JP2021187205A - Tread variable device, pneumatic tire, and grip force control method - Google Patents

Abstract

To provide a tread variable device that can easily adjust the grip force of a pneumatic tire, a pneumatic tire, and a grip force control method.SOLUTION: A tire 1 has a tread part 2, and a belt part 8 and a band part 9 provided inside the tread part 2. The band part 9 has a full band 9A and a pair of edge bands 9B. The edge band 9B is composed of a fiber actuator 30 that is stretchable in the longitudinal direction by receiving voltage supply.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire.

For pneumatic tires mounted on automobiles, it is important to maintain the grip between the tread portion and the road surface in all of driving, braking, and turning of the automobile. Conventionally, a grip force control device for the purpose of improving the grip force has been known (see Patent Document 1). The grip force control device forms an electric circuit from the conductor to the road surface through the tread portion by applying a voltage to the conductor arranged on the tire, and the current flows from the electric circuit to the road surface. It uses the Rabek effect.

Japanese Unexamined Patent Publication No. 2012-766590

However, in the conventional grip force control device, the steel cord (conductor) in the tire and the ground under the road are regarded as a pair of electrodes, and the tread part and the pavement part on the road surface (concrete, asphalt, etc.) are regarded as semiconductors. The electric attractive force (electrostatic adsorption force) generated between the tread portion and the pavement portion and the ground by the Johnsen Labeck effect is used. Therefore, in the above-mentioned conventional technique, when the condition of the electric resistance of the road surface of the traveling road changes due to the presence or absence of the pavement, the difference in the type and thickness of the pavement, the difference in whether the road surface is dry or wet, etc., the tread portion The value of the current flowing from the road surface also fluctuates, and stable grip force cannot be exhibited. Further, since the tread portion and the pavement portion are originally insulators, a high voltage power supply is required to pass a current between the steel cord and the ground (electrode) under the road, and in some cases, a high frequency frequency is required. It is necessary to pass a current, and it is necessary to separately provide a booster circuit and a high frequency circuit. Further, the above-mentioned conventional technique cannot be applied to a tire provided with a conductive slit for discharging static electricity of a vehicle such as an automobile from the tire to the road surface.

An object of the present invention is to provide a tread variable device, a pneumatic tire, and a grip force control method capable of easily adjusting the grip force of a pneumatic tire.

(1) The tread variable device according to one aspect of the present invention is embedded inside a pneumatic tire so as to follow a predetermined direction, and can deform the tread portion of the pneumatic tire by contracting by energization. The actuator is provided with a cord-shaped actuator and a control unit that supplies voltage to the actuator to energize the actuator. The control unit of the actuator responds to a predetermined control signal when a predetermined control signal is input. It is configured to control the energization.

With such a configuration, when a voltage is supplied to the actuator by the control unit, the cord-shaped actuator contracts in the longitudinal direction thereof, so that the tire is tightened in the circumferential direction. As a result, the shape of the tread portion of the tire is deformed, so that the tread portion can generate a grip force according to each operating condition such as driving, braking, and turning of the automobile, and the wet condition of the road surface. It is possible to change the shape.

(2) In the tread variable device of the present invention, the tread portion of the pneumatic tire is formed in a flat shape. In this case, the actuator is provided at both ends of the tread portion in the width direction and has a length of at least one circumference along the circumferential direction of the pneumatic tire.

According to this configuration, when a voltage is supplied to the actuator by the control unit, the actuator contracts in the longitudinal direction to tighten both ends in the circumferential direction, whereby both ends of the tread portion supply voltage. It is further deformed into a curved shape as compared with the previous one, and the ground contact area where both ends touch the road surface becomes smaller. As a result, the shape of the contact patch with the road surface in the tread portion changes from a square shape (substantially square shape) to a round shape (substantially elliptical shape). When the road surface is in a wet state, it is well known that the grip force of the tread portion is higher in the round shape than in the square shape. By supplying a voltage to the actuator, the grip force of the tire on a wet road surface can be improved.

Further, regardless of the condition of the road surface, the shape of the shoulder portion of the tire is larger when the shape of the shoulder portion of the tire is curved, that is, the contact patch area is larger and the grip on the road surface is larger. It is well known that the power is high. From this, it is possible to improve the grip force of the tire during the turning operation by supplying a voltage from the control unit to the actuator when the automobile is turning.

(3) In the tread variable device of the present invention, the pneumatic tire covers the belt portion arranged radially inside the surface of the tread portion and both ends in the width direction of the belt portion. It has an edge band portion arranged along the circumferential direction. In this case, the actuator constitutes the edge band portion.

According to this configuration, since the edge band portion also serves as the actuator, it is not necessary to separately provide the actuator in addition to the edge band portion.

(4) In the tread variable device of the present invention, the tread portion of the pneumatic tire is formed in a flat shape. In this case, the actuator is provided on the shoulder portion or sidewall portion of the pneumatic tire and has a length of at least one circumference along the circumferential direction of the pneumatic tire.

Even with such a configuration, when a voltage is supplied to the actuator by the control unit, the actuator contracts in the longitudinal direction, and the shoulder portion or the sidewall portion is tightened in the circumferential direction. By tightening the shoulder portion or the sidewall portion, both ends of the tread portion are deformed so as to be pulled inward in the radial direction of the tire, and the ground contact region where the both ends touch the road surface becomes smaller.

(5) In the tread variable device of the present invention, the tread portion of the pneumatic tire is formed in a flat shape. In this case, the actuator is provided in the tread portion and has a plurality of straight portions extending along the width direction of the tread portion, and the plurality of straight portions are spaced apart from each other in the circumferential direction of the pneumatic tire. Are arranged apart from each other.

Even with such a configuration, when a voltage is supplied to the actuator by the control unit, the straight line portion arranged in the tread portion contracts in the width direction, and the tread portion expands outward. It is deformed into a curved shape, and the ground contact area where both ends of the tread portion touch the road surface becomes smaller.

(6) In the tread variable device of the present invention, the control unit supplies a voltage to the actuator when the control signal is input.

(7) In the tread variable device of the present invention, the tread portion of the pneumatic tire is formed in a curved shape. In this case, the actuator is provided at the center of the tread portion in the width direction and has a length of at least one circumference along the circumferential direction of the pneumatic tire. Further, the control unit supplies a voltage to the actuator to energize the actuator, thereby tightening the central portion inward in the radial direction to flatten the tread portion, and supplying the voltage when the control signal is input. Stop and return to the original curved shape.

Even with such a configuration, when voltage is not supplied to the actuator by the control unit, the tread portion is maintained in a curved shape, so that the tire grip force on a wet road surface can be sufficiently exerted. It is possible to obtain a sufficient grip force even during a turning operation. Further, when a voltage is supplied to the actuator by the control unit, the tread portion is flattened, so that a high grip force can be exerted on a dry road surface, and also during a driving operation or a braking operation of an automobile. Sufficient grip can be obtained.

(8) In the tread variable device of the present invention, the control signal is an input signal at the time of operation of an operation switch provided on the vehicle equipped with the pneumatic tire.

According to this configuration, the driver of the vehicle can make the control unit supply the voltage to the actuator by operating the operation switch at an arbitrary timing. That is, the driver can arbitrarily adjust the grip force of the tire by deforming the shape of the tread portion at an arbitrary timing at his / her own discretion.

(9) In the tread variable device of the present invention, the control signal is a rainfall signal indicating rainfall in the traveling area of the vehicle equipped with the pneumatic tire.

According to this configuration, when the rainfall signal is input, the control unit automatically supplies a voltage to the actuator. As a result, the tread portion of the tire is automatically deformed so as to have a grip force according to the traveling condition of the vehicle. As a result, a stable grip force can be maintained even when the traveling condition changes.

(10) In the tread variable device of the present invention, the control signal is either a brake signal indicating that the brake of the vehicle has been operated or a speed signal indicating that the speed of the vehicle is equal to or higher than a predetermined speed. Or both are further included.

According to this configuration, it is possible to generate a grip force according to a more detailed running situation in the tire.

(11) The actuator is a cord-shaped member containing a Ti—Ni-based shape memory alloy as a main component, and preferably contracts due to heat generated by energization.

(12) The pneumatic tire according to another aspect of the present invention is mainly composed of a rubber material, and has a tread portion and a radial direction from the ground contact surface of the tread portion so as to follow a predetermined direction. It is provided with a cord-shaped actuator that is embedded inside and can deform the tread portion of the pneumatic tire by contracting by energization.

(13) The grip force control method according to another aspect of the present invention is a method for controlling the grip force of a pneumatic tire containing a rubber material as a main component. The pneumatic tire is embedded inside the pneumatic tire so as to follow a predetermined direction, and includes a cord-shaped actuator capable of deforming the tread portion of the pneumatic tire by contracting by energization. The grip force control method includes an input reception step that accepts an input determination step that determines the input of a predetermined control signal, and supplies a voltage to the actuator based on the input control signal to energize the actuator. This is a method in which a processor executes an energization control step of controlling the grip force of the pneumatic tire by deforming the tread portion.

Since it is configured in this way, it is possible to change the grip property of the pneumatic tire by deforming the shape of the tread portion.

According to the present invention, it is possible to easily adjust the grip force of the pneumatic tire.

FIG. 1 is a partial cross-sectional view of a pneumatic tire for an automobile according to an embodiment of the present invention. FIG. 2 is a schematic view showing the arrangement position of the fiber actuator in the pneumatic tire. FIG. 3 is a schematic diagram showing an example of a vehicle used in the embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of a tread variable device according to an embodiment of the present invention. FIG. 5 is a flowchart showing an example (first processing example) of the procedure of the tread deformation processing executed by the control unit of the tread variable device. FIG. 6 is a conceptual diagram showing a state in which the tread variable device is applied to a pneumatic tire, and shows a state when the band cord is not energized. FIG. 7 is a schematic view showing the shape of the ground contact surface of the tread portion when a normal load is applied in a non-energized state in which the fiber actuator is not energized. FIG. 8 is a conceptual diagram showing a state in which the tread variable device is applied to a pneumatic tire, and shows a state when the band cord is energized. FIG. 9 is a schematic view showing the shape of the ground contact surface of the tread portion when a normal load is applied while the fiber actuator is energized. FIG. 10 is a schematic view showing another arrangement example of the fiber actuator in the pneumatic tire. FIG. 11 is a schematic view showing another arrangement example of the fiber actuator in the pneumatic tire. FIG. 12 is a flowchart showing an example (second processing example) of the procedure of the tread deformation processing executed by the control unit of the tread variable device. FIG. 13 is a flowchart showing an example (third processing example) of the procedure of the tread deformation processing executed by the control unit of the tread variable device. FIG. 14 is a flowchart showing an example (fourth processing example) of the procedure of the tread deformation processing executed by the control unit of the tread variable device. FIG. 15 is a schematic view showing a pneumatic tire for a two-wheeled vehicle to which the tread variable device according to the embodiment of the present invention is applied.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following embodiments are examples that embody the present invention, and do not limit the technical scope of the present invention. In the following description, the axial direction D1 or the width direction D1, the radial direction D2, the central direction D21, and the circumferential direction D3 shown in each figure may be used.

<First Embodiment>
FIG. 1 is a partial cross-sectional view showing a cross-sectional structure of a pneumatic tire 1 (hereinafter abbreviated as “tire 1”) according to an embodiment of the present invention, and FIG. 2 is a schematic view showing the tire 1. In FIG. 1, the left-right direction of the paper surface is the axial direction D1 or the width direction D1 of the tire 1, and the vertical direction is the radial direction D2 of the tire 1. Further, the alternate long and short dash line CL1 in FIG. 1 represents the equatorial plane or the equatorial line of the tire 1, and the alternate long and short dash line CL2 in FIG. 2 represents the central axis of the tire 1.

The tire 1 is mainly composed of a rubber material, and is mainly used by being mounted on a vehicle 10 (see FIG. 3) such as an automobile. In FIG. 1, the tire 1 is incorporated in the rim 11R of the wheel 11. The rim 11R is a regular rim. The inside of the tire 1 is filled with air, and the internal pressure thereof is adjusted to the normal internal pressure.

In the present specification, the state in which the internal pressure of the tire 1 incorporated in the rim 11R is adjusted to the normal internal pressure and no load is applied to the tire 1 is referred to as a normal state. FIG. 1 shows the tire 1 having the normal shape. In the present embodiment, unless otherwise specified, the dimensions and angles of the tire 1 and each part of the tire 1 are measured in the normal state.

Here, the regular rim is a rim defined in the standard on which the tire 1 relies. Specifically, the regular rim is a "standard rim" in the standard (JATTA standard) set by JATTA (Japan Automobile Tire Association), and the standard (TRA) set by TRA (The Tire and Rim Association) in the United States. It is "Design Rim" in the standard) and "Measuring Rim" in the standard (ETRTO standard) defined by ETRTO (European Tire Rim Technical Organization).

Further, the normal internal pressure is the internal pressure defined in the standard on which the tire 1 relies. Specifically, the regular intimidation is the "maximum air pressure" in the JATTA standard, the "maximum value" shown in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard. ".

The tire 1 according to the present embodiment is suitably used as a radial tire for an automobile. As shown in FIG. 1, the tire 1 has a tread portion 2, a pair of shoulder portions 3 located at both ends of the width direction D1 of the tread portion 2, and a central direction D21 from the shoulder portion 3 toward the central axis of the tire 1. It includes a pair of sidewall portions 4 extending inward (inside the radial direction D2) and a pair of bead portions 5 located at the ends of the sidewall portions 4 in the central direction D21.

Further, the tire 1 is arranged inside the carcass 6 from the tread portion 2, the shoulder portion 3, the sidewall portion 4 to the bead core 5A of the bead portion 5, the inner liner 7, and the radial direction D2 of the tread portion 2. A belt portion 8 and a band portion 9 are provided.

The tread portion 2 is composed of a tread rubber 2A made of crosslinked rubber. The tread portion 2 is a portion that comes into contact with the road surface when the vehicle 10 is traveling. The outer surface of the tread portion 2 is a tread surface 21 which is a contact surface with the road surface. In the present embodiment, the tread surface 21 is a substantially flat surface. That is, the tire 1 has the tread portion 2 formed in a flat shape.

A plurality of main grooves 22 and lug grooves 23 forming a tread pattern are formed on the tread surface 21 in order to exhibit tire performance such as grip, braking performance, drainage function, and wear suppression. The plurality of main grooves 22 extend continuously in the circumferential direction D3 (see FIG. 2) of the tire 1 and are arranged at predetermined intervals in the width direction D1 of the tire 1. The lug groove 23 extends so as to intersect the main groove 22, and is formed between the adjacent main grooves 22 on the tread surface 21. The plurality of lug grooves 23 are provided at predetermined intervals in the circumferential direction D3 of the tire 1.

The shoulder portion 3 is a portion corresponding to a corner portion of the tire 1 from the tread portion 2 to the sidewall portion 4. The shoulder portion 3 is a portion connecting the tread portion 2 and the sidewall portion 4, and is formed in a round shape (curved shape) from the end portion of the tread portion 2 in the width direction D1 to the upper end portion of the sidewall portion 4. ing. Generally, a shape in which the curvature of the curved surface of the shoulder portion 3 is small, that is, a shape in which the bending is loose is called a round shoulder. Further, a shape having a large curvature of the curved surface, that is, an acute-angled shape with a sharp bend is called a square shoulder.

When a normal load is applied to the tire 1 in the normal state, the area (ground contact area) of the contact patch between the tread portion 2 and the road surface is larger in the square shoulder than in the round shoulder. Therefore, when the vehicle 10 is traveling on a straight line or a gentle curve, the grip force during driving or braking is better for the square shoulder tire 1. On the other hand, when the vehicle 10 turns, the contact pressure of the shoulder portion 3 is strong and the contact pressure at the center of the tread portion decreases. Therefore, the grip force in this case is better for the tire 1 of the round shoulder. ..

Here, the normal load is a load defined in the standard on which the tire 1 relies. Specifically, the normal load is the "maximum load capacity" in the JATTA standard, the "maximum value" shown in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard. ".

The sidewall portion 4 is made of crosslinked rubber. The sidewall portion 4 is arranged outside the axial direction D1 of the carcass 6. The sidewall portion 4 is connected to the end portion of the tread rubber 2A constituting the tread portion 2 in the width direction D1 and extends along the carcass 6 toward the center direction D21. The sidewall portion 4 protects the carcass 6 on the side portion of the tire 1.

The carcass 6 is arranged inside the tread portion 2 and the pair of sidewall portions 4. The carcass 6 is composed of at least one carcass ply 6A. The carcass ply 6A has a large number of carcass cords (not shown) extending in a direction intersecting the equatorial plane CL1 of the tire 1. In the carcass ply 6A, these carcass cords are coated with a topping rubber made of a predetermined rubber composition. A large number of carcass cords intersect the equatorial plane CL1 of the tire 1 at a predetermined angle (for example, an angle defined within the range of 70 to 90 degrees) along the circumferential direction D3 (see FIG. 2). They are arranged side by side. As the carcass cord, for example, a cord made of organic fibers such as nylon fiber, polyester fiber, rayon fiber, and aramid fiber (hereinafter referred to as "organic fiber cord") is used.

The inner liner 7 is provided inside the carcass 6 and constitutes the inner surface of the tire 1. The inner liner 7 is made of crosslinked rubber having an air blocking property, and plays a role of maintaining the internal pressure of the tire 1.

The bead portion 5 is a portion to be coupled to the wheel, and the tire 1 is fixed to the rim 11R by internal pressure. The bead portion 5 includes a bead core 5A made of a plurality of steel bead wires 5C and an apex rubber 5B. The apex rubber 5B is located outside the bead core 5A in the radial direction D2, and is made of, for example, a crosslinked rubber having high rigidity. The carcass ply 6A is arranged so as to wrap the outside of the bead core 5A and the apex rubber 5B. Specifically, the carcass ply 6A is folded around the bead core 5A from the inside to the outside in the axial direction D1 and extends the outside of the axial direction D1 in the bead portion 5 to the outside of the radial direction D2. The bead core 5A and the apex rubber 5B are arranged in the portion surrounded by the carcass ply 6A in this way.

The belt portion 8 is a band-shaped member extending in the circumferential direction D3 of the tire 1. The belt portion 8 is an example of the belt portion of the present invention. The belt portion 8 is arranged inside the radial direction D2 of the tread portion 2, and is arranged outside the carcass 6. The belt portion 8 plays a role of tightening the carcass 6 in the radial direction D2 to enhance the synthesis of the tread portion 2. The belt portion 8 and the band portion 9 described later form a reinforcing layer for reinforcing the carcass 6.

The belt portion 8 is composed of at least one belt ply 8A. In the present embodiment, the belt portion 8 has two belt plies 8A. The belt portion 8 extends around the tire 1 in the circumferential direction D3 (see FIG. 2).

The belt ply 8A has a large number of belt cords (not shown) extending in a direction intersecting the equatorial plane CL1 of the tire 1. In the belt ply 8A, these belt cords are covered with topping rubber. A large number of belt cords intersect the equatorial plane CL1 of the tire 1 at a predetermined angle (for example, an angle defined within a range of 10 to 35 degrees) along the circumferential direction D3 (see FIG. 2). They are arranged side by side. In the belt portion 8, each belt ply 8A is arranged so that the belt cords intersect with each other. As the belt cord, for example, a steel cord (hereinafter referred to as “steel cord”) or the organic fiber cord is used.

The band portion 9 is a band-shaped member extending in the circumferential direction D3 of the tire 1. The band portion 9 is arranged inside the radial direction D2 of the tread portion 2, and is arranged outside the belt portion 8. The band portion 9 plays a role of restraining the movement of the belt portion 8 and preventing the belt portion 8 from being lifted or peeled off due to the centrifugal force during traveling of the vehicle 10. The band portion 9 and the belt portion 8 described above form a reinforcing layer for reinforcing the carcass 6.

In the present embodiment, the band portion 9 has a full band 9A extending in the circumferential direction D3 and a pair of edge bands 9B. The pair of edge bands 9B is an example of the edge band portion of the present invention.

The full band 9A covers the entire belt portion 8. The full band 9A suppresses the lifting and peeling of the entire belt portion 8. The full band 9A has a band cord (not shown) wound spirally (coiled) in the circumferential direction D3 (see FIG. 2). The full band 9A is a spiral band cord covered with a topping rubber. As the band cord, for example, the steel cord, the organic fiber cord, or a composite cord obtained by twisting a review type of organic fiber cord is used.

The pair of edge bands 9B are provided at positions corresponding to both ends of the tread portion 2 in the width direction D1. Specifically, the pair of edge bands 9B covers both ends of the belt portion 8 in the width direction D1 from the outside of the radial direction D2 of the full band 9A. The edge band 9B suppresses the lifting and peeling of both ends of the belt portion 8.

The edge band 9B has a conductive fiber actuator 30 (an example of a cord-shaped actuator of the present invention) having a length of at least one circumference along the circumferential direction D3 (see FIG. 2). That is, as shown in FIG. 2, the fiber actuator 30 is embedded inside the tire 1, specifically, inside the tread rubber 2A of the tread portion 2, and both ends of the width direction D1 inside the tread portion 2. It is provided for each.

The fiber actuator 30 is formed by winding a conductive metal cord-shaped member a plurality of times in a spiral direction (coil shape) in the circumferential direction D3. The edge band 9B is substantially composed of a spiral fiber actuator 30, and the fiber actuator 30 also serves as a band cord. In the present embodiment, the edge band 9B has a fiber actuator 30 covered with a topping rubber which is an insulator. Therefore, the fiber actuator 30 is insulated by the topping rubber.

The fiber actuator 30 is a cord-shaped (fibrous) actuator that can expand and contract in response to a temperature change. The fiber actuator 30 is a cord-shaped conductive member having a predetermined resistance. The fiber actuator 30 generates heat when a predetermined voltage is supplied to both ends thereof and a current is passed through the fiber actuator 30, and when the temperature exceeds a predetermined set temperature, the fiber actuator 30 contracts in the longitudinal direction, the energization is stopped, and the set temperature is reached. When it becomes less than, it is an actuator that expands in the longitudinal direction and returns to its original shape. When the fiber actuator 30 contracts in the longitudinal direction, the shapes of both ends of the tread portion 2 are deformed by the tensile force at the time of contraction. That is, the fiber actuator 30 is a cord-shaped member capable of deforming the tread portion 2 by contracting due to heat generated by energization.

In the present embodiment, the cord ends at both ends of the fiber actuator 30 are connected to a flat cable (not shown) or the like, and the flat cable is the tire 1 so that the voltage V1 can be supplied to the flat cable from the outside. It is exposed to the outside from between the bead portion 5 and the rim 11R. The set temperature is, for example, a temperature defined in the range of 60 to 100 ° C, preferably around 70 ° C.

In this embodiment, the fiber actuator 30 is applied with biometal fiber (biometal is a registered trademark of Toki Corporation) provided by Toki Corporation (4-1-23 Heiwajima, Ota-ku, Tokyo). Will be done. The biometal fiber is made from a Ti—Ni-based shape memory alloy as a main raw material, and has the property of expanding and contracting only in the longitudinal direction depending on the presence or absence of heating. When the biometal fiber is heated above the set temperature, about 4% of the total length shrinks in the longitudinal direction. In the biometal fiber, the tensile force (force in the contraction direction) at the time of contraction is proportional to the diameter. Therefore, for the tire 1, the biometal fiber having a diameter according to its size, application, and the like is selected. The fiber actuator 30 may be one in which one biometal fiber is spirally wound, and a plurality of the biometal fibers are twisted together in order to generate a stronger tensile force. It is also possible to apply things.

The fiber actuator 30 is not limited to the biometal fiber, and may be, for example, one using a biometal helix provided by Toki Corporation. Further, the fiber actuator 30 can be applied to any structure as long as it is a cord-shaped (fibrous) actuator that can be expanded and contracted in the longitudinal direction by heating. Further, it is not limited to the presence or absence of heat generation, and for example, it can be applied to any configuration, such as a cord-shaped actuator that can expand and contract in the longitudinal direction by being energized.

Since the tire 1 is configured in this way, when a voltage is supplied to the fiber actuator 30 by the control unit 40 described later, the fiber actuator 30 contracts in the longitudinal direction thereof, so that the tire 1 is tightened in the circumferential direction D3. Be done. As a result, the shape of both ends of the tread portion 2 of the tire 1 is deformed, and the shoulder portion 3 is further deformed into a curved shape as compared with that before the voltage supply. As a result, the ground contact area at both ends becomes smaller, and the contact patch shape T10 (see FIGS. 7 and 9) with the road surface in the tread portion 2 changes from a square shape (substantially square shape) to a round shape (substantially elliptical shape). Become.

Generally, when the road surface is in a wet state, it is well known that the grip force of the tread portion 2 is higher in the round shape than in the square shape of the ground contact surface shape T10 of the tread portion 2. Therefore, by supplying a voltage from the control unit 40 to the fiber actuator 30 when the road surface is in a wet state, the grip force of the tire 1 on the wet road surface can be improved.

Further, it is well known that, regardless of the condition of the road surface, when the shape of the shoulder portion 3 of the tire 1 is more curved, the contact area with respect to the road surface is larger and the grip force with respect to the road surface is higher during the turning operation of the automobile. Is. Therefore, by supplying a voltage from the control unit 40 to the fiber actuator 30 when the vehicle 10 is turning, the grip force of the tire 1 during the turning operation can be improved.

Hereinafter, the vehicle 10 to which the tire 1 is mounted will be described with reference to FIG. Here, FIG. 3 is a schematic diagram showing an example of the vehicle 10.

As shown in FIG. 3, the vehicle 10 is a four-wheeled vehicle, and has a total of four wheels in the front and rear, and tires 1 are mounted on each wheel. In the present embodiment, the vehicle 10 is a front engine / front drive vehicle (FF vehicle), the tire 1F mounted on the front wheels is a drive tire, and the tire 1R mounted on the rear wheels is a driven tire.

A well-known wheel speed sensor 51 is attached to each wheel. The wheel speed sensor 51 detects the rotation speed of the tire 1 of the wheel to which the wheel speed sensor 51 is attached. The wheel speed sensor 51 is communicably connected to the control unit 40 via wireless or wired communication, and a signal (detection information) indicating the rotation speed detected by each wheel speed sensor 51 is transmitted to the control unit 40. The wheel speed sensor 51 may have any configuration as long as it can detect the rotational speed of the running tire 1, and the mounting position and detection method thereof are not particularly limited.

A well-known lateral acceleration sensor 52 is attached to the vehicle 10. The lateral acceleration sensor 52 detects lateral acceleration (lateral acceleration) applied to the vehicle 10. The lateral acceleration sensor 52 is communicably connected to the control unit 40 via radio or wire, and a signal (detection information) indicating the lateral acceleration detected by the lateral acceleration sensor 52 is transmitted to the control unit 40. The lateral acceleration sensor 52 may have any configuration as long as it can detect the lateral acceleration applied to the moving vehicle 10, and the mounting position and detection method thereof are not particularly limited.

The vehicle 10 is provided with a well-known steering angle sensor 53. The steering angle sensor 53 detects the steering angle, which is the rotation angle of the steering wheel 12. The steering angle sensor 53 is provided, for example, on the steering shaft of the steering wheel 12. The steering angle sensor 53 is communicably connected to the control unit 40 via wireless or wired communication, and a signal (detection information) indicating the steering angle detected by the steering angle sensor 53 is transmitted to the control unit 40. The steering angle sensor 53 may have any configuration as long as it can detect the steering angle of the steering wheel 12, and the mounting position and detection method thereof are not particularly limited.

A well-known slip ring 13 is provided on each wheel of the vehicle 10. The slip ring 13 is composed of a ring-shaped fixing portion 13A fixed to a non-rotating portion (for example, a knuckle) of a wheel and a ring-shaped rotating portion 13B attached to a rotating portion of the wheel (for example, a wheel 11 or a hub). ing. In the present embodiment, the fixing portion 13A is attached to the rim end surface 11R1 of the rim 11R on the vehicle body side (hub side) of the wheel 11 so as to be concentric with the wheel 11. Therefore, it becomes easy to connect the flat cable exposed to the outside from between the bead portion 5 and the rim 11R to the fixed portion 13A.

The fixing portion 13A is attached to the wheel 11 via an insulating member. The means for attaching the fixing portion 13A to the wheel 11 is not particularly limited, and for example, an adhesive such as an adhesive or double-sided tape, or a fixing means such as a fastening member such as a screw can be considered.

The rotating portion 13B is rotatably mounted on the outer peripheral surface of the fixed portion 13A via a bearing. The fixed portion 13A and the rotating portion 13B each have an electric contact, and even when the rotating portion 13B rotates with the rotation of the tire 1, the electric contacts are always in contact with each other so as to be energized.

The fixed portion 13A is provided with a relay terminal connected to the electric contact, and a power cable laid from the control unit 40 is connected to the relay terminal. Further, one end of the flat cable of the fiber actuator 30 described above is connected to the electric contact of the rotating portion 13B. As a result, the voltage supplied from the control unit 40 through the power cable is supplied to the fiber actuator 30 through the relay terminal and the flat cable. The other end of the flat cable is connected to the chassis ground provided in the vehicle 10.

Further, as shown in FIG. 4, the vehicle 10 is provided with a rain sensor 54, a brake sensor 55, and an operation switch 56. These are communicably connected to the control unit 40. The rain sensor 54 detects the presence or absence of raindrops and the amount of rainfall in the traveling area of the vehicle 10, and transmits a rainfall signal (detection information) indicating the detected value to the control unit 40. When the driver performs a brake operation, the brake sensor 55 detects the presence or absence of the operation and the operation amount, and transmits a brake signal (detection information) indicating the detected value to the control unit 40. The brake sensor 55 is, for example, a rotary encoder or a potentiometer provided on the brake pedal. The operation switch 56 is a switch member operated by a driver, and when operated, the operation signal (an example of the control signal of the present invention) is transmitted to the control unit 40. Since the rain sensor 54, the brake sensor 55, and the operation switch 56 all have conventionally known configurations, detailed description thereof will be omitted.

Hereinafter, the tread variable device 15 according to the embodiment of the present invention will be described with reference to FIG. Here, FIG. 4 is a block diagram showing the configuration of the tread variable device 15.

As shown in FIG. 4, the tread variable device 15 is mounted on the vehicle 10 and includes a control unit 40 and a tire 1.

The control unit 40 includes a control unit 41, a storage unit 42, a communication unit 43, a GPS receiving unit 44, an output unit 45, an input unit 46, a voltage supply unit 47, and the like. The control unit 40 may be one that controls the vehicle 10 in an integrated manner, or may be one that executes only a process of controlling the energization of the fiber actuator 30 of the tire 1. The control unit 40 is an information processing device capable of executing various arithmetic processes.

The communication unit 43 is a communication interface for wirelessly connecting the control unit 40 to a predetermined communication network and executing data communication with an external device via the communication network according to a predetermined communication protocol.

The storage unit 42 is a non-volatile storage medium or storage device such as a flash memory for storing various types of information. For example, the storage unit 42 stores a control program for causing the control unit 41 to execute various processes. The control program is stored in an external storage device such as a server device or an external storage that can communicate with the communication unit 43, is read from the external storage device, and is duplicated in the storage unit 42. Alternatively, the control program is non-temporarily recorded on a computer-readable recording medium such as a CD or DVD, and is read by a reading device (not shown) electrically connected to the control unit 40 and stored in a storage unit. It may be duplicated in 42.

The GPS receiving unit 44 acquires the position information of the traveling position of the vehicle 10. The GPS receiving unit 44 receives a signal from a GPS satellite and further performs predetermined arithmetic processing to detect the position of the vehicle 10 on the earth. The detected position information is transmitted to the control unit 41 and used for grasping the position of the vehicle 10, calculating the moving distance of the vehicle 10, calculating the moving speed of the vehicle 10, and the like.

The output unit 45 is an interface that outputs the results of various processes executed by the control unit 41 to the outside.

The input unit 46 is an interface for connecting to various sensors 51 to 55 provided in the vehicle 10 and an operation switch 56. Signals output from sensors 51 to 55, operation switches 56, and the like are input to the input unit 46. The input signal is transmitted to the control unit 41 and used for the tread deformation processing and various arithmetic processing described later.

The voltage supply unit 47 is connected to the fiber actuator 30 of the tire 1 via a power cable. Upon receiving the drive signal from the control unit 41, the voltage supply unit 47 outputs a predetermined voltage (electric power) capable of heating the fiber actuator 30 to the set temperature or higher. Specifically, the voltage supply unit 47 includes a transformer that transforms the voltage of the battery mounted on the vehicle 10 into a voltage corresponding to the fiber actuator 30, a switching element that turns the power cable on and off, and the like. When the drive signal is input, the voltage supply unit 47 operates the switching element to supply a predetermined voltage to the fiber actuator 30.

The control unit 41 has control devices such as a CPU, a ROM, and a RAM. The CPU is a processor that executes various arithmetic processes. The ROM is a non-volatile memory in which control programs such as a BIOS and an OS for causing the CPU to execute various processes are stored in advance. The RAM is a volatile or non-volatile memory that stores various information, and is used as a temporary storage memory (work area) for various processes executed by the CPU. Then, the control unit 41 controls the voltage supply to the fiber actuator 30 of the tire 1 by executing various control programs stored in advance in the ROM or the storage unit 42 in the CPU.

Specifically, the control unit 41 includes various processing units such as an acquisition processing unit 411, a determination processing unit 412, and a voltage control unit 413. The control unit 41 functions as the various processing units by executing various processes according to the control program on the CPU. Further, a part or all the processing unit included in the control unit 41 may be composed of an electronic circuit. Further, the control program may be a program for causing a plurality of processors to function as the various processing units.

The acquisition processing unit 411 converts the information indicated by the signal based on the signal input from the various sensors 51 to 55 to the input unit. For example, when the acquisition processing unit 411 receives the signal output from the wheel speed sensor 51 at predetermined sampling cycles, the acquisition processing unit 411 converts the signal into the rotation speed of the tire 1 and the traveling speed of the vehicle 10. Further, when the acquisition processing unit 411 receives the signal output from the lateral acceleration sensor 52, the acquisition processing unit 411 converts the signal into the lateral acceleration applied to the vehicle 10. Further, when the acquisition processing unit 411 receives the signal output from the steering angle sensor 53, the acquisition processing unit 411 converts the signal into a steering angle indicating a turning angle when the steering wheel 12 is operated. Further, when the acquisition processing unit 411 receives the signal output from the rain sensor 54, the acquisition processing unit 411 converts the signal into a steering angle indicating a turning angle when the steering wheel 12 is operated. When the acquisition processing unit 411 receives the signal output from the brake sensor 55, the acquisition processing unit 411 converts the signal into the operation amount of the brake pedal at the time of brake operation.

The determination processing unit 412 determines whether or not to supply voltage to the fiber actuator 30 of the tire 1 based on the acquisition information acquired by the acquisition processing unit 411, the operation signal transmitted from the operation switch 56, and the like. conduct. That is, the determination processing unit 412 determines whether or not the voltage supply to the fiber actuator 30 is permitted.

The voltage control unit 413 transmits the drive signal to the voltage supply unit 47 based on the determination result determined by the determination processing unit 412, and causes the fiber actuator 30 to supply a predetermined voltage from the voltage supply unit 47. Specifically, the voltage control unit 413 transmits the drive signal to the voltage supply unit 47 when the voltage supply is permitted by the determination processing unit 412, and stops the drive signal when the voltage supply is not permitted. ..

[Tread deformation processing (first processing example)]
Hereinafter, an example of the procedure of the tread deformation process executed by the control unit 41 will be described with reference to FIG. 5, and the grip force control method of the present invention will be described. FIG. 5 is a flowchart showing an example (first processing example) of the procedure of the tread deformation processing executed by the control unit 41. Here, the tread deformation process is started by executing the control program by the control unit 41. The present invention can be regarded as an invention of a grip force control method for executing one or a plurality of steps included in the tread deformation process.

Further, one or a plurality of steps included in each process described below may be omitted as appropriate. Further, the execution order of each step in each process may be different as long as the same action and effect are produced. Further, in each process described below, each step in each process may be executed by a processor corresponding to the control unit 41 which is the main body of the process, or each process may be executed by a plurality of processors corresponding to the control unit 41. Each step in may be performed in a distributed manner. The same applies to the other embodiments described below.

Further, in the following, it is assumed that the vehicle 10 is in a runnable state in which the engine thereof is started and the control unit 40 is also started.

In step S11, the control unit 41 determines whether or not the vehicle 10 is running. Specifically, the control unit 41 acquires the traveling speed of the vehicle 10 based on the output signal from the wheel speed sensor 51, and when the traveling speed is equal to or higher than the specified speed, the vehicle 10 is traveling. Is determined.

When it is determined that the vehicle 10 is traveling (S11: Yes), the control unit 41 subsequently determines whether or not the operation signal has been input (S12). Step S12 is an example of the input determination step of the present invention.

When it is determined that the operation signal has been input (S12: Yes), the control unit 41 transmits the drive signal to the voltage supply unit 47, and causes the fiber actuator 30 to supply a predetermined voltage from the voltage supply unit 47. (S13). As a result, the fiber actuator 30 of the tire 1 is energized, and as shown in FIG. 8, the fiber actuator 30 contracts in the longitudinal direction thereof. On the other hand, when it is determined that the operation signal has not been input (S12: No), the control unit 41 does not transmit the drive signal to the voltage supply unit 47, and stops the voltage supply by the voltage supply unit 47, or , Maintain the stopped state (S14). Steps S13 and S14 are examples of the energization control steps of the present invention. Since the processing of the procedure of steps S11 to S14 is repeatedly executed while the vehicle 10 is being started, when the processing of step S13 or step S14 is completed, the process returns to step S11 and the processing after step S11 is repeatedly executed. ..

FIG. 6 is a diagram showing a state in which voltage is not supplied to the fiber actuator 30 of the tire 1 when the power is not supplied, and FIG. 7 is a tread portion when the normal load is applied to the vehicle 10 when the vehicle 10 is not energized. It is a figure which shows the contact patch shape T10 of 2. As shown in FIG. 6, when the fiber actuator 30 is not energized, the fiber actuator 30 is not contracted in the longitudinal direction thereof, and therefore the tire 1 is not tightened in the circumferential direction D3 by each fiber actuator 30. In this case, the contact patch shape T10 with the road surface in the tread portion 2 has a square shape (substantially square shape) as shown in FIG. 7.

FIG. 8 is a diagram showing a state when a voltage is supplied to the fiber actuator 30 of the tire 1 when energized, and FIG. 9 is a diagram showing contact of the tread portion 2 when the normal load is applied to the vehicle 10 during the energization. It is a figure which shows the ground shape T10. As shown in FIG. 8, when energized, each fiber actuator 30 contracts in the longitudinal direction thereof, so that the tire 1 is tightened in the circumferential direction D3. As a result, the shapes of both ends of the tread portion 2 of the tire 1 are deformed in the direction toward the inside of the radial direction D2 of the tire 1 (direction of arrow D40 in FIG. 9), and the shoulder portion 3 is further increased as compared with that before the voltage supply. It transforms into a curved shape. In this case, as shown in FIG. 9, the contact patch shape T10 with the road surface in the tread portion 2 changes from the square shape (substantially square shape) before voltage supply to a round shape (substantially elliptical shape).

More specifically, in the ground contact surface shape T10, the maximum ground contact width Wm (= W1) in the width direction D1 does not change, but the maximum ground contact length Lc which is the maximum ground contact length in the circumferential direction D3 at the center of the width direction D1. However, the length L1 before voltage supply changes to a length L2 longer than the length L1. Further, the shoulder grounding vertical width Ls, which is the grounding length in the circumferential direction D3 at the position of 80% of the maximum grounding width Wm, changes to a length L12 shorter than the length L11 before voltage supply. Further, in the ground plane shape T10, the curvature of the curved portion T11 at each corner becomes smaller than that before the voltage supply, and the curved portion T11 changes to a gentler curved shape.

In the present embodiment, the operation signal input in step S12 is a signal input to the control unit 40 by operating the operation switch 56 at an arbitrary timing by the driver of the vehicle 10. For example, when the driver determines that the road surface is wet due to rainfall or the like and a hydroplaning phenomenon may occur during traveling, the driver operates the operation switch 56 to transmit the operation signal to the control unit 40. .. As a result, the contact patch shape T10 of the tire 1 changes from the square shape to the round shape.

As described above, it is generally considered that when the road surface is in a wet state, the grip force of the tread portion 2 is higher in the round shape than in the square shape of the ground plane shape T10 of the tread portion 2. Therefore, when the road surface is in a wet state, the driver operates the operation switch 56 at an arbitrary timing at his / her own discretion to supply a voltage from the control unit 40 to the fiber actuator 30, thereby causing the tire 1 on the wet road surface. The grip force can be improved at any time. That is, the driver can adjust the grip force of the tire 1 in the wet state at any timing.

Further, regardless of the condition of the road surface, it is considered that when the shape of the shoulder portion 3 of the tire 1 is more curved, the contact pressure with respect to the road surface is larger and the grip force with respect to the road surface is higher during the turning operation of the vehicle 10. Has been done. From this, the driver operates the operation switch 56 when turning the vehicle to supply a voltage from the control unit 40 to the fiber actuator 30, thereby improving the grip force of the tire 1 during the turning operation. Can be done. That is, the driver can adjust the grip force of the tire 1 during the turning operation at an arbitrary timing.

In the above-described embodiment, the fiber actuator 30 constituting the edge band 9B is exemplified as an example of the cord-shaped actuator of the present invention, but the present invention is not limited to this configuration. For example, when the band portion 9 of the tire 1 does not have the edge band 9B, the band cords located at both ends of the full band 9A in the width direction D1 may be replaced with the fiber actuator 30. That is, in this case, in the band portion 9, both ends of the full band 9A are configured by the fiber actuator 30, and the other portions are composed of a normal band cord.

Further, the edge band 9B may be formed of a normal band cord, and an insulatingly coated spiral fiber actuator 30 may be provided inside the pair of shoulder portions 3. In this case, the fiber actuator 30 is preferably arranged outside the radial direction D2 in the edge band 9B.

Further, as shown in FIG. 10, an insulatingly coated spiral fiber actuator 30 may be provided on each of the pair of sidewall portions 4. Here, FIG. 10 is a schematic view showing another arrangement example of the fiber actuator 30 of the tire 1, and shows a state in which a voltage is supplied to the fiber actuator 30 when energized. In this configuration, when a voltage is supplied to the fiber actuator 30 by the control unit 40, the fiber actuator 30 contracts in the longitudinal direction, so that the sidewall portion 4 is deformed so as to contract in the arrow direction D41 in FIG. Also in this case, the shoulder portion 3 is attracted to the inside of the radial direction D2 due to the deformation of the sidewall portion 4, and the shoulder portion 3 is further deformed into a curved shape as compared with that before the voltage supply. As a result, the contact patch shape T10 of the tread portion 2 changes from a square shape (substantially square shape) to a round shape (substantially elliptical shape) when the tread portion 2 is not energized.

Further, in the above-described embodiment, the fiber actuator 30 spirally wound a plurality of times in the circumferential direction D3 is exemplified, but the present invention is not limited to this configuration. For example, instead of the fiber actuator 30 described above, the fiber actuator 31 shown in FIG. 11 may be embedded inside the tread portion 2. Here, the fiber actuator 31 has one cord-shaped member arranged inside the tread portion 2 in a meandering shape in the circumferential direction D3. Therefore, the fiber actuator 31 is configured to include a plurality of straight portions 31A extending along the width direction D1 and curved portions 31B connecting the straight portions 31A. A predetermined voltage V1 is supplied to the fiber actuator 31 configured in this way. In this configuration, since a plurality of straight lines 31A are arranged at predetermined intervals (for example, equal intervals) in the circumferential direction D3, when the voltage V1 is supplied to the fiber actuator 31 by the control unit 40, the fiber actuator 31 The straight line portion of is contracted in the width direction D1. As a result, the tread portion 2 is deformed so as to shrink in the arrow direction D42 in FIG. 11, and the tread portion 2 is deformed into a curved shape in which the center of the width direction D1 bulges outward in the radial direction D2. As a result, the contact patch shape T10 of the tread portion 2 changes from a square shape (substantially square shape) to a round shape (substantially elliptical shape) when the tread portion 2 is not energized.

Further, in the above-described embodiment, the tire 1 is exemplified as a radial tire for an automobile, but the tire 1 may be a bias tire, and the present invention is also suitably used for the bias tire. In this case, the fiber actuator 30 may constitute edge bands 9B provided at both ends of the breaker corresponding to the belt portion 8 of the radial tire, or may be provided at both ends of the breaker in the width direction D1. May be.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. FIG. 12 is a flowchart showing an example (second processing example) of the procedure of the tread deformation processing executed by the control unit 41. In the present embodiment, the parts different from the above-described first embodiment will be described, and the other common configurations will be described by adding the same reference numerals as those used in the description of the first embodiment to each figure. The explanation is omitted. The same applies to the other embodiments described below.

[Tread deformation processing (second processing example)]
The tread deformation process in the present embodiment is performed by the control unit 41 when the traveling environment of the vehicle 10 is an environment in which the hydroplaning phenomenon is likely to occur, or when there is a high possibility that the hydroplaning phenomenon actually occurs. Is a process of automatically supplying a voltage to the fiber actuator 30 to deform the contact patch shape T10 of the tread portion 2 from the square shape to the round shape to increase the grip force of the tire 1.

As shown in FIG. 12, in step S11, the control unit 41 determines whether or not the vehicle 10 is running. Specifically, the control unit 41 acquires the traveling speed of the vehicle 10 based on the output signal from the wheel speed sensor 51, and when the traveling speed is equal to or higher than the specified speed, the vehicle 10 is traveling. Is determined. When it is determined that the vehicle 10 is running (S11: Yes), the control unit 41 proceeds to the next step S21.

In step S21, the control unit 41 determines whether or not rainfall has been detected based on the output signal (rainfall signal) from the rain sensor 54. Step S21 is an example of the input determination step of the present invention. When rainfall is detected in step S21, the control unit 41 proceeds to the next step S22. If no rainfall is detected, the control unit 41 does not transmit the drive signal to the voltage supply unit 47, stops the voltage supply by the voltage supply unit 47, or maintains the stopped state (S14).

In step S22, the control unit 41 determines whether or not the traveling speed of the vehicle 10 is equal to or higher than a predetermined speed set value. Step S22 is an example of the input determination step of the present invention. The speed set value is a set value stored in the RAM of the control unit 41 or the storage unit 42. The speed setting value is set to a speed at which a hydroplaning phenomenon is likely to occur when the weather is rain, and is set to a speed set within a range of, for example, 50 km / h or more and 100 km / h or less. ..

When it is determined in step S22 that the traveling speed is equal to or higher than the speed set value (S22: Yes), the control unit 41 determines in the next step S23 based on the output signal (brake signal) from the brake sensor 55. Determine if there was a brake operation. It is considered highly likely that the hydroplaning phenomenon will occur when the traveling speed is equal to or higher than the speed set value and the brake operation is performed. Therefore, when it is determined in step S23 that the brake operation has been performed (S23: Yes), the control unit 41 transmits the drive signal to the voltage supply unit 47, and the voltage supply unit 47 determines the fiber actuator 30. A voltage is supplied (S13). As a result, the contact patch shape T10 of the tire 1 changes from the square shape to the round shape, and the grip force of the tire 1 is improved. As a result, the incidence of hydroplaning is reduced.

When the traveling speed is less than the speed set value or the brake operation is not detected, the control unit 41 shifts to step S24. In step S24, the control unit 41 determines whether or not each tire 1 is idling. The control unit 41 calculates the rotation speed of the wheel 11 based on the output signal from the wheel speed sensor 51 provided for each wheel, and the tire 1 spins (idle) from the difference between the rotation speed and the traveling speed of the vehicle 10. Determine if it is slipping). When it is determined that the tire 1 is idling, it is considered that the grip force of the tire 1 is reduced with respect to the wet road surface. Therefore, the control unit 41 transmits the drive signal to the voltage supply unit 47 to supply a predetermined voltage to the fiber actuator 30 from the voltage supply unit 47 (S13). On the other hand, when the tire 1 is not idling, the control unit 41 does not transmit the drive signal to the voltage supply unit 47, stops the voltage supply by the voltage supply unit 47, or maintains the stopped state (S14). .. When the process of step S13 or step S14 is completed, the process returns to step S11, and the processes after step S11 are repeatedly executed.

<Third Embodiment>
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. FIG. 13 is a flowchart showing an example (third processing example) of the procedure of the tread deformation processing executed by the control unit 41. In the present embodiment, the parts different from the tread deformation processing of the second embodiment described above, that is, steps S31 to S32 will be described, and the description of other common configurations will be omitted.

[Tread deformation processing (third processing example)]
As shown in FIG. 13, when it is determined in step S11 that the vehicle 10 is running (S11: Yes), the control unit 41 shifts to the next step S31.

In step S31, the control unit 41 determines whether or not the vehicle 10 is traveling on the highway. For example, the control unit 41 is based on map information including information on the expressway and information on the general road on which the other vehicle 10 can travel, and position information of the traveling position of the vehicle 10 received by the GPS receiving unit 444. Then, it is determined whether the road currently being driven is an expressway or a general road. The map information is stored in the storage unit 42.

When it is determined in step S31 that the travel path is an expressway, the control unit 41 changes the speed setting value to a first threshold value corresponding to the expressway. Here, the first threshold value is a set value at which the hydroplaning phenomenon is considered to be likely to occur on a highway, and is set to, for example, 100 km / h.

Further, in step S31, when it is determined that the travel path is a general road, the control unit 41 changes the speed setting value to a second threshold value corresponding to the general road. Here, the second threshold value is a set value at which the hydroplaning phenomenon is considered to be likely to occur on a general road, and is set to, for example, 50 km / h.

When the change in step S32 or S33 is completed, the control unit 41 executes the process of shifting to step S21 as described above.

As described above, in the present embodiment, the speed setting value used for the determination in step S22 is changed to the threshold value according to the type of the traveling road actually traveled, so that the speed setting value is changed according to the type of the traveling road. It is possible to adjust the grip force of the tire 1.

<Fourth Embodiment>
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a flowchart showing an example (fourth processing example) of the procedure of the tread deformation processing executed by the control unit 41. In this embodiment, the parts different from the tread deformation treatments of the first to third embodiments described above will be described, and the description of other common configurations will be omitted. The present embodiment is different in that in the tread deformation process of the first embodiment, steps S41 and S42 are performed instead of step S12.

[Tread deformation processing (4th processing example)]
As shown in FIG. 14, when it is determined in step S11 that the vehicle 10 is running (S11: Yes), the control unit 41 shifts to the next step S41.

In step S41, the control unit 41 determines whether or not the traveling speed of the vehicle 10 is equal to or higher than the speed set value. Note that step S41 is the same process as step S22 described above.

When it is determined in step S41 that the traveling speed is equal to or higher than the speed set value (S41: Yes), the control unit 41 determines that the steering wheel 12 is based on the output signal from the steering angle sensor 53 in the next step S42. The steering angle is detected, and it is determined whether or not the steering angle is equal to or greater than a predetermined angle set value. Step S42 is an example of the input determination step of the present invention. The angle set value is a set value stored in the RAM of the control unit 41 or the storage unit 42. The angle setting value is set to an angle at which slip may occur due to the lateral acceleration applied to the vehicle 10 when traveling on a curved road. When the traveling speed is equal to or higher than the speed set value and the steering angle of the steering wheel 12 is equal to or higher than the angle set value, the grip force of the vehicle 10 due to the vehicle 10 performing a turning operation while traveling on a curved road. Is likely to decrease. Therefore, when it is determined in step S42 that the steering angle is equal to or greater than the angle set value (S42: Yes), the control unit 41 transmits the drive signal to the voltage supply unit 47 from the voltage supply unit 47. A predetermined voltage is supplied to the fiber actuator 30 (S13). As a result, the contact patch shape T10 of the tire 1 changes from the square shape to the round shape, and the grip force of the tire 1 is improved.

When the traveling speed is less than the speed set value or the steering angle is less than the angle set value, the control unit 41 shifts to step S43. In step S43, the control unit 41 detects the lateral acceleration applied to the vehicle 10 based on the output signal from the lateral acceleration sensor 52, and determines whether or not the lateral acceleration is equal to or higher than a predetermined threshold value. .. When it is determined that the lateral acceleration is equal to or higher than the threshold value, it is considered that the grip force of the tire 1 is reduced during the turning operation. Therefore, the control unit 41 transmits the drive signal to the voltage supply unit 47 to supply a predetermined voltage to the fiber actuator 30 from the voltage supply unit 47 (S13). On the other hand, when it is determined that the lateral acceleration is less than the threshold value, the control unit 41 does not transmit the drive signal to the voltage supply unit 47, and stops or stops the voltage supply by the voltage supply unit 47. Maintain the state (S14). When the process of step S13 or step S14 is completed, the process returns to step S11, and the processes after step S11 are repeatedly executed.

As described above, in the present embodiment, the grip force of the tire 1 is increased when the steering angle of the steering wheel 12 is equal to or greater than the angle set value, and the grip force is increased even when the lateral acceleration applied to the vehicle 10 is equal to or greater than the threshold value. Since it is raised, the vehicle 10 can be stably traveled during a turning operation while traveling on a curved road.

<Fifth Embodiment>
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 15 is a schematic view showing a pneumatic tire 100 (hereinafter abbreviated as “tire 100”) for a motorcycle to which the tread variable device 15 according to the embodiment of the present invention is applied. FIG. 15 shows a non-energized state in which the fiber actuator 30 is not energized. Since the tire 100 has the same configuration as the tire 1 described above except that the applicable vehicle is different, different configurations will be described below, and the description of other common configurations will be omitted.

The tire 100 is suitably used as a radial tire or a bias tire for a motorcycle. Since a motorcycle turns due to the frictional force generated between the tread portion 2 in contact with the road surface and the road surface, as shown in FIG. 15, the tire 100 grips the tread even when the vehicle body is tilted. The portion 2 is formed in a curved shape when viewed from the front.

The tire 100 according to the present embodiment has a curved tread portion 2, a pair of shoulder portions 3 located at both ends of the width direction D1 of the tread portion 2, and a central direction from the shoulder portion 3 toward the central axis of the tire 1. It includes a pair of sidewall portions 4 extending toward D21 (inside the radial direction D2) and a pair of bead portions 5 located at the ends of the sidewall portions 4 in the central direction D21. Further, the tire 100 is arranged inside the carcass 6 from the tread portion 2, the shoulder portion 3, the sidewall portion 4 to the bead core 5A of the bead portion 5, the inner liner 7, and the radial direction D2 of the tread portion 2. A belt portion 8 and a band portion 9 are provided. Unlike the tire 1 described above, the tire 100 does not have the shoulder portion 3. The tire 100 has substantially the same configuration as the tire 1 described above, except that the tread portion 2 is formed in a curved shape and the shoulder portion 3 is not provided.

In the present embodiment, the fiber actuator 30 is provided at the center of the tread portion 2 in the width direction D1 and has a length of at least one circumference along the circumferential direction D3 of the tire 100. That is, as shown in FIG. 15, the fiber actuator 30 is embedded inside the tire 100, specifically, inside the tread rubber 2A of the tread portion 2, and is the central portion in the width direction D1 inside the tread portion 2. It is provided in.

The band portion 9 is a cord-shaped fiber actuator 30 wound in a spiral direction (coil shape) a plurality of times in the circumferential direction D3, and the spiral fiber actuator 30 is covered with the topping rubber. ..

A predetermined voltage V1 is supplied to both ends of the fiber actuator 30 by the control unit 40. In the present embodiment, when a voltage is supplied to the fiber actuator 30 by the control unit 40, the fiber actuator 30 contracts in the longitudinal direction thereof, so that the central portion of the tire 1 in the width direction D1 is tightened in the circumferential direction D3. As a result, the shape of the central portion of the tread portion 2 of the tire 1 is deformed, and the tread portion 2 is deformed into a flat shape (the shape shown by the broken line in FIG. 15) as compared with that before the voltage supply. As a result, the shape of the contact patch of the tread portion 2 with the road surface changes from a round shape (substantially elliptical shape) to a square shape (substantially square shape) when the tread portion 2 is not energized.

On the other hand, when the voltage supply by the control unit 40 is stopped, the fiber actuator 30 expands to the original length, so that the tightening of the central portion of the tire 1 in the width direction D1 is released. As a result, the shape of the central portion of the tread portion 2 of the tire 1 is restored, and the tread portion 2 returns to the curved shape. As a result, the shape of the contact patch of the tread portion 2 with the road surface changes from a square shape (substantially square shape) to a round shape (substantially elliptical shape) when energized.

Since the tire 100 is configured in this way, the grip force on the road surface can be adjusted by supplying a voltage to the fiber actuator 30 according to the traveling state of the vehicle.

1,100: Pneumatic tire 2: Tread part 3: Shoulder part 4: Side wall part 5: Bead part 6: Carcus 7: Inner liner 8: Belt part 9: Band part 9A: Full band 9B: Edge band 10: Vehicle 11: Wheel 15: Tread variable device 21: Tread surface 22: Main groove 23: Lag groove 30, 31: Fiber actuator 40: Control unit 41: Control unit 47: Voltage supply unit 411: Acquisition processing unit 412: Judgment processing unit 413 : Voltage control unit 444: GPS receiver unit

Claims (13)

A cord-shaped actuator that is embedded inside the pneumatic tire so as to follow a predetermined direction and can deform the tread portion of the pneumatic tire by contracting when energized.
A control unit that supplies voltage to the actuator to energize the actuator is provided.
The control unit is a tread variable device that controls energization of the actuator in response to the control signal when a predetermined control signal is input. In the pneumatic tire, the tread portion is formed in a flat shape.
The tread variable device according to claim 1, wherein the actuator is provided at both ends in the width direction of the tread portion and has a length of at least one circumference along the circumferential direction of the pneumatic tire. The pneumatic tire covers the belt portion arranged radially inside the surface of the tread portion and both ends in the width direction of the belt portion, and the edge band is arranged along the circumferential direction. With a part,
The tread variable device according to claim 2, wherein the actuator constitutes the edge band portion. In the pneumatic tire, the tread portion is formed in a flat shape.
The tread variable device according to claim 1, wherein the actuator is provided on a shoulder portion or a sidewall portion of the pneumatic tire and has a length of at least one circumference along the circumferential direction of the pneumatic tire. In the pneumatic tire, the tread portion is formed in a flat shape.
The actuator is provided on the tread portion and has a plurality of straight portions extending along the width direction of the tread portion, and the plurality of straight portions are arranged at predetermined intervals in the circumferential direction of the pneumatic tire. The tread variable device according to claim 1. The tread variable device according to any one of claims 2 to 5, wherein the control unit supplies a voltage to the actuator when the control signal is input. In the pneumatic tire, the tread portion is formed in a curved shape.
The actuator is provided at the center of the tread portion in the width direction, and has a length of at least one circumference along the circumferential direction of the pneumatic tire.
The control unit supplies a voltage to the actuator to energize it, thereby tightening the central portion inward in the radial direction to flatten the tread portion, and stops supplying the voltage when the control signal is input. The tread variable device according to claim 1, which returns the original curved shape. The tread variable device according to any one of claims 1 to 7, wherein the control signal is an input signal at the time of operation of an operation switch provided on a vehicle equipped with the pneumatic tire. The tread variable device according to any one of claims 1 to 8, wherein the control signal is a rainfall signal indicating rainfall in a traveling area of a vehicle equipped with the pneumatic tire. The control signal is
The tread variable device according to claim 9, further comprising one or both of a brake signal indicating that the brake of the vehicle has been operated and a speed signal indicating that the speed of the vehicle is equal to or higher than a predetermined speed. The tread variable device according to any one of claims 1 to 10, wherein the actuator is a cord-shaped member containing a Ti—Ni-based shape memory alloy as a main component and contracts due to heat generated by energization. Pneumatic tires mainly made of rubber material
With the tread part
It is provided with a cord-shaped actuator which is embedded in the radial direction inside the ground contact surface of the tread portion so as to follow a predetermined direction and can deform the tread portion of the pneumatic tire by contracting by energization. Pneumatic tires. It is a grip force control method that controls the grip force of pneumatic tires whose main component is rubber material.
The pneumatic tire is
It is equipped with a cord-shaped actuator that is embedded inside the pneumatic tire so as to follow a predetermined direction and can deform the tread portion of the pneumatic tire by contracting by energization.
An input determination step that determines the input of a predetermined control signal, and
An energization control step that controls the grip force of the pneumatic tire by supplying a voltage to the actuator based on the input control signal to energize the actuator and deforming the tread portion.
Grip force control method that is executed by the processor.

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