WO2001091200A1

WO2001091200A1 - Ignition pulse generator

Info

Publication number: WO2001091200A1
Application number: PCT/DE2001/001861
Authority: WO
Inventors: Josef RÖDIGER
Original assignee: Roediger Josef
Priority date: 2000-05-20
Filing date: 2001-05-17
Publication date: 2001-11-29
Also published as: AU6579301A; AU6579501A; WO2001091276A1; WO2001091519A1; DE10025028A1; DE10025028C2; AU6579401A

Abstract

The invention relates to an ignition pulse generator, namely a voltage converter for generating high voltage pulses of up to 30 KV, to be controlled with direct current pulses in the extra-low voltage range. The ignition pulse generator is made-up of a magnetomechanical converter consisting of the magnetostrictive actuator core (2) and the coil (1) surrounding it, with a flux guiding plate (25); an insulator (3) and an electromechanical converter which is configured as a piezoignition element (4). The two converter elements are clamped one between the other in an axial direction, in a mechanical fixing device. The voltage is converted as a result of the simultaneous exploitation of the magnetostrictive effect and the direct piezoelectric effect. The ignition pulse generator is used for igniting technical gases and for electrically igniting pyrotechnical ignition compositions.

Description

ignition pulse

The invention relates to a voltage converter for generating high-voltage pulses.

The ignition pulse generator is used to ignite technical gases in the industrial sector, in the automotive sector, in lighting technology and in the home. Special applications are high-voltage igniters for burners, heating and cooking devices, ignition modules for internal combustion engines and high-voltage ignition generators for HID lamps (xenon lamps) in motor vehicles and electrical igniters for pyrotechnic igniters.

When it comes to generating high-voltage ignition pulses, two fundamentally different types of converters are currently used.

These are ignition coils or two-stage high-voltage transformers in combination with a capacitor discharge, which are voluminous and complex, which is contrary to the current trend towards miniaturization. Other solution variants are based on the direct piezo effect. Using new, further developed materials and technologies, high-voltage converters have been developed for a wide variety of applications.

Simple variants work with manual or electromagnetic actuation of the piezo ignition elements in conjunction with supporting spring mechanisms. A pure electromechanical converter such as the Piezo Transformer IV only reaches its maximum voltage in the event of resonance. The piezoelectric transformer described in 121 requires a control voltage of 100V for usable power conversion even when using a multi-layer actuator. The piezoelectric generator / 3 / uses a piezo element by means of electromagnetic excitation to charge a capacitor. A rectifier diode, a load resistor, a capacitor and a breakdown diode with a correspondingly high dielectric strength are required for the generation of the ignition pulse. The converter 141 consists of a magnetomechanical converter on the input side and an electromechanical converter on the output side. The functional elements are in Axial direction and are subject to mechanical preload. To set the operating point, the magnetomechanical transducer is also provided with a premagnetization device. An oscillator with a frequency of 600 Hz to 3 kHz (resonance frequency 43 kHz) is used for the control, which feeds the coil of the converter with alternating current. The converter can be used to generate a high voltage of a few 100V from a battery voltage, which is used to control the backlighting of liquid crystal screens. It is not possible to generate high-energy ignition pulses with this converter. The mechanical pretension with the resulting shortening of the piezo element has a negative effect on the achievable ignition voltage, and the pre-magnetization causes the magnetostrictive core to undergo a proportional stretch, which reduces the work capacity in the same ratio. In addition, the insulation is not designed for the generation of high voltage and the temperature expansion of the functional elements is not sufficiently taken into account. The use of special piezo ignition elements would be much cheaper.

This issue has already been dealt with in the pre-registration DE 100 25 028 A1 / 5 /.

The object of the invention is to provide a novel ignition pulse generator which can generate high-voltage, high-voltage ignition pulses of up to 30 kV from a low voltage from 3 V and which enables simple and precisely reproducible control.

Another object of the invention is the safe isolation of the high-voltage ignition pulses, which can be dissipated both in a mass-related and mass-free manner. It is a further object of the invention to provide an ignition pulse generator which is designed for high vibration loads and a wide temperature range.

Another important object of the invention is to provide a compact and closed ignition module which allows miniaturization in accordance with the energy conversion and the generated ignition voltage and can be easily integrated into existing systems.

The object of the invention is achieved in that a magnetomechanical transducer with an electromechanical transducer in the axial direction via a fixed, unalterable common clamping is directly coupled and they form a self-contained functional unit. The magnetomechanical transducer consists of a magnetostrictive core, which is surrounded by a coil with an associated soft iron circuit. The electromechanical transducer consists of a piezo ignition element with surface electrodes attached on the end. At least one of the surface electrodes of the piezo ignition element is insulated from the other components via a ceramic body. The principle of operation of the ignition pulse generator is based on the simultaneous use of the magnetostrictive effect and the direct piezo effect. The practical implementation of the interaction of the two physical solid-state effects is based on the principle of the motor generator, with the magnetomechanical converter operating in motor mode and the electromechanical converter operating in generator mode. This is done by means of purely translatory movements in the μm range, with the actuating forces that build up at the same time. Electrical energy is converted into mechanical energy and mechanical energy into electrical energy with little loss. With this operating principle, transmission ratios of 1 to 10,000 can be achieved in a simple manner. Another significant advantage is the implementation of an ignition pulse generator with an extremely compact design and an absolutely safe electrical isolation between low voltage and high voltage. The innovative ignition pulse generator enables a reproducible and precise triggering of high-energy ignition pulses and ignition pulse sequences.

The simple and modular design of the new ignition pulse generator creates the ideal conditions for automated mass production, which significantly reduces the manufacturing costs. For a safe function and efficient energy conversion, some important features of the invention have to be taken into account when designing the novel ignition pulse generator.

When using a closed cylindrical shape (sleeve) for mechanical clamping of the functional elements, a slot must be provided in the longitudinal direction in the area of the magnetomechanical transducer, since the sleeve forms a massive short-circuit ring, which leads to high electrical losses. When screwing and tightening, care must also be taken that the torque is not transferred to the functional elements, which is why it must be possible to fix the position for assembly. Due to the very different coefficients of thermal expansion of the individual In order to maintain function and efficiency, thermomechanical temperature compensation must be provided for all components.

Since supermagnetostrictive materials have a low relative magnetic permeability, special care must be taken to ensure that the magnetic resistance is kept as low as possible by means of a large air gap area.

For better heat dissipation and high vibration resistance and to achieve a higher current density in the winding and to largely suppress the effect of the skin effect, it is advantageous if the coil of the electromagnetic transducer is wound from a copper foil strip. A hermetically sealed housing should be provided in order to protect the functional elements from the direct influence of environmental influences on the one hand and on the other hand to increase the insulation capacity and service life by introducing extremely dry air. To ensure that the resulting heat loss can be dissipated well in continuous operation, a heat-conducting medium should ensure good heat transfer between the functional elements and the housing for this application and the housing should be designed as a heat sink.

To control the ignition pulse generator, a direct current pulse is fed into the coil of the magnetomechanical transducer, so that a magnetic field is built up in the coil, as a result of which the magnetostrictive actuator core expands and the piezo-ignition element compresses. Due to the mechanical tension that compresses the piezoelectric ignition element, a high voltage is generated at the electrodes on the face side, which discharges for a very short time when the breakdown voltage of the spark gap connected in parallel is reached.

Since only a direct current pulse is fed into the coil, the magnetic field in the coil collapses again after the current has been switched off, as a result of which the magnetostrictive actuator core contracts. The contraction of the magnetostrictive actuator core again leads to the expansion of the piezo ignition element, as a result of which a high voltage with opposite polarity is now generated, which is discharged over the spark gap.

Two exemplary embodiments and the operating principle of the ignition pulse generator are explained below with reference to drawings. The associated drawings show:

Fig. 1 representation of the principle of action

2 sectional view of the ignition pulse generator with cylindrical clamping (axis section A - A from FIG. 3)

Fig. 3 Spatial view of the ignition pulse generator with cylindrical clamping

4 shows a sectional view of the ignition pulse generator with a clamping frame (horizontal section BB from FIG. 5)

5 shows a sectional view of the ignition pulse generator with a clamping frame (vertical section C - C from FIG. 4)

10

Figure 1 shows in simplified form the basic transducer elements 1 to 5 of the ignition pulse generator and their basic arrangement and their interaction. To achieve the intended effect is a magnetomechanical transducer, consisting of a coil 1, a magnetostrictive actuator core 2 and a flux guide plate

15 24, with a piezo ignition element 4 via a fixed, unrelenting clamping, shown here in simplified form with the acting clamping force + F and -F, mechanically rigidly coupled in the axial direction. In order to avoid a short circuit of the electrodes 5.1 and 5.2 of the piezoelectric ignition element 4, the mechanical coupling takes place via the ceramic insulator 3.

20 Using the magnetostrictive effect and the direct piezo effect at the same time, the arrangement described above is used to implement a miniature motor generator that enables voltage conversion via purely translatory movements in the μm range with the actuating forces that build up at the same time. The magnetomechanical transducer, consisting of a coil 1, a magnetostrictive

25 ven actuator core 2 and a flux guide plate 24, works here in engine operation and the piezo ignition element 4 acts as a generator.

If a current is fed into the coil 1 of the magnetostrictive actuator core 2, a magnetic field builds up in it, whereby the magnetostrictive actuator core 2 experiences a change in length in the direction of magnetization. In the case of a fixed

30 voltage now acts this change in length with the accompanying thrust force on the piezo ignition element 4, whereby this is compressed. The magnitude of the voltage generated between the two electrodes 5.1 and 5.2 is mainly determined by the acting force, the length and the piezoelectric voltage constant of the piezo ignition element 4. The cross section and the for that Piezoelectric charge constants, which are decisive for energy conversion, determine the size of the electrical charge generated. If a spark gap is connected in parallel to the piezo ignition element, charge equalization takes place when the breakdown voltage is reached.

5 After switching off the current of the coil 1 of the magnetostrictive actuator core 2, the magnetic field collapses again, as a result of which the magnetostrictive actuator core 2 is shortened again and the piezo ignition element 4 is lengthened again. As a result, a voltage with reverse polarity is generated at the electrodes 5.1 and 5.2, which discharges again when the breakdown voltage is reached via the spark gap.

10 The further feeding of direct current pulses into the coil 1 leads to the repetition of this process, whereby an ignition pulse sequence is generated.

Figure 2 shows a possible design example of the ignition pulse generator in a cylindrical housing.

15 According to this invention, the ignition pulse generator consists of a magnetomechanical transducer, consisting of the coil 1, the magnetostrictive actuator core 2 and the pole plate 7, a piezo ignition element 4, a ceramic insulator 3 with a lead-through contact 17 and sealing ring 20, a perforated bimetal cap 8, the clamping sleeve 9 with fine thread 15 and the clamping ring 10 together.

20 First, the coil 1 is inserted into the clamping sleeve 9 in such a way that the coil connections 6 are guided outwards through the slot 13.1. The slot 13.1 is to be closed with a non-conductive material so that a hermetically sealed housing is created. Then all other components are placed in the clamping sleeve 9 in the previously mentioned order in a symmetrical manner and then with the clamping ring

25 10 screwed together with fine thread 15. It should be installed in a chamber with the lowest possible humidity. After completion, the holding openings 12 are to be closed. With the sealing ring 20, the lower area with the magnetostrictive actuator core 2 located therein and the piezo ignition element 4 is blocked off at the top. To transfer the torque when entering

3o screw the clamping ring onto the piezo ignition element 4 and the magnetostrictive actuator core 2, which would be damaged by excessive torsional or transverse loads, the ceramic insulator 3 has two holding grooves 11, which are accessible from the outside via the holding openings 12 and when the clamping ring is tightened 14 should serve to secure the position. The size of the clamping force can easily be determined by evaluating the generated voltage of the piezo ignition element 4 can be detected. The thermomechanical temperature compensation is taken from the perforated bimetal cap 8. The perforated bimetallic cap 8 can compensate for the length difference between the clamping sleeve 9 and the magnetostrictive actuator 2, the piezoelectric ignition element 4 and the ceramic insulator 3, which is created by thermal expansion, over a very wide temperature range and while maintaining the set clamping force. The clamping sleeve 9 consists of a soft magnetic alloy and on the one hand absorbs the clamping forces and on the other hand it serves to conduct the magnetic flux in the area of the magnetomechanical transducer. In order to achieve the highest possible magnetic flux through the magnetostrictive actuator core 2, the magnetic flux is passed through the magnetostrictive actuator core 2 via a soft magnetic iron circuit consisting of the lower part of the clamping sleeve 9 and the pole plate 7. The pole plate 7 is designed such that the length of the air gap 19 is very small and the area of the air gap is very large. Since the pole plate 7 is firmly clamped between the magnetostrictive actuator core 2 and the piezo ignition element 4, it must follow the working movement. For this reason, the mass of the pole plate 7 must be kept small. In order to avoid a short-circuit ring, through which high electrical losses would occur, the clamping sleeve 9 and the pole plate 7 are each provided with a slot 13.1 and 13.2. If a DC pulse is fed into the coil 1 via the coil connections 6, a magnetic field is generated by it.

The magnetic flux guided over the magnetostrictive actuator core 2 causes it to expand, as a result of which the piezo ignition element 4 is compressed. The pressure and tensile forces that build up are absorbed by the clamping, consisting of the clamping sleeve 9, the ceramic insulator 3, the bimetallic cap 8 and the clamping ring 10, and ensure that the mechanical stress generated in the piezoelectric ignition element 4 is maintained.

Due to the mechanical tension, which compresses the piezo ignition element 4, a high voltage arises at the front electrodes 5.1 and 5.2, which discharges for a very short time when the breakdown voltage of the spark gap connected in parallel is reached. The guidance of the generated ignition pulse voltage of the piezo ignition element 4 takes place from the negative electrode 5.2 via the pole plate 7 and the magnetostrictive actuator core 2 to the clamping sleeve 9. The upper electrode 5.1 the ignition pulse voltage to the outside via the feed-through contact 17, which is located in the ceramic insulator 3.

Since only a direct current pulse is fed into the coil 1, the magnetic field collapses again after the current is switched off, as a result of which the magnetostrictive actuator core 2 contracts again. The contraction of the magnetostrictive actuator core 2 simultaneously leads to the expansion of the piezo ignition element 4, as a result of which a high voltage with opposite polarity is now generated, which is discharged over the spark gap. In this exemplary embodiment of the ignition pulse generator, the guidance of the ignition pulse voltage is ground-related.

FIG. 3 shows a three-dimensional view of the ignition pulse generator previously described in FIG. 2 in a closed sleeve construction.

FIGS. 4 and 5 show a further design example of the ignition pulse generator with a frame clamping. FIG. 4 shows a horizontal section (BB from FIG. 5) and FIG. 5 shows a vertical section (CC from FIG. 4) of the ignition pulse generator. According to this invention, the ignition pulse generator consists of a magnetomechanical transducer consisting of the coil 1, the magnetostrictive actuator core 2, the flux guide plate 24 and the pole plate 7, a ceramic insulator 3, a piezo ignition element 4, a ceramic body 16, a wedge bearing 22, a wedge 23 and the tenter 21 together. The functional elements of the ignition pulse generator are mounted on the common carrier board 26 and encapsulated with the housing 27. To clamp the magnetomechanical transducer, consisting of the coil 1, the magnetostrictive actuator core 2, the pole plate 7 and the flux guide plate 24, and the piezo-ignition element 4 with insulator 3, the ceramic body 16 and the wedge bearing 22 with the functional elements located in between are placed in the clamping frame 21 placed and clamped with the wedge 23. The thermomechanical temperature compensation takes place via the tensioning frame 21, which consists of a composite material or an alloy, where the thermal elongation is set such that the thermal elongation of the magnetostrictive actuator core 2 and of the piezoelectric ignition element 4 is equal to the thermal elongation of the tensioning frame 21. The piezo-ignition element 4 with its two electrodes 5.1 and 5.2 is mounted between the ceramic body 16 and the ceramic insulator 3 for mass-free guidance of the ignition pulse voltage. The ignition pulse voltage is conducted to the outside via the two high-voltage plug connectors 18, which are located in the ceramic body 16. The ground connection of the housing 27 takes place via the soldering lug 25.

The functional sequences of the ignition pulse generator with frame clamping are completely identical to the functional sequences of the construction example in FIG. 2.

The two design examples clearly show how easy it is to solve the insulation and safety problems in an extremely compact design and what variation options are available for miniaturization.

The ceramic body 16 (FIGS. 4 and 5) is designed in such a way that the electromechanical transducer can be prefabricated as a module. At low ignition pulse voltages, the ceramic body 16 (FIGS. 4 and 5) can be replaced by a molded plastic part with ceramic disks inserted on both sides, thereby reducing the production costs.

Another important advantage of the ignition pulse generator according to the invention is the adaptability to a wide variety of areas of application and environmental influences, such as vibration, temperature and air humidity, as well as dust, dirt and splash water. The simple and modular structure of the ignition pulse generator and its adaptability in terms of system integration and miniaturization create the ideal conditions for rapid implementation in marketable products.

Reference:

IV PIEZOELECTRIC CERAMIC TRANSFORMER

C. B. Roellgen 12/19/1995

Endrich Bauelemente-Vertriebs-GmbH, Nagold 121 Piezoelectric transformer DE 4131553A1

/ 3 / PIEZOELECTRIC GENERATOR UNIT FOR SPACE VEHIGLES US 3,389,275 141 Converter JP 08162689 A 151 Solid state voltage converter DE 10025028 A1

Literature:

CeramTec: Piezoelectric components

(Company lettering with list of literature - piezoceramic, basics, applications), CeramTec

AG, run

Göran Engdahl: Handbook of Giant Magnetostrictive Materials Academic Press, ISBN 0-12-238640-X

Legend

1 spool

2 magnetostrictive actuator

3 ceramic insulator

4 piezo ignition element

5.1 positive electrode

5.2 negative electrode

6 coil connections

7 pole plate

8 bimetal cap

9 adapter sleeve

10 tension ring

11 holding groove

12 holding opening

13.1 slot 1

13.2 slot 2

14 ring groove

15 fine threads

16 ceramic body

17 feed-through contact

18 high-voltage connectors

19 air gap

20 sealing ring

21 stenter

22 wedge bearings

23 wedge

24 flow baffle

25 solder tail

26 carrier board

27 housing

Claims

claims

1. Ignition pulse generator, consisting of a magnetomechanical transducer, which is composed of a magnetostrictive actuator core and the coil surrounding it with a soft iron circuit, an insulator and an electromechanical transducer, the transducer elements of which are arranged one behind the other in the axial direction and firmly in a mechanical holder are connected, characterized in that

- That the magnetostrictive actuator core (2) consists of a positive supermagnetostrictive material,

- That the insulator (3) consists of ceramic or a glass-like material,

- That the electromechanical transducer consists of special piezo ignition elements (4) and

- That there is thermomechanical temperature compensation.

2. Ignition pulse generator according to claim 1, characterized in

- That the coil (1) of the magnetomechanical transducer is fed with direct current pulses, so that a magnetic field is built up in the coil of the magnetomechanical transducer, which then collapses again, as a result of which the magnetostrictive actuator core (2) expands and contracts again and

- That thereby the piezo ignition element (4) is compressed and thereby generates a high voltage, which is discharged in the form of an ignition pulse over a spark gap connected in parallel and generates a high voltage with opposite polarity during the subsequent expansion of the ignition element and is discharged again via the spark gap.

3. Ignition pulse generator according to claim 1, characterized in

- That the mechanical mounting of the functional elements is designed as an adapter sleeve (9) with a bottom and at the upper end a fine thread (15) is inserted for clamping,

- That in the upper area there are lateral holding openings (12) for fixing the position of the insulator (3), - That in the lower part over the length of the magnetomechanical transducer a slot (13.1) is introduced in the longitudinal direction and

- That the slot 13.1 is sealed with a non-conductive material.

4. ignition pulse generator according to claim 1, characterized in

- That the mechanical mounting of the functional elements consists of fiber composite material and is designed as a frame like a ring deformed to the chain link and

- That the bearing blocks for the application of force on the one hand as a ceramic body (16) and on the other hand as a wedge bearing (22) are executed.

5. ignition pulse generator according to claim 1, 3 and 4, characterized in that a bimetal (8) is used for thermomechanical temperature compensation.

6. Ignition pulse generator according to claim 1, 3 and 4, characterized in that the mechanical holder consists of an alloy or a composite material with adapted thermal elongation for thermomechanical temperature compensation.

7. ignition pulse generator according to claim 1, 3 and 4, characterized in that the piezo ignition element (4) with an electrode (5.1) on the ceramic insulator (3) and the other electrode (5.2) has a conductive connection to the mechanical holder.

8. Ignition pulse generator according to claim 1, characterized in that the piezoelectric ignition element (4) with the electrodes (5.1 and 5.2) lies between the ceramic insulator (3) and the ceramic body (16).

9. ignition pulse generator according to claim 1, 3 and 4, characterized in that the pole plate (7) forms a large air gap area to the soft iron circuit and has a small mass.

10. ignition pulse generator according to claim 1, 3 and 4, characterized in that the winding of the coil (1) of the magnetomechanical transducer consists of an insulated copper foil tape.

11. Ignition pulse generator according to claim 1, 3 and 4, characterized in

that the functional elements, including extremely dry air, are accommodated in a hermetically sealed housing,

- That the housing (27) is designed as a heat sink with an enlarged surface and

- That a heat transfer medium is introduced to dissipate the heat loss.