stability The control for enabling accurately.

  An embodiment of the present invention will be described with reference to FIGS. This in-wheel motor-equipped sensor-equipped wheel bearing device includes a bearing 10 that rotatably supports the wheel 1, an electric motor 20 for traveling, and a brake 30 on the inner peripheral side of the wheel 1. is there. In this specification, the side closer to the outer side (right side in FIG. 1) in the vehicle width direction of the vehicle with the wheel bearing device attached to the vehicle is called the outboard side, and the side closer to the center of the vehicle ( The left side of FIG. 1 is called the inboard side.

  As shown in FIG. 1, the wheel 1 includes a wheel 4 including a cylindrical rim 2 and a ring-shaped disk 3 attached to the inner peripheral surface of the rim 2, and a tire 5 is attached to the outer periphery of the rim 2. It is provided. The disk 3 is attached to the approximate center of the axial width of the rim 2.

  As shown in FIG. 2, the bearing 10 includes an outer member 11 in which a double row rolling surface 13 is formed on the inner periphery, and an inner member 12 in which a rolling surface 14 facing each of the rolling surfaces 13 is formed. And a plurality of rolling elements 15 interposed between the rolling surfaces 13 and 14 of the outer member 11 and the inner member 12. The bearing 10 is a double-row angular ball bearing type, and the rolling elements 15 are formed of balls, and are held by a cage (not shown) for each row. The rolling surfaces 13 and 14 are arc-shaped in cross section, and each rolling surface 13 and 14 is formed so that the contact angle is outward. The end portions on the outboard side and the inboard side of the bearing space between the outer member 11 and the inner member 12 are respectively sealed with seal members 16.

  The outer member 11 serves as a rotation-side raceway, and has a flange 11a attached to the disk 3 at the end on the outboard side on the outer periphery, and is formed as an integral part. The flange 1a is provided with attachment holes 11b at a plurality of locations in the circumferential direction, and the outer member 11 is attached to the disk 3 with attachment bolts and nuts 6 inserted into the attachment holes 11b.

  The inner member 12 serves as a fixed raceway, and is formed on the base ring 17 having a disk portion 17a on the inner periphery near the outboard side end, and on the outer periphery of the inboard side end of the base ring 17. The inner ring 18 is fitted to the small diameter portion. The rolling surfaces 14 of each row are formed on the base wheel 17 and the inner ring 18. The inner ring 18 is fixed and integrated with the base wheel 17 by caulking the end of the base wheel 17 on the outboard side. A brake mounting hole 17 b is provided in the disc portion 17 a of the base wheel 17.

  The traveling electric motor 20 is provided closer to the inboard side than the inboard side rolling surfaces 13 and 14 between the outer member 11 and the inner member 12. The traveling electric motor 20 of this embodiment is of a radial gap type in which a radial gap is provided between a stator 21 fixed to the inner member 12 and a rotor 22 attached to the outer member 11. An axial gap type in which an axial gap is provided between the rotor 21 and the rotor 22 may be employed. A cap 23 is attached to the opening on the inboard side between the outer member 11 and the inner member 12.

  The brake 30 includes a brake wheel 31 attached to the disk 3 together with the outer member 11, an operation part 33 having a brake pad 32 capable of frictional contact with the brake wheel 31, and a drive part 34 for operating the brake pad 32. In addition, an electric brake using a brake electric motor 35 is used as a drive source of the drive unit 34. The brake wheel 31 is composed of a brake disc. A pair of brake pads 32 are provided so as to sandwich the brake wheel 31 therebetween. One brake pad 32 is fixed to the brake frame 36, and the other brake pad 32 is attached to an advancing / retracting member 37 that is linearly movable on the brake frame 36. The advancing / retracting direction of the advancing / retracting member 37 is a direction facing the brake wheel 31. The advance / retreat member 37 is prevented from rotating with respect to the brake frame 36. The brake frame 36 is fitted into a brake mounting hole 17b provided in the disc portion 17a of the inner member base wheel 17, and is fixed to the disc portion 17a by a fixing member 38.

  The drive unit 34 includes the brake electric motor 35 and a ball screw 39 that converts the rotational output of the electric motor 35 into a reciprocating linear motion and transmits the brake pad 32 as a braking force. The output of the electric motor 35 is It is transmitted to the ball screw 39 via the deceleration transmission mechanism 40. In the ball screw 39, a screw shaft 41 is supported by the brake frame 36 through a bearing 42 so as to be rotatable only, and a nut 43 is fixed to the advance / retreat member 37. The advance / retreat member 37 and the nut 43 may be integral with each other.

  The ball screw 39 includes a screw shaft 41 and a nut 43, and a plurality of balls 44 interposed between screw grooves formed to face the outer peripheral surface of the screw shaft 41 and the inner peripheral surface of the nut 43. The nut 43 has a circulation means (not shown) for circulating the ball 44 interposed between the screw shaft 41 and the nut 43 through an endless path. The circulation means may be of an external circulation type using a return tube or a guide plate, or may be of an internal circulation type using an end cap or a piece. Since the ball screw 39 reciprocates over a short distance, the ball screw 39 does not have the circulating means, for example, a plurality of balls 44 between the screw shaft 41 and the nut 43 are retained by a retainer (not shown). A retained retainer type may be used.

  The deceleration transmission mechanism 40 is a mechanism that decelerates and transmits the rotation of the brake electric motor 35 to the screw shaft 41 of the ball screw 39, and is constituted by a gear train. In this example, the speed reduction transmission mechanism 40 includes a gear 45 provided on the output shaft of the electric motor 35 and a gear 46 provided on the screw shaft 41 and meshing with the gear 45. In addition to this, the deceleration transmission mechanism 40 may be composed of, for example, a worm and a worm wheel (not shown).

  The brake 30 includes an operation unit 52 that controls the electric motor 35 in accordance with an operation of an operation member 51 such as a brake pedal. The operation unit 52 is provided with antilock control means 55. The operation unit 52 includes the operation member 51, an operation sensor 54 that can detect the operation amount and operation direction of the operation member 51, and a control device 53 that controls the electric motor 35 in response to a detection signal of the operation sensor 54. The control device 53 is provided with the antilock control means 55. The control device 53 includes means for generating a motor control signal and a motor drive circuit (none of which is shown) capable of controlling the motor current by the motor control signal.

  The antilock control means 55 is a means for preventing the rotation lock of the wheel 1 by adjusting the braking force by the electric motor 35 according to the rotation of the wheel 1 at the time of braking by the operation of the operation member 51. The anti-lock control means 55 detects the rotational speed of the wheel 1 during the braking, and reduces the driving current of the electric motor 35 or temporarily when the rotational lock of the wheel 1 or its sign is detected from the detected speed. A process of adjusting the braking force, that is, the tightening force of the brake pad 32, is performed by generating a reverse rotation output at the same time. For detecting the rotational speed of the wheel 1, for example, the output of the rotational speed sensor 56 that detects the rotational speed of the rotor 22 of the traveling electric motor 20 can be used.

  The wheel bearing device is fixed to the vehicle body via a suspension device including a knuckle 7 attached to the inner periphery of the inner member 12. The suspension device is provided with damping means 8 such as a damper or a shock absorber that attenuates and transmits the force acting on the wheel 1 and the ground contact point of the road surface to the vehicle body.

  The forces acting on the ground contact point of the wheel 1 and the road surface are the force Fz in the vertical direction (normal direction of the wheel 1 at the ground contact point), the force Fy in the left-right direction (the axial direction of the wheel 1), and the front-rear direction. The force Fx in the (traveling direction) is combined. The wheel bearing device is provided with sensors for measuring the forces in the three axial directions. The vertical force Fz and the horizontal force Fy are obtained from the output of the radial strain measurement sensor 60 that detects the radial strain εz of the inner member 12 that is the stationary raceway of the bearing 10. The force Fx in the front-rear direction is obtained from the output εd of the current sensor 63 that detects the current amount I of the traveling electric motor 20 and the brake force sensor 64 that detects the brake force of the brake 30. The brake force sensor 64 may be a sensor that directly measures the tightening force of the brake pad 32, but the control signal of the antilock control means 55 can be used instead of directly measuring the brake force. In addition, the deformation of the brake frame 36 caused by tightening the brake pad 32 may be measured by a strain sensor and used as a braking force.

  As shown in FIG. 3, these sensors 60, 63, 64 are connected to an estimation unit 65 and an abnormality determination unit 66 that process the output of each sensor. These estimation means 65 and abnormality determination means 66 are provided, for example, in an electric control unit (ECU) 67 of an automobile. The estimation means 65 and the abnormality determination means 66 may be incorporated in an electronic circuit device (not shown) such as a circuit board provided for each axle unit. On the output side of the electric control unit 67, the traveling electric motor 20, the brake electric motor 35, and the suspension device damping means 8 are connected.

  Since the change in the radial distortion of the inner member 12 that is the fixed side raceway is different depending on the magnitude of the vertical force and the horizontal force acting on the ground contact point between the wheel 1 and the road surface, the vertical force and the horizontal By obtaining the relationship between the directional force and the radial strain through experiments and simulations, the vertical force and the horizontal force can be calculated. The estimation means 65 determines the wheel based on the output of the radial strain measuring sensor 60 from the relationship between the vertical force and the horizontal force and the radial strain determined and set in advance through experiments and simulations. 1 and the vertical force and the horizontal force acting on the ground contact point of the road surface are calculated.

  Further, since the amount of current flowing through the traveling electric motor 20 and the magnitude of the braking force acting on the brake 30 differ depending on the magnitude of the longitudinal force acting on the ground contact point of the wheel 1 and the road surface, The magnitude of the force in the front-rear direction can be calculated by obtaining the relationship between the amount of current and the braking force through experiments and simulations. Based on the relationship between the force in the front-rear direction that has been obtained and set in advance through experiments and simulations, the amount of current, and the braking force, the estimating unit 65 determines whether the wheel 1 and the road surface Calculate the longitudinal force acting on the contact point. Although it is possible to estimate the force in the front-rear direction even from a single measurement result of the current amount of the electric motor 20 for traveling or the brake force of the brake 30, the force in the front-rear direction can be accurately determined by comparing and comparing the two. Can be estimated.

  Based on the various information thus obtained, an output for controlling the attitude of the vehicle is output from the electric control unit 67. For example, the rotational speed of the left and right wheels 1 is controlled by outputting to the electric motor 20 for traveling so that the turning is performed smoothly. The braking is controlled by outputting to the brake electric motor 35 so that the wheel 1 is not locked during braking. In order to prevent the vehicle body from being greatly tilted to the left and right during turning and from being largely tilted back and forth during acceleration and braking, suspension control is performed by outputting to the damping means 8 of the suspension device. In addition, the abnormality determination unit 66 outputs an abnormality signal when it is determined that the force in the three-axis direction exceeds an allowable value. This abnormal signal can also be used for vehicle control of an automobile. Furthermore, if the action force between the wheel and the road surface is output in real time, more precise posture control becomes possible.

  The radial strain measuring sensor 60 is installed as shown in FIGS. 4 and 5, for example. That is, the radial strain measuring sensor 60 is attached to the sensor attachment member 72 to form a sensor unit 71, and the sensor unit 71 is fixed to the inner periphery of the inner member 12 of the bearing 10. The sensor mounting member 72 has a substantially arc shape elongated in the circumferential direction along the inner peripheral surface of the inner member 12, and contact fixing portions 72 a and 72 b projecting to the outer peripheral side of the arc are formed at both ends thereof. In addition, a notch 72c that opens to the outer peripheral side of the arc is formed at the center of the sensor mounting member 72, and a radial strain measurement is made of a strain sensor on the inner peripheral surface of the arc located on the back of the notch 72c. Sensor 60 is affixed. The cross-sectional shape of the sensor mounting member 72 is, for example, a rectangular shape, but may be various other shapes.

The sensor unit 71 is fixed to the inner periphery of the inner member 12 by the contact fixing portions 72 a and 72 b of the sensor mounting member 72 so that the longitudinal direction of the sensor mounting member 72 faces the circumferential direction of the inner member 12. The contact fixing portions 72a and 72b are fixed to the inner member 12 by fixing with bolts or bonding with an adhesive. At locations other than the contact fixing portions 72 a and 72 b of the sensor mounting member 72, a gap is generated between the inner surface of the inner member 12. The first contact fixing portion 72a, which is one of the contact fixing portions 72a and 72b, is the inner member 12 at a circumferential location where the inner member 12 is most greatly deformed in the radial direction by a load acting on the inner member 12. Fixed to. The second contact fixing portion 72b is fixed at a location where there is less deformation in the radial direction than the fixed location.
In the case of this embodiment, the fixing location of the first contact fixing portion 72a is the position directly above the entire circumference of the inner member 12 (the position opposite to the road surface), and the fixing location of the second contact fixing portion 72b is The position is several tens of degrees from the position just above, for example, about 30 to 40 degrees below.

  The sensor mounting member 72 is preferably one that does not undergo plastic deformation at the maximum expected value of the force acting on the contact point between the wheel and the road surface. As a material of the sensor mounting member 72, a metal material such as copper, brass, and aluminum can be used in addition to a steel material.

As a strain sensor used for the radial strain measuring sensor 60, various types of strain sensors can be used. For example, a metal foil strain gauge is used. When the strain sensor is composed of a metal foil strain gauge, the sensor mounting member 72 is not limited to the strain of the strain sensor in consideration of the durability of the metal foil strain gauge even when the expected maximum external force is applied to the bearing 10. The amount is preferably 1500 microstrain or less.
In addition, when the strain sensor is constituted by a semiconductor strain gauge, the sensor mounting member 72 is not limited to the strain of the strain sensor in consideration of the durability of the semiconductor strain gauge even when the maximum expected external force is applied to the bearing 10. The amount is preferably 1000 microstrain or less.

  When a load is applied to the outer member 11, which is the rotating raceway of the bearing 10, by the force acting on the contact point between the wheel 1 and the road surface, the inner member 12 is deformed via the rolling elements 15. The sensor mounting member 72 is deformed by being transmitted to the sensor mounting member 72 mounted on the inner periphery of the inner member 12. The strain of the sensor mounting member 72 is measured by a radial strain measuring sensor 60 which is a strain sensor. At this time, the sensor mounting member 72 is deformed in accordance with the radial deformation of the fixing portion of the sensor mounting member 72 in the inner member 12, but the sensor mounting member 72 has an arc shape compared to the inner member 12, and the notch portion. Since 72c is provided and rigidity is reduced at the position of the notch 72c, a strain larger than the strain of the inner member 12 appears in the sensor mounting member 72. For this reason, a slight distortion of the inner member 12 can be accurately detected by the radial distortion measuring sensor 60.

Of the two contact fixing portions 72a and 72b of the sensor mounting member 72, the first contact fixing portion 72a has a diameter larger than that of the other portions of the inner member 12 due to the force acting on the ground contact point between the wheel and the road surface. It is preferable to be attached at a location where the directional deformation is significant. The inner member 12 differs in the degree of radial deformation caused by the vertical force and the horizontal force acting on the ground contact point between the wheel and the road surface, depending on each part in the circumferential direction. According to the result of FEM (finite element method) analysis, the vertical force acting on the contact point between the wheel and the road surface and the radial deformation of the inner member 12 with respect to the left-right force are the positions on the opposite road surface side and the road surface side. That is, the position directly above and below in the vertical direction is the largest. In this embodiment, since the first contact fixing portion 72a is arranged at a position directly above the vertical direction, which is the position where the radial deformation of the inner member 12 is the largest, the sensitivity of the inner member 12 is improved. Distortion can be detected.
That is, when the first contact fixing portion 72a is attached to a location that is greatly deformed in the radial direction as compared with other locations in the inner member 12, the sensor attachment member 72 is a second contact fixing portion that is less deformed. 72b becomes a fulcrum, and the first contact fixing portion 72a is greatly deformed as the inner member 12 is largely deformed. For this reason, the mounting position of the sensor 60 for measuring radial strain of the sensor mounting member 72 causes further distortion, and the sensor for measuring radial strain 60 detects the distortion of the inner member 12 with higher sensitivity. be able to.

  Of the contact fixing portions 72a and 72b, the second contact fixing portion 72b is different from the first contact fixing portion 72a in the direction of radial distortion caused by the force acting on the contact point between the wheel and the road surface. It is good also as a place where forward and backward differ. For example, at the position above the lateral position (position 90 degrees above the road surface position) of the inner member 12 and the position below the lateral position (position close to the road surface), the contact point between the wheel and the road surface The direction of the radial deformation of the inner member 12 with respect to the acting force in the left-right direction is a different direction. When the first contact fixing portion 72a is at a position directly above the inner member 12 (opposite road surface side position), if the second contact fixing portion 72b is at a position lower than the position directly below the inner member 12, both contacts The directions of deformation of the inner member 12 in the fixing portions 72a and 72b are different from each other. As described above, if the second contact fixing portion 72b and the first contact fixing portion 72a are different from each other in the direction of the radial distortion of the inner member 12, the distortion on both sides is added. As a result, the deformation of the inner member 12 is largely transmitted to the sensor mounting member 72, so that even greater strain can be detected, and the strain of the inner member 12 can be detected with higher sensitivity.

  Since the sensor unit 71 including the sensor mounting member 72 and the radial strain measuring sensor 60 mounted on the sensor mounting member 72 is mounted on the inner member 12 of the bearing 10, the sensor for detecting the lateral load is compact in the vehicle. Can be installed. Since the sensor attachment member 72 is a simple part attached to the inner member 12, by attaching the radial strain measurement sensor 60 to the sensor attachment member 72, it can be excellent in mass productivity, and the cost can be reduced.

  As shown in FIG. 6, the sensor units 71 may be provided at two locations. This makes it possible to detect a load with higher accuracy. Similarly, by providing the sensor units 71 at a plurality of three or more locations, it becomes possible to detect a load with higher accuracy. At that time, when it is difficult to install a plurality of sensor units 71 due to space reasons or the like, as shown in FIG. 7, the contact fixing portion fixed to the inner periphery of the inner member 12 is divided into two sensor units. 71 may be shared.

FIG. 8 shows a reference proposal example in which sensors different from the above-described embodiment are provided as sensors for measuring the vertical force and the horizontal force among the three axial forces acting on the contact point between the wheel and the road surface. It shows a bearing device for a vehicle wheel according. FIG. 9 is a block diagram of a control system of the wheel bearing device. In this wheel bearing device, the force Fz in the vertical direction is obtained from the output of the radial strain measurement sensor 61 that detects the radial strain εz of the inner member 12 that is the stationary raceway of the bearing 10, and the horizontal direction The force Fy is obtained from the output of the axial strain measuring sensor 62 that detects the axial strain εy of the inner member 12 that is the stationary raceway of the bearing 10. The force Fx in the front-rear direction is obtained from the output εd of the current sensor 63 that detects the current amount I of the traveling electric motor 20 and the brake force sensor 64 that detects the brake force of the brake 30 as in the above embodiment.

  Since the change in the radial strain of the inner member 12 that is the fixed side raceway is different depending on the magnitude of the vertical force acting on the ground contact point of the wheel 1 and the road surface, the relationship between the vertical force and the radial strain in advance. Can be calculated through experiments and simulations to calculate the magnitude of the vertical force. Based on the relationship between the vertical force and the radial strain previously determined and set through experiments and simulations, the estimating means 65 uses the output of the radial strain measuring sensor 61 to connect the wheel 1 and the road surface. Calculate the vertical force acting on the point.

  Further, since the axial distortion of the inner member 12 that is the stationary side raceway varies depending on the magnitude of the lateral force acting on the ground contact point between the wheel 1 and the road surface, the relationship between the lateral force and the axial distortion in advance. Can be calculated by experiments and simulations to calculate the size in the left-right direction. The estimation means 65 determines the contact between the wheel 1 and the road surface based on the output of the axial strain measuring sensor 62 based on the relationship between the lateral force and the axial strain previously obtained and set through experiments and simulations. The lateral force acting on the point is calculated.

  For example, the radial strain measuring sensor 61 is installed as shown in FIGS. That is, the sensor 61 for radial strain measurement is attached to the sensor attachment member 74 to form a sensor unit 73, and the sensor unit 73 is fixed to the knuckle 7. The sensor attachment member 74 is an elongated member having a distal end bent in a hook shape, and a radial strain sensor 61 including a displacement sensor is attached to the distal end of the sensor attachment member 74. The base portion of the sensor mounting member 74 is a contact fixing portion 74 a for mounting to the knuckle 7.

The sensor unit 73 is attached to the knuckle 7 by fixing the contact fixing portion 74a of the sensor attachment member 74 to the knuckle 7 with an adhesive or the like. In the case of this reference proposal example , the radial strain measuring sensor 61 is a non-contact type displacement sensor such as an eddy current type, and the radial strain measuring sensor 61 is the radial direction of the inner peripheral surface of the inner member 12. In order to measure the displacement of the inner member 12, the inner member 12 is attached to the sensor attachment member 74 at a predetermined interval.

  The axial strain measuring sensor 62 is installed as shown in FIGS. 10 and 12, for example. That is, the sensor 62 for axial strain measurement is attached to the sensor attachment member 76 to form a sensor unit 75, and the sensor unit 75 is fixed to the knuckle 7. The sensor attachment member 76 is a linear and elongated member, and an axial strain sensor 62 made of a displacement sensor is attached to the tip of the sensor attachment member 76. A base portion of the sensor mounting member 76 is a contact fixing portion 76 a for mounting to the knuckle 7.

The sensor unit 75 is attached to the knuckle 7 by fixing the contact fixing portion 76a of the sensor attachment member 76 to the knuckle 7 with an adhesive or the like. In the case of this reference proposal example , the axial strain measuring sensor 62 is a non-contact type displacement sensor such as an eddy current type, and the axial strain measuring sensor 62 is the surface of the disk portion 17a of the inner member 12. Are attached to the sensor attachment member 76 at a predetermined interval with respect to the surface of the disk portion 17a.

  As a displacement sensor used for the radial strain measuring sensor 61 and the axial strain measuring sensor 62, in addition to the eddy current type, a magnetic type, an optical type, an ultrasonic type, a contact type sensor, etc. A sensor capable of detecting a type of displacement can be used. An appropriate sensor may be selected in accordance with various conditions. The sensor mounting members 74 and 76 of the radial strain measuring sensor 61 and the axial strain measuring sensor 62 are made of a material having rigidity that does not deform due to an external force when the sensor units 73 and 75 are mounted on the knuckle 7. Has been.

  When a load is applied to the outer member 11 which is the rotating raceway of the bearing 10 due to the vertical force acting on the contact point between the wheel 1 and the road surface, the inner member 12 is deformed via the rolling elements 15, The displacement in the radial direction of the inner member 12 due to the deformation is measured by a radial strain measuring sensor 61 provided on the sensor mounting member 74 mounted on the knuckle 7. Further, when a load is applied to the outer member 11 that is the rotating raceway of the bearing 10 due to the lateral force acting on the ground contact point between the wheel 1 and the road surface, the inner member 12 is deformed via the rolling elements 15. Then, the axial displacement of the inner member 12 due to the deformation is measured by the axial strain measuring sensor 62 provided on the sensor attachment member 76 attached to the knuckle 7. Since the sensor attachment members 74 and 76 are attached to the knuckle 7 by the contact fixing portions 74a and 76a, even if the inner member 12 is deformed, the sensor attachment members 74 and 76 are hardly deformed. Since the displacement sensors 61 and 62 attached to the sensor attachment members 74 and 76 measure the displacement of the surface of the inner member 12, the displacement measurement accuracy is high. The accuracy of the directional force is also increased.

  Since the sensor mounting unit 74 including the sensor mounting member 74 and the radial strain measuring sensor 61 mounted on the sensor mounting member 74 is mounted on the inner member 12, the sensor for detecting the vertical load is compact in a wheel bearing device. Can be installed. Similarly, since the sensor unit 75 comprising the sensor mounting member 76 and the axial strain measuring sensor 62 mounted on the sensor mounting member 76 is mounted on the inner member 12, the sensor for detecting the lateral load is used as a wheel bearing. It can be installed in a compact device. Since the sensor attachment members 74 and 76 are simple parts that can be attached to the inner member 12, attaching the radial strain measurement sensor 61 and the axial strain measurement sensor 62 to the sensor attachment members 74 and 76 provides excellent mass productivity. And cost reduction can be achieved.

  In the above embodiment, the brake 30 is electrically operated, but the brake may be hydraulic. FIG. 13 is a diagram showing the configuration of the hydraulic brake. The hydraulic brake 80 applies a braking force by sandwiching a brake wheel 86 between a pair of brake pads 85 and 85 provided in a brake caliper 81. The brake caliper 81 is installed on the knuckle 7 of the suspension device. Inside the brake caliper 81 is provided a cylinder chamber that accommodates the piston 84 so as to be able to move forward and backward by the hydraulic pressure of the brake fluid, and the brake pads 85 and 85 are attached to the piston 84. In the cylinder chamber in the brake caliper 81, the hydraulic pressure of the brake fluid is supplied from the master cylinder 88, which has one end of the pedal force of the operation member 87 such as a brake pedal, to the hydraulic pressure of the brake fluid via the brake pipe (or brake hose) 89. Given.

  A fluid pressure gauge 82 for measuring the fluid pressure of the brake fluid is provided at an arbitrary position in the brake fluid path from the master cylinder 88 through the brake pipe 89 into the brake caliper 81. The relationship between the pressing force between the brake wheel 86 and the brake pads 85 and 85 and the hydraulic pressure of the brake fluid is obtained in advance through experiments and simulations, so that the pressing force is detected from the measurement result of the hydraulic pressure gauge 82. Can do. In this case, the force in the front-rear direction acting on the contact point between the wheel 1 and the road surface can be estimated by using the measured value of the hydraulic pressure gauge 82 as the output of the brake force sensor 64.

1 is a cross-sectional view of an in-wheel motor-equipped sensor-equipped wheel bearing device according to an embodiment of the present invention. It is explanatory drawing which combined the figure which expands and shows the principal part of the bearing apparatus for wheels, and the block diagram of the brake control system. It is a block diagram of the attitude | position control system of the bearing apparatus for wheels. It is a front view of the inward member and the sensor for radial direction distortion which shows the example of attachment of the sensor for radial direction distortion measurement. (A) is a front view of the radial strain measuring sensor, and (B) is a bottom view thereof. It is a front view of the inner member which shows the example of a different attachment of the sensor for radial direction strain measurement, and the sensor for radial direction strain measurement. It is a front view of the inner member and the radial strain measuring sensor showing still another example of attachment of the radial strain measuring sensor. It is sectional drawing of the bearing apparatus for wheels with a sensor with a built-in in-wheel type motor concerning a reference proposal example . It is a block diagram of the attitude | position control system of the bearing apparatus for wheels. It is a front view of an inner member, a radial strain measuring sensor, and an axial strain measuring sensor showing an example of attachment of the radial strain measuring sensor and the axial strain measuring sensor. (A) is a plan view of the radial strain measuring sensor, and (B) is a side view thereof. (A) is a top view of the sensor for axial distortion measurement, (B) is the side view. It is sectional drawing which shows the structure of a hydraulic brake.

Explanation of symbols

1 ... wheel
DESCRIPTION OF SYMBOLS 7 ... Knuckle 10 ... Bearing 11 ... Outer member 12 ... Inner member 15 ... Rolling element 20 ... Electric motor 21 for driving | running | working ... Stator 22 ... Rotor 30 ... Brake 31 ... Brake wheel 32 ... Brake pad 35 ... Electric motor 60 for brake , 61 ... Sensor for measuring radial strain 62 ... Sensor for measuring axial strain 63 ... Current sensor 64 ... Brake force sensor 65 ... Estimating means 66 ... Abnormality determining means 71, 73, 75 ... Sensor units 72, 74, 76 ... Sensors Mounting member 72a ... 1st contact fixing | fixed part 72b ... 2nd contact fixing | fixed part 72c ... Notch part 74a, 76a ... Contact fixing | fixed part

Claims (7)

A double row rolling element is interposed between the inner member and the outer member, a knuckle of a suspension device is attached to the inner member, a wheel is attached to the outer member, and a stator of an electric motor is attached to the inner member. In the wheel bearing device in which the outer member is provided with the rotor of the electric motor,
By detecting the distortion of the inward member, the force in at least one of the three axial forces in the vertical direction, the horizontal direction, and the front-rear direction perpendicular to each other acting on the contact point between the wheel and the road surface A sensor-equipped wheel bearing device with an in-wheel motor built-in sensor, characterized in that a sensor for measuring the sensor is provided and the sensor is fixed to the inner periphery of the inner member.   In Claim 1, as one of the sensors for measuring the force in the three axial directions, a radial strain measuring sensor for measuring the radial strain of the inner member is provided, and the output of the radial strain measuring sensor is provided. A wheel bearing device with an in-wheel motor-equipped sensor provided with estimation means for estimating a vertical force and a horizontal force acting on a contact point between a wheel and a road surface.   3. The radial strain measurement sensor according to claim 2, wherein the radial strain measurement sensor is a strain sensor that is attached to the inner member via a sensor attachment member and measures the strain of the sensor attachment member. It has at least two contact fixing parts separated from each other in the circumferential direction with respect to the member, and has at least one notch part between adjacent contact fixing parts, and the radial strain measuring sensor is provided in this notch part. An in-wheel motor-equipped sensor-equipped wheel bearing device that is arranged.   In Claim 1, as one of the sensors for measuring the force in the three axial directions, a radial strain measuring sensor for measuring the radial strain of the inner member is provided, and the output of the radial strain measuring sensor is provided. A wheel bearing device with an in-wheel motor-equipped sensor provided with an estimation means for estimating a vertical force acting on a contact point between a wheel and a road surface.   2. The axial strain measuring sensor for measuring the axial strain of the inner member is provided as one of the sensors for measuring the force in the three axial directions according to claim 1, and an output of the axial strain measuring sensor is provided. A wheel bearing device with an in-wheel motor-equipped sensor provided with estimation means for estimating a lateral force acting on a contact point between a wheel and a road surface.   The wheel bearing device with an in-wheel motor-equipped sensor according to claim 1, wherein a brake wheel and a brake pad of a brake are provided on the inner member and the outer member, respectively. In Claim 6 , as one of the sensors for measuring the force in the three axial directions, a current sensor for measuring a current amount of the electric motor and a brake force sensor for measuring a braking force acting on the brake are provided, An in-wheel motor-equipped sensor-equipped bearing device provided with an estimation means for estimating a longitudinal force acting on a contact point between the wheel and the road surface from outputs of the current sensor and the brake force sensor.

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