JPH03273912A - Tire air pressure controller - Google Patents

Abstract

PURPOSE:To regulate air pressure of a tire arbitrarily without feeding air from the outside by providing a pressurizing body disposed in the air in a tire, which is made of shape memory alloy which can transform itself from the condition of a decreased volume to that of an increasing volume reversibly. CONSTITUTION:When the switch 26 of an electromagnet 16 is turned on during driving a vehicle, a magnetic field is generated by the magnetic body 24 of the electromagnet 16 and a coil 30, and the angular velocity of a coil 18, that is to say, alternating current in proportion to vehicle speed is obtained. When the alternating current reaches a certain value, a pressurizing body 22 transforms itself by heat generation of a heat generation device 20 to increase its volume. Consequently, the air in a tire 14 is compressed to increase air pressure. On the other hand, when the vehicle speed drops and the current goes down, or the switch 26 is turned off, the volume of the pressurizing body 22 decreases, thus air pressure in the tire 14 returns to its original magnitude.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tire air pressure adjustment device for automobiles and other vehicles.

(Prior art) An air pressure holding device made of a tube or the like is attached to the inside of a tire mounted on a disc wheel, and the air pressure of the air pressure holding device is adjusted from the outside to change the volume of the air pressure holding device, thereby adjusting the tire air pressure. A device has been proposed (Japanese Unexamined Patent Publication No. 173307/1983).

This adjustment device requires a pressurizing device for feeding air into the air pressure holding device from the outside. In this case, to supply air to the air pressure retainer of a rotating tire, a pressurizing device such as a compressor rotates with the tire, or the pressurizing device is fixedly attached, while the pressurizing device The pipe connecting the tire and the air pressure retainer is configured to rotate together with the tire.

As a result, in the former case, the tire has a large rotational inertia, and in the latter case, a joint between the rotating and stationary parts of the tube is required. Moreover, in the latter case, if a drive shaft is present, the structure will be complicated, such as passing a tube through the drive shaft.

In view of the above, an air pressure adjustment device capable of adjusting tire air pressure without introducing air from outside has been developed, and a separate application has been filed for this (Utility Application No. 1-114745). This air pressure adjustment device adjusts the air pressure of a tire mounted on a disc wheel that is rotatably supported by a carrier, and includes a permanent magnet attached to the carrier and a magnetic field generated by the permanent magnet. A coil attached to the disc wheel, a heat generator that generates heat by the electric current generated in the coil, and a shape memory alloy that can be reversibly deformed into a state where the volume decreases and a state where the volume increases. and a pressurizing body disposed in the air inside the tire.

(Problem to be Solved by the Invention) In the air pressure adjustment device that was filed separately, a permanent magnet is attached to the carrier, so when the vehicle speed increases, the volume of the pressurizing body changes and the tire air pressure inevitably changes. Therefore, the tire air pressure cannot be adjusted by the driver's will or by a control device such as a computer.

Therefore, an object of the present invention is to provide an adjustment device that can adjust the tire air pressure without introducing air from outside, and that can change the tire air pressure according to the will of the driver or by a control device. There is a particular thing.

(Means for Solving the Problems) The present invention is a device for adjusting the air pressure of a tire mounted on a disc wheel rotatably supported by a carrier, the device controlling the air pressure of a tire mounted on a disc wheel rotatably supported by a carrier, the air pressure being controlled by a magnetic body attached to the carrier and a switch. an electromagnet having a first coil connected to a power source and arranged around the magnetic body, and a second coil attached to the disk wheel so as to rotate in a magnetic field generated by the electromagnet; A heat generator that generates heat due to the current generated in the second coil, and a shape memory alloy that is reversibly deformable between a reduced volume state and an increased volume state, and is disposed in the air inside the tire. and a pressurizing body. The pressurized body is heated to 2 by the heat generator.
It is assumed that there are two volumetric states.

(Function and Effect) When the switch is turned on, a magnetic field is generated from the electromagnet. In this state, when the disk wheel rotates and the second coil passes through the magnetic field, an alternating current is generated in the second coil. The alternating current is guided to the heat generator and generates heat, and when the amount of heat generated reaches a predetermined value, the pressurizing body deforms. For example, if a pressurized body is programmed to increase in volume when its temperature rises, then when the vehicle reaches a certain speed, the volume of the pressurized body increases and the tire air pressure increases. . Thereafter, when the speed of the vehicle decreases or the switch is turned off, the amount of heat generated by the heat generator decreases, the volume of the pressurizing body decreases, and the tire air pressure returns to its original state.

Since a pressurizing device such as an air compressor is not required, both space and weight can be reduced.

During normal driving, the air pressure is lowered to lower the tire's longitudinal spring constant, ensuring a comfortable ride when driving at low speeds and suppressing the occurrence of vibration phenomena, while when driving at high speeds, the tire air pressure is increased to ensure steering stability. can do.

If the air pressure of all four tires is configured to be adjustable according to the present invention, when the vehicle speed reaches a predetermined speed, the air pressure of any tire can be adjusted in two levels by turning the switch ON/OFF. Therefore, by storing in the pressurizing body a state in which the volume increases when the temperature increases, the following effects can be obtained.

By turning on the switches related to all four tires of a vehicle when driving at high speeds, it is possible to suppress the generation of so-called standing waves, which are waves that occur at the rear of the tire contact patch due to the increase in air pressure in the tires when driving at high speeds. .

Furthermore, since the limit lateral acceleration during high-speed turns increases, stability during high-speed turns can be improved.

When there is a possibility of sudden braking during high-speed driving, the stability of the vehicle during braking can be improved by turning on only the switches related to the two front tires.

On a winding road, by turning on only the switches related to the two front tires, it is possible to change the initially set characteristic of weak understeer to oversteer or neutral steer, as will be explained in detail later. It is.

Regarding high-speed straight-line stability and lane change performance, it is more stable if the front tire air pressure is lower than the rear tire air pressure, so if these are important, turn on only the switches related to the two rear tires. Bye.

(Embodiment) As shown in FIGS. 1 to 3, the tire air pressure adjustment device adjusts the air pressure of a tire 14 mounted on a disc wheel 12 rotatably supported by a carrier 10. It includes an electromagnet 16, a coil 18, a heat generator 20, and a pressurizing body 22.

The carrier 10 is a steering knuckle for steering or an axle carrier for non-steering, and rotatably supports the disc wheel 12. A tire 14 is attached to the disc wheel 12.

The structure itself is known. The carrier 10 has a stationary part 11 that is stationary relative to the disc wheel 12.

The electromagnet 16 includes a magnetic body 24 and a first coil 30 connected to a power source 28 via a switch 26 and arranged around the magnetic body 24 . In the illustrated embodiment, four magnetic bodies 24 are attached to the stationary portion 11 of the carrier 10 at equal intervals, and an electric wire 32 connected to a power source 28 and a switch 26 is wound around each magnetic body 24 to form a coil 30. When forming the coil 30, as shown in the figure, N poles are formed at the radially outer portions of the two magnetic bodies 24, and S poles are formed at the radially outer portions of the remaining two magnetic bodies 24. , the electric wire 32 is wound around the magnetic body 24.

The second coil 18 is attached to the disk wheel so that it rotates in the magnetic field generated by the electromagnet 16. In the illustrated embodiment, the coil 18 is connected to the disc wheel 12
The magnetic body 19 is arranged so as to surround four magnetic bodies 19 provided at equal intervals on the rim portion 13 of the magnetic body 13, and penetrates into the magnetic field.

The heat generator 20 generates heat by the current generated in the coil 18, and is formed by covering a heating wire with an insulating material. It is preferable that a portion of this heat generator 20 is attached to a portion of the pressurizing body that is less deformed, which will be described later.

The pressurizing body 22 is formed of a shape memory alloy, and can be reversibly deformed into a state where the volume decreases and a state where the volume increases. The pressurizing body 22 is placed in the air inside the tire 14 and is brought into two volume states by the heat generator 20.

In the embodiment shown in FIG. 4, the pressurizing body 22 is formed into an annular belt-like shape as a whole, and a concave-convex portion 23 extending in the circumferential direction is provided in the central portion. Both side portions excluding the unevenness 23 are bonded to the rim portion 13, and the volume of the space sandwiched between the unevenness 23 and the rim portion 13 is the volume when the pressurizing body 22 is reduced. When the pressure body 22 is at a high temperature, its unevenness 23 disappears, and the pressure body 22 expands as shown by the imaginary line to have an increased volume.

A heat generator 20 is arranged between the unevenness 23 and the rim portion 13.

In the illustrated embodiment, of the heating wires wound three times around the heat generator 20, those on both sides are stuck to the unevenness 23 of the pressurizing body 22, and the heating wires in the middle are attached to the unevenness 23 of the pressurizing body 22. It is formed so as to come into contact with the unevenness of the pressurizing body 22 when it decreases.

The pressurizing body 22 is stored so that the volume is in a decreasing state at a temperature below the transformation point, and the volume is in an increasing state as shown by the imaginary line at a temperature exceeding the transformation point.

After performing such processing, the pressurizing body 22 is attached to the rim portion 13.

The switch 26 of the electromagnet 16 is turned ON and OFF by manual operation by the driver or by CPU control. When the switch 26 is turned on while the vehicle is running, the electromagnet 16
A magnetic field is generated by the magnetic body 24 and the coil 30, and while the coil 18 passes through this magnetic field, an alternating current proportional to the angular velocity of the coil 18, that is, the vehicle speed, is obtained from Faraday's law of electromagnetic induction.

When the alternating current reaches a certain value, the pressurizing body 22 is deformed by the heat generated from the heat generator 20, and its volume increases. As a result, the air inside the tire 14 is compressed,
Air pressure increases. When the speed of the vehicle decreases and the current value decreases, or when the switch 26 is turned off, the volume of the pressurizing body 22 decreases and the air pressure of the tire 14 returns to its original level.

The basic configuration of the embodiment shown in FIGS. 5 to 8 is as follows:
This is the same as in the previous embodiment. That is, the tire air pressure adjustment device adjusts the air pressure of a tire 44 mounted on a disc wheel 42 rotatably supported by a carrier 40, and includes an electromagnet 46, a coil 48,
It includes a heat generator 50 and a pressurizing body 52.

The electromagnet 46 is a magnetic body 54 attached to the carrier 40.
and a coil 60 arranged around the magnetic body 54 and connected to a power source 58 via a switch 56.

The arrangement of the magnetic bodies 54 is the same as the arrangement of the magnetic bodies 24 shown in FIG. Further, the coil 48 also has the same configuration as the coil 18 and has the same arrangement.

The heat generator 50 generates heat by the current generated in the coil 48, and is formed by covering a heating wire with an insulating material. It is made of a shape memory alloy that can be reversibly deformed, is placed in the air inside the tire 44, and is made into two volume states by the heat generator 50.

In the air pressure regulator shown in FIGS. 5 to 8, two permanent magnets 62 are attached to the carrier 40 and are parallel to the electromagnets 46. N of two permanent magnets 62
The pole and the south pole are located corresponding to the north pole and south pole of the electromagnet 46, respectively.

A coil 64 is attached to disk wheel 42 for rotation in the magnetic field generated by permanent magnet 62. In the illustrated embodiment, the coil 64 is arranged so as to surround four magnetic bodies 66 provided at equal intervals on the rim portion 43 of the disk wheel 42, and enters into the magnetic field generated by the permanent magnet 62. ing.

The coil 48 placed in the magnetic field of the electromagnet 46 and the coil 64 placed in the magnetic field of the permanent magnet 62 are either shielded from each other's magnetic fields by magnetic shielding, or the magnetic field generated by each magnet is shielded from the other coil. The position of the magnet, the direction of the magnetic field, etc. shall be determined so as not to have a substantial effect on the

As shown in FIG. 9, the heat generator 68 is arranged in parallel with the heat generator 50 on the rim portion 43, and the pressurizing body 70 is connected to the heat generator 6.
It covers 8. The heat generator 68 generates heat by the current generated in the coil 64, and has the same configuration as the heat generator 50.

On the other hand, the pressurizing body 70 is made of a shape memory alloy, is reversibly deformable between a state in which its volume is decreased and a state in which its volume is increased, and has the same configuration as the pressurizing body 52. The pressurizing body 70 is placed in the air inside the tire 44 and is brought into two volume states by the heat generator 68.

As shown in FIG. 10, the pressurizing body 7o is formed of a flat portion 71a and uneven portions 71b continuous on both sides of the flat portion 71a, and a heat generator 6 is provided on the uneven portion 71b.
8, and the uneven portion 71b is placed on the disc wheel 42.
It is also possible to arrange the pressurizing bodies in series, so to speak, such that the pressurizing body 52 with the heat generator 50 is attached to the flat part 71a of the pressurizing body 70 on the other hand. In this embodiment, the extended state and the contracted state are stored in the uneven portion 71b of the pressurizing body 70, and the compressed state is stored in the pressurizing body 52 in the same manner as described above.

In the embodiment shown in FIGS. 5 to 8, the magnetic field by the electromagnet 46 is generated by turning the switch 56 ON/OFF, but the magnetic field by the permanent magnet 62 is always generated. Therefore, the vehicle speed is low and the switch 56 is OFF.
When the volume of the two pressurizing bodies 52 and 70 is decreased, the volume of the pressurizing body 70 is increasing as the vehicle speed increases, but since the switch 56 is OFF, the volume of the pressurizing body 52 is reduced. is decreasing, the vehicle speed is increasing, and the pressurizing body 7
The air pressure can be changed in three stages: a state in which the volume of the pressure body 52 increases, and a state in which the volume of the pressurizing body 52 increases when the switch 56 is turned on.

In this way, the tire pressure can be changed in three stages, so by setting the initial tire pressure to be suitable for normal driving, you can adjust the front tire pressure and the rear tire pressure when driving at high speeds. Balance can be easily achieved. That is, the initial air pressure of the tires is set to be suitable for normal driving, and the volumes of all pressurizing bodies are maintained in a reduced state. Then, a state of high air pressure during high-speed running is obtained by turning off the switch 56 and increasing the volume of the heating body 70 by the action of the permanent magnet 62, the coil 64, and the heat generator 68. When there is a high possibility of sudden braking,
Turn on the switch 56 only for the front tire, and the electromagnet 46,
Unbalance can be created by increasing the volume of the heating body 52 by the coil 48 and the heat generator 50, thereby further increasing the air pressure.

As described above, the volume of the pressurizing body increases when the amount of heat generated by the heat generator is large, that is, when the temperature is high, and the volume decreases when the temperature is low. Alternatively, the characteristics of the pressurizing body may be reversed, that is, when the heat generation amount of the heat generator is large, the volume decreases, and when the heat generation amount of the heat generator is small, the volume may be increased.

The reason why the initially set characteristic of weak understeer can be changed to oversteer by turning on only the switches related to the two front tires is as follows.

The stability factor h, which is an index of understeer-oversteer characteristics, is given by: Here, 1 is the wheel base, g is the acceleration of gravity, W, , W2 is the ground load of the front and rear wheels, CI, C2
is the cornering power of the front and rear wheels; when h > 0, it is called understeer, and when Kh < 0, it is called oversteer.

As shown in Fig. 11, the ground load A of the front wheels of the FF vehicle is
Recommended load B when the air pressure is 1.7 kgf/cm,
Recommended load B2 when air pressure is 2.4kgf/cI11
If the air pressure is increased, the cornering power C1 of the front wheels increases, and from the above equation, K
h<0.

[Brief explanation of drawings]

Fig. 1 is a front view of the air pressure adjustment device showing a tire in cross section, Fig. 2 is a side view of the air pressure adjustment device showing the tire in cross section, Fig. 3 is a perspective view with a part of the tire cut away, and Fig. 4 The figure is a sectional view showing a heat generator and a pressurizing body, FIG. 5 is a front view of another embodiment of the air pressure regulating device showing a tire in cross section, and FIG. 7th cross-sectional view cut by
The figure is a sectional view taken along the line 7-7 of Fig. 5, Fig. 8 is a perspective view of a partially broken tire, and Figs. 9 and 10.
The figure is a sectional view showing another example of a heat generator and a pressurizing body,
FIG. 11 is a characteristic diagram of cornering power versus load. 10. 12. 14. 16. 18. 20. 22. 24. 26. 28, 2 40: Carrier, 42: Disc wheel, 44: Tire, 46: Electromagnet, 30.48.60: Coil, 50.68: Heat generator, 52.70: Pressure body, 54.66: Magnetic body , 56: Switch, 58: Power supply, : Permanent magnet.

Claims (1)

[Claims] A device for adjusting the air pressure of a tire mounted on a disc wheel rotatably supported by a carrier, the device being arranged around a magnetic body attached to the carrier and connected to a power source via a switch. an electromagnet having a first coil, a second coil attached to the disc wheel so as to rotate in a magnetic field generated by the electromagnet; and heat generated by the current generated in the second coil. a pressurizing body disposed in the air inside the tire, the pressurizing body being made of a shape memory alloy that is reversibly deformable between a reduced volume state and an increased volume state; Tire pressure regulating device with two volume states by a heat generator.