JP2017191043A - Tire testing apparatus and tire testing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire test apparatus and a tire test method capable of detecting a measurement abnormality in a tire test. SOLUTION: This is a tire test device that rotates a tire while applying a predetermined contact load, and is a plurality of load detectors that support the contact load of the tire by dividing it and measure the force acting on the rotating tire. Based on the load calculation means that calculates the load value of the force acting on the tire based on the signals output individually from the plurality of load detectors, and the output difference of the signals output individually from the plurality of load detectors. A tire test device including a failure detecting means for detecting a failure of a load detector. [Selection diagram] Fig. 2

Description

  The present invention relates to a tire testing apparatus and a tire testing method, and more particularly to a tire testing apparatus and a tire testing method capable of detecting a measurement abnormality in a tire test.

  Conventionally, in a tire manufacturing process, a tire test is performed in which a sample is extracted from a plurality of manufactured tires, and whether the product has a predetermined performance is evaluated by a test. In such a tire test, the tire is grounded on a simulated road surface such as a drum simulating the road surface, and the tire is rotated in a state where a predetermined ground load is applied to the tire. The force acting on the tire, such as contact load and rolling resistance, is measured by the measurement sensor.

JP 2013-195389 A

However, the multi-component force measuring sensor according to Patent Document 1 has a problem that it is difficult to understand the failure even if the failure occurs in itself. In the multi-component force sensor disclosed in Patent Document 1, a strain body that is distorted by a ground load (vertical force) or rolling resistance force (front / rear force) acting on the tire is fixed to a fixed body that rotatably supports a spindle shaft to which the tire is fixed. Are formed, and a strain gauge is provided on each strain body to detect the amount of strain, thereby measuring the ground contact load, rolling resistance, etc. of the tire.
However, except for the case where the strain gauge is disconnected, the strain gauge outputs some measurement value even if an abnormality has occurred, so that a tire test may be performed based on an erroneous measurement value. In order to prevent this, first, the measured ground load is regularly inspected for correctness. However, when an abnormality such as a small contact load measured in the inspection is found, there is a concern that the test results performed in the period from the previous periodic inspection cannot be guaranteed.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a tire testing apparatus and a tire testing method capable of detecting a measurement abnormality in a tire test.

As a configuration of a tire test apparatus for solving the above-mentioned problem, a tire test apparatus that rotates while applying a predetermined ground load to the tire, supports the ground load of the tire by dividing it, and supports the rotating tire. From a plurality of load detectors for measuring the acting force, a load calculation means for calculating a load value of the force acting on the tire based on signals output individually from the plurality of load detectors, and a plurality of load detectors A failure detecting means for detecting a failure of the load detector based on an output difference between individually output signals is provided.
According to this configuration, it is possible to detect a failure of the load detector when performing a tire test.
As another configuration, the plurality of load detectors are provided on the circumference centered on the rotation center axis of the tire and at symmetrical positions in the front-rear direction and the up-down direction of the tire. A detector failure can be detected.
As another configuration, the plurality of load detectors include a plurality of contact load measurement load detectors that measure the tire contact load, and a plurality of rolling resistance measurement load detectors that measure the tire rolling resistance force. Therefore, it is possible to detect an abnormality in the measurement of the contact load and the measurement of the rolling resistance force.
As another configuration, a plurality of load detectors for measuring a ground load and a plurality of load detectors for measuring a rolling resistance force are composed of a robust load cell whose measurement direction is defined in one direction, and a plurality of contact load measurements. The load detector for measuring is provided with the measurement direction facing the direction of applying the ground load, and the load detector for measuring the rolling resistance force is provided with the measuring direction facing the front and rear direction of the tire orthogonal to the direction of applying the ground load. Therefore, it is possible to accurately measure the ground load and rolling resistance.
In addition, as another configuration, a plurality of load detectors for measuring the ground load and a plurality of load detectors for measuring the rolling resistance force are provided so that the measurement directions are orthogonal to each other via one force transmission member. The load and rolling resistance can be measured with higher accuracy.
Further, as an aspect of a tire test method for solving the above-described problem, a tire test method for measuring a load acting on a tire by rotating the tire while applying a predetermined contact load to the tire, the load acting on the tire being measured. A load calculating step of providing a plurality of load detectors for supporting the divided force and measuring the divided load, and calculating a load acting on the tire based on signals individually output from the plurality of load detectors; And a failure detection step of detecting a failure of the load detector based on an output difference between signals individually output from the plurality of load detectors.
According to this aspect, when the tire test is performed, a failure of the load detector can be detected.

1 is a schematic view of a tire testing apparatus. It is the perspective view and exploded perspective view of a load measuring device. It is a block diagram of a load detector. It is a figure which shows a bridge circuit. It is the upper side figure of a load measuring device, a top view, and sectional drawing. It is a figure which shows load measurement. It is a figure which shows the other form of a load measuring device.

  Hereinafter, the present invention will be described in detail through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included in the invention. It is not necessarily essential to the solution, but includes a configuration that is selectively adopted.

  FIG. 1 is a schematic view showing an embodiment of a tire testing apparatus 1. As shown in FIG. 1, the tire testing device 1 includes a cylindrical drum 3 that rotates by driving of a motor 2, a tire load device 5, and a control device 50. The drum 3 is provided coaxially with the rotation center axis C <b> 1 of the rotation shaft 4 that rotates by driving of the motor 2. The outer peripheral surface 3a of the drum 3 is processed to simulate an actual road surface as a simulated road surface. By grounding the tire T that is rotatably supported on the outer peripheral surface 3a of the drum 3, a ground load Fz that is a vertical force acting on the tire T, a longitudinal force Fx that generates a rolling resistance force, a lateral force Fy, and the like. A tire test to be measured is performed. In the following description, each direction is specified as an Fz direction, an Fx direction, and an Fy direction. The Fz direction is an application direction in which a load is applied to the tire T, the Fx direction is the front-rear direction of the tire T, and Fy is the width direction of the tire T. The tire T is mounted on a tire load device 5 that is disposed so as to face the outer peripheral surface 3 a of the drum 3.

  The tire load device 5 includes a load generation unit 6 and a tire support unit 7. The load generating unit 6 includes, for example, a servo motor 8 and a screw jack 9. The servo motor 8 is connected to the screw jack 9 via the coupling 10, and the rotation is controlled based on a signal output from the control device 50. The screw jack 9 includes a cylinder 9 </ b> A that protrudes and retracts by a forward or reverse rotational force input from the servomotor 8, and is provided so that the extending and retracting direction of the cylinder 9 </ b> A is orthogonal to the rotation center axis C <b> 1 of the drum 3.

  The tire support portion 7 includes a linear rail 13, a load measuring device 11, and a tire attachment shaft 12. The linear rail 13 includes a rail 14 laid so as to extend in a direction orthogonal to the extending direction of the rotating shaft 4 of the drum 3, and a slider 15 movably provided on the rail 14. The slider 15 is provided with a base 17, and the load measuring device 11 is installed on the base 17. The load measuring device 11 is connected to the cylinder 9 </ b> A of the screw jack 9, and moves closer to and away from the outer peripheral surface 3 a of the drum 3 together with the base 17 as the cylinder 9 </ b> A protrudes and retracts.

FIG. 2 is an external perspective view and an exploded perspective view of the load measuring device 11 according to the present embodiment.
As shown in FIG. 2, the load measuring device 11 is provided with a tire mounting shaft 12, and a first support member 23 to which a force acting on the tire T is input, and a plurality of first support members 23 that support the first support member 23. One load detector 20, a second support member 24 that supports the plurality of first load detectors 20, a plurality of second load detectors 21 that support the second support member 24, and a plurality of second detectors. And a third support member 25 connected to the load generator 6. In the present embodiment, since the longitudinal force of the tire T is measured by the first load detector 20, the first load detector 20 is referred to as the longitudinal force detector 20. In addition, since the vertical force that is the ground load of the tire T is measured by the second load detector 21, the second load detector 21 is referred to as the vertical force detector 21.

  FIG. 3 is a configuration diagram of the load detector. FIG. 4 is a diagram illustrating a bridge circuit. As shown in FIGS. 3A and 3B, the longitudinal force detector 20 and the vertical force detector 21 (hereinafter sometimes simply referred to as a force detector) are each configured by the same load cell, for example. In the present embodiment, for example, a parallelogram type (Roval type) including four strain gauges 35 and a bridge circuit 60 is applied to the load cell. The Rovalval type load cell is provided with fixing portions 31, 31 fixed to the support members 23, 24, 25 and through holes 32 at both ends in the longitudinal direction of a metal material such as a long prismatic aluminum alloy or SUS. Thus, a pair of thin beam portions 33, 33 for connecting the fixing portions 31, 31 on both sides in parallel are provided. Each of the beam portions 33 and 33 is provided with two strain generating portions 34 surrounded by the inner peripheral surface 32a and the outer surface 33a of the through hole 32. Strain gauges 35 for detecting the amount of extension strain and the amount of contraction strain are respectively attached to the outer surfaces 33a of the strain generating portions 34. In such a robust load cell, the force measurement direction is defined so as to detect only the load in the direction in which the beam portions 33 and 33 are arranged (hereinafter referred to as measurement direction), and the two directions are orthogonal to the measurement direction other than the measurement direction. About, it functions as a member which transmits the force from one fixing | fixed part 31 to the other fixing | fixed part 31, or supports force.

As shown in FIG. 4, the four strain gauges 35 are connected to a bridge circuit that places two sheets for detecting the amount of elongation strain and two sheets for detecting the amount of contraction strain on opposite sides. As shown in FIG. 3C, in the load type load cell, when a load P is input to one fixed portion 31, the shape changes from a rectangular shape to a parallelogram shape. Since this deformation | transformation shifts | deviates to a measurement direction and the fixed parts 31 and 31 maintain a parallel state, it deform | transforms into a parallelogram shape, Therefore A highly accurate measurement can be performed.
That is, the input direction of the load P is constant because the one fixed portion 31 moves like a parallel link without rotating around the other fixed portion 31 due to the load P input to the one fixed portion 31. Therefore, highly accurate measurement is possible. In addition, along with this deformation, in one beam portion 33, one of the strain generating portions 34a and 34d is subjected to an extension force, and the other strain generating portions 34b and 34c are subjected to a compressive force. Therefore, the strain gauges 35a and 35d provided in the strain generating portions 34a and 34d detect the amount of elongation strain. Further, the amount of shrinkage distortion is detected by the strain generating portions 34b and 34c.

  The bridge circuit 60 is electrically connected to the control device 50 and includes an input terminal 61 to which a voltage is input from the control device 50 and an output terminal 62 that outputs a voltage to the control device 50. That is, when a load is applied to the fixed portion 31 on one end side of the load cell 30 in a state where a predetermined voltage is input from the control device 50 to the input terminal 61 of the bridge circuit 60, the load is generated in proportion to the magnitude of the load. The amount of expansion / contraction strain of the strain portions 34a to 34d changes, the resistance of the strain gauge 35 changes correspondingly, and an output voltage signal corresponding to the magnitude of the load is generated at the output terminal 62. The generated output voltage signal is output to the test control means 51 of the control device 50, and the test control means 51 calculates the output voltage signal as a load value of the longitudinal force or the vertical force.

As shown in FIGS. 2 and 5, each support member 23, 24, 25 is generally constituted by a flat plate member having a constant thickness, extends in the Fz direction and the Fx direction, and is provided in parallel to each other.
As shown in FIGS. 2 and 5A, the first support member 23 is formed in a symmetrical shape in the Fz direction and the Fx direction in plan view, and includes an axle mounting portion 36 and a longitudinal force detector mounting portion 37. . The axle mounting portion 36 is configured as, for example, a plurality of screw holes provided at equal intervals on one circumference at the center of one surface side. The tire mounting shaft 12 includes a flat disk-shaped flange portion 12A and a columnar support shaft 12B that supports the tire T. A hub for fixing a rim on which the tire T is mounted is provided on the outer periphery of the support shaft 12B via a bearing (not shown). When the tire mounting shaft 12 is fixed to the axle mounting portion 36, the rotation center axis C2 of the tire T is orthogonal to the surface (one surface on which the axle mounting portion 36 of the first support member 23 is provided). The rotation center axis C2 of the tire T is parallel to the rotation center axis C1 of the drum 3. For example, when a flat ground is assumed in the tire test, the same position (height) as the rotation center axis C1 in the Fx direction. Furthermore, when an inclined ground is assumed, it is provided so as to be displaced in the Fx direction with respect to the rotation center axis C1. In the following description, the surface on which the axle mounting portion 36 is provided is referred to as a reference surface 23a.

  Four longitudinal force detector attachment portions 37 are provided on the plate thickness surface 23b on one circumference around the rotation center axis C2 of the tire T so as to surround the rotation center axis C2. Specifically, the longitudinal force detector mounting portion 37 has two locations on the respective sides at the same distance from the rotation central axis C2 on the Fz direction drum side and the load side, and on the Fx direction stepping side and the kicking side. A total of four places are provided so as to be the same distance from the rotation center axis C2. That is, the longitudinal force detector mounting portion 37 is located at the corner of the rectangle where the intersection of the diagonals of the rectangle whose longitudinal direction is the Fz direction is located on the rotation center axis C2 in the plan view shown in FIG. . In each longitudinal force detector mounting portion 37, the longitudinal force detector 20 is bolted so that the measurement direction is in the same direction as the Fx direction and the extension direction extends to the back side in a state orthogonal to the reference surface 23a. The one end side is fixed by fixing means such as a nut.

  The second support member 24 is formed in a symmetrical shape in the Fz direction and the Fx direction in plan view, and a plurality of longitudinal force detections that fix the other end side of the longitudinal force detector 20 having one end side fixed to the first support member 23. And a plurality of vertical force detector mounting portions 39 for fixing one end side of the vertical force detector 21. That is, the second support member 24 serves as a force transmission member that transmits the load input from the tire mounting shaft 12 to the longitudinal force detector 20 to the vertical force detector 21, and the load input to the longitudinal force detector 20. It functions as a supporting member to support. The front / rear force detector mounting portions 38 are provided at four locations on the plate thickness surface 24b so that the other end sides of the front / rear force detectors 20 extending from the first support member 23 are fixed while maintaining the mutual parallel state. Provided.

  As shown in FIGS. 2 and 5, when the vertical force detector mounting portion 39 is integrated with the first support member 23 by the four longitudinal force detectors 20, a plurality of vertical force detectors 21 are connected to the tire T. Is provided on the plate thickness surface 24b so as to be positioned on one circumference centered on the rotation center axis C2. Specifically, the vertical force detector mounting portion 39 has two locations on the respective sides at the same distance from the rotation center axis C2 on the Fz direction drum side and the load side, and on the Fx direction stepping side and the kicking side. A total of four places are provided so as to be the same distance from the rotation center axis C2. That is, the vertical force detector mounting portion 39 is located at the corner of the rectangle where the intersection of the diagonals of the rectangle whose longitudinal direction is the Fx direction is located on the rotation center axis C2 in the plan view shown in FIG. . In each vertical force detector mounting portion 39, the vertical force detector 21 is bolted so that the measurement direction is in the same direction as the Fx direction and the extension direction is orthogonal to the reference surface 23a and extends to the tire side. The one end side is fixed by fixing means such as a nut.

  As shown in FIG. 5, the third support member 25 includes a base portion 41 made of a rectangular flat plate having a constant thickness, an upper protruding piece 42 and a lower side protruding from the upper and lower ends of the base portion 41 toward the tire side. A protruding piece 43 is provided. The base 41 includes a connecting body 44 on the back side. The connecting body 44 is composed of a column extending in the Fz direction, and one end side is connected to the load generating unit 6, and the other end side is fixed to the back surface of the base 41. Specifically, as shown in FIG. 5C, the connecting body 44 is preferably provided on the back side of the base portion 41 so as to be positioned on the extension of the tire mounting shaft 12. Each of the protruding pieces 42 and 43 includes a vertical force detector mounting portion 45 for mounting the vertical force detector 21 with one end fixed to the second support member 24 on each end face in the Fz direction. The vertical force detector mounting portions 45 are provided at four locations so that the other end sides of the vertical force detectors 21 extending from the second support member 24 are fixed while maintaining the mutual parallel state.

  According to the above configuration, the longitudinal force detector 20 that connects the first support member 23 and the second support member 24, and the vertical force detector 21 that connects the second support member 24 and the third support member 25 are all rotation centers. It extends parallel to the axis C2. Further, the four longitudinal force detectors 20 and the four vertical force detectors 21 are located on concentric circles.

  The control device 50 is constituted by a so-called computer, and includes a CPU, ROM, RAM, etc. as a computing means provided as hardware resources, a keyboard, a mouse, or an input means such as a magnetic or optical drive, A display means such as a monitor, a network interface, an external connection interface (external IF) for connecting an external device, and the like are provided. The CPU executes a process described later according to a program stored in the storage unit, thereby causing the control device 50 to function as each unit described later.

  The control device 50 calculates the load such as the vertical force and the longitudinal force based on the test control means 51 for controlling the tire test and the signal voltage output from each longitudinal force detector 20 and the vertical force detector 21. Means 52 and failure detection means 53 for detecting an abnormality of the detector based on the output values output for each voice from each longitudinal force detector 20 and each vertical force detector 21.

The test control means 51 controls the overall processing of the tire test, controls the rotational speed of the motor 2 that rotationally drives the drum 3, and applies the load value previously input as a command value to the tire T. Control of the rotation speed of the servo motor 8 of the load device 5 and supply of power supply voltage (electric power) to the detectors 20 and 21 constituting the load measuring device 11 are controlled. Further, when a signal for notifying the stop of the test is input from the failure detecting means 53, a control for stopping the tire test is performed.
The load calculation means 52 includes a vertical force calculation unit that calculates vertical force (ground load value) based on the sum of output values individually output from the four vertical force detectors 21, and the four longitudinal force detectors 20. A longitudinal force calculator that calculates a load value as a longitudinal force based on the sum of the output values individually output. The load calculation means 52 includes conversion data for converting the output values (voltage values) of the signals output from the longitudinal force detectors 20 and the vertical force detectors 21 into load values. For example, the conversion data is configured as a function that outputs a load value when an output value is input.
As shown in FIG. 6, when the four longitudinal force detectors 20 are 20a, 20b, 20c, and 20d, and the four vertical force detectors 21 are 21a, 21b, 21c, and 21d, the load calculating means 52 is as follows. As described above, the load values are individually calculated from the output values individually output from the longitudinal force detectors 20a to 20d based on the conversion data, and the longitudinal force and the vertical force are calculated based on the calculated load values.
The longitudinal force calculation unit calculates the sum of the calculated load values (the load value measured by 20a + the load value measured by 20b + the load value measured by 20c + the load value measured by 20d). Calculate the force.
The vertical force calculation unit calculates the sum of the calculated load values (the load value measured by 21a + the load value measured by 21b + the load value measured by 21c + the load value measured by 21d). Calculate the force.
Note that the load calculation means 52 can also calculate the couple Mx around the Fx direction axis and the couple Mz around the Fz direction axis based on the individually calculated load values. In this case, the couple Mx is calculated by (the load value measured by 21a + the load value measured by 21d) − (the load value measured by 21b + the load value measured by 21c). The couple Mz is calculated by (load value measured by 20a + load value measured by 20b) − (load value measured by 20c + load value measured by 21d).

The failure detection means 53 is output from the vertical force detector failure detection unit that detects an abnormality based on the output difference between the output values individually output from the four vertical force detectors 21 and the four longitudinal force detectors 20. And a front-rear force detector failure detector for detecting an abnormality based on the output difference between the output values.
As shown in FIG. 6, when the four longitudinal force detectors 20 are 20a, 20b, 20c, and 20d and the four vertical force detectors 21 are 21a, 21b, 21c, and 21d, the failure detection means 53 is as follows. Detect anomalies like
The detection of the failure of the longitudinal force detectors 20a to 20d is performed when Ex is greater than or equal to the threshold value αx, where (20a output value + 20d output value) − (20b output value + 20c output value) is Ex. If any of the force detectors 20a to 20d is detected as having a failure, and smaller than the threshold value αx, it is detected as having no failure. In addition, the detection of the failure of the vertical force detectors 21a to 21d is performed when Ez is equal to or greater than the threshold value αz, where (21a output value + 21d output value) − (21b output value + 21c output value) is Ez. Detects that there is a failure in any of the vertical force detectors 21a to 21d, and detects that there is no failure if it is smaller than the threshold value αz.
Then, the failure detection means 53 outputs a signal for notifying the test control means 51 of the test stop when a failure is detected in any of the longitudinal force detectors 20a to 20d and the vertical force detectors 21a to 21d. In the failure detection process in the failure detection means 53, it has been described that a failure is detected by directly processing the output values (voltage values) of the signals output from the detectors 20a to 20d and 21a to 21d. However, for example, the load value converted by the load calculating means 52 may be used as the output value to detect a failure.

  Further, as another detection method for the failure in the detector in the failure detection means 53, when (20a output value + 20b output value) − (20c output value + 20d output value) is Emx, Emx is equal to or greater than the threshold value βx. In this case, it is detected that there is a failure in any of the longitudinal force detectors 20a to 20d, and if it is smaller than the threshold value βx, it is detected that there is no failure. Further, the failure detection of the vertical force detectors 21a to 21d is performed when Emz is equal to or greater than the threshold value βz, where (21a output value + 21b output value) − (21c output value + 21d output value) is Emz. Can detect that there is a failure in any of the vertical force detectors 21a to 21d, and if it is smaller than the threshold value βz, it can also be detected that there is no failure.

More preferably, the abnormality detection with higher accuracy can be performed by combining the two abnormality detection methods.
Note that the detection of the failure of the detectors 20a to 20d and 21a to 21d is not limited to the above method. For example, based on the diagonal relationship about the rotation center axis C2 in FIG. 6, (20a output value + 20c output value) − (20b output value + 20d output value) or (21a output value + 21c). The output value) − (21b output value + 21d output value) may be compared with a threshold value to detect a failure.
The detection of the failure of the detector by the failure detection means 53 is performed by the four longitudinal force detectors 20a to 20d and the four vertical force detectors 21a to 21d in the present embodiment about the rotation center axis C2 of the tire T, respectively. Since they are provided on the same circumference and symmetrically in the front-rear direction and the up-down direction of the tire, the output values from the detectors 20a to 20d and 21a to 21d are directly handled as described above. It can be detected by calculation. That is, the measurement abnormality of the detector can be detected with high accuracy without performing complicated arithmetic processing.

Hereinafter, the operation of the tire testing apparatus 1 will be described.
First, a test condition such as a contact load value to be applied to the tire T is input via the input means, the contact load value is set in the control device 50, and the tire test is started. Hereinafter, this ground load value is referred to as a set load value. By starting the tire test, electric power is supplied from the control device 50 to each of the longitudinal force detectors 20a to 20d and each of the vertical force detectors 21a to 21d. A measured value in a no-load state is input from the longitudinal force detectors 20a to 20d and the vertical force detectors 21a to 21d to the control device 50 as power is supplied. The measured values of the detectors 20a to 20d and 21a to 21d input to the control device 50 are subjected to failure determination by the failure detection means 53. The failure detection means 53 outputs a signal notifying that the tire test is stopped to the test control means 51 when a failure is detected. Note that the failure detection means 53 continues monitoring whether there is a failure as it is when no failure is detected.
The test control means 51 drives the servo motor 8 to extend the cylinder 9 </ b> A of the screw jack 9 toward the drum 3 so that a set load value is applied to the tire T. When the tire T comes in contact with the drum 3 due to the extension of the cylinder 9 </ b> A, the vertical force acting on the tire T is measured by the vertical force detectors 20 of the load measuring device 11. The measured vertical force is output to the load calculation means 52 and the failure detection means 53 of the control device 50. The load calculating unit 52 calculates the vertical force based on the measurement values individually measured from the four vertical force detectors 21 and outputs the calculated vertical force to the test control unit 51. The test control means 51 compares the input vertical force with the set load value, and controls the drive of the servo motor 8 so that the input vertical force becomes the set load value.
Further, the failure detection means 53 determines the presence / absence of a failure of the vertical force detector 21 based on the difference between the measurement values individually measured from the four vertical force detectors 21 and determines whether the four vertical force detectors 20 Monitor status.

Next, when the vertical force is set to the set load value and no failure detection signal is input from the failure detection unit 53, the test control unit 51 rotates the motor 2 that is the rotation drive source of the drum 3. A signal is output, and the drum 3 is rotated at a predetermined rotational speed so that the tire T rotates at a predetermined rotational speed. As the drum 3 rotates, the tire T rotates in a driven manner. As the tire T rotates, a resultant force obtained by synthesizing forces in the Fx direction, the Fy direction, and the Fz direction acts on the tire mounting shaft 12 according to the performance of the tire T.
Of the resultant force acting on the tire mounting shaft 12, the component in the Fx direction is measured by the four longitudinal force detectors 20, and the component in the Fz direction is measured by the four vertical force detectors 21.
The measurement values individually measured by the four longitudinal force detectors 20 and the four vertical force detectors 21 are output to the load calculation unit 52 and the failure detection unit 53.
In the load calculation means 52, the longitudinal force is calculated based on the total value of the measurement values individually measured by the four longitudinal force detectors 20, and the total of the measurement values individually measured by the four vertical force detectors 21. The vertical force is calculated based on the value.
Further, the failure detection means 53 determines the presence / absence of a failure of the longitudinal force detector 20 based on the difference between the measurement values individually measured by the four longitudinal force detectors 20, and individually detects the failure by the four vertical force detectors 21. Whether or not the vertical force detector 21 has failed is determined based on the total value of the measured values. In this determination, if a failure is detected in either the longitudinal force detector 20 or the vertical force detector 21, a test stop signal is output to the test control means 51.
The test control means 51 outputs a signal to the servo motor 8 so that the tire T is separated from the drum 3 and returned to the initial position after the rotation of the drum 3 is stopped by inputting the test stop signal. To finish the tire test.

As described above, by configuring the load measuring device 11 as described above, the force generated on the tire T rolling on the outer peripheral surface 3 a of the drum 3 is transmitted from the tire mounting shaft 12 to the first support member of the load measuring device 11. The force input to the first support member 23 is supported by the four longitudinal force detectors 20, and the force supported by the plurality of longitudinal force detectors 20 is supported by the second support member 24. Further, the force supported by the second support member 24 is supported by the plurality of vertical force detectors 21, and the force supported by the four vertical force detectors 21 is supported by the third support member 25.
In this way, since the force generated in the tire T is transmitted and supported in series, the same force acts on each member 23, 24, 25 and each detector 20, 21, so each detector 20, The vertical force and the longitudinal force measured by 21 can be accurately measured.
Further, since the longitudinal force Fx input from the tire mounting shaft 12 is equally divided and supported by the four longitudinal force detectors 20, the force supported by each longitudinal force detector 20 is Fx / 4. . Therefore, since the output value output from the longitudinal force detector 20 outputs the same value if there is no failure, or any different value if there is a failure, the failure can be detected easily and reliably.
Further, the four longitudinal force detectors 20a to 20d and the four vertical force detectors 21a to 21d in the present embodiment are respectively on the same circumference around the rotation center axis C2 of the tire T, and in the longitudinal direction of the tire. Since it is provided at a position symmetrical in the vertical direction, the output values input from the detectors 20a to 20d and 21a to 21d are converted into load values, and the longitudinal force and vertical force are obtained by the simple calculation as described above. Can be calculated. That is, it is possible to accurately calculate the longitudinal force and the vertical force without performing complicated calculation processing.
The mutual positional relationship of the four longitudinal force detectors 20a to 20d and the mutual positional relationship of the four vertical force detectors 21a to 21d are not limited to the above and can be appropriately changed. For example, the load measuring device 11 having the above-described configuration is a load such as a couple force Mx around the Fx axis and a couple Mz around the Fz axis based on the measured values measured by the detectors 20a to 20d and 21a to 21d. It is also possible to calculate a value. The calculation of the couple Mx and the couple Mz requires a complicated calculation because the distance from the rotation center axis C2 to each of the detectors 20a to 20d and 21a to 21d is affected. In such a case, the calculated couple Mx and couple Mz include a calculation error, which may reduce the measurement accuracy. For this reason, as described above, it is preferable to arrange the detectors 20a to 20d and 21a to 21d, respectively.

  Although the above embodiment has been described as measuring both the vertical force and the longitudinal force, the load measuring device 11 may be configured to detect either the vertical force or the longitudinal force. Further, by attaching the detector in the direction of measurement parallel to the direction of the rotation axis of the tire T, the lateral force of the tire (force in the Fy direction) can also be measured.

Moreover, although the said embodiment demonstrated the quantity of the longitudinal force detector 20 and the vertical force detector 21 in the load measuring device 11 as four, it is not limited to this.
For example, as shown in FIG. 7, the load measuring device 11 may be configured with two longitudinal force detectors 20 and two vertical force detectors 21. Even in this configuration, the output values individually output from the two longitudinal force detectors 20 and the output values individually output from the two vertical force detectors 21 are converted into load values, and based on the sum thereof. It is possible to measure longitudinal force and vertical force. Also, the longitudinal force detection is performed by comparing the difference between the output values individually output from the two longitudinal force detectors 20 and the difference between the output values individually output from the two vertical force detectors 21 with threshold values. It is possible to detect a failure of the device 20 and a failure of the vertical force detector 21.
Two or more load measuring devices 11 are preferable from the viewpoint of failure detection, and three or more that can surround the rotation center axis C2 are preferable from the viewpoint of accuracy of load measurement. Thus, by using three or more detectors that measure the force in each direction, one plane can be defined. For example, when the number of front-rear force detectors 20 is three, one fixing part 31 and the other fixing part 31 are each located on one plane, and these two planes are parallel to each other. One of the two planes corresponds to the first support member 23 and the other corresponds to the second support member 24. Therefore, the longitudinal force acting on the tire T can move the first support member 23 in parallel in the measurement direction of the three longitudinal force detectors 20, so that the measurement accuracy can be improved.

1 tire testing device, 3 drums, 11 load measuring device,
20 longitudinal force detector (load cell), 21 vertical force detector (load cell),
T tires.

Claims (6)

A tire testing device that rotates while applying a predetermined contact load to a tire,
A plurality of load detectors for measuring the force acting on the rotating tire while supporting and dividing the ground load of the tire;
Load calculating means for calculating a load value of a force acting on the tire based on signals individually output from the plurality of load detectors;
A tire testing apparatus comprising failure detection means for detecting a failure of the load detector based on an output difference between signals individually output from the plurality of load detectors.   2. The tire testing device according to claim 1, wherein the plurality of load detectors are provided on the same circumference around the rotation center axis of the tire and symmetrically in the front-rear direction and the up-down direction of the tire. The plurality of load detectors are:
A plurality of contact load measuring load detectors for measuring the contact load of the tire;
The tire testing device according to claim 1 or 2, comprising a plurality of rolling resistance measuring load detectors for measuring the rolling resistance of the tire. The plurality of load detectors for measuring a ground load and the plurality of load detectors for measuring a rolling resistance force are composed of a Robert type load cell in which a measurement direction is defined in one direction,
The plurality of load detectors for measuring a ground load are provided with a measurement direction directed toward the direction of application of the ground load,
The tire test apparatus according to claim 3, wherein the rolling resistance measuring load detector is provided with a measurement direction directed in a front-rear direction of the tire orthogonal to the contact load application direction.   The tire testing device according to claim 4, wherein the plurality of contact load measuring load detectors and the plurality of rolling resistance force measuring load detectors are provided so that measurement directions are orthogonal to each other via one force transmission member. . A tire test method for measuring a load acting on a tire by rotating the tire while applying a predetermined ground load,
Provided with a plurality of load detectors for measuring the force acting on the rotating tire while supporting by dividing the load acting on the tire,
A load calculating step of calculating a load value of a force acting on the tire based on signals individually output from the plurality of load detectors;
A failure detection step of detecting a failure of the load detector based on an output difference between signals individually output from the plurality of load detectors.

Images