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WO2002037535A2 - Piezo-electrical actuator with automatic release on loss of power - Google Patents

Piezo-electrical actuator with automatic release on loss of power Download PDF

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Publication number
WO2002037535A2
WO2002037535A2 PCT/DE2001/004099 DE0104099W WO0237535A2 WO 2002037535 A2 WO2002037535 A2 WO 2002037535A2 DE 0104099 W DE0104099 W DE 0104099W WO 0237535 A2 WO0237535 A2 WO 0237535A2
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WO
WIPO (PCT)
Prior art keywords
rotor
piezo
clamping
piezos
movement
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DE2001/004099
Other languages
German (de)
French (fr)
Other versions
WO2002037535A3 (en
Inventor
Hans Richter
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Individual
Original Assignee
Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to AU2002215834A priority Critical patent/AU2002215834A1/en
Priority to JP2002540189A priority patent/JP2004513310A/en
Publication of WO2002037535A2 publication Critical patent/WO2002037535A2/en
Publication of WO2002037535A3 publication Critical patent/WO2002037535A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
    • F16D65/16—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake
    • F16D65/18—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for drawing members together, e.g. for disc brakes
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
    • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
    • H02N2/101—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors using intermittent driving, e.g. step motors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
    • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
    • H02N2/12—Constructional details
    • H02N2/123—Mechanical transmission means, e.g. for gearing
    • H02N2/126—Mechanical transmission means, e.g. for gearing for conversion into linear motion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2121/00—Type of actuator operation force
    • F16D2121/18—Electric or magnetic
    • F16D2121/28—Electric or magnetic using electrostrictive or magnetostrictive elements, e.g. piezoelectric elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2125/00—Components of actuators
    • F16D2125/18—Mechanical mechanisms
    • F16D2125/20—Mechanical mechanisms converting rotation to linear movement or vice versa
    • F16D2125/34—Mechanical mechanisms converting rotation to linear movement or vice versa acting in the direction of the axis of rotation
    • F16D2125/40—Screw-and-nut
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2125/00—Components of actuators
    • F16D2125/18—Mechanical mechanisms
    • F16D2125/58—Mechanical mechanisms transmitting linear movement
    • F16D2125/582—Flexible element, e.g. spring, other than the main force generating element
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2127/00—Auxiliary mechanisms
    • F16D2127/02—Release mechanisms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2129/00—Type of operation source for auxiliary mechanisms
    • F16D2129/06—Electric or magnetic
    • F16D2129/08—Electromagnets

Definitions

  • the invention relates to a piezoelectric actuator, in particular one for relatively high drive forces or drive powers, and in particular for use as an actuator for a motor vehicle wheel brake.
  • the basic structure of such a piezoelectric drive comprises a series of piezo packs each designed as a stack of piezo elements, which are arranged between a reference part serving as a stator and a driven part serving as a rotor, in such a way that the stack height of the piezo elements in each piezo pack is perpendicular to the surface of the driven part and to the direction of the relative movement between the reference part and the driven part.
  • These piezo stacks are used to selectively generate a clamping force between the reference part and the driven part and are therefore referred to below as clamping piezos.
  • clamping piezos are each fixed to the reference part with one end (the term end in each case referring to the piezo element stack arrangement) and are supported on the driven part with the other end without being fixed thereon.
  • the orientation of the row in which these clamping piezos are arranged next to one another runs transversely to the direction of the relative movement between the driven part and the reference part, that is to say axially along the rotating driven part.
  • Further piezo packets each also configured as a piezo element stack, which are referred to below as step piezos because of their function, are oriented with their stack height direction approximately perpendicular to the stack height direction of the clamping piezos and in the direction of the relative movement between the reference part and the abrasion part.
  • step piezos are each fixed at one end to the reference part and connected at the other end to the end of a clamping piezo (or a subset of clamping piezos) which is supported on the driven part.
  • clamping piezos There are two groups of clamping piezos and two groups of step piezos. These are electrically controlled so that one group of clamping piezos is activated, that is to say electrically charged in the sense of expansion, and these clamping piezos are clamped against the driven part, while the other group of clamping piezos is deactivated, i.e. in the release position, that is, not with the stripping section is connected in a clamping manner. Then the group of step piezos assigned to the clamping piezos connected is activated so that the relevant step piezos expand and thereby deflect the ends of the clamp piezos clamped on the driven part by a corresponding distance in the direction of movement of the driven part.
  • the driven part moves a corresponding distance below the clamping piezo of the other clamping piezo group, which is in the release position.
  • the control is switched over, i.e. the previously clamping clamp piezos are switched into the release position, as are the associated step piezos, so that the previously clamped clamp piezos release themselves from the clamped position and return to their starting position, while at the same time the other group of clamp piezos, the were previously in the release position, switched to the clamping position by activation and then their step piezos are also activated.
  • the two groups of clamping piezos, each with associated step piezos generate a continuous sequence of steps through their alternating use, as a result of which the driven part is moved step by step. Since this control of the piezos takes place in the frequency range of a few kilohertz, for example 25 kHz, a quasi-continuous rotary movement of the driven part relative to the reference part is obtained.
  • the invention has for its object to provide such an arrangement that it can be used to actuate a motor vehicle wheel brake, which of course does not exclude other applications with corresponding requirements.
  • the rotating output movement of the output part must be converted into an axial movement, for example to move and tension a brake shoe against a brake disc.
  • the brake is released by actuating the piezoelectric drive with the reverse direction of rotation of the driven part, which can be done by appropriately modified control of the clamping and step piezo.
  • the present invention addresses this particular problem.
  • the arrangement according to the invention is thus characterized in that the power take-off part is activated in the event of a power failure in such a way that an electrically activated axial locking becomes ineffective and enables an axial deflection of at least the part of the power take-off part connected to the brake shoe by a certain axial distance.
  • Fig. 1 in axial section an embodiment of the invention
  • Fig. 2 shows a cross section through the piezo drive
  • Figure 1 shows in axial section a piezo drive according to the invention for actuating a motor vehicle wheel brake in conjunction with a disc brake assembly.
  • the piezomotor then has a stator 5 and a rotor 6.
  • stator 5 two piezopacket arrangements are arranged symmetrically, namely two rows of clamping piezos 7, each of which is connected to one another by a transversely rigid bridge 8 within the row in question, and which are supported with their free end via running shoes 9 on the rotor 6, and in each case a row of step piezos 10 assigned to the respective row of clamping piezos, the front end of which is connected to the respective running shoe 9 of the associated clamping piezos 7.
  • This symmetrical piezo double arrangement has the advantage that the transverse forces exerted on the rotor 6 by the two opposing clamping piezo series 7 mutually compensate for one another.
  • the step piezos 10 are not visible in FIG. 1.
  • the rotor 6 is designed on its circumference as a screw thread spindle, so that due to this design the rotating step movement, which is generated by the step piezos 10, is immediately converted into an axial displacement movement.
  • a pressure ram 11 is arranged in the rotor 6 in a rotationally fixed but axially displaceable manner, which carries a head 12 mounted in a spherical cap at the front.
  • a bellows 13 connects the head 12 to the housing 1 and prevents dirt from entering the mechanism.
  • An electromagnet 14 is arranged in the rear region of the rotor 6, and in this there is a leaf spring assembly 15 which extends in the axial direction. As long as the electromagnet 14 is excited by the flow of electrical current, the spring assembly 15 has the illustrated extended position in which it is held by the electromagnet 14.
  • the spring assembly 15 axially supports the rear end of the plunger 11 on the rear part of the rotor 6.
  • the electromagnet 14 becomes ineffective and the spring assembly 15 buckles, as shown in dashed lines in FIG. 1.
  • the pressure stamp 11 can move back by a corresponding axial distance, so that the brake is released in any case if the power failure should occur when the brake is actuated, ie the pressure stamp 11 acting on the brake shoes 3.
  • the wheel can therefore continue to rotate freely and there is no locking.
  • the spring assembly 15 works on the toggle principle. This means that when the electromagnet 14 is excited, a moderate force of attraction is sufficient to bring the spring assembly 15 into the extended position, and the spring assembly 15 can absorb high axial forces in this extended position.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)
  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
  • Control Of Position Or Direction (AREA)

Abstract

Piezo-electrical actuator with automatic release on loss of power, comprising a regulating element, embodied as an axially-acting plunger (11), axially supported by means of a pressure support (15) which is articulated by means of a toggle joint and held in the extended position by means of an electromagnet (14) during operation.

Description

Piezoelektrischer Stellantrieb mit automatischer Freischaltung bei Stromausfall Piezoelectric actuator with automatic activation in the event of a power failure

Die Erfindung betrifft einen piezoelektrischen Stellantrieb, und zwar insbesondere einen solchen für verhältnismäßig hohe Antriebskräfte bzw. Antriebsleistungen, und insbesondere zur Verwendung als Betätigungsorgan für eine Rraftfahrzeugradbremse.The invention relates to a piezoelectric actuator, in particular one for relatively high drive forces or drive powers, and in particular for use as an actuator for a motor vehicle wheel brake.

Das Grundkonzept eines solchen piezoelektrischen Antriebs ist beispielsweise aus dem deutschen Gebrauchsmuster 94 19 802 bekannt.The basic concept of such a piezoelectric drive is known, for example, from German utility model 94 19 802.

Der Grundauf au eines solchen piezoelektrischen Antriebs umfasst eine Reihe von jeweils als Piezoelementenstapel ausgebildeten Piezopaketen, die zwischen einem als Stator dienenden Bezugsteil und einem als Rotor dienenden Abtriebteil angeordnet sind, und zwar so, daß die Stapelhöhe der Piezoelemente in jedem Piezopaket senkrecht zur Oberfläche des Abtriebsteils und zur Richtung der Relativbewegung zwischen Bezugsteil und Abtriebsteil verläuft. Diese Piezostapel dienen zum selektiven Erzeugen einer Klemmkraft zwischen Bezugsteil und Abtriebsteil und werden daher im folgenden als Klemmpiezos bezeichnet. Diese Klemmpiezos sind jeweils mit einem Ende (wobei der Begriff Ende sich jeweils auf die Piezoelementenstapelanordnung bezieht) am Bezugsteil festgelegt und stützen sich mit dem anderen Ende auf dem Abtriebteil ab, ohne daran festgelegt zu sein. Die Orientierung der Reihe, in welcher diese Klemmpiezos nebeneinander angeordnet sind, verläuft quer zur Richtung der Relativbewegung zwischen Abtriebsteil und Bezugsteil, das heißt also axial entlang des drehenden Abtriebsteils. Weitere, ebenfalls jeweils als Piezoelementenstapel ausgebildete Piezopakete, die wegen ihrer Funktion nachstehend als Schrittpiezos bezeichnet werden, sind mit ihrer Stapelhöhenrichtung etwa senkrecht zur Stapelhöhenrichtung der Klemmpiezos und in Richtung der Relativbewegung zwischen Bezugsteil und Abriebsteil orientiert. Diese Schrittpiezos sind jeweils mit einem Ende wiederum am Bezugsteil festgelegt und mit dem anderen Ende mit dem sich auf dem Abtriebsteil abstützenden Ende jeweils eines Klemmpiezos (oder einer Untergruppe von Klemmpiezos) verbunden.The basic structure of such a piezoelectric drive comprises a series of piezo packs each designed as a stack of piezo elements, which are arranged between a reference part serving as a stator and a driven part serving as a rotor, in such a way that the stack height of the piezo elements in each piezo pack is perpendicular to the surface of the driven part and to the direction of the relative movement between the reference part and the driven part. These piezo stacks are used to selectively generate a clamping force between the reference part and the driven part and are therefore referred to below as clamping piezos. These clamping piezos are each fixed to the reference part with one end (the term end in each case referring to the piezo element stack arrangement) and are supported on the driven part with the other end without being fixed thereon. The orientation of the row in which these clamping piezos are arranged next to one another runs transversely to the direction of the relative movement between the driven part and the reference part, that is to say axially along the rotating driven part. Further piezo packets, each also configured as a piezo element stack, which are referred to below as step piezos because of their function, are oriented with their stack height direction approximately perpendicular to the stack height direction of the clamping piezos and in the direction of the relative movement between the reference part and the abrasion part. These step piezos are each fixed at one end to the reference part and connected at the other end to the end of a clamping piezo (or a subset of clamping piezos) which is supported on the driven part.

Es sind zwei Gruppen von Klemmpiezos und zwei Gruppen von Schrittpiezos vorhanden. Diese werden elektrisch so angesteuert, daß jeweils die eine Gruppe von Klemmpiezos aktiviert, das heißt im Sinne einer Expansion elektrisch beaufschlagt wird und diese Klemmpiezos sich klemmend an das Abtriebsteil anlegen, während die andere Gruppe von Klemmpiezos deaktiviert, also in Lösestellung, das heißt nicht mit dem Abtriebsteil klemmend geschaltet ist. Dann wird die der klemmend geschalteten Klemmpiezogruppe zuge- ordnete Gruppe von Schrittpiezos aktiviert, so dass die betreffenden Schrittpiezos sich dehnen und dadurch die auf dem Abtriebsteil klemmenden Enden der Klemmpiezos um eine entsprechende Distanz in Bewegungsrichtung des Abtriebsteils auslenken. Dadurch bewegt sich das Abtriebsteil um eine entsprechende Distanz unter dem in Lösestellung geschalteten Klemmpiezos der anderen Klemmpiezogruppe hinweg. Danach wird die An- Steuerung umgeschaltet, das heißt die zuvor klemmenden Klemmpiezos werden in Lösestellung geschaltet, ebenso die zugehörigen Schrittpiezos, so daß die zuvor klemmenden Klemmpiezos sich aus der Klemmstellung lösen und in ihre Ausgangslage zurückkehren, während gleichzeitig die andere Gruppe von Klemmpiezos, die vorher in der Lösestellung waren, durch Aktivierung in die klemmende Position geschaltet und danach auch deren Schrittpiezos aktiviert werden. Auf diese Weise erzeugen die beiden Gruppen von Klemmpiezos mit jeweils zugeordneten Schrittpiezos durch ihren alternierenden Einsatz eine fortlaufende Schrittfolge, wodurch das Abtriebsteil schrittweise bewegt wird. Da diese An- steuerung der Piezos im Frequenzbereich von einigen Kilohertz, zum Beispiel 25 kHz, erfolgt, erhält man eine quasi-kontinuierliche Drehbewegung des Abtriebsteils relativ zum Bezugsteil. Der Erfindung liegt die Aufgabe zugrunde, eine solche Anordnung dahingehend auszubilden, daß sie zur Betätigung einer Kraftfahrzeugradbremse einsetzbar ist, was selbstverständlich andere Anwendungsfälle mit entsprechenden Anforderungen nicht ausschließt.There are two groups of clamping piezos and two groups of step piezos. These are electrically controlled so that one group of clamping piezos is activated, that is to say electrically charged in the sense of expansion, and these clamping piezos are clamped against the driven part, while the other group of clamping piezos is deactivated, i.e. in the release position, that is, not with the stripping section is connected in a clamping manner. Then the group of step piezos assigned to the clamping piezos connected is activated so that the relevant step piezos expand and thereby deflect the ends of the clamp piezos clamped on the driven part by a corresponding distance in the direction of movement of the driven part. As a result, the driven part moves a corresponding distance below the clamping piezo of the other clamping piezo group, which is in the release position. Then the control is switched over, i.e. the previously clamping clamp piezos are switched into the release position, as are the associated step piezos, so that the previously clamped clamp piezos release themselves from the clamped position and return to their starting position, while at the same time the other group of clamp piezos, the were previously in the release position, switched to the clamping position by activation and then their step piezos are also activated. In this way, the two groups of clamping piezos, each with associated step piezos, generate a continuous sequence of steps through their alternating use, as a result of which the driven part is moved step by step. Since this control of the piezos takes place in the frequency range of a few kilohertz, for example 25 kHz, a quasi-continuous rotary movement of the driven part relative to the reference part is obtained. The invention has for its object to provide such an arrangement that it can be used to actuate a motor vehicle wheel brake, which of course does not exclude other applications with corresponding requirements.

Wird ein solcher piezoelektrischer Stellantrieb zur Betätigung einer Kraftfahrzeugradbremse eingesetzt, muß die drehende Abtriebsbewegung des Abtriebsteils in eine Axialbewegung umgesetzt werden, um beispielsweise ein Bremsbacke gegen eine Bremsscheibe zu bewegen und zu spannen. Das Lösen der Bremse erfolgt durch Betätigung des piezoelektrischen Antriebs mit umgekehrter Drehrichtung des Abtriebsteils, was durch entsprechend modifizierte Ansteuerung der Klemm- und Schrittpiezos erfolgen kann.If such a piezoelectric actuator is used to actuate a motor vehicle wheel brake, the rotating output movement of the output part must be converted into an axial movement, for example to move and tension a brake shoe against a brake disc. The brake is released by actuating the piezoelectric drive with the reverse direction of rotation of the driven part, which can be done by appropriately modified control of the clamping and step piezo.

Während bei der herkömmlichen hydraulischen Kraftfahrzeugbremse die Bremsbacken in die Lösestellung vorgespannt sind und beim Wegnehmen des Hydraulikdrucks, also beim Loslassen des Bremspedals, sich aufgrund der von der Vorspannung erzeugten Rückstell- kraft in die Lösestellung bewegen, ist dies bei dem elektromechanischen Piezoantrieb nicht der Fall. Fällt aus irgendwelchen Gründen die Speisespannungszufuhr zu den Piezos weg, bleibt der Antrieb stehen. Bei der Anwendung als Kraftfahrzeugradbremse muß also dafür Sorge getragen werden, daß im Falle einer Störung in Gestalt eines Stromausfalls nicht der Piezoelektrische Antrieb in der Schließstellung der Bremse stehen bleiben kann und damit ein Lösen der Bremse unmöglich wird.While in the conventional hydraulic motor vehicle brake the brake shoes are biased into the release position and when the hydraulic pressure is released, ie when the brake pedal is released, they move into the release position due to the restoring force generated by the bias, this is not the case with the electromechanical piezo drive. If for any reason the supply voltage to the Piezos is cut off, the drive stops. When used as a motor vehicle wheel brake, care must be taken to ensure that, in the event of a fault in the form of a power failure, the piezoelectric drive cannot remain in the closed position of the brake, making it impossible to release the brake.

Mit der Lösung dieses speziellen Problems befasst sich die vorliegende Erfindung.The present invention addresses this particular problem.

Diese Aufgabe wird durch die im Patentanspruch 1 angegebene Anordnung gelöst. Vor- teilhafte Ausgestaltungen der Erfindung sind Gegenstand der Unteransprüche.This object is achieved by the arrangement specified in claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

Die erfindungsgemäße Anordnung ist also dadurch gekennzeichnet, daß das Abtriebsteil bei Stromausfall derart freigeschaltet wird, daß eine elektrisch aktivierte axiale Arretierung wirkungslos wird und ein axiales Ausweichen mindestens des mit der Bremsbacke verbun- denen Teils des Abtriebsteils um eine gewisse Axialdistanz ermöglicht. Im folgenden wird ein Ausführungsbeispiel der Erfindung unter Bezugnahme auf die anliegenden Zeichnungen näher beschrieben, in denen zeigt:The arrangement according to the invention is thus characterized in that the power take-off part is activated in the event of a power failure in such a way that an electrically activated axial locking becomes ineffective and enables an axial deflection of at least the part of the power take-off part connected to the brake shoe by a certain axial distance. An exemplary embodiment of the invention is described in more detail below with reference to the accompanying drawings, in which:

Fig. 1 im Axialschnitt eine Ausführungsform der Erfindung, undFig. 1 in axial section an embodiment of the invention, and

Fig. 2 einen Querschnitt durch den Piezoantrieb derFig. 2 shows a cross section through the piezo drive

Anordnung nach Figur 1.Arrangement according to FIG. 1.

Figur 1 zeigt im Axialschnitt einen Piezoantrieb nach der Erfindung zur Betätigung einer Kraftfahrzeugradbremse in Verbindung mit einer Scheibenbremsanordnung. Das GehäuseFigure 1 shows in axial section a piezo drive according to the invention for actuating a motor vehicle wheel brake in conjunction with a disc brake assembly. The housing

1 des Piezomotors ist mit einem Arm 2 verbunden, der ein Wiederlager für den vom Pie- zomotor erzeugten Anpressdruck auf ein Bremsbackenpaar 3 dient, das mit der Bremsscheibe 4 eines Rads zusammenwirkt.1 of the piezomotor is connected to an arm 2, which serves as a bearing for the contact pressure generated by the piezomotor on a pair of brake shoes 3, which cooperates with the brake disc 4 of a wheel.

Der innerhalb des Gehäuses 1 angeordnete Piezomotor ist in seinen Einzelheiten aus FigurThe details of the piezo motor arranged within the housing 1 are from FIG

2 besser erkennbar, wo das Gehäuse 1, der Arm 2 usw. weggelassen sind. Danach weist der Piezomotor einen Stator 5 und einen Rotor 6 auf. In dem Stator 5 sind zwei Piezopa- ketanordnungen symmetrisch angeordnet, nämlich zwei Reihen von Klemmpiezos 7, die jeweils durch eine quersteife Brücke 8 innerhalb der betreffenden Reihe miteinander verbunden sind, und die sich mit ihrem freien Ende über Laufschuhe 9 am Rotor 6 abstützen, und jeweils eine der betreffenden Klemmpiezoreihe zugeordneten Reihe von Schrittpiezos 10, deren vorderes Ende mit dem jeweiligen Laufschuh 9 des zugehörigen Klemmpiezos 7 verbunden ist. Diese symmetrische Piezodoppelanordnung hat den Vorteil, daß die von den beiden gegenüberstehenden Klemmpiezoreihen 7 auf den Rotor 6 ausgeübten Querkräfte sich gegenseitig kompensieren. Die Schrittpiezos 10 sind in Figur 1 nicht sichtbar.2 better recognizable where the housing 1, the arm 2, etc. are omitted. The piezomotor then has a stator 5 and a rotor 6. In the stator 5, two piezopacket arrangements are arranged symmetrically, namely two rows of clamping piezos 7, each of which is connected to one another by a transversely rigid bridge 8 within the row in question, and which are supported with their free end via running shoes 9 on the rotor 6, and in each case a row of step piezos 10 assigned to the respective row of clamping piezos, the front end of which is connected to the respective running shoe 9 of the associated clamping piezos 7. This symmetrical piezo double arrangement has the advantage that the transverse forces exerted on the rotor 6 by the two opposing clamping piezo series 7 mutually compensate for one another. The step piezos 10 are not visible in FIG. 1.

Wie aus Figur 1 hervorgeht, ist der Rotor 6 an seinem Umfang als Schraubgewindespindel gestaltet, so daß aufgrund dieser Gestaltung die drehende Schrittbewegung, die durch die Schrittpiezos 10 erzeugt wird, gleich in eine axiale Verschiebebewegung umgesetzt wird. Im Rotor 6 ist drehfest, aber axial um eine gewisse Distanz verschieblich, ein Druckstempel 11 angeordnet, der vorne einen in einer Kalotte gelagerten Kopf 12 trägt. Ein Faltenbalg 13 verbindet den Kopf 12 mit dem Gehäuse 1 und verhindert das Eindringen von Schmutz in den Mechanismus.As can be seen from FIG. 1, the rotor 6 is designed on its circumference as a screw thread spindle, so that due to this design the rotating step movement, which is generated by the step piezos 10, is immediately converted into an axial displacement movement. A pressure ram 11 is arranged in the rotor 6 in a rotationally fixed but axially displaceable manner, which carries a head 12 mounted in a spherical cap at the front. A bellows 13 connects the head 12 to the housing 1 and prevents dirt from entering the mechanism.

Im rückwärtigen Bereich des Rotors 6 ist ein Elektromagnet 14 angeordnet, und in diesem befindet sich ein Blattfederpaket 15, das sich in Axialrichtung erstreckt. Solange der Elektromagnet 14 durch elektrischen Stromfluß erregt ist, hat das Federpaket 15 die dargestellte gestreckte Position, in der es vom Elektromagneten 14 festgehalten wird. Das Federpaket 15 stützt das rückwärtige Ende des Druckstempels 11 am rückwärtigen Teil des Rotors 6 axial ab.An electromagnet 14 is arranged in the rear region of the rotor 6, and in this there is a leaf spring assembly 15 which extends in the axial direction. As long as the electromagnet 14 is excited by the flow of electrical current, the spring assembly 15 has the illustrated extended position in which it is held by the electromagnet 14. The spring assembly 15 axially supports the rear end of the plunger 11 on the rear part of the rotor 6.

Tritt nun eine Störung ein die mit einem Stromausfall oder einer Unterbrechung des Stromflusses zum Elektromagneten 14 verbunden ist, so wird der Elektromagnet 14 wirkungslos und das Federpaket 15 knickt ein, wie in Figur 1 gestrichelt dargestellt ist. Durch das Einknicken kann der Druckstempel 11 um eine entsprechende Axialdistanz zurückweichen, so daß die Bremse auf jeden Fall gelöst wird, wenn der Stromausfall bei betätigter Bremse, also auf die Bremsbacken 3 wirkendem Druckstempel 11 auftreten sollte. Das Rad kann sich demnach ungehindert weiter drehen und es tritt keine Blockierung ein.If a malfunction occurs which is connected to a power failure or an interruption of the current flow to the electromagnet 14, the electromagnet 14 becomes ineffective and the spring assembly 15 buckles, as shown in dashed lines in FIG. 1. By the buckling, the pressure stamp 11 can move back by a corresponding axial distance, so that the brake is released in any case if the power failure should occur when the brake is actuated, ie the pressure stamp 11 acting on the brake shoes 3. The wheel can therefore continue to rotate freely and there is no locking.

Wie man sieht, arbeitet das Federpaket 15 nach dem Kniehebelprinzip. Das heißt bei Erregung des Elektromagneten 14 genügt eine mäßige Anziehungskraft, um das Federpaket 15 in die Strecklage zu bringen, und das Federpaket 15 kann in dieser Strecklage hohe Axialkräfte aufnehmen. As you can see, the spring assembly 15 works on the toggle principle. This means that when the electromagnet 14 is excited, a moderate force of attraction is sufficient to bring the spring assembly 15 into the extended position, and the spring assembly 15 can absorb high axial forces in this extended position.

Claims

Patentansprüche claims 1. Piezoelektrischer Stellantrieb mit automatischer Freischaltung bei Stromausfall, mit einem Stator (1), einem Rotor (6), und mindestens einer Reihe von am Stator (1) festgelegten und radial auf den Rotor (6) wirkenden Klemmpiezopaketen (7) sowie einer entsprechenden Anzahl von am Stator festgelegten und auf die mit dem Rotor zusam- menwirkenden Enden der Klemmpiezopakete (7) wirkenden Schrittpiezopaketen (10), wobei mindestens zwei Gruppen von Klemm- und Schrittpiezopaketen (7, 10) vorgesehen sind, die alternierend zur Wirkung gebracht werden, um den Rotor (6) quasikontinuierlich in Drehbewegung zu versetzen, und wobei der Rotor (6) aufgrund seiner Drehbewegung eine axiale Translationsbewegung eines Druckstempels (11) erzeugt, und wobei der Druckstempel um eine gewisse Distanz axial verschiebbar gelagert, jedoch über eine Druckstütze (15) axial an einem die axiale Translationsbewegung ebenfalls ausführenden Bauteil (6) abgestützt ist, und wobei die Druckstütze (15) Kniehebelartig ausgebildet und mittels eines stromdurchflossenen Elektromagneten (14) im Betrieb in der Streckstellung gehalten wird, bei stromlosen Elektromagneten (14) je- doch kniehebelartig einknicken kann.1. Piezoelectric actuator with automatic activation in the event of a power failure, with a stator (1), a rotor (6), and at least one row of clamping piezo packs (7) fixed to the stator (1) and acting radially on the rotor (6), and a corresponding one Number of step piezo packs (10) fixed on the stator and acting on the ends of the clamping piezo packs (7) interacting with the rotor, at least two groups of clamping and step piezo packs (7, 10) being provided, which are brought into effect alternately, in order to set the rotor (6) in a quasi-continuous rotary motion, and wherein the rotor (6) generates an axial translational movement of a pressure stamp (11) due to its rotational movement, and wherein the pressure stamp is axially displaceable by a certain distance, but via a pressure support (15 ) is axially supported on a component (6) which also executes the axial translation movement, and wherein the pressure support (15) is toggle lever type g and is held in the extended position by means of a current-carrying electromagnet (14), but can buckle like a toggle lever in the case of currentless electromagnets (14). 2. Stellantrieb nach Anspruch 1 , wobei die Druckstütze (15) als in Axialrichtung des Rotors (6) verlaufendes Blattfederpaket ausgebildet ist.2. Actuator according to claim 1, wherein the pressure support (15) is designed as a leaf spring assembly extending in the axial direction of the rotor (6). 3. Stellantrieb nach Anspruch 1 oder 2, wobei der Rotor (6) als Gewindespindel ausgebildet ist und die Klemmpiezostapel (7) über entsprechende Schuhe (9) mit den Gewindegängen zusammenwirken, derart, daß die Schrittbewegung zugleich in eine axiale Translationsbewegung des Rotors (6) umgesetzt wird, und wobei der Druckstempel (11) in einer Bohrung des Rotors (6) gelagert ist, die auch den Elektromagneten (14) aufnimmt. 3. Actuator according to claim 1 or 2, wherein the rotor (6) is designed as a threaded spindle and the clamping piezo stack (7) interact with the threads via corresponding shoes (9), such that the step movement simultaneously into an axial translation movement of the rotor (6 ) is implemented, and wherein the pressure stamp (11) is mounted in a bore of the rotor (6) which also receives the electromagnet (14).
PCT/DE2001/004099 2000-11-05 2001-11-02 Piezo-electrical actuator with automatic release on loss of power Ceased WO2002037535A2 (en)

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JP2002540189A JP2004513310A (en) 2000-11-05 2001-11-02 Piezoelectric actuator with automatic release function when power is lost

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US7187103B2 (en) 2001-06-06 2007-03-06 Miniswys Sa Piezoelectric drive
WO2007045428A1 (en) * 2005-10-18 2007-04-26 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Disc brake with an electric motor actuator and an emergency releasing device
WO2013020873A1 (en) * 2011-08-05 2013-02-14 Physik Instrumente (Pi) Gmbh & Co. Kg Piezoelectric rotary drive for a shaft

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DE102005035597A1 (en) * 2005-07-29 2007-02-01 Robert Bosch Gmbh Bellows for a self-energizing, electro-mechanical disc brake and disc brake with such a bellows
DE102005035608A1 (en) 2005-07-29 2007-02-08 Robert Bosch Gmbh Self-energizing electromechanical disc brake
DE102006014250A1 (en) * 2006-03-28 2007-10-04 Robert Bosch Gmbh Self-energizing electromechanical friction brake for use as vehicle brake for braking vehicle wheel, has detachable support for friction brake lining, which eases after detaching
JP4826942B2 (en) * 2006-03-31 2011-11-30 日立オートモティブシステムズ株式会社 Electric disc brake and electric disc brake assembly method

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US4623044A (en) * 1983-12-22 1986-11-18 Jidosha Kiki Co., Ltd. Brake apparatus
JPS63266228A (en) * 1987-04-17 1988-11-02 Honda Motor Co Ltd Brake device
DE9419802U1 (en) * 1994-12-10 1996-04-04 Richter, Hans, 86163 Augsburg Stepper motor
DE19928140A1 (en) * 1998-09-21 2000-03-23 Hans Richter Compensating sound waves with electroactive drive, using actuators arranged vibrating in housing forming at least one drive element with at least two actuator pairs together with clamping actuators and hub actuator
JP2001086700A (en) * 1999-09-16 2001-03-30 Asmo Co Ltd Electrically-driven actuator

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7187103B2 (en) 2001-06-06 2007-03-06 Miniswys Sa Piezoelectric drive
EP1396012B2 (en) † 2001-06-06 2010-07-28 miniswys SA Piezoelectric drive
WO2007045428A1 (en) * 2005-10-18 2007-04-26 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Disc brake with an electric motor actuator and an emergency releasing device
WO2013020873A1 (en) * 2011-08-05 2013-02-14 Physik Instrumente (Pi) Gmbh & Co. Kg Piezoelectric rotary drive for a shaft
JP2014518507A (en) * 2011-08-05 2014-07-28 フィジック インストゥルメント（ピーアイ）ゲーエムベーハー アンド ツェーオー．カーゲー Piezoelectric rotary drive for shaft
US9106158B2 (en) 2011-08-05 2015-08-11 Physik Instrumente (Pi) Gmbh & Co. Kg Piezoelectric rotary drive for a shaft

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