FR2491270A1 - ACTUATING DEVICE ELECTRICALLY CONTROLLED - Google Patents

Abstract

THE INVENTION CONCERNS AN ELECTRICALLY CONTROLLED ACTUATOR AND PROVIDED WITH A PIEZO-ELECTRIC CONVERTER 4 ACTING ON A ROD 5, CONSISTING OF PIEZO-DISCS OF OXIDE AND WHICH IS PROVIDED BETWEEN A BASE PLATE 1 TO WHICH IT IS LINK AND A GUIDE PLATE 2 CONNECTED TO BASE PLATE 1 BY SPACER ELEMENTS 3. EACH SPACER ELEMENT 3 CONSISTS OF A STACK OF OXIDE PIEZO-DISCS WHOSE POLARIZATION AXIS IS ORIENTED PERPENDICULAR AT THE POLARIZATION AXIS OF THE PIEZO-ELECTRIC CONVERTER 4; THE SPACING ELEMENTS AND THE CONVERTER CAN BE CONTROLLED ELECTRICALLY AS WELL AS INDIVIDUALLY AS A UNISON. APPLICATION TO VALVES, PUMPS, INJECTORS, ETC.

Description

The present invention relates to an organ of ac-

  electrically controlled and provided with a

  piezoelectric weaver acting on a rod,

  of a stack of oxide piezo discs, which is

  placed between a base plate to which it is bonded and a guide plate connected to the base plate by

spacer elements.

  Actuators in the form of piezoelectric converters are known and,

  as far as they are concerned, it is also known that they

  put in place order times which are gold-

  from 50 to 100 micro-seconds. However, they do not allow

  only very small actuation races which, together with

  used battery dimensions are about 0.03 mm.

  This is obviously sufficient, as has already been proposed,

  for their use as pre-control valves in connection

  sound with two-way switching valves of the so-called "logistors" type, but it is not possible to

  use directly as actuators for

  hydraulics, pumps, etc. These piezoelectric actuators of

  known type, apart from the fact that they do not allow

  only very small work

  that they can only be used in a range of

  limited temperatures for which they were designed. AT-

  With the construction structure that is conventionally adopted (ceramic-steel combination), they behave in temperature so that the working

  reduced or increased considerably, depending on the

  riau. For highly variable temperatures, we do not

  does not want to use actuators of this kind.

  It is therefore an object of the invention to provide an actuating member, operating in accordance with the principle

  piezoelectric and which, in addition to its fast speed,

  well-known command drive, a sufficient work

  large, exclusively influenced by the tension

  and not by variations in temperature.

  This problem is solved according to the invention in that each spacing element consists of a stack of

  oxide piezo-discs whose axis of polarization is o-

  perpendicular to the polarization axis of the piezoelectric converter and that the spacers and the converter can be controlled

  electrically both individually and in unison.

  Thus, in comparison with known solutions, a working stroke is obtained which is approximately doubled and it is possible to use said members even in

  highly variable temperature conditions. These properties

  allow the use of, for example, the operating organ

  according to the invention for direct or indirect injection

  of fuel in internal combustion engines, to ensure the digital positioning of operating cylinders of hydraulic control systems, etc. The invention is explained below in detail,

  with the aid of an exemplary nonlimiting implementation illus-

  by a schematic representation of an organ of

  piezoelectric actuation and a 3-way valve

tracks, powered by this organ.

  Figure 1 is a longitudinal section of a

  operating mechanism according to the invention and a three-way plate valve actuated by said member,

  Figure 2 is a cross-section of the organization

actuation of Figure 1, -

  Figure 3 is a longitudinal section of an example

  application of the actuating member as injection

fuel,

  Figure 4 shows another example of injection

fuel.

  Figure 1 shows a longitudinal section of a

  piezoelectric actuating member which comprises a

  base 1 and a guide plate 2, which are interconnected, in the example considered, by four spacer elements 3. Each spacer element 3 is composed of

  of a stack of laminated oxide piezo-discs, whose

  of polarization is oriented perpendicular to the

  main x of the actuator. In this respect, it should be noted that a piezo-disk oxide expands, when

  the application of an electrical voltage and in

  across this voltage, in the direction of its polarization axis, and contracts in correspondence

  in a direction perpendicular to this axis of polarization

  tion. Concentrated to the main axis of the actuating member, there is provided another stack of oxide piezo-discs which is bonded to the base plate and whose axis of

  polarization is oriented in the direction of the main axis

  pal while its other end is connected to the rod 5

  of the actuating member. This stack of plates

  The piezoelectric converter 4 is arranged around this piezoelectric converter 4. The spacing elements 3, which connect the base plate 1 to the guide plate 2 and which are arranged symmetrically, as shown in FIG.

  shows the section of Figure 2. The stem of the organ of ac-

  is guided through a hole in the

  that guide 2 concentrically to the main axis.

  The stack of piezoelectric plates of the conver-

  weaver 4 and spacers 3 are connected in a conventional manner, and not shown, with the corresponding electrical power supply conductors. By applying an electrical voltage to the converter 4, the plate stack is expanded and the rod moves away from the base plate 1. By simultaneous application of electrical voltages to the stack of plates forming the spacers 3, these compress in the direction of the main axis and they thus pull the guide plate 2 towards the base plate 1. It thus occurs between the guide plate 2 and the rod 5 a relative movement that has a magnitude of approximately

  value twice that of a piezoelectric

  of known type and comparable dimensions. Because the plate stacks of the spacer elements and the converter are formed from an identical material having an identical thermal coefficient and have

  equal lengths, temperature variations do not

  no relative movement between the stem and the plate

guidance.

  Depending on the application envisaged, it is possible to switch between them the orientations of the axes

  polarization of the converter 4 and space elements

  in such a way that, when applying a

  electrical connection, the rod 5 is pulled towards the base plate and the guide plate 2 is moved away

of the base plate.

  In an example of application of the

  According to the invention, this is associated in FIG. 1 with a three-way plate valve.

  whose body 6 is rigidly connected to the guide plate

  2. In the cavity formed between the body and the guide plate, there is provided a valve plate 7, which is pushed by an elastic washer 8 against the rod 5. In the-condition of rest of the body of actuation, the plateau

  valve 7 ensures the closure of an annular channel 9

  placed in the guide plate 2 and which is connected to a con-

  In the case of the annular channel 9 provided in the valve plate 7, there is provided in the valve body 6 a second annular channel 10 which is connected to a pressure line A. In the valve body 6, there is provided a discharge port B arranged concentrically to

  the main axis. In the valve plate 7, it is

  seen holes 11 which should allow the unhindered flow of a fluid - gas or liquid - through the valve.

  In the position shown, the pressure duct

  A is connected to the discharge port B so that the

  fluid under pressure can flow from A to B.

  actuation member, the valve plate 7 is pushed down against the forces exerted by the spring washer 8. Consequently the annular channel 10 is closed, along with the pressure conduit A In this position, the discharge port B is connected to the return duct C so that it can occur

immediate pressure drop.

  It might also be considered to arrange the organization

  according to the invention as a pump and also to arrange the two-way valves required for this

  pump in the manner of the actuator according to the invention.

  vention. For this purpose, it would be necessary to arrange the valve plate 7 of Figure 1 in the form of a piston and create the necessary ducts suction and discharge. The

  fluid to be discharged would be, when applying a

  sucked from the lower side of the piston and pushed back from the

  upper part of it and then, when the voltage is cut off, it would be pushed back to the lower side and sucked from the

upper side.

  In FIG. 3, a longitudinal section is shown.

  dinal, as another example of application of the invention, a

  fuel injector. The basic structure of the

  the operating mechanism is known from FIG. 1 and, as described above, a baseplate 1, a

  guide plate 2, spacers 3, a conver-

  wiper 4 and a rod 5. The rod 5 is rigidly connected to a valve plate 12 which, when the actuating member is at rest, is applied against the guide plate 2 and

  closes an annular channel 9 formed in the guide plate

  and is connected to a fuel intake duct A. This fuel intake duct is subjected to a high pressure. When a voltage is applied to the piezoelectric stack of plates, an annular gap is established between the guide plate 2 and the valve plate 12, the width of which is approximately proportional to the applied voltage. and the fuel flows from the annular channel 9

  radially outwards and, depending on the

  the interval and the pressure of the fuel, it is

  is more or less sprayed in the form of a fog.

  In order to ensure proper distribution of the fuel, the guide plate is provided in this area with a curved deflector surface 13a which may for example have grooves of different curvatures or spiral shapes to make it possible to obtain a known manner for example a bell spray, jets having different angular orientations, turbulence fuel, etc. FIG. 4 shows an exemplary embodiment of such a fuel injector in the case of an actuator comprising stacks of

  piezoelectric plates permuted, the rod 5 being

  to the base plate 1 when applying a voltage. Inside the guide plate 2, a cavity is provided against the lower surface of which

  applies, in the rest condition, the plateau of

  12 connected rigidly to the rod 5 and ensuring the closure of an annular channel 10 formed in said surface and which is again connected to the fuel supply conduit A. The valve plate 12 is provided with an appendix 13 which has deflecting surfaces 13b, already described with reference to FIG. 3, to improve the distribution of the

  fuel. When applying a voltage, the

  annular valle opens and fuel flows under high pressure, radially inward, it is deflected by deflecting surfaces and it is injected into

the combustion chamber.

  In addition to an interval width command that

  proportional to the voltage, it is possible to

  to carry out a proportional flow control as well

  tional to the frequency that proportional to the pulse duration so that one can get any unfolding

  of the injection, of the curve following a law of

  to intermittent injection (inside a

  injection phase covering, for example, 18 degrees of rotation

crankshaft).

  It is also conceivable to arrange an injection

  fuel tank in the form of a three-way valve according to Figure 1 and associated with a return duct

  in which a non-return valve, or a

or both in parallel.

Claims (1)

CLAIM   - Elotrically controlled actuating member and provided with a piezoelectric converter acting on   a stem, consisting of a pile of oxy piezo-disks   of and which is arranged between a base plate to which it is bonded and a guide plate connected to the base plate by spacers, characterized in that each spacing element (3) is composed of a stack of oxide piezo-discs whose polarization axis is oriented perpendicular to the polarization axis of the   piezoelectric converter (4) and that the elements   spacers and the converter may be   electrically, both individually and nisson.