DE102008029534B4 - Tire module with piezoelectric transducer - Google Patents

Abstract

Tire module for detecting tire condition variables, comprising a piezoelectric transducer with a bending element (1, 1 '), wherein the bending element is coupled to piezoelectric material or consists of piezoelectric material, wherein the tire module is made in two parts with a first (7, 7') and a second (6, 6 ') module part, which are placed on one another or inserted into one another and are movable relative to each other in at least one approach direction, and wherein the bending element (1, 1') by means of at least one clamping device (2, 3, 2 ') is fixed to the second module part (6, 6 ') and is deformed relative to each other in the approach direction by a mechanical interaction with the first module part (7, 7') during a movement of the two module parts (6, 7, 6 ', 7') , wherein at least one deforming element (5, 5 ') is arranged on the first module part (7, 7'), which with the bending element (1, 1 ') during a movement of the two module parts (6, 7; 7 ') interacts mechanically relative to one another and the bending element (1, 1') is deformed, wherein a damping element (4, 4 ') is arranged on the second module part (6, 6'), the damping element (4, 4 ') is arranged opposite the deformation element (5, 5 ') arranged on the first module part (7, 7'), and wherein the bending element (1, 1 ') is at least partially situated between deformation element (5, 5') and damping element (4, 4 ') ') is located.

Description

The invention relates to a tire module and its use in a tire pressure monitoring system.

In modern motor vehicles are increasingly used devices that detect defects and malfunction of various areas in the vehicle early and report to the driver. This includes, for example, the collection of tire air pressure to avoid defects or accidents due to low tire inflation pressure. In many of the systems already used for this purpose, a tire module is arranged on each wheel, in particular in the interior of the tire. A tire module usually comprises at least one sensor for detecting a tire parameter, in particular the tire air pressure, as well as a transmitting unit and optionally an associated evaluation electronics. The supply of the electronic components with electrical energy can be done for example by a battery, a microgenerator with piezoelectric element or a transponder coil or by a combination of at least two of these elements.

When using a microgenerator to power a tire module mounted in the tire interior, it is useful if the microgenerator is configured to withstand the loads for at least the life of the tire. It is advantageous if the microgenerator with the other components, such. makes the components, a compact module.

The DE 10 2004 031 810 A1 describes a tire control system which generates electrical energy via a piezoelectric element disposed within the tire.

The DE 10 2005 000 996 A1 provides that a spring element of a tire module is designed as a rod, torsion or leaf spring. At a non-clamped end of the spring element, a seismic mass is arranged, which is acted upon by the rolling of the tire with a pulse. The storage of the seismic mass on the spring element results in a spring mass oscillator, which has an increased efficiency in contrast to conventional piezoelectric energy converters. To achieve a compact design, a piezoelectric element is mounted directly on the spring element, so that a deflection of the spring element leads to an expansion or compression of the piezoelectric layer, so that at the corresponding contact surfaces, an electrical voltage can be tapped. A vibration is generated by the tire module moving on a straight path during the unwinding at each load pass while traveling in a circular path after the lint exit. During the orbit, the centrifugal force acts on the seismic mass, in latsch it is ideally force-free. Due to the centrifugal force of the spring-mass oscillator is deflected and strives in Latsch to return to its rest position. There are over- and reverberations, whereby the seismic mass is in motion even during the phases of constant force, ie between the transitions. However, the high mobility of such a spring-mass oscillator involves the risk of increased susceptibility to damage, eg by material fatigue or sudden, strong forces, such as in curbside crossing o.ä. may occur.

From the DE 603 10 104 T2 a current generator for mounting in the interior of a pneumatic tire is known, wherein the current generator comprises a piezoelectric element, provided for contact with the piezoelectric element actuating mass and a control circuit which is in electrical communication with the piezoelectric element, wherein the actuating mass for deflecting the piezoelectric element is provided as a result of external forces acting in use on the actuating mass to generate an electrical charge, the control circuit forming at least a portion of the actuating mass.

From the DE 10 2007 001 361 A1 a power generating device for a tire sensor module of a vehicle tire is known, comprising: a piezoelectric element which is adjustable between a first stable bending position and a second stable bending position and outputs an electric piezoelectric voltage in the adjustment between the stable bending positions, and a return device for the mechanical adjustment of the Piezoelementes of the first stable bending position in the second stable bending position, wherein the restoring device can be activated by a force acting on the energy generating device deformation. This deformation can occur in particular in a deformed tire area of the vehicle tire above its tire footprint. The piezo element is clamped with its end portions in recordings and has two oppositely curved stable bending positions with unstable intermediate states. Here, the restoring device and the receptacles are mounted in two relatively adjustable housing areas.

From the DE 10 2007 010 782 A1 For example, a tire module is known with a piezoelectric transducer for attachment to an inside of a tire, especially a vehicle tire. To For example, the piezoelectric transducer includes a plurality of elastic bending portions formed of piezoelectric material and a deflection limiting means that protects the elastic bending portion from excessive bending.

From the DE 101 55 125 B4 a device for converting mechanical energy into electrical energy with a piezoelectric transducer is known, wherein the piezoelectric transducer is preferably a multilayer piezoelectric transducer, and wherein for deforming the piezoelectric transducer, a, having a mechanical energy storage, designed as a lever mechanism deformation mechanism is provided, wherein by a Weguntersetzung the deformation of the Deformation mechanism when storing the mechanical energy is greater than in the delivery of mechanical energy to the piezoelectric transducer so that a force acting on the piezoelectric transducer force is achieved by leverage, which is reinforced by the achieved by the leverage effect factor of Wegverkürzung.

Based on this prior art, the present invention seeks to provide an alternative tire module with a piezoelectric transducer for mounting inside a tire. The tire module should be as compact as possible and offer good protection against destruction of the piezoelectric transducer. In addition, the structure of the tire module with a piezoelectric transducer should allow sufficient recovery of electrical energy to supply at least a portion of the components of the tire module.

This object is achieved by the tire module according to claim 1.

The invention is based on the idea of designing the tire module in two parts, wherein the first and the second module parts are placed on one another or inserted into one another and can be moved towards each other in at least one direction. In such a movement towards each other, the bending element of the piezoelectric transducer, which is attached by means of one or more clamping devices on the second module part, deformed by mechanical interaction with the first module part. By the piezoelectric material of the transducer, the deformation energy is converted into electrical energy.

Preferably, the piezoelectric transducer or the piezoelectric material via the clamping device (s) is electrically contacted. This is advantageous because the clamping device (s) does not move / move relative to the module (part). On the other hand, electrical contacts in other places can be destroyed by the relative movement over time.

In order to achieve a controlled relative movement of the two module parts, a guide element is preferably arranged on at least one of the two module parts, which guides the two module parts relative to one another in the direction of approach. For example, prevents a bulging of the two module parts, which can lead to damage or destruction of the bending beam. In order to achieve a stable guidance, a guide element is particularly preferably arranged on each module part. In a can-shaped embodiment of the two-part tire module, the guide elements on the first and second module parts are most preferably designed in the form of mating edges. This ensures a high stability against parallel displacements of the module parts with a simple construction.

According to the tire module according to the invention, at least one deformation element is arranged on the first module part, which deforms the bending element in a movement of the two module parts relative to each other by mechanical interaction. With a suitable choice of the material and / or the shape of the deformation element as a damage of the bending element is avoided by the mechanical interaction with the first module part.

To allow disassembly of the tire module into its two parts, e.g. is necessary in the case of replacement of one of the two module parts, the bending element is preferably loosely on the deformation element. The bending element is therefore not connected to the first module part.

Preferably, a damping element between the two module parts is arranged. This springs the movement of the module parts against each other and replaces e.g. a guide on the module parts. Particularly preferably, the damping element is a silicone foam, since this is resilient and can be produced inexpensively. Advantageously, a damper element made of silicone foam in the form of the edge of the base of the tire module is inserted between the two module parts in order to avoid a slip-stick effect with a simple structure.

In order to protect the bending element on the side of the second module part, a damper element is arranged on the second module part, wherein the damper element is positioned substantially opposite to the deforming element disposed on the first module part, and the bending element extends at least partially between the deforming element and the damper element. So the place of the Bending element, on which the mechanical interaction between the bending element and the deformation element occurs, supported on the other side of the bending element. For the reasons already mentioned above, the damping element is particularly preferably a silicone foam.

According to one development of the invention, a seismic mass is arranged on one (for example the second) module part, in order thus to reinforce the relative movement of the module part and to compensate for a deceleration of the relative movement by friction losses between the module parts. The seismic mass essentially supports a movement of the two module parts relative to one another in the direction of approach. This increases the energy yield of the converter. The seismic mass is particularly preferably attached to a side facing away from the other (for example, the first) module part, so that, despite the smallest possible dimensions of the tire module, there is no obstruction due to a lack of space in the approximation of the first and second module parts.

Preferably, the seismic mass comprises at least one electronic component of the tire module, particularly preferably it comprises all electronic components of the tire module, which are not directly connected to the bending beam. As a result, a part of the tire module mass itself is used as a seismic mass. The mass of the tire module is thus not increased by a seismic dummy mass. The least possible weight of the tire module is e.g. necessary to avoid imbalance in the tires. Electronic components, which are very particularly preferred for arrangement as a seismic mass, are a printed circuit board and / or a battery and / or a sensor element and / or a transmitter.

The tire module is preferably mounted on the inside of the tire in the area of the tread, since the forces acting here are largest at Latscheintritt and exit. For this purpose, the first module part is particularly preferably fastened to the tire because the bending element is not connected to it. Thus, in the case of an exchange of the bending element, the first module part can remain in the tire.

Preferably, the seismic mass is arranged on the second module part, to which also the bending element is attached. As a result, essential components of the tire module are combined in the same (second) module part, and can thus be e.g. If necessary, simply be exchanged together.

According to a further preferred embodiment of the tire module according to the invention, this comprises at least one stop element which limits the movement of the two module parts relative to one another in at least one direction. This results in e.g. avoid excessive deformation of the bending element. Particularly preferably, the movement in the direction of approach is limited by a stop element, so that upon movement of the module parts towards each other, no breakage of the bending element can occur. Alternatively or additionally, the movement of the two module parts in the direction opposite to the direction of approach is limited by a stop element in order to prevent a detachment of the second module part from the first module part.

The tire module is preferably designed in the form of a can, one module part corresponding to the bottom of the can and the other module part to the can lid, wherein the bending element is arranged inside the tire module. As a result, a compact tire module is achieved with good protection of the bending element. The shape of the can base is arbitrary, however, a simple geometric shape, such as. round or oval or rectangular or square base, due to the ease of manufacture advantageous.

According to one embodiment of the invention, the approach direction of the two module parts is substantially perpendicular to the base of the tire module to minimize lateral forces on the bending element, wherein the base surfaces of the two module parts are substantially parallel and corresponds to the base of a module part of the base of the tire module ,

In order to save material costs and installation space, the piezoelectric material is preferably electrically contacted via the clamping device (s) of the bending element.

According to another preferred embodiment of the tire module according to the invention, the tire module is designed in two parts, wherein a first and a second module part are placed on each other or inserted into each other and wherein the two module parts by at least one guide element, which is arranged on at least one of the two module parts, guided relative to each other be so that the two module parts are moved by an acting in the tire acceleration change substantially in one direction against each other, and wherein the second module part is connected by means of at least one clamping device with the bending element, wherein upon movement of the two module parts against each other, the bending element, is deformed in particular by a deformation element arranged on the first module part.

An advantage of the tire module according to the invention is the compact and closed Construction of the system. This protects the bending beam on the one hand against external influences and on the other against excessive deformation, since a deformation of the bending beam takes place in a controlled manner by the relative movement of the module parts and the mechanical interaction of the bending beam with the second module part. The degree and type of deformation are limited by the module structure.

The invention also relates to the use of the tire module in a tire pressure monitoring system.

Further preferred embodiments of the invention will become apparent from the subclaims and the following description with reference to figures.

• 1 ein erstes Ausführungsbeispiel eines erfindungsgemäßen Reifenmoduls, und
• 2 ein zweites Ausführungsbeispiel eines erfindungsgemäßen Reifenmoduls.

It show schematically

• 1 a first embodiment of a tire module according to the invention, and
• 2 A second embodiment of a tire module according to the invention.

1 schematically shows a first embodiment of a tire module according to the invention. The first embodiment is a symmetric microgenerator. By way of example, a can-shaped microgenerator with a round base area is proposed for this purpose. This is essentially made of a lower part 7 and an upper part 6 educated. The box has guide elements on the edge 12 . 13 where it can also be pulled apart. The two module parts 6 and 7 sit by the guides 12 and 13 in or on each other, so that the two parts 6 and 7 relative to each other in a spatial direction (indicated by the arrow) can move against each other. bottom 7 of the generator is attached according to the example on the inner liner of the tire. This is on the lower part 7 of the tire module an adhesive foot 8th attached, with which the tire module is attached to the innerliner. The upper part 6 carries the electronics or parts of the electronics as a seismic mass 9 , This may be, for example, one or more of the following: a circuit board, an integrated circuit, a battery, a transmitter for transmitting data from the tire to a receiver (eg, on the vehicle body), a receiver for receiving data from a transmitter (eg on the vehicle body), a sensor or tire condition sensor (eg pressure sensor, temperature sensor).

Inside the tire module is a bending element 1 which is coupled to piezoelectric material or consists of piezoelectric material (eg a piezo bimorph with piezoceramic). The bending element 1 can be designed arbitrarily, eg bar-shaped or round. For example, a bending beam will be described. bending beam 1 is at its two ends over two camps 2 . 3 with the upper part of the module 6 connected. flexure 1 can with or without preload in the bearings 2 . 3 to be appropriate. Camps 2 . 3 may be formed individually or as a continuous ring. They should impress as little bending moment as possible. Bottom touches lower shell 7 with the area 5 loose the bending element 1 , Camps 2 . 3 serve for fastening the bending element 1 and optionally for contacting the piezoelectric material.

Due to an acceleration change in latitude and / or latitude, forces act on the two parts 6 and 7 of the tire module. The two parts 6 and 7 , and with it the camps 2 . 3 and the area 5 , move against each other, causing the piezoelectric bending element 1 is deformed. The generated electrical energy can be stored or used to operate electrical components.

For example, sitting (in the approximate center of the flexure 1 ) opposite the area 5 above the bending element 1 a spring damper 4 made of silicone foam. spring shock absorber 4 is according to the example with the module part 6 connected.

The deflection (stroke) of the bending element 1 is by stops 11 . 11 ' limited in both directions. For example, the upper part becomes 6 by formations 11 on the lower part 7 held. Towards the lower part 7 (towards each other) the bearings work 2 . 3 as attacks 11 ' , The stop 11 ' should the overstretching of the piezoceramic 1 prevent and is due to the large seismic mass 9 already effective at low driving speed.

An advantage of the symmetrical structure of the first embodiment is that the "slip-stick effect" (jerking of mutually moved solids) on the guide 12 . 13 between part 6 and 7 is avoided. To the in 1 shown bending line of the bending element 1 However, a special clamping of the bending beam must be achieved 1 in the storage areas 2 and 3 be realized, which absorbs little moment and shear forces, because of the bending beam 1 otherwise statically overdetermined stored and the resulting burden to less energy input, possibly even the destruction of the bending beam 1 , leads. For example, a simple guide is advantageous, the sliding of the bending beam 1 in the storage areas 2 and 3 parallel to the bending beam length or bending element surface allows.

2 schematically shows a second embodiment of a tire module according to the invention. The second embodiment is an asymmetric microgenerator. The asymmetrical embodiment contains in principle similar components as the symmetrical first embodiment. In contrast to the first embodiment, the bending beam 1' which is coupled to piezoelectric material or consists of piezoelectric material, at one end via a bearing 2 ' with the upper part 6 ' connected. The other end of the bending beam 1' loosely touches the lower shell 7 ' in that area 5 ' , Due to an acceleration change in latitude and / or latitude, forces act on the two parts 6 ' and 7 ' of the tire module, and the two parts 6 ' and 7 ' , and with it the camp 2 ' and the contact area 5 ' , move against each other, causing the piezoelectric bending element 1' is deformed.

The warehouse 2 ' serves for fastening the bending element 1' and optionally for contacting the piezoelectric material.

Example is located at the top 6 ' , the contact area 5 ' opposite, a spring damper 4 ' made of silicone foam, which the open end of the bending beam 1' opposite the area 5 ' fixed.

The deformation of the bending element 1' is through the warehouse 2 ' , which according to the first embodiment as a stop 11 ' works, limited.

An advantage of the asymmetrical embodiment is that the clamping of the bending element 1' particularly easy to implement (because one-sided). A possible slip-stick effect can eg by a crown of the inside of the guide 12 . 13 be mitigated. Another advantage of the asymmetrical embodiment is that the tolerances for the asymmetric version are easier to comply with, because the deflection must be about twice as large with the same size.

If one in the first or second embodiment, the leadership 12 . 13 between upper and lower shell 7 . 6 replaced by an inserted spring damper (eg a ring of silicone foam), while suffering on the one hand, the transverse stiffness, a necessary property to ensure the robustness of the microgenerator, on the other hand, the slip-stick effect is avoided and simplifies the structure.

In order to keep the total mass of the tire module as low as possible, no seismic dummy mass is used according to the two described embodiments, but the modulus mass itself as a seismic mass 9 used. For example, parts or all of the electronics are arranged on the upper module part.

The invention is particularly suited to tire condition variables, such as To determine the tire pressure and / or the tire temperature with an energy self-sufficient system. For this purpose, the tire module comprises, for example, at least one sensor, e.g. a pressure sensor and / or a temperature sensor.

LIST OF REFERENCE NUMBERS

1, 1 '

Piezo bimorph (bending beam made of piezoelectric material or connected to piezoelectric material)

2, 2 '

Bearing (jig), e.g. with contact

3

Bearing (jig), e.g. with contact

4, 4 '

Silicone foam (damper element)

5, 5 '

Deformation element (bending beam 1 is loose)

6, 6 '

upper shell (second module part)

7, 7 '

lower shell (first module part)

8th

adhesive base

9

Payload (seismic mass)

11

attack

11 '

camp 2 . 2 ' . 3 also acts as a stop

12

Guide element of the first module part

13

Guide element of the second module part

Claims (12)

Tire module for detecting tire condition variables, comprising a piezoelectric transducer with a bending element (1, 1 '), wherein the bending element is coupled to piezoelectric material or consists of piezoelectric material, wherein the tire module is made in two parts with a first (7, 7') and a second (6, 6 ') module part, which are placed on one another or inserted into one another and are movable relative to each other in at least one approach direction, and wherein the bending element (1, 1') by means of at least one clamping device (2, 3, 2 ') is fixed to the second module part (6, 6 ') and is deformed relative to each other in the approach direction by a mechanical interaction with the first module part (7, 7') during a movement of the two module parts (6, 7, 6 ', 7') wherein at least one deformation element (5, 5 ') is arranged on the first module part (7, 7'), which mechanically interacts with the bending element (1, 1 ') relative to one another during a movement of the two module parts (6, 7, 6', 7 ') and thus deforms the bending element (1, 1'), a damping element (4, 4 ') is arranged on the second module part (6, 6'), wherein the damper element (4, 4 ') with respect to the on the first module part (7, 7') arranged deformation element (5, 5 ') is arranged, and wherein the Bending element (1, 1 ') is at least partially between deformation element (5, 5') and damper element (4, 4 '). Tire module after Claim 1 , characterized in that at least one guide element (12, 13) is arranged on at least one of the two module parts (6, 7, 6 ', 7'), which the two module parts (6, 7, 6 ', 7') relative to each other in the approach direction leads. Tire module after Claim 1 or 2 , characterized in that the bending element (1, 1 ') loosely rests on the deformation element (5, 5'). Tire module according to at least one of the preceding claims, characterized in that the damping element (4, 4 ') between the two module parts (6, 7, 6', 7 ') is arranged. Tire module according to at least one of the preceding claims, characterized in that on the one, in particular second, module part (6, 6 '), in particular on a side facing away from the other, in particular first, module part (7, 7'), a seismic mass ( 9) is arranged. Tire module after Claim 5 , characterized in that the seismic mass (9) comprises at least one electronic component, in particular a printed circuit board and / or a battery and / or a sensor element and / or a transmitter. Tire module according to at least one of the preceding claims, characterized in that the first module part (7, 7 ') on a tire, in particular by gluing (8), is fixed, wherein the first module part (7, 7') in particular on the inside of Tire is arranged in the tread area. Tire module according to at least one of the preceding claims, characterized in that it comprises at least one stop element (11, 11 ', 12, 13), which movement of the two module parts (6, 7, 6', 7 ') relative to each other in at least one Direction, in particular in the direction of approach (11 ') and / or in the opposite direction (11) limited. Tire module according to at least one of the preceding claims, characterized in that the tire module is a can-shaped, in particular with a round or oval or rectangular or square base. Tire module according to at least one of the preceding claims, characterized in that the approaching direction is substantially perpendicular to a base surface of the tire module. Tire module according to at least one of the preceding claims, characterized in that the piezoelectric material of the piezoelectric transducer via the clamping device (s) (2, 3, 2 ') is electrically contacted. Use of a tire module according to one of Claims 1 to 11 in a tire monitoring system.

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