Patent Description:
There has been known a test vehicle (hereinafter referred to as an "on-road tire testing device") capable of performing an on-road tire test for testing various performances of an automobile tire by running on an actual road surface such as an automobile test course with the test tire mounted thereon.

An on-road tire testing device described in <CIT> (Patent Document <NUM>) is a vehicle obtained by modifying a bus and providing with a test facility. In the on-road tire test, it is necessary to apply a large torque (driving force, braking force) that rapidly changes to a test wheel while rotating a test wheel on which a test tire is mounted at a high speed. In order to perform such driving by a commonly used electric motor, an electric motor having a large capacity is required, but it is difficult to install such a large electric motor in the vehicle. Therefore, the on-road tire testing device disclosed in Patent Document <NUM> is configured to drive and brake the test wheel by using a hydraulic motor.

<CIT> discloses an apparatus for measuring friction characteristics of a vehicle-travelled surface comprising a wheeled vehicle having a test wheel assembly pivotally suspended therefrom by a parallelogram suspension arrangement. <CIT> discloses a tire testing apparatus for measuring tire characteristics.

In the vehicle of the on-road tire testing device of Patent Document <NUM>, a hydraulic pressure supply device for supplying hydraulic pressure to the hydraulic motor is installed. Therefore, a large space in the vehicle is occupied by the hydraulic pressure supply device, and a space for installing test equipment and a work space for an operator to work in the vehicle cannot be sufficiently secured.

In addition, if the hydraulic oil leaks from the hydraulic system, the test tire and the road surface may be contaminated by the hydraulic oil and cause a decrease in accuracy of the test.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable the on-road tire test without using a hydraulic system.

According to an embodiment of the present invention, as defined in claim <NUM>, there is provided a tire testing device comprising: a vehicle; and a test unit provided in the vehicle and capable of supporting a test wheel on which a test tire is mounted in a state in which the test wheel is in contact with a road surface, wherein the test unit including a power unit configured to output power for rotationally driving the test wheel, and wherein the power unit includes: a rotation output unit configured to output a rotational motion of a rotation speed corresponding to a traveling speed of the vehicle; and a torque applying unit including a first motor and configured to add torque generated by the first motor to the rotational motion to output the torque, wherein the rotation output unit includes: a driven wheel configured to contact a road surface; a first axle coupled to the driven wheel; and a first transmission mechanism configured to couple the first axle to an input shaft of the torque applying unit.

Further features of the invention can be found in the subsidiary claims.

In the tire testing device described above, the first transmission mechanism may include a first drive pulley coupled to the first axle, a first driven pulley coupled to the input shaft of the torque applying unit, and a first toothed belt stretched between the first drive pulley and the first driven pulley.

In the tire testing device described above, the torque applying unit may include a rotatably supported rotating frame attached to the first motor; and a first shaft disposed coaxially with the rotating frame and coupled to a shaft of the first motor, the rotating frame being rotationally driven by the rotation output unit.

In the tire testing device described above, the first driven pulley may be coupled to the rotating frame.

The tire testing device described above may further include a pair of second bearings configured to rotatably support the rotating frame, the rotating frame being cylindrical and including a motor housing portion configured to house the first motor, and a pair of shaft portions disposed on both sides of the motor housing portion in an axial direction and having a smaller diameter than the motor housing portion, the rotating frame being rotatably supported by the pair of second bearings at the pair of shaft portions.

In the tire testing device described above, the test unit may include an axle unit configured to rotatably support the test wheel, and an alignment unit capable of adjusting an orientation of the test wheel and a load acting on the test wheel.

In the tire testing device described above, the alignment unit may include a load adjustment mechanism capable of adjusting the load acting on the test wheel, and the load adjustment mechanism may include a first movable frame movable vertically, a linear guide configured to guide the vertical movement of the first movable frame, and a first drive unit configured to drive the first movable frame vertically.

In the tire testing device described above, the test unit may include a base frame fixed to a frame of the vehicle, the linear guide may include a rail attached to one of the base frame and the first movable frame, and a carriage attached to the other of the base frame and the first movable frame and capable of traveling on the rail, the first drive unit may include a motion converter, and a second motor configured to drive the motion converter, the motion converter may include a main body attached to the base frame, and a movable part being movable vertically with respect to the main body, and the first movable frame may be fixed to the movable part.

In the tire testing device described above, the alignment unit may include a camber angle adjustment mechanism capable of adjusting a camber angle of the test wheel, the camber angle adjustment mechanism including a second movable frame being rotatable about an Eφ axis parallel to a traveling direction of the vehicle, a first pivot projecting from the second movable frame coaxially with the Eφ axis, a third bearing configured to rotatably support the first pivot, and a φ drive unit configured to rotationally drive the second movable frame.

The tire testing device described above may further include a curved guide configured to guide rotation of the second movable frame.

In the tire testing device described above, the alignment unit may include a slip angle adjustment mechanism capable of adjusting a slip angle of the test wheel, the slip angle adjustment mechanism including a third movable frame being rotatable about an Eθ axis orthogonal to each of an Eλ axis being a rotation axis of the test wheel and the Eφ axis, a second pivot projecting from the third movable frame coaxially with the Eθ axis, a fourth bearing configured to rotatably support the second pivot, and a θ drive unit configured to rotationally drive the third movable frame.

The axle unit may include a spindle, a fifth bearing configured to rotatably support the spindle, and a wheel hub coaxially attached to a distal end of the spindle and to which the test wheel is to be attached.

In the tire testing device described above, the axle unit may include a braking device configured to brake rotation of the spindle.

The tire testing device described above may further include a power transmission unit configured to transmit power output from the power unit to the spindle, the power transmission unit including a sliding constant velocity joint having one end coupled to the spindle.

In the tire testing device described above, the torque applying unit may include a speed reducer configured to reduce an output of the first motor, and the first shaft may be coupled to a shaft of the first motor via the speed reducer.

In the tire testing device described above, an inertia moment of a rotor of the first motor may be <NUM>. <NUM>·m<NUM> or less.

In the tire testing device described above, a rated output of the first motor may be 7kW to 37kW.

In the tire testing device described above, the φ drive unit may include a first gear disposed coaxially with the Eφ axis, a first pinion meshing with the first gear, and a third motor configured to rotationally drive the first pinion.

In the tire testing device described above, the first gear may be attached to one of the first movable frame and the second movable frame, and the third motor may be attached to the other of the first movable frame and the second movable frame.

In the tire testing device described above, the curved guide may include an arc-shaped curved rail disposed concentrically with the Eφ axis and attached to one of the first movable frame and the second movable frame, and a carriage attached to the other of the first movable frame and the second movable frame and capable of traveling on the curved rail.

In the tire testing device described above, the θ drive unit may include a second gear disposed coaxially with the Eθ axis, a second pinion meshing with the second gear, and a fourth motor configured to rotationally drive the second pinion.

In the tire testing device described above, the second gear may be attached to one of the second movable frame and the third movable frame, the fourth motor may be attached to the other of the second movable frame and the third movable frame, and the fourth bearing may be attached to the second movable frame.

In the tire testing device described above, the axle unit may include a casing to which a fifth bearing is attached, and a plurality of piezoelectric elements arranged around the spindle, and the piezoelectric elements may be sandwiched between the fifth bearing and the casing and fastened with bolts for attaching the fifth bearing to the casing.

In the tire testing device described above, the power transmission unit may include a second shaft coupled to the power unit, a sixth bearing configured to rotatably support the second shaft, a third shaft coupled to the sliding constant velocity joint, a seventh bearing configured to rotatably support the third shaft, and a torque sensor configured to detect torque transmitted by the power transmission unit, and the second shaft may be coupled to the third shaft via the torque sensor.

In the tire testing device described above, the torque applying unit may include a second transmission mechanism configured to couple the first shaft to an input shaft of the power transmission unit, the second transmission mechanism including a second drive pulley coupled to the first shaft, a second driven pulley coupled to the spindle, and a second toothed belt stretched between the second drive pulley and the second driven pulley.

In the tire testing device described above, the second toothed belt may have core wires of steel wires or carbon fibers.

According to an embodiment of the present invention, there is provided an on-road tire testing device capable of driving a test wheel without using a hydraulic system.

In the following description, the same or corresponding components are denoted by the same or corresponding reference numerals, and redundant description thereof will be omitted. In each drawing, for convenience of description, some components are omitted or shown in a cross section. In each drawing, in a case where a plurality of items having the same reference sign are shown, the reference sign is not necessarily assigned to all the plurality of items, but assignment of the reference sign to some of the plurality of items is appropriately omitted.

An on-road tire testing device according to an embodiment of the present invention described below is a self-propelled tire testing device modified from a large-sized passenger automobile (hereinafter referred to as a "bus vehicle"). The on-road tire testing device is a device capable of testing various performances of a test tire T with respect to a road surface in various states by traveling on a road surface such as an automobile test course in a state where a test wheel W (<FIG>) on which the test tire T is mounted is made to contact the road surface.

The on-road tire testing device is a device in which a test unit <NUM> and its accessory device are mounted on a vehicle <NUM> obtained by modifying a rear engine, rear wheel drive (hereinafter referred to as "RR") bus vehicle being a base vehicle. Since the RR (or a front engine, front wheel drive (hereinafter referred to as "FF")) bus vehicle does not have a drive shaft disposed at the central part of the vehicle, there is an advantage that the degree of freedom of arrangement of the test unit <NUM> is high.

<FIG>, <FIG>, and <FIG> are a side view, a rear view, and a plan view, respectively, showing an arrangement of the test unit <NUM> in the on-road tire testing device. In <FIG>, a rear portion of the vehicle <NUM> is not shown.

In the following description, front, rear, up, down, left, and right directions are defined as directions when facing a traveling direction of the vehicle <NUM> (i.e., when seated on a not-shown driver's seat). A front side is defined as an X-axis positive direction, a rear side is defined as an X-axis negative direction, a left side is defined as a Y-axis positive direction, a right side is defined as a Y-axis negative direction, an upper side is defined as a Z-axis positive direction, and a lower side is defined as a Z-axis negative direction.

<FIG> and <FIG> are a plan view and a front view, respectively, of the test unit <NUM>. The test unit <NUM> includes a base frame <NUM> fixed to a frame (not shown) of the vehicle <NUM>, an alignment unit 2a held by the base frame <NUM>, an axle unit <NUM> supported by the alignment unit 2a, and a power unit <NUM> configured to drive axles (spindles <NUM> illustrated in <FIG>) of the test wheel W.

A part of the power unit <NUM> (a pickup unit <NUM> which will be described later) is installed on the base frame <NUM>, and the remaining part (a torque applying unit <NUM> and a power transmission unit <NUM> which will be described later) is installed on a lifting frame <NUM>, which will be described later, of the alignment unit 2a.

The axle unit <NUM> (<FIG>) is a unit configured to rotatably support the test wheel W, and includes a spindle <NUM> (<FIG>) being an axle that rotates integrally with the test wheel W. The axle unit <NUM> is supported by the alignment unit 2a so that its height and orientation can be changed.

The alignment unit 2a is a unit capable of adjusting a load (a test load) applied to the test wheel W and an orientation (a slip angle and a camber angle) of the test wheel W.

The power unit <NUM> is a unit configured to supply power to the test wheel W, and its output shaft is coupled to the spindle <NUM>.

As shown in <FIG>, the power unit <NUM> includes a pickup unit <NUM>, a torque applying unit <NUM>, and a power transmission unit <NUM>. The pickup unit <NUM> (a rotation output unit) includes a pickup wheel <NUM> (a driven wheel) that comes into contact with the road surface, and acquires a rotational motion at a rotational speed corresponding to a traveling speed of the vehicle <NUM> from the road surface and outputs the acquired rotational motion. The torque applying unit <NUM> generates a braking force and a driving force (hereinafter, referred to as a "braking/driving force") to be applied to the test wheel W, and adds the braking/driving force (i.e., torque) to the rotational motion output from the pickup unit <NUM> to output the braking/driving force. The torque applying unit <NUM> makes it possible to apply a torque to the test wheel W by changing a phase of the rotational motion acquired by the pickup unit <NUM> (i.e., the torque applying unit <NUM> makes it possible to apply a driving force or a braking force between the road surface and the test wheel W. The power output from the torque applying unit <NUM> is transmitted to the test wheel W via the power transmission unit <NUM> and the spindle <NUM>. The power acquired from the road surface by the pickup unit <NUM> is transmitted to the road surface via the test wheel W. That is, the power unit <NUM> constitutes a power circulation system together with the test wheel W and the road surface.

<FIG> is a diagram illustrating a schematic structure of the pickup unit <NUM> and the torque applying unit <NUM>. The pickup unit <NUM> includes a bearing <NUM>, an axle <NUM> rotatably supported by the bearing <NUM>, a wheel hub <NUM> coaxially coupled to one end of the axle <NUM>, the pickup wheel <NUM> attached to the wheel hub <NUM>, and a first belt transmission mechanism <NUM> (first transmission mechanism) configured to transmit rotation of the axle <NUM> to the torque applying unit <NUM>.

The first belt transmission mechanism <NUM> includes a drive pulley 216a attached to the other end of the axle <NUM>, a driven pulley 216c attached to a housing <NUM>, which will be described later, of the torque applying unit <NUM>, and a toothed belt 216b stretched between the drive pulley 216a and the driven pulley 216c.

The pickup wheel <NUM> is a driven wheel that contacts the road surface, is driven by the road surface when the vehicle <NUM> travels, and rotates at a peripheral speed that is the same as a traveling speed of the vehicle <NUM>. The rotation of the pickup wheel <NUM> is transmitted to the torque applying unit <NUM> via the wheel hub <NUM>, the axle <NUM>, and the first belt transmission mechanism <NUM>.

The torque applying unit <NUM> includes bearings 224A and 224B, a cylindrical housing <NUM> (a rotating frame) rotatably supported by the bearings 224A and 224B, a motor <NUM>, a speed reducer <NUM>, and a shaft <NUM> attached to the housing <NUM>, and a second belt transmission mechanism <NUM> (a second transmission mechanism) configured to transmit a rotation of the shaft <NUM> to the power transmission unit <NUM>. If the motor <NUM> has a capability of generating a torque to be applied to the test wheel W, the shaft <NUM> may be directly coupled to a shaft <NUM> of the motor <NUM> without providing the speed reducer <NUM>. In this case, the shaft <NUM> of the motor <NUM> and the shaft <NUM> may be integrally formed.

The housing <NUM> includes substantially cylindrical first body portion 220a (a motor housing portion) and second body portion 220c, and substantially cylindrical shaft portions 220d and 220e that are thinner than the first body portion 220a. The shaft portion 220d is coupled to the right end of the first body portion 220a coaxially (i.e., such that the first body portion 220a and the shaft portion 220d share the center line), and the shaft portion 220e is coaxially coupled to the left end of the first body portion 220a via the second body portion 220c. The right shaft portion 220d is rotatably supported by the bearing 224A, and the left shaft portion 220e is rotatably supported by the bearing 224B.

The driven pulley 216c of the first belt transmission mechanism <NUM> is attached to a distal end of the left shaft portion 220e. The housing <NUM> is rotationally driven by the pickup unit <NUM>. That is, the housing <NUM> is rotationally driven at a rotation speed proportional to the traveling speed of the vehicle <NUM> by the power acquired by the pickup unit <NUM> and transmitted by the first belt transmission mechanism <NUM>.

The motor <NUM> is accommodated in a hollow portion of the first body portion 220a. The motor <NUM> may be disposed coaxially with the housing <NUM> (i.e., such that rotation axes of the motor <NUM> and the housing <NUM> coincide with each other). By disposing the motor <NUM> coaxially with the housing <NUM>, unbalance of a rotating portion of the torque applying unit <NUM> is reduced, and the rotating portion can be smoothly rotated (i.e., can be rotated with less unnecessary fluctuations in the rotation speed and the torque). A stator 221b of the motor <NUM> is fixed to the first body portion 220a with a plurality of bolts 220b. A flange 221c on an output side of the motor <NUM> is coupled to a case of the speed reducer <NUM> via a coupling tube 22a. The case of the speed reducer <NUM> is fixed to a flange formed at a left end of the first body portion 220a. That is, the stator 221b of the motor <NUM> and the case of the speed reducer <NUM> are fixed to the housing <NUM>.

The shaft <NUM> of the motor <NUM> is connected to an input shaft of the speed reducer <NUM>, and a shaft <NUM> coaxially accommodated in the housing <NUM> is connected to an output shaft of the speed reducer <NUM>. A torque output from the motor <NUM> is amplified by the speed reducer <NUM> and transmitted to the shaft <NUM>.

The shaft <NUM> is rotatably supported by a pair of bearings 220f provided on an inner periphery of the left shaft portion 220e of the housing <NUM>. A distal end side of the shaft <NUM> protrudes to the outside from an opening provided at the left end of the housing <NUM> and is rotatably supported by a bearing 224C.

The shaft <NUM> is connected to the second belt transmission mechanism <NUM>. The second belt transmission mechanism <NUM> includes a drive pulley 228a attached to a distal end of the shaft <NUM>, a driven pulley 228c attached to a shaft <NUM>, which will be described later, of the power transmission unit <NUM> (<FIG>), and a toothed belt 228b stretched between the drive pulley 228a and the driven pulley 228c. An output of the torque applying unit <NUM> is transmitted to the power transmission unit <NUM> via the second belt transmission mechanism <NUM>.

The torque applying unit <NUM> includes an electrical connecting unit <NUM> configured to electrically connect the motor <NUM> attached to the rotating housing <NUM> to an amplifier 221a (<FIG>) installed outside the torque applying unit <NUM>. The electrical connecting unit <NUM> includes a substantially cylindrical shaft portion 225a coupled to the right shaft portion 220d of the housing <NUM>, a bearing 225d configured to rotatably support the shaft portion 225a, a plurality of slip rings 225b coaxially attached to an outer periphery of the shaft portion 225a, a plurality of brushes 225c in contact with outer peripheral surfaces of the slip rings 225b, and a support part 225econfigured to support the brushes 225c and the bearing 225d.

A cable 221d of the motor <NUM> passes through a hollow portion of the shaft portion 220d of the housing <NUM>. A plurality of electric wires constituting the cable 221d pass through a hollow portion of the shaft portion 225a of the electrical connecting unit <NUM> and are connected to the corresponding slip rings 225b, respectively. The brushes 225c are connected to the amplifier 221a (<FIG>) via a not-shown cable.

The torque applying unit <NUM> includes a rotary encoder <NUM> configured to detect a rotation speed of the housing <NUM>. A main body of the rotary encoder <NUM> is attached to the support part 225e of the electrical connecting unit <NUM>, and a shaft of the rotary encoder <NUM> is connected to the shaft portion 225a.

According to the torque applying unit <NUM> configured as described above, the stator 221b of the motor <NUM> fixed to the housing <NUM> is rotationally driven at the rotation speed proportional to the traveling speed of the vehicle <NUM> by the rotational motion acquired from the road surface by the pickup unit <NUM> and, at the same time, the shaft <NUM> of the motor <NUM> is rotationally driven (in the present embodiment, the rotation of the shaft <NUM> is further decelerated by the speed reducer <NUM>), the resultant of these two rotations is output from the shaft <NUM>, and the test wheel W is rotationally driven by the resultant rotational motion.

In the present embodiment, outer diameters of the pickup wheel <NUM> and the test wheel W are the same, numbers of teeth of the drive pulley 216a and the driven pulley 216c of the first belt transmission mechanism <NUM> are the same, and numbers of teeth of the drive pulley 228a and the driven pulley 228c of the second belt transmission mechanism <NUM> are the same. That is, the power unit <NUM> of the present embodiment is configured such that the test wheel W is rotationally driven at a peripheral speed equal to the traveling speed of the vehicle <NUM> in a state where the driving of the motor <NUM> is stopped.

By incorporating the torque applying unit <NUM> into the power unit <NUM>, it becomes possible to separate power source into a power source (the pickup unit <NUM>) for controlling the rotation speed of the test wheel W and a power source (the motor <NUM>) for controlling the torque. Thereby, it becomes possible to reduce a capacity of each power source, and it becomes possible to control the rotation speed and the torque applied to the test wheel W with higher accuracy. In addition, in the present embodiment, since the pickup unit <NUM> that takes in a part of a kinetic energy of the vehicle <NUM> and reuses the kinetic energy as a power source is adopted as the power source for controlling the rotation speed, a motor for controlling the rotation speed is not required. Therefore, downsizing, weight reduction, and cost reduction of the power source for controlling the rotation speed are realized.

As described above, the motor <NUM> is a power source for generating a braking/driving force (torque) to be applied to the test wheel W. The motor <NUM> is required to accurately reproduce a sudden torque change applied to the tire during braking/driving, and high acceleration performance is required for the motor <NUM> to reproduce the sudden torque change. In the present embodiment, as the motor <NUM>, an ultra-low-inertia high-output AC motor in which the inertia moment of the rotor is <NUM>. <NUM>·m<NUM> or less and the rated output is 7kW to 37kW is used. By using such an ultra-low-inertia high-output AC servo motor, it becomes possible to apply braking/driving force that changes at a high frequency exceeding <NUM> to the test wheel W.

<FIG> is a diagram illustrating a schematic structure of the power transmission unit <NUM>. The power transmission unit <NUM> includes shafts <NUM> and 241R, bearings <NUM> and 242R, a torque sensor <NUM>, and a sliding constant velocity joint <NUM>. The shafts <NUM> and 241R are rotatably supported by the bearings <NUM> and 242R, respectively, and are coupled to each other via the torque sensor <NUM>. A torque transmitted by the power transmission unit <NUM> is detected by the torque sensor <NUM>. The driven pulley 228c of the second belt transmission mechanism <NUM> is attached to a left end of the shaft <NUM>. A right end of the shaft 241R is connected to an input shaft 245a of the sliding constant velocity joint <NUM>. An output shaft 245b of the sliding constant velocity joint <NUM> is connected to the spindle <NUM> (<FIG>).

The sliding constant velocity joint <NUM> is configured to be able to smoothly transmit rotation without rotational fluctuation regardless of an operating angle (an angle formed by the input shaft 245a and the output shaft 245b). The sliding constant velocity joint <NUM> is also variable in length. By connecting the spindle <NUM> via the sliding constant velocity joint <NUM>, even if the position and/or orientation of the spindle <NUM> is changed by the alignment unit 2a, smooth power transmission to the spindle <NUM> is maintained.

<FIG>, <FIG> and <FIG> are diagrams illustrating a schematic structure of the alignment unit 2a. <FIG> is an arrow view taken along a line D-D of <FIG>.

The alignment unit 2a includes a load adjustment mechanism <NUM>, a camber angle adjustment mechanism <NUM>, and a slip angle adjustment mechanism <NUM>.

The load adjustment mechanism <NUM> is a mechanism that adjusts the load applied to the test wheel W by changing a height of the spindle <NUM>. The load adjustment mechanism <NUM> includes a lifting frame <NUM> (a first movable frame) that is movable vertically with respect to the base frame <NUM>, a plurality of linear guides <NUM> (in the present embodiment, three pairs of linear guides <NUM>) configured to guide the vertical (Z axis direction) movement of the lifting frame <NUM>, and a Z drive unit <NUM> configured to drive the lifting frame <NUM> vertically.

The lifting frame <NUM> is accommodated in a hollow portion of the base frame <NUM> having a gate shape (∩ shape) as viewed from a side (i.e., as viewed in the Y-axis direction) The linear guide <NUM> includes a rail 32a extending vertically and one or more (in the present embodiment, two) carriages 32b capable of traveling on the rail 32a. The rail 32a of each linear guide <NUM> is attached to the base frame <NUM>, and the carriage 32b is attached to the lifting frame <NUM>.

The Z drive unit <NUM> (a first drive unit) includes a motor <NUM> and a motion converter <NUM> configured to convert rotational motion of the motor <NUM> into linear motion in the Z axis direction. The motion converter <NUM> is a screw jack in which a speed reducer such as a worm gear device and a feed screw mechanism such as a ball screw are combined. However, a motion converter of another type may be used. A main body 352a of the motion converter <NUM> is fixed to the base frame <NUM>, and a movable part (a rod 352b that can move vertically) is fixed to the lifting frame <NUM>.

When the motion converter <NUM> is driven by the motor <NUM>, the lifting frame <NUM> moves vertically together with the rod 352b. Accordingly, the test wheel W supported by the lifting frame <NUM> moves vertically via the camber angle adjustment mechanism <NUM>, the slip angle adjustment mechanism <NUM>, and the axle unit <NUM>, and a load corresponding to a height of the test wheel W acts on the test wheel W.

The camber angle adjustment mechanism <NUM> is a mechanism for adjusting a camber angle, which is an inclination of the test wheel W with respect to the road surface, by changing an orientation of the spindle <NUM> around an Eφ axis (an axis extending in the front-rear direction and passing through the center of the test wheel W). The camber angle adjustment mechanism <NUM> includes a φ rotating frame <NUM> (a second movable frame) rotatable about the Eφ axis, a pair of bearings <NUM> rotatably supporting the φ rotating frame <NUM>, a pair of curved guides <NUM> guiding the rotation of the φ rotating frame <NUM>, and a pair of left and right φ drive units <NUM> (second drive units) rotationally driving the φ rotating frame <NUM>.

As shown in <FIG>, the φ rotating frame <NUM> and the lifting frame <NUM> also have a gate shape (a ∩ shape) when viewed in the Y axis direction. The φ rotating frame <NUM> is accommodated in a cavity of the ∩ shaped lifting frame <NUM>. Pivots <NUM> that project outward (i.e., in a direction away from an Eθ axis described later) coaxially with the Eφ axis are provided to wall portions of the φ rotating frame <NUM> on the front side and the rear side, respectively. The pivots <NUM> are rotatably supported by a pair of bearings <NUM> fixed to the lifting frame <NUM>, respectively. The φ rotating frame <NUM> is supported to be rotatable about the Eφ axis with the pivots <NUM> as support shafts. It is noted that the bearings <NUM> may be attached to the φ rotating frame <NUM>, and the pivots <NUM> may be attached to the lifting frame <NUM>.

The curved guide <NUM> includes an arc-shaped curved rail 42a disposed concentrically with the Eφ axis, and one or more (in the present embodiment, two) carriages 42b that can travel on the curved rail 42a. Either of the curved rails 42a and the carriages 42b is attached to the lifting frame <NUM>, and the other is attached to the φ rotating frame <NUM>.

As illustrated in <FIG>, the φ drive unit <NUM> includes a pair of spur gears <NUM> attached to wall portions of the lifting frame <NUM> on the front side and the rear side, respectively, a pair of pinions <NUM> meshing with the pair of spur gears <NUM>, respectively, and a pair of motors <NUM> configured to rotationally drive the pair of pinions <NUM>, respectively. Each spur gear <NUM> is a segment gear formed in an arc shape about the Eφ axis (i.e., coaxial with the Eφ axis). Each motor <NUM> is attached to the φ rotating frame <NUM>, and each pinion <NUM> is coupled to a shaft <NUM> of the motor <NUM>.

When the pinions <NUM> are rotationally driven by the motors <NUM>, the pinions <NUM> roll on the pitch cylinders of the spur gears <NUM>, and the φ rotating frame <NUM> rotates about the Eφ axis together with the motors <NUM> having the pinions <NUM> attached to the shaft thereof with respect to the lifting frame <NUM> to which the spur gears <NUM> are integrally coupled. Accordingly, the test wheel W supported by the φ rotating frame <NUM> via the slip angle adjustment mechanism <NUM> and the axle unit <NUM> rotates about the Eφ axis, and the camber angle changes. It is noted that the spur gears <NUM> may be attached to the φ rotating frame <NUM>, and the motors <NUM> may be attached to the lifting frame <NUM>.

The slip angle adjustment mechanism <NUM> is a mechanism configured to adjust a slip angle, which is an inclination of the test wheel W (more specifically, a wheel center plane perpendicular to the axle) with respect to the traveling direction (X axis direction) of the vehicle <NUM>, by changing an orientation of the spindle <NUM> about the Eθ axis (an axis extending vertically through the center of the test wheel W). As illustrated in <FIG>, the slip angle adjustment mechanism <NUM> includes a θ rotating frame <NUM> (a third movable frame) rotatable about the Eθ axis, a bearing <NUM> rotatably supporting the θ rotating frame <NUM>, and a θ drive unit <NUM> configured to rotationally drive the θ rotating frame <NUM>.

The θ rotating frame <NUM> is accommodated in a cavity of the φ rotating frame <NUM> having a gate shape (∩ shape) when viewed in the Y-axis direction. A pivot <NUM> projecting coaxially with the Eθ axis is provided on an upper surface of the θ rotating frame <NUM>. The pivot <NUM> is rotatably supported by the bearing <NUM> fixed to a top plate of the φ rotating frame <NUM>. The θ rotating frame <NUM> is supported to be rotatable about the Eθ axis with the pivot <NUM> as a support shaft.

The θ drive unit <NUM> includes a spur gear <NUM> attached to the θ rotating frame <NUM>, a pinion <NUM> meshing with the spur gear <NUM>, and a motor <NUM> for rotationally driving the pinion <NUM>. The spur gear <NUM> is coaxially coupled to the pivot <NUM>. The motor <NUM> is attached to the φ rotating frame <NUM>, and the pinion <NUM> is coupled to a shaft of the motor <NUM>.

As illustrated in <FIG>, the axle unit <NUM> is attached to a lower end of the θ rotating frame <NUM>. The axle unit <NUM> includes a frame <NUM> attached to the θ rotating frame <NUM>, a bearing <NUM> attached to the frame <NUM>, the spindle <NUM> rotatably supported by the bearing <NUM>, a six-component force sensor <NUM> configured to detect a force acting on the spindle <NUM>, a disc brake <NUM> (a braking device) configured to suppress rotation of the spindle <NUM>, and a wheel hub <NUM> coaxially attached to a distal end of the spindle <NUM>. A wheel rim Wr (<FIG>) of the test wheel W is to be attached to the wheel hub <NUM>.

The frame <NUM> of the axle unit <NUM> is attached to the θ rotating frame <NUM> via the six-component force sensor <NUM>. The six-component force sensor <NUM> includes a plurality of (in the present embodiment, four) piezoelectric elements. The plurality of piezoelectric elements are arranged at constant intervals on a circumference with an Eλ axis as a center thereof, are sandwiched between the frame <NUM> of the axle unit <NUM> and the θ rotating frame <NUM>, are fastened by bolts for attaching the frame <NUM> of the axle unit <NUM> to the θ rotating frame <NUM>, and preloads are applied thereto. A hole through which the bolt passes is formed to each piezoelectric element so that the preload is uniformly applied.

The disc brake <NUM> includes a disc rotor <NUM> coaxially attached to a distal end of the spindle <NUM> and a motorized caliper <NUM> attached to the frame <NUM>. A braking force acts on the spindle <NUM> when the disc rotor <NUM> is sandwiched from both sides by a pair of brake pads built in the caliper <NUM>.

The alignment unit 2a is configured such that the Eθ axis, the Eφ axis, and the Eλ axis intersect at one point at the center of the test wheel W so that the position of the test wheel W does not move even when the camber angle (φ angle) or the slip angle (θ angle) is changed.

<FIG> is a block diagram illustrating a schematic configuration of a control system of the on-road tire testing device. The control system includes a controller <NUM> configured to control operation of the entire device, a measurement unit <NUM> configured to perform various measurements, and an interface unit <NUM> configured to perform input and output with the outside.

The motor <NUM> of the torque applying unit <NUM>, the motor <NUM> of the load adjustment mechanism <NUM>, the motor <NUM> of the camber angle adjustment mechanism <NUM>, and the motor <NUM> of the slip angle adjustment mechanism <NUM> are connected to the controller <NUM> via amplifiers 221a, 351a, 451a, and 551a, respectively. The caliper <NUM> of the disc brake <NUM> is also connected to the controller <NUM>.

The controller <NUM> and each of the amplifiers 221a, 351a, 451a, and 551a are communicably connected by optical fibers, and high-speed feedback control can be performed between the controller <NUM> and each of the amplifiers 221a, 351a, 451a, and 551a. This enables synchronous control with higher accuracy (high resolution and high accuracy on the time axis).

The six-component force sensor <NUM> of the axle unit <NUM>, the rotary encoder <NUM> of the torque applying unit <NUM>, and the torque sensor <NUM> of the power transmission unit <NUM> are connected to the measurement unit <NUM>. In the measurement unit <NUM>, after analog signals from the six-component force sensor <NUM> (a plurality of piezoelectric elements) are amplified and converted into digital signals, measurement values of six component forces (forces Fx, Fy, and Fz in the X axis, the Y axis, and the Z axis direction, and moments Mx, My, and Mz about the respective axes) are calculated based on the digital signals. In the measurement unit <NUM>, after the analog signal from the torque sensor <NUM> is amplified and converted into a digital signal, a measurement value of a torque of the test wheel W is calculated based on the digital signal.

Pieces of phase information detected by rotary encoders RE built in the motors <NUM>, <NUM>, <NUM>, and <NUM>, respectively, are input to the controller <NUM> via respective amplifiers 221a, 351a, 451a, and 551a.

The interface unit <NUM> includes, for example, one or more of a user interface for performing input and output with a user, a network interface for connecting to various networks such as a local area network (LAN), and various communication interfaces such as a universal serial bus (USB) and a general purpose interface bus (GPIB) for connecting to external devices. The user interface includes, for example, one or more of various operation switches, indicators, various display devices such as a liquid crystal display (LCD), various pointing devices such as a mouse and a touch pad, and various input/output devices such as a touch screen, a video camera, a printer, a scanner, a buzzer, a speaker, a microphone, and a memory card reader/writer.

The controller <NUM> drives the motor <NUM> of the torque applying unit <NUM> such that a deviation between the measured value and a target value of the torque of the test wheel W is eliminated. It is noted that the driving of the motor <NUM> may be controlled based on the measured value of the torque My detected by the six-component force sensor <NUM>.

The above is the description of the embodiments of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible. For example, configurations obtained by appropriately combining configurations such as embodiments explicitly illustrated in the present specification and/or configurations such as embodiments obvious to those skilled in the art from the description in the present specification are also included in the embodiments of the present application.

In the above-described embodiments, the servomotors (the motors <NUM>, <NUM>, <NUM>, and <NUM>) are used to drive the torque applying unit <NUM> and the adjustment mechanisms (the load adjustment mechanism <NUM>, the camber angle adjustment mechanism <NUM>, and the slip angle adjustment mechanism <NUM>) of the alignment unit 2a, respectively. However, other types of electric motor such as a DC servo motor or a stepping motor capable of controlling a driving amount (a rotation angle) may be used.

The toothed belt 228b in the above-described embodiments has core wires being steel wires. As the toothed belt 228b, a belt having core wires formed of so-called super fibers such as carbon fibers, aramid fibers, and ultrahigh molecular weight polyethylene fibers may be used. By using lightweight and high-strength core wires such as carbon core wires, it becomes possible to use a motor having a relatively low output, and it becomes possible to downsize the torque applying unit <NUM>. A commonly used automotive or industrial timing belt may also be used as the toothed belt 228b.

The above-described embodiments are configured such that the braking force can be applied to the test wheel W by the two mechanisms, namely, the torque applying unit <NUM> and the disc brake <NUM>. However, the braking force may be applied only by the torque applying unit <NUM> without providing the disc brake <NUM>.

In the above-described embodiments, as illustrated in <FIG>, the torque applying unit <NUM> and the power transmission unit <NUM> of the power unit <NUM> are installed on the lifting frame <NUM> and are configured to be movable vertically together with the axle unit <NUM>. However, the entire power unit <NUM> may be installed on the base frame <NUM>.

In the above-described embodiments, spur gears are used for the φ drive unit <NUM> of the camber angle adjustment mechanism <NUM> and the θ drive unit <NUM> of the slip angle adjustment mechanism <NUM>. However, other types of gears such as a bevel gear, a cylindrical worm gear, and a face gear may be used instead.

In the above-described embodiments, in each of the first belt transmission mechanism <NUM> (the first transmission mechanism) and the second belt transmission mechanism <NUM> (the second transmission mechanism), a belt transmission mechanism in which a toothed belt is used as a winding intermediate node, but the present invention is not limited to this configuration. In at least one of the belt transmission mechanisms, a flat belt or a V-belt may be used in place of the toothed belt. In place of the belt mechanism, another type of winding transmission mechanism such as a chain transmission mechanism or a wire transmission mechanism, or other types of power transmission mechanism such as a ball screw mechanism, a gear transmission mechanism, or a hydraulic mechanism may be used.

In the above-described embodiments, a toothed belt having the same high rigidity as the toothed belt 228b of the second belt transmission mechanism <NUM> is used as the toothed belt 216b of the first belt transmission mechanism <NUM>. However, since a large torque does not act on the first belt transmission mechanism <NUM>, a toothed belt having lower rigidity such as a standard timing belt for a large vehicle may be used.

Claim 1:
A tire testing device comprising:
a vehicle (<NUM>); and
a test unit (<NUM>) provided in the vehicle and capable of supporting a test wheel (W) on which a test tire (T) is mounted in a state in which the test wheel is in contact with a road surface,
wherein the test unit includes a power unit (<NUM>) configured to output power for rotationally driving the test wheel, and
wherein the power unit includes:
a rotation output unit (<NUM>) configured to output a rotational motion of a rotation speed corresponding to a traveling speed of the vehicle;
wherein the rotation output unit includes:
a driven wheel (<NUM>) configured to contact the road surface;
a first axle (<NUM>) coupled to the driven wheel; and
a first transmission mechanism (<NUM>) configured to couple the first axle to an input shaft (220e) of a torque applying unit (<NUM>),
characterized in that the torque applying unit (<NUM>) includes a first motor (<NUM>) and is configured to add torque generated by the first motor (<NUM>) to the rotational motion to output the torque.