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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Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Cited By (3)

Families Citing this family (4)

Citations (5)

• 2001
  • 2001-11-02 AU AU2002215834A patent/AU2002215834A1/en not_active Abandoned
  • 2001-11-02 JP JP2002540189A patent/JP2004513310A/ja active Pending
  • 2001-11-02 WO PCT/DE2001/004099 patent/WO2002037535A2/de active Application Filing

Patent Citations (5)

Non-Patent Citations (1)

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