JP2007003218A - Tire characteristic measuring device and tire characteristics measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evaluate a tire characteristic such as an envelope characteristic of a tire with a prescribed load. <P>SOLUTION: This tire characteristic measuring device has a flat grounding plate 12 on which the tire is grounded; a tire support part 14 for supporting a tire center shaft, and moving the tire freely in the far-and-near direction relative to the grounding plate for grounding and non-grounding of the tire on the grounding plate; an axial force sensor 20 provided on the tire support part 14, for detecting an axial force acting on the tire center shaft; a cleat 18 acting as a projection to the tire grounded on the grounding plate 12 when being projected; and a processing device 26 for calculating an axial force variation generated according to occurrence of projection of the cleat as the tire characteristic, when the tire is grounded on the grounding plate 12 under the condition wherein the inter-axis distance between the tire center shaft and the grounding plate 12 surface is constant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tire characteristic measuring apparatus and a tire characteristic measuring method for evaluating tire characteristics, and more specifically to an apparatus and a method for evaluating envelope characteristics which are one of tire vibration characteristics.

In general, the ride performance of automobiles has impact mitigation characteristics such as vibration and sound when passing through road steps, and tire damping characteristics and envelope characteristics greatly contribute to this impact mitigation characteristics. It is known. The tire envelope characteristic is a characteristic that, when the tire depresses a cleat or the like, the tire absorbs the unevenness of the cleat and relaxes so that the unevenness of the ground is not transmitted from the tire to the vehicle side.
Conventionally, the envelope characteristic has been measured by measuring a spring constant (wire spring constant) by pressing a tire on a protrusion such as a cleat, and using this wire spring constant as an evaluation index of the envelope characteristic.

Specifically, the wire spring constant is shown on the graph when the horizontal axis represents the deflection of the tire when the tire is pressed against a protrusion such as a cleat, and the vertical axis represents the axial force acting on the tire central axis. In the characteristic curve, an average gradient from 1000 to 2000 (N) of axial force is obtained, and this average gradient is used as a linear spring constant.
However, this linear spring constant merely calculates an average gradient in the above characteristic curve, and there is a problem that it is not an evaluation index representing an envelope characteristic in a state where an actual predetermined load is applied.

  On the other hand, the following Patent Document 1 discloses a measuring method and a measuring device for measuring a behavior such as an axial force when a test tire is stepped on a smooth drum surface provided with a single protrusion enveloped by a test tire. Has been.

JP 2004-85297 A

  In general, the vibration that acts on the center axis of the tire when the tire steps on the cleat, etc. is the input vibration that functions as an input source that is mitigated by the tire envelope characteristics among the vibration that the tire receives from the ground surface due to the shape of the cleat. While being affected by the tire damping characteristics and vibration transmission characteristics, it is affected by the transmission system that transmits the input vibration to the tire central axis. However, since the axial force acting on the tire center axis measured in the apparatus and method of Patent Document 1 is affected by both the input vibration and the transmission system, the axis measured on the tire center axis Force cannot be used as an index of an envelope characteristic indicating a relaxation effect in the input vibration.

  Accordingly, an object of the present invention is to provide a tire characteristic measuring apparatus and a tire characteristic measuring method capable of evaluating tire characteristics such as an envelope characteristic of a tire under a predetermined load.

  In order to achieve the above object, the present invention provides a tire characteristic measuring apparatus for evaluating tire characteristics, which supports a flat ground plate on which a tire is grounded, a tire central axis, and supports the tire to the ground plate. A tire support part that freely moves a tire in a perspective direction with respect to the ground plate for grounding and non-grounding, and an axial force that is provided in the tire support part and detects an axial force acting on the tire central axis A sensor, a cleat provided on the ground plate so as to freely protrude from the surface of the ground plate, and a protrusion that projects from a tire that contacts the ground plate when the protrusion is formed; and the tire central axis and the contact A processing device for calculating, as tire characteristics, the amount of change in axial force caused by the presence or absence of protrusion of the cleat when the tire is grounded to the grounding plate under a condition where the distance between the shafts to the ground plane is constant; Have To provide a tire property measurement apparatus according to claim.

At that time, when the perspective direction in which the tire moves with respect to the grounding plate is the vertical direction, the rotation traveling direction of the tire is the front-rear direction, and the tire central axis direction is the left-right direction, the grounding plate is the tire support portion. And a moving means that moves in the front-rear direction or the left-right direction with respect to the tire supported by the tire, and the axial force sensor detects an axial force that acts in the vertical direction on the central axis of the tire when the tire contacts the ground. It is preferable to detect at least one of the longitudinal force acting on the central axis of the tire in the longitudinal direction and the lateral force acting on the central axis in the lateral direction.
Further, when the tire is moved with respect to the ground plane, the perspective direction is the up-down direction, the rotation traveling direction of the tire is the front-rear direction, and the center axis direction of the tire is the left-right direction, the tip of the cleat is the left-right direction It is preferable to form a semi-cylindrical shape in which a semicircular arc-shaped cross section is continuously formed.
In addition, when the perspective direction in which the tire moves with respect to the ground plate is the vertical direction, the rotation traveling direction of the tire is the front-rear direction, and the central axis direction of the tire is the left-right direction, the cleat is viewed from the vertical direction A circular shape is preferred.

  Furthermore, the present invention is a tire characteristic measuring method for evaluating tire characteristics by grounding a tire on a ground plane, the tire center axis when the tire is grounded on the ground plane by applying a predetermined load to the ground plane and the ground plane Measuring the distance between the shafts, and projecting the cleats from the ground contact surface, and stepping on the tire to ground the tire to the ground contact surface so as to be the distance between the shafts, Measuring the axial force acting on the central axis of the tire that has stepped on the cleat, and using the amount of change obtained by subtracting the predetermined load from the measured axial force as a tire characteristic evaluation index. A characteristic tire characteristic measuring method is provided.

  In that case, the tire is provided with a tread pattern, and the cleat protrudes at a plurality of different positions in the ground contact surface of the tire, and the cleat is stepped on the cleat each time the cleat is provided at the plurality of positions. It is preferable to obtain the amount of change and use the average value of the amount of change as an evaluation index for tire characteristics.

  In the present invention, a tire when a cleat is stepped on the tire at the same center distance as the distance between the center axis of the tire and the contact surface when the tire is grounded with a set load applied without cleats. The axial force acting on the central axis is measured, and the axial force fluctuation amount with and without cleat is calculated. For this reason, this axial force fluctuation amount corresponds to an envelope characteristic generated when the tire depresses the cleat during traveling under a constant load condition, and can be used as an evaluation index as a vibration input in the harshness characteristic and the road noise characteristic.

  A tire characteristic measuring device and a tire characteristic measuring method of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

A tire characteristic measuring device (hereinafter referred to as “device”) 10 shown in FIG. 1 causes a stationary (non-rotating) tire T to contact a grounding surface, and at that time, depending on the presence or absence of cleats (projections) provided on the grounding surface, This is a device that obtains the amount of change in the acting axial force and uses this amount of change as an evaluation index for envelope characteristics.
The apparatus 10 includes a flat ground plate 12 for grounding the tire T, a tire support portion 14 for mounting and supporting the tire T for grounding the tire T, and a perspective view of the tire support portion 14 with respect to the ground plate 12. A moving mechanism 16 that moves in the direction, a cleat 18 that is provided so as to protrude freely from the surface of the grounding plate 12, and that protrudes with respect to the tire T that contacts the grounding plate 12 when protruding, and a support unit 14. An axial force sensor 20 that detects an axial force acting on the central axis of the tire, a distance sensor 22 that measures an inter-axis distance between the tire central axis of the tire T and the surface of the ground plate 12, and the ground plate 12 includes ground contact plate moving mechanisms 24a and 24b that move the cleat 18 relative to the tire T by moving the 12 in the front-rear direction and the left-right direction along the plane.
The ground plate 12 is provided with a hole for freely raising and lowering the cleat 18, and the cleat 18 is raised and lowered using a lifting mechanism (not shown) and protrudes from the hole.

In addition, the apparatus 10 includes a processing device 26, a control device 28, and drive motors 30a to 30d. The drive motors 30a to 30d are connected to the control device 28, and the drive motors 30a to 30d are mechanically connected to the moving mechanism 16, the elevating mechanism (not shown) of the cleat 18, and the ground plate moving mechanisms 24a and 24b, respectively. .
In FIG. 1, out of the axial force acting on the tire central axis, the axial force in the perspective direction with respect to the ground contact surface is Fz, the axial force in the rotation traveling direction of the tire T is Fx, and the central axial direction of the tire T Is defined as Fy. Further, hereinafter, the perspective direction in which the tire T moves with respect to the ground plate 12 is defined as the vertical direction, the rotational advance direction of the tire T is defined as the front-rear direction, and the central axis direction of the tire T is defined as the left-right direction.

The tire support portion 14 extends in parallel to the ground plate 12 from a moving block 17 that is moved up and down by a moving mechanism 16, and a mounting hub (not shown) for mounting the tire T is provided at the tip. An axial force sensor 20 that measures the axial force of the tire T and a distance sensor 22 that measures the interaxial distance between the tire center axis and the surface of the ground plate 12 are provided in the vicinity of the tip of the tire support portion 14. .
The axial force sensor 20 is a sensor that measures axial forces Fz, Fx, and Fy that act on the tire center axis of the mounted tire T, and a gauge type or piezo type load cell is used.
The distance sensor 22 is a sensor that measures an inter-axis distance between the surface of the ground plate 12 and the tire central axis, and for example, a laser displacement meter is used. The distance sensor 22 is used to make the distance between the shafts constant, as will be described later, when measuring the axial force of the tire due to the presence or absence of the protrusion of the cleat 18.

The moving mechanism 16 and the ground plate moving mechanisms 24a and 24b are configured to be provided with linear ball screws, and by driving the drive motors 30a to 30c, the ball screws rotate to be integrated with the tire support unit 14. The moving block 17 is moved in the vertical direction, and the ball screw is rotated to move the grounding plate 12 in the front-rear direction and the left-right direction.
The control device 28 drives the drive motor 30c to rotate the ball screw of the moving mechanism 16 for raising and lowering the support portion 14 on which the tire T is mounted, and drives the drive motors 30a and 30b to cleat the tire T. The grounding plate 12 having 18 is moved freely in the front-rear and left-right directions. Further, the control device 28 drives the drive motor 30d to move the cleat 18 up and down.

The cleat 18 is longer in the left-right direction than the tire width, which is the maximum width in the left-right direction of the tire T, and is disposed in the left-right direction through the center of the ground contact surface of the tire T. Further, when the harshness characteristic is evaluated using the envelope characteristic, the protrusion height of the cleat 18 from the ground plate 12 is preferably 1 to 5% of the outer diameter of the tire T.
As shown in FIG. 2A, the tip of the cleat 18 has a shape in which a semi-cylindrical body in which a semicircular cross section is continuously formed in the left-right direction is connected to a columnar base body.
In order to evaluate the harshness characteristic (frequency band: 150 Hz or less) of the vehicle by the envelope characteristic, the radius of the semicircular arc shape of the semi-cylindrical body at the tip of the cleat 18 is preferably 5 to 20 mm. Has a radius of 8-12 mm, most preferably 10 mm.

  In the present invention, in addition to the form of the cleat shown in FIG. 2 (a), as shown in FIGS. 2 (b) to (d), a hemisphere is formed at the tip of the cylindrical cleat, hemispherical cleat, or cylinder. It may be a complex shaped cleat provided. In such a cleat, the length of the cleat in the left-right direction is preferably 1/10 or less of the total width of the tire. For example, the shape when the cleat is viewed from above and below forms a circular shape, and the circular shape at this time has a radius of 10 mm. The height of the cleat at that time is preferably 3 to 5 mm. These cleats are used for evaluating road noise characteristics (frequency band: 200 Hz to 800 Hz) in a vehicle.

  The processing device 26 has an axial force when the tire T is grounded with a set load under the condition that the cleat 18 does not protrude from the ground plate 12, and a condition where the cleat 18 protrudes from the ground plate 12, that is, the tire T is cleat 18. This is a device that calculates the amount of change in the axial force due to the presence or absence of the cleat 18 using the axial force under the condition of stepping on, and evaluates this calculation result as an evaluation index of the envelope characteristic.

In such a processing apparatus 26, an evaluation index of the envelope characteristic is obtained in the following flow.
First, the drive motor 30 c is driven by the control of the control device 28, and the tire support portion 14 on which the tire T is mounted descends to ground the tire T on the ground plate 12. At this time, the distance between the center axis of the tire and the surface of the ground plate 12 is measured by the distance sensor 22. That is, as shown in FIG. 3A, the tire T is grounded with a set load when the cleat 18 is not present, and the distance between the axes between the tire T and the ground plate 12 at this time is measured by the distance sensor 22. taking measurement. The processing unit 26 records and holds the distance between the axes at this time.

Next, under the control of the control device 28, the tire support 14 is raised and the tire T is brought into a non-grounding state.
Next, the drive motor 30 d is driven to raise the cleat 18 from the ground plate 12 and cause the cleat 18 to protrude from the surface of the ground plate 18.
Thereafter, the information on the inter-axis distance recorded and held in the processing device 26 is supplied to the control device 28, and the tire support portion 14 on which the tire T is mounted again descends, and the space between the tire T and the plane of the grounding plate 12 is lowered. The distance between the axes is controlled so as to be the distance between the axes. At this time, since the tire T is stepped on the cleat 18, the axial force acting on the tire central axis changes even if the distance between the axes is the same. For example, as shown in FIG. 4, the axial force increases by ΔFz from the state without cleat (FIG. 3 (a)) to the state with cleat (FIG. 3 (b)).

The processing device 26 calculates this axial force change amount ΔFz as an evaluation index of the envelope characteristic.
The calculated axial force variation ΔFz varies depending on the position within the ground contact surface of the tire T in the case of the cleat as shown in FIGS. For example, as shown in FIGS. 5A and 5B, when the cleat is displaced in the front-rear direction and the left-right direction with respect to the center of contact on the ground contact surface of the tire T, not only the axial force in the vertical direction but also the front-rear direction The axial force in the direction and the left-right direction also changes depending on the presence or absence of cleat. Therefore, in the case of such a cleat, the processing device 26 may calculate the axial force change amounts ΔFx and ΔFy in addition to the axial force change amount ΔFz according to the relative position of the cleat with respect to the ground contact surface of the tire T.

In this way, the distance between the axes of the tire when the same load as the actual load set in the vehicle is applied and the tire is grounded in a state where there is no cleat is measured. Then, the axial force acting on the tire central axis when the tire is stepped on is measured to calculate the axial force variation ΔFz, ΔFx, ΔFy with or without the cleat. For this reason, these changes can be evaluated as vibration inputs generated when the tire depresses the cleat during traveling under a constant load condition.
In the case of a cleat having a small size as shown in FIGS. 2 (b) to 2 (d), when the tire T is stepped on, the size of the tread pattern provided on the tire T becomes equivalent to that of the tread pattern. Results vary greatly depending on location. For this reason, it is preferable that the amount of change in the axial force, which is an evaluation index of the envelope characteristics, is performed a plurality of times, for example, five times or more while changing the position of the cleat. For example, the ground plate 12 may be moved slightly in the front-rear direction and the left-right direction, and measurement may be performed at a total of nine positions (3 × 3 positions), and the average value of the axial force change amount may be used as an evaluation index. In this case, when evaluating as input characteristics in road noise characteristics, the height of the cleat is preferably 2% or less with respect to the outer diameter of the tire T.

  The tire characteristic measuring device and the tire characteristic measuring method of the present invention are not limited to the above embodiment, and various improvements and modifications may be made without departing from the gist of the present invention. Of course.

1 is a schematic configuration diagram of an embodiment of a tire characteristic measuring device according to the present invention. (A)-(d) is a figure which shows the form of the cleat used in the tire characteristic measuring apparatus of this invention. (A) And (b) is a figure explaining the tire characteristic measuring method of this invention. It is a figure which shows an example of the result obtained with the tire characteristic measuring method of this invention. (A) And (b) is a figure explaining the tire characteristic measuring method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tire characteristic measuring apparatus 12 Grounding plate 14 Tire support part 16 Moving mechanism 17 Moving block 18 Cleat 20 Axial force sensor 22 Distance sensor 24a, 24b Ball screw 26 Processor 28 Controller 30a-30d Drive motor

Claims (6)

A tire characteristic measuring device for evaluating tire characteristics,
A flat ground plate on which the tire contacts the ground;
A tire support that supports the tire central axis and moves the tire freely in a perspective direction with respect to the ground plate for grounding and non-grounding of the tire to the ground plate;
An axial force sensor that is provided in the tire support and detects an axial force acting on the tire central axis;
A cleat which is provided on the ground plate so as to freely protrude from the surface of the ground plate, and which becomes a protrusion with respect to a tire which contacts the ground plate at the time of the protrusion;
When the tire is grounded to the ground plate under the condition that the center distance between the tire central axis and the surface of the ground plate is constant, the amount of change in the axial force caused by the presence or absence of the protrusion of the cleat is determined. A tire characteristic measuring apparatus comprising: a processing device that calculates the characteristic. When the perspective direction in which the tire moves relative to the grounding plate is the vertical direction, the rotational travel direction of the tire is the front-rear direction, and the tire central axis direction is the left-right direction,
A moving means for moving the grounding plate in the front-rear direction or the left-right direction with respect to the tire supported by the tire support;
The axial force sensor detects an axial force acting in the vertical direction on the central axis of the tire when the tire is grounded, and acts on the central axis of the tire in the longitudinal direction and acts on the central axis in the lateral direction. The tire characteristic measuring device according to claim 1 which detects at least one axial force of right-and-left force. When the perspective direction in which the tire moves relative to the grounding plate is the vertical direction, the rotational travel direction of the tire is the front-rear direction, and the central axis direction of the tire is the left-right direction,
The tire characteristic measuring device according to claim 1, wherein a tip of the cleat has a semi-cylindrical shape in which a semicircular arc-shaped cross section is continuously formed in the left-right direction. When the perspective direction in which the tire moves relative to the grounding plate is the vertical direction, the rotational travel direction of the tire is the front-rear direction, and the central axis direction of the tire is the left-right direction,
The tire characteristic measuring device according to claim 1, wherein the cleat has a circular shape when viewed from the vertical direction. A tire characteristic measurement method for evaluating tire characteristics by grounding a tire on a ground surface,
Measuring an inter-axis distance between the tire center axis and the ground plane when a predetermined load is applied to the tire and grounded on the ground plane;
Projecting the cleat from the ground contact surface and stepping on the tire to ground the tire to the ground contact surface so as to be the distance between the shafts;
Measuring the axial force acting on the central axis of the tire that has stepped on the cleat;
And a step of using a change amount obtained by subtracting the predetermined load from the measured axial force as an evaluation index of tire characteristics. The tire is provided with a tread pattern,
The cleat protrudes at a plurality of different locations on the ground contact surface of the tire, and each time the cleat is provided at a plurality of locations, the amount of change when the tire is stepped on the cleat is obtained, and the average value of the amount of change is determined by tire characteristics. The tire characteristic measuring method according to claim 5, which is used as an evaluation index.

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