DE102010017638B4 - air spring - Google Patents

Abstract

Air spring (1) with a device for generating energy (10), the device for generating energy (10) of the air spring (1) having a pressure chamber (13) designed as a pressure-resistant, airtight housing with at least two elastic walls (12), each at least one piezo element (15) is arranged in the at least two elastic walls (12) and the device for generating energy (10) is arranged inside the air spring (1), the pressure chamber (13) having an internal pressure which corresponds to the nominal internal pressure of the air spring (1) is almost the same, with changes in the internal pressure of the air spring (1) compared to the internal pressure of the pressure chamber (13), the elastic walls (12) being deformable, with an electrical voltage being able to be generated by the piezo elements (15), thereby characterized in that the air spring (1) has an electronic extreme value detector (19), a microcontroller (20) and a non-volatile memory (23), the extreme value detector (19) being connected to the piezo elements (15) of the device for generating energy (10) is in direct electrical operative connection and the voltage signals of the piezoelectric elements (15) can be measured by the extreme value detector (19), each extreme value of voltage measured by the extreme value detector (19) being transmitted in the form of an electrical square-wave pulse to the microcontroller ( 20) can be transferred and the number of square-wave pulses can be counted by the microcontroller (20) and the sum of the counted square-wave pulses can be stored in the electronic memory (23).

Description

The invention relates to an air spring with a device for generating energy.

Devices for generating energy are also referred to as "energy harvesters" and are used, for example, to supply power to tire sensors.

A typical device of this type is in U.S. 7,116,036 B2 disclosed. The solution proposed in this document is optimized for frequencies from 100 to 500 Hz, as they occur in tires. The amplitudes that occur are relatively small. In addition, due to the rotation in the tire there is a risk of imbalance, so that the device must be particularly small and light.

Electronic sensors and storage and transmission modules are also being used to an increasing extent in air springs, which are intended to determine the number of load cycles in addition to the physical variables such as pressure or stroke.

Up until now, this has usually required an external energy source. The sensors are often arranged in the elastic bellows wall. Such an air spring is, for example, in the previously unpublished application 10 2009 044 627. 3 (published as DE 10 2009 044 627 A1 ) disclosed.

However, it is not always advantageous to arrange the electronic elements in the bellows wall since the space available is very limited as a result. In addition, a separate energy supply is associated with additional effort.

With air springs, pressures from 4 bar usually occur. The air pressure fluctuations in the air spring are also significantly greater than in tires, since the air springs sometimes perform considerable strokes. The stroke frequency is significantly lower than in tires. A solution as in the U.S. 7,116,036 B2 is therefore not optimally usable for air springs.

The object of the invention is to simplify counting of the load changes of the air spring and to optimize the known electronic systems for generating energy for use in air springs.

This object is achieved in that the device for generating energy from the air spring has a pressure chamber designed as a pressure-resistant, airtight housing with at least two elastic walls, with at least one piezo element being arranged on each of the at least two elastic walls and the device for generating energy inside the air spring is arranged, wherein the pressure chamber has an internal pressure which is almost the same as the nominal internal pressure of the air spring, the elastic walls being deformable when the internal pressure of the air spring changes in relation to the internal pressure of the pressure chamber, and an electrical voltage being able to be generated by the piezo elements.

Such a device can be easily adjusted to the static and dynamic pressure conditions in an air spring by varying the size and the internal pressure. Due to the relatively large pressure differences in an air spring, the deformations of the elastic walls of the pressure chamber are large enough for the piezo elements to generate a resilient electrical voltage. A transmission mechanism for transmitting the movements of the walls of the pressure chamber to the piezo elements can be omitted.

In a development of the invention, the device for generating energy, the pressure chamber, has an opening designed as a throttle, via which the interior of the pressure chamber is in operative connection with the interior of the air spring.

Such a throttle enables a further improved coordination of the pressure conditions between the pressure chamber and the interior of the air spring. With an optimal design, resonance effects can also be used, which improve the energy yield of the piezo elements.

In a development of the invention, the device for generating energy has at least one full-wave rectifier and a voltage regulator, the piezo elements being connectable in series and the voltages that can be generated by the piezo elements being convertible into an almost constant supply voltage via the full-wave rectifier and the voltage regulator.

By connecting the piezo elements in series, a total voltage that is higher than that of the individual voltages can be generated. By rectifying and controlling, an almost constant, loadable supply voltage can be generated, the course of which over time is largely independent of the pressure changes in the air spring.

In a development of the invention, the device for generating energy has an electrical energy store.

The energy store has the advantage that the supply voltage at the output of the energy store remains constant at least temporarily, even if the pressure changes in the air spring are relatively small and only low voltages are generated by the piezo elements.

In a further development of the invention, the air spring has an electronic extreme value detector, a microcontroller and a non-volatile memory, with the extreme value detector being in direct electrical operative connection with the piezo elements of the device for generating energy and the voltage signals of the piezo elements being measurable by the extreme value detector, with each Extreme value detector measured voltage extreme value can be transferred in the form of an electrical square-wave pulse to the microcontroller electrically coupled to the extreme value detector and the number of square-wave pulses can be counted by the microcontroller and the sum of the counted square-wave pulses can be stored in the electronic memory.

Due to the fact that the piezo elements generate a voltage peak with each load change due to the associated pressure changes, the device for generating energy can also be used directly as a load change counter in addition to generating energy for other sensors. A separate arrangement is no longer required for this.

In a development of the invention, the air spring has a temperature sensor with an analog-to-digital converter (AD converter), which can be supplied with energy by the device for generating energy, and whose signals can be transmitted to the microcontroller via the AD converter, with a load coefficient can be calculated by the microcontroller from the number of square-wave pulses received from the extreme value detector and the corresponding temperature values received from the AD converter of the temperature sensor and can be stored in the non-volatile memory.

Through the combination of temperature values and number of load changes, a damage-indicating coefficient can be determined directly for each air spring.

In a development of the invention, the air spring has a radio device that is electrically connected to the non-volatile memory and the energy store.

With the help of a radio device, the results stored in the memory are contactless and can be called up at any time. A separate power supply for the radio device is not required.

An example of the invention is explained in more detail below with reference to the drawing.

• 1 eine erfindungsgemäße Luftfeder im Längsschnitt,
• 2a, 2b eine Druckkammer in zwei Betriebszuständen im Querschnitt,
• 3 eine Schaltung zur Energieversorgung und Lastwechselzählung als Prinzipschaubild.

It shows

• 1 an air spring according to the invention in longitudinal section,
• 2a , 2 B a pressure chamber in two operating states in cross section,
• 3 a circuit for energy supply and load change counting as a schematic diagram.

In 1 an air spring 1 according to the invention is shown in principle. The air spring 1 has a rolling piston 2 which is welded together from a casing part and a base part 4 . A rolling bellows 5 is arranged on the piston 2 and is firmly flanged to an end plate 6 at its end remote from the rolling piston 2 . The end plate 6 has an opening 7 through which compressed air can be introduced into the interior of the air spring 1 by means of an air connection, not shown here. The end plate 6 also has a fastening bolt 8 . A device for generating energy and counting load changes 10 with a pressure chamber 11 is arranged on the side of the end plate 6 assigned to the interior of the air spring 1 .

In the 2a and 2 B the structure of the pressure chamber 11 is shown in principle using two operating states. The ones in both 2a and 2 B The pressure chamber 11 shown has two elastic walls 12 and a pressure chamber 13 . Two other walls 14 are rigid. A piezoelectric element 15 is fastened on the side of the elastic walls 12 facing the pressure chamber 13 in such a way that the piezoelectric elements 15 can be elastically deformed together with the elastic walls 12 .

The 2a shows the pressure chamber 11 in a state in which the pressure inside 13 of the pressure chamber 11 is greater than the ambient pressure, the 2 B shows the pressure chamber 11 in a state in which the pressure inside 13 of the pressure chamber 11 is lower than the ambient pressure.

Since the pressure in the air spring changes constantly depending on the deflection, the pressure chamber 11 changes its state in accordance with the changes in the ambient pressure, which corresponds to the internal pressure of the air spring. As a result, the elastic walls 12 deform more or less continuously, with the piezo elements 15 each generating electrical voltages.

In 3 a circuit for energy supply and load change counting is shown in principle, in which the piezoelectric elements 15 are connected in series and connected to a full-wave rectifier 16. In the full-wave rectifier 16, the alternating voltages from the piezoelectric elements 15 can be rectified. The rectified voltage from the full-wave rectifier 16 can be introduced into a voltage regulator 17 in which the rectified voltage can be regulated to a voltage that is compatible with an energy store 18 .

The electrical signals that can be taken from the full-wave rectifier 16 can also be transferred to an extreme value detector 19 . In the extreme value detector 19, the signals can be converted into square-wave voltage pulses, which can be processed by a microcontroller 20.

The circuit also has a temperature sensor 21, via which the temperature of the air surrounding it can be measured and forwarded in the form of an analog electrical signal. The analog signal can be transferred to an analog/digital converter 22 . In the analog-to-digital converter 22, the analog signals of the temperature sensor 21 can be converted into digital pulses, which can also be transmitted to the microcontroller 20. The signals introduced can be continuously calculated in the microcontroller 20 to form damage coefficients, which can be stored in a non-volatile data memory 23 .

A radio module 24 is electrically connected to the data memory 23, with the coefficients stored in the data memory 23 being able to be transmitted contactlessly by radio to an external evaluation unit (not shown here).

Reference List

1

air spring

2

rolling piston

3

jacket part

4

bottom part

5

rolling bellows

6

end plate

7

Opening in the end plate 6

8th

mounting bolts

10

Device for generating energy and counting load changes

11

pressure chamber

12

elastic walls of the pressure chamber 11

13

pressure room

14

further walls of the pressure chamber 11

15

piezo element

16

full wave rectifier

17

voltage regulator

18

energy storage

19

extreme value detector

20

microcontroller

21

temperature sensor

22

analog to digital converter

23

data storage

24

radio module

Claims (3)

Air spring (1) with a device for generating energy (10), the device for generating energy (10) of the air spring (1) having a pressure chamber (13) designed as a pressure-resistant, airtight housing with at least two elastic walls (12), each at least one piezo element (15) is arranged in the at least two elastic walls (12) and the device for generating energy (10) is arranged inside the air spring (1), the pressure chamber (13) having an internal pressure which corresponds to the nominal internal pressure of the air spring (1) is almost the same, with changes in the internal pressure of the air spring (1) compared to the internal pressure of the pressure chamber (13), the elastic walls (12) being deformable, with an electrical voltage being able to be generated by the piezo elements (15), thereby characterized in that the air spring (1) has an electronic extreme value detector (19), a microcontroller (20) and a non-volatile memory (23), the extreme value detector (19) being connected to the piezo elements (15) of the device for generating energy (10) is in direct electrical operative connection and the voltage signals of the piezoelectric elements (15) can be measured by the extreme value detector (19), each extreme value of voltage measured by the extreme value detector (19) being transmitted in the form of an electrical square-wave pulse to the microcontroller ( 20) can be transferred and the number of square-wave pulses can be counted by the microcontroller (20) and the sum of the counted square-wave pulses can be stored in the electronic memory (23). Air spring (1) after claim 1 , characterized in that the air spring (1) has a temperature sensor (21) with an analog-to-digital converter (22) which can be supplied with energy by the device for generating energy (10) and whose signals are transmitted via the AD converter ( 22) can be transferred to the microcontroller (20), in which case a load coefficient can be calculated by the microcontroller (20) from the number of square-wave pulses received from the extreme value detector (19) and the corresponding temperature values received from the AD converter (22) of the temperature sensor (21) and can be stored in the non-volatile memory (23). Air spring (1) after claim 1 or 2 , characterized in that the air spring (1) has a radio device (24) electrically connected to the non-volatile memory (23) and the energy store (18).

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