JPH04300703A - Tire air pressure controlling device - Google Patents

Abstract

PURPOSE:To obtain both ride comfort at low speed vehicle running and steering stability at high speed vehicle running. CONSTITUTION:A tire air pressure controlling device comprises a first air room 3 formed between a tire 1 and a wheel rim 2 retaining the tire 1, a second air room 4 formed in the first air room 3, communicating to the first air room 3 through a communication path, and a centrifugal response valve to open or close the communication path according to the magnitude of centrifugal force occurring with rotation of the tire 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire air pressure control device that can change tire air pressure in accordance with the traveling speed of a vehicle.

0002

2. Description of the Related Art The air pressure in the tires of a vehicle affects not only the ride comfort of the vehicle, but also the driving performance. Therefore, attempts have been made to change the air pressure of the tires in accordance with the driving speed.

[0003] As such a tire air pressure control device,
For example, there is a device disclosed in Japanese Patent Application Laid-Open No. 62-53204, in which a cylinder communicating with the tire air pressure is attached to the wheel rim in the radial direction, and a centrifugal cylinder having an appropriate mass is placed inside the cylinder. A force-responsive piston is provided, and when the vehicle is running at high speed, the piston moves due to centrifugal force and pushes the air inside the cylinder into the air chamber of the tire, thereby increasing the air pressure.

0004

[Problems to be Solved by the Invention] However, in the configuration described in the above publication, since the cylinder chamber on the opposite side of the piston from the tire air chamber side communicates with the atmosphere, air leaks to the outside through the piston sliding surface. Not only is there a risk of leakage, but if the air pressure is to be increased by, for example, 20%, the cylinder becomes large and the dynamic balance of the tire is deteriorated, making it difficult to put it into practical use.

[0005] Therefore, the present invention has an extremely simple structure, and
Another object of the present invention is to provide a tire air pressure control device that is configured to utilize centrifugal force, but has no risk of air leakage and no problem of deteriorating dynamic balance.

[0006]

[Means for Solving the Problems] In a tire air pressure control device according to the present invention, a second air chamber is provided inside a first air chamber formed between a tire and a wheel rim, and a second air chamber is provided with a first air chamber through a communication path. It is characterized in that it is formed in such a manner as to communicate with the chamber, and is provided with a valve that opens and closes the communication passage in response to centrifugal force. The valve closes the communication passage in response to an increase in centrifugal force, thereby increasing the longitudinal spring constant of the tire compared to that at low speeds, ensuring ride comfort at low speeds and improving maneuverability at high speeds. I am trying to balance both.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of an embodiment of the present invention, 1
2 is a tire, and 2 is a wheel rim that holds the tire 1. A first air chamber 3 is formed in an annular shape between the tire 1 and the wheel rim 2. On the wall surface of the wheel rim 2 on the first air chamber 3 side, a partition wall 5 is provided around the entire circumference of the wheel rim 2 for forming a second air chamber 4 inside the first air chamber 3 and coaxially therewith. It is fixed. A centrifugal force responsive valve 20 is provided on the inner wall surface of the partition wall 5 . As shown in FIGS. 2 to 4, the centrifugal force-responsive valve 20 includes a cylinder 6 fixed to the inner wall surface of the partition wall 5 with its axis directed in the radial direction of the wheel rim 2, and a cylinder 6 that slides inside the cylinder 6. The piston is provided so as to be airtight with respect to the inner wall surface of the cylinder 6. The piston 7 is normally moved by the biasing force of a coil spring 8 compressed between the piston 7 and the end wall 6a of the cylinder 6 on the side far from the wheel rim 2 (the upper end wall in FIGS. 1 to 3). It is in contact with an end wall (a lower end wall in FIGS. 1 to 3) 6b of the cylinder 6 on the side closer to the wheel rim 2. In order to obtain an appropriate mass, the piston 7 may include a weight 9 such as a lead ball, depending on its material.

A hole 10 is formed in the end wall 6a of the cylinder 6 on the side far from the wheel rim 2, and the hole 10 communicates the inside of the cylinder 6 with the second air chamber 4. In the wall portion 6c, a hole 11 is made at a position midway between the end walls 6a and 6b, and a hole 12 that substantially coincides with this hole 11 is also made in the partition wall. Therefore, in a normal state (the state shown in FIG. 3), a communication path 13 that passes through the cylinder 6 from the holes 12 and 11 and exits to the hole 10 is formed between the first and second air chambers 3 and 4. Second air chamber 3
, 4 are in communication with each other. Note that an end wall 6b of the cylinder 6 on the side closer to the wheel rim 2 is open to the second air chamber 4.

In the above configuration, when the vehicle is stationary or running at low speed, the piston 7 comes into contact with the end wall 6b of the cylinder 6 on the side closer to the wheel rim 2 due to the biasing force of the coil spring 8, and the centrifugal force responsive valve 20 is in a state where the communication path 13 is opened. Therefore, since the first and second air chambers 3 and 4 communicate with each other via the communication path 13, if the volume of the first air chamber 3 is V1 and the volume of the second air chamber 4 is V2, the tire air Volume V is V=V1+V2
becomes. Next, when tire 1 rotates at high speed, piston 7
moves inside the cylinder 6 against the biasing force of the spring 8 due to centrifugal force, and as shown in FIG. The communication path 13 communicating between the two is closed. Therefore, the tire air volume V decreases to V=V1. Even if the piston 7 moves further, the communication passage 13 remains closed.

By the way, it is known that the longitudinal spring constant k, which represents the elastic force of a tire, is proportional to ρS2/V (ρ is the air pressure, S is the ground contact area), and if ρS2 is constant, the tire longitudinal spring constant k is inversely proportional to the tire air volume V. In other words, the ratio kL/ of the tire longitudinal spring constant kL during low-speed running and the tire longitudinal spring constant kH during high-speed running is kL/
kHz is proportional to V1/V1+V2, so V1/
When V1+V2=85%, for the same tire, if kL is the tire longitudinal spring constant when the air pressure is 1.6Kg/cm2, then kH is the tire longitudinal spring constant when the air pressure is 2.0Kg/cm2.
It will be equivalent to increasing it to cm2. therefore,
This makes it possible to achieve both ride comfort at low speeds and maneuverability at high speeds. Furthermore, according to this embodiment, depending on the mass of the piston 7 and the strength of the coil spring 8,
Tuning is easy because the traveling speed for closing the communication passage 13 of the centrifugal force responsive valve 20 is set, and since the centrifugal force responsive valve 20 is provided in the second air chamber 4, the first air chamber 3 There is no risk of the air inside leaking to the outside.

0012

[Effects of the Invention] As is clear from the above description, according to the present invention, as the rotational speed of the tire increases, the tire air chamber volume decreases after a certain speed. It is possible to achieve both ride comfort at low speeds and maneuverability at high speeds, prevent the occurrence of standing caused by insufficient tire pressure when driving at high speeds, and reduce running resistance, which reduces fuel consumption. can be improved. Furthermore, since the centrifugal force responsive valve is provided inside the tire, there is no risk of air inside the tire leaking to the outside through the centrifugal force responsive valve.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the invention.

FIG. 2 is a perspective view of an embodiment of the invention.

FIG. 3 is a sectional view showing the state of the centrifugal force responsive valve applied to the present invention during low speed running.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

5 is a sectional view showing the state of the centrifugal force-responsive valve of FIG. 3 during high-speed running; FIG.

[Explanation of symbols]

1 tire 2
wheel rim 3
First air chamber 4 Second air chamber 5 Partition wall 6 Cylinder 7
piston 8
coil spring 9
Weights 10, 11, 12 Hole 13 Communication path

Claims (3)

[Claims] Claims: 1. A first air chamber formed between a tire and a wheel rim holding the tire; and a first air chamber formed within the first air chamber and communicating with the first air chamber through a communication passage. A tire air pressure control device comprising: a second air chamber; and a centrifugal force-responsive valve that opens and closes the communication passage depending on the magnitude of centrifugal force acting as the tire rotates. 2. The tire air pressure control device according to claim 1, wherein the valve is configured to close the communication passage in response to an increase in centrifugal force. 3. The tire air pressure control device according to claim 1, wherein the communication path is formed by a hole provided in a partition wall that partitions the first air chamber and the second air chamber.