NO346332B1

NO346332B1 - Method and device for detecting wear of a tire

Info

Publication number: NO346332B1
Application number: NO20200210A
Authority: NO
Inventors: Rolf Eckhoff
Original assignee: Fyster As
Priority date: 2020-02-18
Filing date: 2020-02-18
Publication date: 2022-06-07
Also published as: NO20200210A1; EP4107012A1; WO2021165291A1

Description

Method and device for detecting wear of a tire

Introduction

The invention relates to wear indicating arrangement for tires. More specifically, the invention relates to a method and device for detecting wear of a tire.

Background

During use, a tire is worn in the tread area which is a part of a tire that normally has a groove pattern which is in contact with the ground. The tread area is specifically designed to provide traction for stopping, starting, cornering and to provide long lasting wear.

Wear of a tire takes place over the time it is used due to friction forces working between the tire and a road surface. The friction force will also result in wear on the road surface. In the wintertime, when studded tires are often used, the road surface will be especially exposed to wearing due to studs tearing up the road surface.

Worn tires will result in increased breaking distance. This is especially the case in wet weather. Without sufficient tread in a tire, aquaplaning may occur when a layer of water builds between the tire and the road surface, thus leading to a loss of traction that prevents the vehicle from responding to control inputs. This may have severe consequences.

Tires should be removed from service and replaced when they reach a certain tread depth. This depth is the distance from the tread surface to the bottom of the main grooves.

If worn tires are not replaced in time accidents are more likely to happen due to skidding on bald or nearly bald tires. Also, excessively worn tires are more susceptible to damage from road hazards.

The common prior known method for determining wear on a tire is visual inspection. A combination of knowledge of the time a tire is used, and visual inspection is the most a common way of determining if a tire should be replaced. When performing a visual inspection, the tread depth is measured, and the tire is inspected for scratches etc.

Some tires have tread wear indicators that are located at the base of the main grooves and that are equally spaced around the tire. Built-in tread wear indicators look like narrow strips of smooth rubber across the tread that will appear on the tire when a certain point of wear is reached.

It is well known that tires are often not sufficiently inspected and that accidents occur due to poor quality of tires.

In addition to manual inspection, there are devices for automatically detecting the wear state of a tire. Known devices for indicating wear of a tire are complex and expensive and typically comprise devices arranged in the wheel between the tire and the rim. They normally require powered electronics with sufficient power to transmit the state of the tire wear. Powering by using cables is not a good option due to rotation of the wheel. The same applies to the use of batteries since these will require inspection and maintenance since the voltage will drop over time.

WO-2006/098840 describes a system and method for monitoring tread wear of a tire by means of frequency identification (RFID) technology. An RFID tag is embedded in the tread of a tire at one or more wear points. An RF tag reader periodically monitors signals from the at least one RFID tag. Absence of an RFID signal indicates that the RFID tag is destroyed, and thus that the tire covering the tag has been worn down.

EP-2368724 A1 describes a tire wear detection device comprising a piezoelectric element and a transmitter that are included in the rim of a tire. Signals from the wear detector are combined with signals from a pressure sensor unit indicating internal air pressure of the tire. The pressure sensor is arranged in the wheel. The signals from the piezoelectric element and the pressure sensor are received in a receiver unit arranged on a vehicle body.

JP-3875349 B2 describes a transmitter in a vehicle transmitting a signal to a passive transponder, typically an antenna, in the tread of a tire. When the tire is worn, the transponder is destroyed, i.e. worn off, and a response signal is not sent back. This solution does not require powered electronics in the wheel but does require a transceiver installed in the vehicle.

Known solutions for automatically detecting wear of a tire are mostly based on complex devices installed in the wheel and/or in the vehicle the wheel is mounted to.

The applicant has previously developed an alternative solution providing a simple and inexpensive way of automatically detecting and indicating tire wear independently of any transmitter or receiver installed in the vehicle the wheel is mounted to. The solution is based on a device detecting moisture for indicating wear of a tire. This solution is described in WO 2014198334 A1.

The present solution provides an alternative way of detecting and indicating wear of a tire where air is used as the means for activating a power source. The solution provides a simple and cheap way of detecting wear of a tire.

When a tire has been worn to a certain degree, air will at some point penetrate and activate a battery that will start generating power to a transmitter, thus indicating that the tire has been worn.

Summary of the invention

An object of the present invention is to provide a simple inexpensive way of automatically detecting and indicating tire wear.

In one aspect of the invention, this is achieved by a method for detecting and indicating wear of a tire by means of a transmitter installed in the tire. The transmitter is adapted to transmit signals when supplied with power.

Power is provided by placing a zinc-air battery below a wear surface in a tread area of the tire, where the battery is adapted for supplying power to the transmitter when exposed to air.

In one embodiment, signals comprising an identification of the transmitter are transmitted when the tread area is sufficiently worn down such that the zinc-air battery is exposed to air.

In one embodiment, two or more zinc-air batteries are place in the tread zone of the tire. If for instance two zinc-air batteries are placed at different locations in the tread area of a tire, a transmitter can be adapted to only transmit signals when both batteries are activated, i.e. when the power produced is above a certain minimum limit.

In one embodiment, one or more sensors are placed in the tire for measuring pressure and temperature. The sensors are connected to the transmitter.

The invention is further defined by a wear detection device for detecting and indicating wear of a tire. The device comprises a transmitter adapted to transmit signals when supplied with power. The transmitter is installed in the tire. The detection device further comprises a zinc-air battery which is placed below a wear surface in a tread area of the tire. The battery is connected to the transmitter and supplies power to the transmitter when exposed to air.

Detailed description of the invention

As mentioned, the object of the present invention is to provide a method and a device for detecting and indicating wear of a tire 10.

The invention will now be explained in detail with reference to figure 1 showing the wear detection device for detecting and indicating wear of a tire 10. The device comprises a transmitter 20 that is installed in the tire. The transmitter 20 is adapted to transmit signals when supplied with power.

The power supply is provided by a zinc-air battery 30 placed below a wear surface in a tread area 15 of the tire 10. The battery 30 is connected to the transmitter 20 for supplying power to the transmitter 20 when the battery 30 is exposed to air.

Zinc–air batteries are powered by oxidizing zinc with oxygen supplied from the air. By placing the battery 30 below the wear surface it will be shielded from air until the wear surface is sufficiently worn down such that air reaches the battery. In this way the battery will act as a sensor since it will be activated and provide power to the transmitter 20 when exposed to air.

When a battery 30 is placed in a tread area 15 of a tire 10 and below a wear surface, air will not reach the battery before a certain amount of wear surface has been worn down. In one embodiment, the wear surface can be rubber from the tire itself or it can be a wear surface made in a different material. The wear surface may also comprise several stacked wear surfaces, e.g. rubber from the tire 10 itself and below that, another wear surface made in another material.

Each wear surface may thus comprise different thicknesses and/or materials such that each surface has a different time span to be worn down during use.

In one embodiment, the wear detection device comprises two or more zinc-air batteries 30 placed at different depths in the tread zone of the tire. This will enable detection of wear and degree of wear of a tire 10. Each battery can be placed below wear surfaces with different wear properties. The transmitter can respond and transmit a signal according to the voltage supplied. When for instance only one battery 30 is activated, one type of signal is sent from the transmitter. When two or more batteries are activated, thus providing higher voltages, another type of signal is transmitted. In its simplest form, type of signals can be based on transmitting power where higher transmitted power indicates that more batteries 30 are activated. Signals transmitted from the transmitter 20 can also comprise sensor data as well as voltage supplied.

Figure 1 shows an example of an embodiment of the invention. In this embodiment, the device comprises the zinc-air battery 30 as well as other means, all of which are placed in a cavity in the tread area 15 of a tire 10. More specifically this embodiment of the device comprises said zinc-air battery 30 as well as signal transmitting means connected to each other. The signal transmitting means comprising a transmitter 20 for transmitting a signal indicating wear of the tire when air is detected. The cavity can be a hole that is drilled, milled or pre-moulded in the tread area 15 of the tire 10.

The cavity can also be a housing holding the different parts of the wear detection device. The housing is inserted in the tread area 15 of the tire 10. The outside of the housing can be fitted with barbs such that when the housing is mounted in the cavity of the tire it will stick. As mentioned, the wear surface can for instance be rubber from the tire itself or it can be wear surface made in a different material, both of which are located above the cavity or the housing as in the last example.

In one embodiment of the invention the means for generating power comprises at least one zinc-air battery which will have a double function since it will act as an air detector 30 and power source when air penetrates through a worn wear surface.

When air reach the battery 30 it will be activated and generate energy that will provide power to transmitter 20 for transmitting a signal indicating wear of the tire.

The signal transmitting means can be standard known means comprising a radio transmitter 20 with corresponding electronics. In its simplest embodiment the information sent from the signal transmitting means can be a carrier wave with a set frequency and possibly as a pulsed signal. In a system comprising several tires, the identification of the device will also be added to the carrier wave.

The wear surface 15 above the battery 30 should be made in a material and with a thickness that is adjusted to kind of use of the tire 10, and that will give the desired time delay before the wear surface is worn down. For tires comprising the inventive device and that are mounted on heavy duty vehicles, the wear surface should be thicker and made of a material that is more resistant to wear that for lighter vehicles like private cars.

In one embodiment of the invention, the device further comprises a unique electronic identification such that it is possible to differentiate between different devices comprised in corresponding tires on a vehicle. A wear signal is then sent together with an identification of the device.

The battery can be placed in an airtight housing, i.e. the cavity where the battery is placed is air tight. This will be airtight until the wear surface is worn down due to friction forces exerted from the road on the wear surface. Wear of a tire will thus be detected and indicated since the wear detection device is installed in the tread area 15 of the tire 10 and will be worn simultaneously as the tread area 15 of the tire is worn.

The degree of wear of a tire will thus be reflected by the degree of wear of the wear surface of the device. How fast a wear surface of the device is worn will depend on the construction material used and where in the tread area 15 the device is located.

To receive the signals sent from the transmitter 20 in the device, a receiver must be used. One type of receiver used can be one mounted in the vehicle where the tires are mounted. Another type may be a portable receiver. The only requirement is that the receiver can receive the signals transmitted from the transmitter.

In one embodiment, the transmitter is a Bluetooth transmitter and the receiver is a Bluetooth receiver. The Bluetooth receiver can for instance be a mobile phone controlled by a dedicated application running on it.

When mounting new tires 10 on a vehicle, each with the inventive device installed, the ID of each device can be registered in said application as well as where on the vehicle each device is installed. The registration can be automated by using known techniques, for instance bar codes, RFID etc.

Other feasible options for receiving signals from the inventive wear detection device, for detecting and indicating wear of a tire, is for instance by using a receiver installed in a fixed location like a garage or service station.

One example of such an installation is at a petrol station where for instance a receiver is installed nearby a petrol pump. An indication of a worn tire 10 can then be given if a vehicle with a worn tire is located next to the pump.

As mentioned, the wear detection device according to the invention is installed in the tire 10 and at least the zinc-ait battery 30 is installed in the tread area 15 of the tire. The tread area 15 of a tire 10 is the area of a tire 10 in contact with the ground and thus the area of a tire 10 which is exposed to frictional forces wearing the tire. The location where the battery 30 is placed in the tire 10 is critical since it is the interplay between the wear surface of the tire 10 and location of the device relative to the wear surface that will determine the accuracy of detection of air and thus the degree of wear of a tire.

The wear surface of the device has preferably the same shape as the surface of the tread area 15 of the tire 10 it is installed in and the device is placed a few millimetres below the tread area 15 of the tire 10.

In one embodiment of the invention the device further comprises one or more additional sensors 40 for detecting other physical parameters than air.

Rerubbering for retreading a tire 10 is often performed on heavy duty tires 10 used for trucks, tips and other vehicles exposed to mayor wear of tires. When performing rerubbering of a tire 10, the inventive wear detection device can be placed in the worn tread area 15 prior to performing the rerubbering.

The present invention provides a flexible and inexpensive way of detecting and indicating wear of a tire 10.

Claims

1. A method for detecting and indicating wear of a tire (10) by means of a transmitter (20) installed in the tire, the transmitter (20) is adapted to transmit signals when supplied with power, c h a r a c t e r i z e d i n:

placing a zinc-air battery (30) below a wear surface in a tread area (15) of the tire (10), where the battery (30) is adapted for supplying power to the transmitter (20) when exposed to air.

2. The method according to claim 1, by transmitting signals comprising an identification of the transmitter (20) when the tread area (15) is sufficiently worn down such that the zinc-air battery (30) is exposed to air.

3. The method according to claim 1 or 2, by placing two or more zinc-air batteries (30) in the tread area (15) of the tire (10).

4. The method according to any of the previous claims, by further placing one or more sensors (40) in the tire (10) for measuring pressure and temperature.

5. The method according to any of the previous claims, by enclosing the zincair battery (30) in a housing.

6. A wear detection device for detecting and indicating wear of a tire (10), where the device comprises a transmitter (20) adapted to transmit signals when supplied with power, were the transmitter (20) is installed in the tire (10), c h a r a c t e r i z e d i n further comprising

a zinc-air battery (30) placed below a wear surface in a tread area (15) of the tire (10), where the battery (30) is connected to the transmitter (20) for supplying power to the transmitter (20) when exposed to air.

7. The wear detection device according to claim 6, further comprising a housing for enclosing the zinc-air battery (30).

8. The wear detection device according to claim 6, further comprising one or more sensors (40) for measuring pressure and temperature.

9. The wear detection device according to any of the claims 6 to 8, further comprising two or more zinc-air batteries (30) placed in the tread zone (15) of the tire (10).