WO2008034825A1

WO2008034825A1 - Tyre module with piezoelectric transducer

Info

Publication number: WO2008034825A1
Application number: PCT/EP2007/059850
Authority: WO
Inventors: Jakob Schillinger; Dietmar Huber; Manfred Krapf; Günther ROMHART; Klaus Liebrich
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2006-09-19
Filing date: 2007-09-18
Publication date: 2008-03-27
Also published as: DE102007044723A1

Abstract

A tyre module (1) with a piezo element (2) which is arranged on an inner side of a tyre is intended to make available an improved tyre module (1) with a piezoelectric energy transducer for mounting in the interior of a tyre. For this purpose, there is provision according to the invention for the tyre module (2) to be surrounded at least partially by an encapsulating material (8).

Description

Tire module with piezoelectric transducer

The invention relates to a tire module with a piezo element, which is arranged on an inner side of a tire, and a tire pressure monitoring system with such a tire module.

In modern automobiles, tire air pressure sensing devices are increasingly used to avoid defects or accidents due to incorrect tire air pressure. In many of these systems, a tire module is arranged on each wheel, in particular in the interior of the tire. A tire module often comprises at least one sensor for detecting at least one tire parameter, in particular the tire air pressure, as well as a transmitting unit and optionally evaluation electronics. The power supply of the electronic components can, for. B. by a battery, an energy converter with piezoelectric element or a transponder coil done.

From DE 44 02 136 Al a system for determining the operating parameters of vehicle tires is known in which a sensor unit, an evaluation and a piezoelectric element is arranged on a support body, which supplies the other system components with energy. The piezoelectric element has a multilayer structure.

EP 1 614 552 A1 discloses a bridge-shaped patch with an electromechanical transducer for use in a vehicle tire. In the electric power generation system having a piezoelectric element disclosed in WO 2006/003052, the piezoelectric element is surrounded by a cover formed as a fixed casing or a globtop and thus protected from a surrounding potting compound ,

When using an energy converter to power a tire module mounted in the tire interior, it must be ensured that the energy converter is designed to withstand the stresses throughout the life of the tire. It is advantageous if the energy converter with the other components, such. As the electronic components, a compact module forms.

Based on this prior art, the present invention seeks to provide an improved tire module with piezoelectric energy converter for mounting inside a tire.

This object is achieved in that the tire module is at least partially surrounded by a Umschließungsmaterial.

Advantageous embodiments of the invention are the subject of the dependent claims.

The invention is based on the consideration that a tire module that makes use of an acceleration change to convert motion and / or deformation energy into electrical power requires a seismic mass that is deflected by the acceleration that arises during driving. A mass which can also be used as a seismic mass is available both through the piezoelectric element itself and through an enclosure which typically serves for protection and / or fastening.

In order to achieve a particularly durable attachment of the tire module in the tire interior, even at high loads, the tire module is advantageously positively or non-positively and in a particularly advantageous embodiment form-fit and frictionally embedded in the enclosing material.

In order to enable an attachment of the tire module in the tire interior, even after the production of the tire in the retrofit process, and a particularly high energy production, a suitable for flexible attachment of the tire module in the tire interior attachment means is advantageously provided.

In order to achieve a self-sufficient power supply of the tire module and thus a signal transmission to an associated receiving unit in the motor vehicle, the piezoelectric element is advantageously designed as a piezoelectric transducer element for generating electrical energy.

In order that the piezoelectric transducer element can be protected against weathering and other influences, it is advantageously completely surrounded by the enclosing material. To generate electrical energy, a mechanical force acting on the piezoelectric transducer element is required. To achieve this force, the enclosing material is advantageously designed as a seismic mass for the piezoelectric transducer element. - A -

In order to be able to achieve an increase in energy production, an additional seismic mass is advantageously embedded in the enclosing material, the specific gravity of which is expediently higher than that of the enclosing material.

To achieve a particularly high mechanical force by a particularly large lever, the additional seismic mass is spatially separated from the piezoelectric transducer element embedded in the enclosing material.

In order to be able to optimally adapt the piezoelectric wall element to the shape and the design of the tire module, this is expediently annular, flat, strip-shaped, fibrous, foil-like or fabric-like.

Usually, the piezoelectric wall element is designed as a single layer. In a particularly advantageous embodiment, in order to achieve a temperature compensation with simultaneous doubling of the signal voltage, the piezoelectric wall element is designed in multiple layers.

In order to be able to select the manufacturing process which is as advantageous as possible for the overall design, different production methods, such as transfer malls, injection mounts, overmolds or potting, are provided for embedding the piezoelectric transducer element in the enclosing material. The arrangement of the piezoelectric transducer element is advantageously carried out on a carrier layer in order to exclude as far as possible mechanical damage to the piezoelectric transducer element, and in a particularly advantageous embodiment on a printed circuit board in order to provide electrical contacts.

In order to receive and / or evaluate and / or transmit information, a number of further electronic components, in particular a pressure and / or temperature sensor, an evaluation circuit and a transmitting and / or receiving unit, are advantageously arranged on the carrier layer.

In order to reliably protect the carrier layer with the piezoelectric transducer element and the other electronic components against weathering and other influences, the carrier layer with the components is advantageously completely, possibly also surrounded by multi-layered enclosing material.

In order to achieve a particularly reliable electrical connection of the piezoelectric transducer element, its contacting is advantageously carried out in adhesive, solder, pressure contact or bonding wire technology.

In order to store energy permanently and to evaluate and transmit the measurement signals, the piezoelectric transducer element is expediently with an electrical memory, for. As a capacitor or Elko, in a particularly advantageous embodiment of a rectifier connected. In order to be able to deduce the lathe width of the tire from the temporal position of the piezoelectric charging currents, the tire module advantageously comprises one or more additional electrical taps for decoupling the generated voltage.

The advantages achieved by the invention are in particular that the tire module has a simple and space-saving design and is protected by the embedding in the enclosing material and the piezoelectric energy converter effectively ensures the power supply of the tire module for the extraction, evaluation and transmission of information.

To increase driving safety and / or driving comfort sensors are usually mounted in motor vehicles on the wheel or in the rim, which measure the tire pressure and / or the temperature (tire pressure sensor). A further improvement is achieved if in addition the latitude or latitudinal length, ie the length of the tire footprint, is detected. This value can be used to improve the control of the brake systems, the damper systems and / or the drive system. Known tire pressure monitoring systems usually derive their energy from a battery or are supplied via an electromagnetic field (transponder systems). Since these energy sources have disadvantages, among others, in terms of costs, disposal, service life and weight, an increasing attempt is being made to use self-sufficient supply systems. Care should be taken that the mounting of the sensor module takes place at a location that can not lead to damage during assembly or disassembly of the tire on the rim. Rolls a tire of a motor vehicle, motorcycle, scooter, commercial vehicle, bicycle or airplane on a surface from, so there is always a flattened footprint - the so-called Laces. During the rotational movement of the tire, the centrifugal acceleration acts on a tire module which is arranged on the tire inner liner, in particular in the area of the tire tread. If the module is located within the footprint, however, only the acceleration due to gravity is active. When entering and exiting the lane pass, the radius of the tire is reduced (flattening) and there is an increase in acceleration.

A tire module that makes use of an acceleration change to convert kinetic energy and / or strain energy into electrical energy requires a seismic mass that is deflected by the acceleration. The idea of the invention is that the enveloping mass of the tire load sensor (tire module) is the seismic mass of an energy converter with at least one piezoelectric element (piezoelectric element).

For this purpose, at least one piezoelectric element is completely or partially, in particular positive and / or non-positive, embedded in the Umhüllmasse. The piezoelectric element may be annular, planar, strip-shaped, fibrous, foil-like or fabric-like. In addition, the piezoelectric element can be designed in one or more layers. The embedding of the piezoelectric element is carried out by Transfermolden, Injection golden, Overmolden or potting. As Ummüllmasse (enclosing material) plastics are suitable materials such. As thermoplastics, thermosets (eg epoxy), potting materials, silicones, paints or the like.

The piezoelectric material may be a piezoelectric ceramic, in particular lead zirconate titanate (PZT), or a piezoelectric film, in particular of polyvinylidene fluoride (PVDF).

The piezoelectric element is used together with an electrical circuit and / or other electronic components, eg. As sensors, in particular a pressure sensor, evaluation, transmitting and / or receiving devices for the exchange of control and data signals, storage, etc., applied to a substrate (circuit board). This shoring unit is fully ummoldet, partially and / or multi-layered. The resulting tire module is attached by means of suitable fasteners (attachment means) on the inner liner flexible (loose, movable).

The tire module is arranged on the innerliner of the tire such that a partially different surface pressure is produced on the encapsulation material during the slippage pass at the transition from the centrifugal acceleration to the gravitational acceleration and vice versa. In other words, during the transition into and out of the luffing area, the tire module according to the invention experiences different contact forces which, via the direct coupling of the enveloping mass to the piezo element (s), result in a small but sufficient, reversible elastic deformation of the piezo element (s). s) leads. This deformation generates an electrical charge which, after rectification, forms an electrical memory (eg capacitor, Electrolytic capacitor or accumulator) charges and / or provides the trigger signals for the Latschweitenmessung. It is also conceivable that the piezo element is used solely for generating the trigger signals for the latitude measurement and the power supply is supplied by a battery or a transponder module.

The shape of the enveloping compound and the position of the piezoelectric element (in the tire module) are selected in such a way that as much charge as possible is generated in the transition zone from and into the lathe zone. In this case, electrical charge by bending, torsional, shear, tensile, compressive and / or tensile forces acting on the sensor element can be generated.

The generation of electrical energy by the piezoelectric transducer element is typically done by spatially different contact forces on the enclosing material, which lead to bending, torsional, shear, tensile, compressive and / or tensile forces on the piezoelectric transducer element.

Upon reaching a certain minimum voltage of the electrical memory and / or upon receipt of a trigger signal, the electrical memory supplies the measuring electronics of the tire module. This performs a measurement and transmits the measured data to an HF receiver via an RF transmitter (HF: high frequency). The discharge of the electrical memory is up to a lower threshold voltage, which is sufficient, part of the measuring electronics, z. As the part for determining the Latschlänge continue to supply voltage. That is, in a preferred embodiment, the charging voltage of the electrical storage is in several Divisions divided into: "Transmit voltage range", "Latch voltage range" and "No function".

In a simplistic manner, this can be done by an additional tap on the piezoelectric element In a preferred embodiment, therefore, the tire module for decoupling the acceleration voltage has one or more additional electrical taps on the piezoelectric element, and embodiments with several piezoelectric transducers are also conceivable.

The mounting surface for the piezo element also serves as a mounting and wiring surface for the electrical circuit and / or the electrical components of the tire load sensor (tire module).

It is furthermore preferred, but not absolutely necessary, for at least one additional mass to be enamelled in the tire module in order to increase energy production.

In contrast to the known alternative methods of energy recovery / conversion by means of piezoelectric element in this invention, a flexible (loose) connection between the tire module / piezoelectric element and the tire is used. Adhesion of the tire module to the tire or embedding in the tire is not performed. On the tire an attachment means (adhesive patch), z. B. by gluing, attached. In or on this, the tire module (loose) is arranged, for. B. by attaching, inserting, hooking or the like. The tire module is so arranged, limited by the attachment means, movable in the tire. An embodiment of the invention will be explained in more detail with reference to a drawing. Show:

1 schematically shows an annular tire module,

2 shows schematically a flat tire module,

Fig. 3, 4, 5 schematically the electrical connection of the

Piezoelementes in various embodiments.

Identical parts are provided with the same reference numerals in all figures.

Fig. 1 shows schematically an example according to the annular tire module 1 with annular piezoelectric element 2. A piezoelectric element 2 is mounted on a carrier layer 4, for. B. PCB, arranged on which also other components 6, such. As electronic circuits, sensors or other electronic components are arranged. These components 6 are embedded in a wrapping compound 8 (enclosing material), which encloses the components 6. The Umhüllmasse 8 is carried out according to the example annularly with a hole in the middle. The tire module 1 is placed on the innerliner of the tire by means of an attachment means 10, a fastening patch (eg, adhesive patch) comprising an approximately mandrel-like formation 12 (attachment pin). For this purpose, the attachment means 10 (fixing patch) z. B. glued by means of an adhesive surface 11 on the inner liner of the tire, not shown here. The tire module 1 is placed with the hole on the mounting pin 12. The fixing patch 10 um- This protects the attachment means 10 against abrasion or damage by the Umhüllmasse 8 and also serves as an abutment for the tire module 1. In the wrapping 8 is, for example, an annular additional mass 16, the already existing by the wrapping material 8 seismic mass raised, embedded. The additional mass 16 is preferably arranged in the region of the outer edge of the wrapping compound 8.

FIG. 2 schematically shows an exemplary flat piezoelectric element 2 or planar tire module 1. A piezoelectric element 2 is mounted on a carrier layer 4, for example a piezoelectric element 2. B. PCB, arranged on which also other components 6, such. As electronic circuits, sensors or other electronic components are arranged. These components 6 are embedded in a wrapping compound 8, which encloses the components 6. The surface of Umhüllmasse 8 can z. B. be round, square, rectangular or polygonal executed. In the wrapping compound 8, an additional mass 16 is embedded according to the example. The additional mass 16 is preferably arranged in the central region of the surface of the enveloping mass 8. To attach the tire module 1 to the tire, the sensor module 1 (tire module) is inserted into a fastening patch 10 (attachment means) and / or fixed to the inner liner 18 by a belt or a plurality of straps.

The attachment patch 10 is adhered, for example, via an adhesive surface on the inner liner 18, but there are also other mounting options are conceivable. The attachment means 10 has hook-shaped side parts 20 or a circumferential, tapered edge. By bending the side parts 20, it is possible to insert the tire module 1 in the attachment means 10. The tire module 1 is loose in the Attachment means 10 and is prevented by the hook-shaped side parts 20 from falling out.

In a preferred embodiment, the printed circuit board 4 in the region of the piezoelectric element 2 has a cutout. As a result, the piezoelectric element 2 can be completely embedded in enclosing material 8.

FIG. 3 schematically illustrates an embodiment for the electrical connection of the piezoelectric element. It is a frontal electrical connection of the piezoelectric element 2 to a printed circuit board 4 with cutout, wherein the end faces 22 are each arranged on the right and left of the piezoelectric element. The electrical connection is done by gluing or soldering to the adhesive or solder joints 24. The adhesive or the solder material is also used here for attachment of the piezoelectric element 2 to the circuit board 4. The piezoelectric element 2 is not shown here with a rectifier circuit with a charge storage and / or connected to a trigger circuit for the Latschweitenmessung.

4 shows a planar electrical connection of the piezoelectric element 2 to a circuit board 4 with cutout. The flat contacts 26 are arranged on and below the piezoelectric element. The lower contact 26 is guided for easier tapping via a conductor 27 upwards. The electrical connection is done in each case by means of a bonding wire 28. The piezoelectric element 2 is attached via splices 24 to the circuit board 4.

5 shows a piezoelectric element 2 with a flat electrical tap in plan view. On the upper side An additional tap 30 is attached. By means of this additional tap 30, a decoupling of the piezoelectric voltage is additionally carried out. This arises, as already described above, proportional to the acceleration. This signal is preferably used to determine the latitudinal length and to obtain information to be determined from the latitudinal length.

LIST OF REFERENCE NUMBERS

1 tire module

2 piezo element

4 carrier layer

6 electrical components

8 enclosing material

10 attachment means

11 adhesive surface

12 fixing pin

14 protection ring

16 additional mass

18 inner liners

20 side panel

22 front side

24 adhesive or solder joint

26 contact surface

27 electrical conductors

28 bonding wire

30 additional electrical tap

Claims

Claims:

A tire module (1) having a piezoelectric element disposed on an inner side of a tire, characterized in that the tire module (1) is at least partially surrounded by a surrounding material (8).

2. Tire module (1) according to claim 1, characterized in that the piezoelectric element (2) is at least partially embedded in the enclosing material (8) of the tire module (1) positively and / or non-positively.

3. tire module (1) according to claim 1 or 2, characterized in that the tire module (1) via an attachment means (10) is arranged flexibly on or in the tire inner side.

4. tire module (1) according to one of claims 1 to 3, characterized in that a number of Piezoelemen- th (2) is designed as a piezoelectric transducer elements.

5. tire module (1) according to claim 4, characterized in that the piezoelectric transducer element is completely embedded in the enclosing material (8).

6. tire module (1) according to claim 4 or 5, characterized in that the enclosing material (8) is designed as a seismic mass for the piezoelectric transducer element.

7. tire module (1) according to one of claims 4 to 6, characterized in that in the enclosing material

(8) an additional seismic mass (16) is embedded.

8. tire module (1) according to claim 7, characterized in that the additional seismic mass (16) is spatially separated from the piezoelectric transducer element in the enclosing material (8) embedded.

9. tire module (1) according to one of claims 4 to 8, characterized in that the piezoelectric transducer element is designed annular, flat, strip-shaped, fibrous, film-like or fabric-like.

10. tire module (1) according to one of claims 4 to 9, characterized in that the piezoelectric transducer element is designed in one or more layers.

11. Tire module (1) according to one of claims 4 to 10, characterized in that the piezoelectric transducer element is embedded by Transfermolden, Injektionsmolden, Overmolden or potting in the enclosing material (8).

12. tire module (1) according to one of claims 4 to 11, characterized in that the piezoelectric transducer element on a carrier layer (4), in particular a printed circuit board, is arranged.

13. Tire module (1) according to claim 12, characterized in that on the carrier layer (4) at least one further electronic component is arranged.

14. tire module (1) according to claim 12 or 13, characterized in that the carrier layer (4) with the / the arranged thereon element (s) is completely embedded in the enclosing material (8).

15. Tire module (1) according to one of claims 4 to 14, characterized in that the electrical contacting tion of the piezoelectric transducer element in adhesive, solder, pressure contact or bonding wire technology is performed.

16. tire module (1) according to one of claims 4 to 15, characterized in that the piezoelectric transducer element is connected via a rectifier with an electrical memory.

17. tire module (1) according to claim 16, characterized in that the piezoelectric transducer element is connected to a trigger electronics.

18. Tire module (1) according to one of claims 4 to 17, characterized in that the piezoelectric transducer element at least one further electrical Ab- handle (30) for decoupling the voltage generated.

19. tire pressure monitoring system with a tire module (I] according to any one of claims 1 to 18.