WO2018106147A1

WO2018106147A1 - Capacitive electrical machine with tensioned electrodes

Info

Publication number: WO2018106147A1
Application number: PCT/RU2017/000901
Authority: WO
Inventors: Евгений Анатольевич ОБЖИРОВ
Original assignee: Евгений Анатольевич ОБЖИРОВ
Priority date: 2016-12-09
Filing date: 2017-12-05
Publication date: 2018-06-14
Also published as: RU2016148472A; RU2663499C2; RU2016148472A3

Abstract

A capacitive electrical machine with tensioned electrodes relates to the broad class of transformers for converting electrical energy into mechanical energy and vice versa by means of the electrostatic forces of Coulomb attraction between opposite charges. Capacitive electrical machines can be used in industry and engineering as electric motors and generators in a very broad range of fields. In order to increase the power of a capacitive electrical machine, the present invention proposes using electrodes in the form of strips or films or thin wires in a state of constant tension, which are fastened in such a state in the structure of the capacitive electrical machine, thus making it possible to house a large number of interacting plane parallel electrodes in a limited space. The solutions claimed in the present invention achieve the technical results of an increase in power and specific power and an improvement in other power characteristics of electrostatic transformers, i.e. capacitive electrical machines.

Description

DESCRIPTION OF THE INVENTION

Capacitive electric machine with tension electrodes.

Capacitive electric machines with tension electrodes (EMEs) belong to a wide class of converters designed to transform electric energy into mechanical and inverse transforms and acting due to the electrostatic forces of Coulomb attraction between electric charges of opposite signs placed on parallel flat electrodes or electrodes a different configuration.

Industrial applicability.

The EMEs claimed in the present invention can be used in industry and technology as motors and actuators that convert electrical energy into mechanical energy, for example, in robotics, in actuators of electric locks and other locking devices, and in many other areas of technology. Also, EMEs can be used as a inverse converter of mechanical energy into electrical energy; in this quality, EMEs can be used both as a generator of electric current pulses of both high voltage and any other value necessary for household and industrial electrical engineering. In particular, the declared electrostatic micromotors and microgenerators can be used wherever piezoelectric transducers are used now, including as voltage-controlled relays, as micromotors in servos and in many other devices.

Current state of the art.

The first electrostatic converters appeared long before the discovery of the principle of electromagnetic induction. A wide class of electrical machines operating on the principles of electrostatics is known, which contain at least one pair of electrodes designed to accumulate electric charges of the opposite sign, by which electrodes interact with each other. Such an interaction of the electrodes is more convenient and easier to describe through the dynamics of their capacitive characteristics, since any pair of electrodes can be considered as an electric capacitor of variable capacitance (KPE), the capacitance of which depends on the geometry of the electrodes, their relative position and the dielectric characteristics of the medium located between the electrodes. A change in any of these factors leads to a change in capacitance, a change in the capacitance of charged electrodes leads to a change in the potential difference between the electrodes and the electric energy of the KPI, and can be produced in many mechanical ways. It is this rigid connection of the mechanical characteristics of the device with its electrical capacitance and with the electrical voltage that underlies the energy conversion in this type of electrical machines, therefore they are often called capacitive, although other names may occur.

In addition, there are numerous electric machines that also operate due to electrostatic forces, but which cannot be described as KPIs. The famous Van de Graaff generator, which uses a dielectric tape, which is the rotor of the generator. The principle of operation of the generator is to induce an electric charge on the tape in the contact area of the tape with a grounded metal shaft (generator stator) when creating a potential difference between the shaft and the tape, and in the subsequent transfer of this charge to the collector brush, which removes the induced charge on the charge storage, moreover, due to the fact that the mutual electric capacitance of the dielectric tape and the stator during this transfer decreases many times, the potential difference of the charges on the drive with respect to to a grounded stator is many times greater than the initial difference of the excitation potentials. A known modification of the Van de Graaff generator is the pelletron, which works according to the same principle, in which instead of a dielectric tape a tape is used, consisting of many conductive electrodes isolated from each other and forming a chain of alternating electrodes (pellets) and a dielectric base. To describe the present invention and determine the current level technology is important that: firstly, these pellets are galvanically isolated from each other; secondly, only the rotor has a tape shape, while the metal shaft (stator) is neither a tape nor a solid plate, that is, only one tape is used in the generator; thirdly, this tape has only natural tension on the shafts of the generator and the tape moves relative to these shafts, while in the claimed invention, specially tensioned tapes either move together with the frame on which they are stretched, or are motionless. Therefore, the above characteristics of the Van de Graaff generator and pelletron allow us to state the absence of their relevance to the present invention.

A wide class of piezoelectric machines based on the direct and inverse piezoelectric effect is also known. In many ways, these devices can be considered as analogues of electrostatic capacitive converters, since their work is based on the same principle of tight connection of geometric characteristics and potential difference of opposing surfaces of piezoceramic work elements. Piezoelectric micromotors, sometimes called ultrasonic, are widely used. In many respects, for example, in specific power and energy efficiency, these devices are already successfully competing with and surpassing electromagnetic electric machines. For example, they are widely used in camera lens control systems. The disadvantages of these machines include expensive production technology and a relatively small resource of work, as well as technological problems when trying to increase the size and power of the device.

For capacitive converters, described as KPIs, it is common that their capacitance periodically changes from a maximum value of C _max to a minimum value of C _m , _n and vice versa. When the EME operates in the generator mode, the CPE electrodes in the C _max position are charged with some initial excitation charges, then the CPE capacitance is reduced to C _m j _n , as a result of which the charge energy and the potential difference created by them increase, which is the purpose of generation. When operating in a potential difference is applied to the KPE electrodes in the position C _m j _{n of the} engine; under the influence of electrostatic forces, the KPE moves to the C _max position, while doing mechanical work.

In the general case, the power of such a converter is greater, the more they differ in magnitude of C _max and C _min . Since C _{min is} technically easy to reduce to almost zero, the efficiency and power of the EME will be the greater, the more C _max . Increasing this EME value is one of the main tasks for increasing the power and other power characteristics of EMEs, which is the ultimate goal of the solutions claimed in the present invention.

Among EMEs, two broad classes of machines that are the subject of the present invention can be distinguished: electrostatic planar actuators and shear converters.

These EME classes are variable capacitors (KPE), built on the basis of a conventional flat capacitor, consisting of two flat electrodes, superimposed on top of each other through a dielectric layer separating the conductive parts of the electrodes. Let the contact surface area of the electrodes S, the thickness of the dielectric layer d, its dielectric constant e _d . The capacitance of such a capacitor is C = e ₀ e _d S / d, where e ₀ is the electric constant equal to 8.85 ^* 10 ^{~ 12} (F / m). Often there are descriptions of EMEs, in which the layer of dielectric is the air gap. Due to the poor electrical strength and low dielectric constant of air, such devices have very low power and efficiency.

Changing the capacitance of a flat capacitor is possible in three mechanical ways.

Firstly, the capacitance of a flat capacitor can be changed by changing the distance between the plates d, the principle of the work of the electrostatic planar actuator (EPA), which in English terminology is often called Comb drive, is based on this principle. EPA consists of two plane-parallel electrodes placed parallel to each other on variable distance. Sometimes one of the plates is suspended above the second on a spring. The change in the capacity of such a device occurs by changing the distance between the plates in the direction perpendicular to the plates. In the present invention, EMEs built on this principle are called planar EMEs.

Secondly, the capacitance of a flat capacitor can be changed by changing the contact surface area of the plates S by shifting one electrode relative to another. In the present invention, EMEs built on this principle are called shift EMEs.

Thirdly, the capacitance of a flat capacitor can be changed by changing the dielectric constant of the dielectric e _d by replacing one dielectric in the space between the plates with a dielectric with a different dielectric constant. To change the capacitance of the capacitor, it is possible to partially replace the dielectric between the plates of the capacitor with a conductive material, while this conductive material should not be electrically connected to the plates of the capacitor, by the nature and general properties of changing the capacitance of the capacitor, this option can be considered as a special case of replacing one dielectric with another, since the conductive material placed between the plates of the capacitor, due to electrostatic induction, is equivalent to a dielectric with Extremely high dielectric constant. EMEs built on this principle are a shift EME.

All of these methods are well known and studied and are the general level of technology. In this case, it is possible to implement any combination of these three methods.

In the present invention, to increase the power and power characteristics of EMEs of the types described above, it is proposed to use electrodes made in the form of tapes or films in a constant tension state and fixed in a tensioned state in the EME structure, or in their own stiffening frame. It is possible to use tensioned wires, which in many cases greatly simplifies the assembly of EMEs. Disclosure of the invention.

As noted above, to increase the power of EMEs, it is necessary to increase the maximum capacity of EME C _max . In all the above options, the C _max position is reached when the electrode plates are in the state of maximum tight contact with each other, therefore, the first technical task to increase the power of such EMEs is the manufacture of electrodes whose surfaces are as smooth and flat as possible. Any deterioration in the surface quality of interacting electrodes increases the number and size of air gaps between the surfaces of the electrodes in a state of abutting each other and, as a consequence, leads to a decrease in C _max, and eventually to a decrease in power Aimé. The proposed technical solution - tension electrodes - largely solves this problem, since the stretched film simultaneously has both smoothness and a perfect flat surface. The mechanical methods for treating the surface of the electrodes are either in principle incapable of achieving the desired purity of treatment, or are very expensive.

It should also be noted that in order for the types of EME described above to have a high specific power (power divided by the mass of the EME), the electrodes should be as thin as possible, have the maximum possible contact surface and be located as close to each other as possible. In fact, it is possible to use electrically conductive and dielectric materials up to several microns thick, such materials (metal foil and polymer films) are produced by the industry in a wide assortment, respectively, the maximum distance between the electrodes can be reduced to hundreds or even tens of microns, which makes it possible to obtain EMEs of really high specific power .

However, the use of such materials in the described cases leads to a serious technical problem - the thinner the film, the lower the coefficient of elasticity of the film (ceteris paribus, it is directly proportional to the thickness of the film), and the greater the elastic deformation that occurs in the films during their electrostatic interaction together. Films adhere to each other under the influence of electrostatic forces, and when they are separated from each other during EME operation, strains (elastic stresses) arise in the films, leading to stretching of the films, and such stretching in thin films can be tens or hundreds of microns.

For a planar EME, this leads to the fact that the interacting films remain in a state of partial or even complete overlap of contact surfaces on each other in working positions, when there should not be such an overlap, in fact, such residual adhesion means that the achievable value of C _min will be close to the value of C _max. This makes it impossible to work EME with electrodes made of thin films, or at least significantly reduces either the power and generated voltage of the EME (in generator mode), or the power and force transmitted to an external mechanical drive (in engine mode).

For shear EMEs, this leads to the fact that a friction force arises between the films adhering to each other, which can either completely block the movable parts of the EME and make the EME impossible, or significantly reduce the power and efficiency of the EME.

To solve this problem, you can also use tension electrodes, which in the process of manufacturing EME must be fixed in their structural positions under elastic tension in a stretched form. The greater the initial tension of the electrodes (initial internal tension), the less subsequent elastic deformations that occur in the electrodes under the influence of an external force stretching the electrode. Indeed, according to Hooke's law: F = kx, where F is the elastic force, k is the coefficient of elasticity, x is the tensile value. The initial tension means that kxo + kxH ^ x, where x ₀ is the common tension corresponding to the initial tension of the electrode, k _t is the analog of the coefficient of elasticity for the tensioned electrode, which implies:

that is, the greater the initial tensile tension x ₀ , the greater the "stiffness" of the electrode, which, in fact, is a fairly obvious fact.

Electrodes can be tensioned as in special frames electrodes designed for this, and in the housings of electrode sections in a variety of ways. As a result of this technical solution, it becomes possible to use the most thin tape or film electrodes, or electrodes made of thin wires, in the design of the EME. Achievable technical result of this is the multiply increased specific power and power of EME.

EME version with shear tension electrodes.

A very promising EME model with tension electrodes is shear EME. It is possible to combine many tensioned electrodes into two sections of plane-parallel electrodes, one of which is a rotor and the other is a stator, each section consists of a section frame and a set of plane-parallel or tapes, or films, or wires stretched in the section frame so that the electrodes are arranged in series with each other after another. In this case, a gap space is formed between adjacent stator electrodes, the width of which is equal to or close to the width of one or all of the rotor electrodes (if the rotor electrodes are the same width), and gap spaces are formed between adjacent rotor electrodes, the width of which is equal to or close to the width of one , or all stator electrodes (if the stator electrodes are the same width), and the rotor and stator electrodes are completely or partially placed in these slit spaces of each other so that those elements of the rotor frame and stat The holes to which the section electrodes are attached were shifted relative to each other at a right angle or another angle relative to the axis perpendicular to the plane of the surfaces of the rotor and stator electrodes, and did not interfere with the shift of the rotor electrodes relative to the stator electrodes. This design means that the rotor and stator electrodes are stretched perpendicular to each other (deviation from a right angle is possible) inside their frames, the power side elements of which are also perpendicular to each other and do not interfere with the sliding of the rotor electrodes between the stator electrodes. Such a combination of electrodes makes it possible to make EMEs with many electrodes operating simultaneously and synchronously - hundreds and thousands of electrodes placed compactly in limited volume, which allows to obtain a multiple increase in power and power characteristics of EME.

In addition, each tape electrode can have a complex sectorial design, for example, consist of many conductive strips separated by dielectric strips (a design similar to pelletron pellets), but unlike a pelletron, these strips must be combined into units of a single switching to a power supply and / or load. This design allows you to design EMEs in which the full amplitude of the oscillation of the capacitance can occur at the minimum possible rotor shifts with a high frequency. Let the stator and rotor have the same sectorial structure - the width of all conductive strips and dielectric strips is the same, the strips alternate one after another. The C _max is reached when the conductive strips of the rotor and the stator are located exactly opposite each other, and the C _t; _{n is} achieved when the conductive strips of the stator are exactly opposite the dielectric strips of the rotor and vice versa. With the same rotor displacement relative to the stator for two EMEs that differ only in the width of the strips, all other things being equal, the EME in which the strips are thinner will produce a larger number of operating cycles for changing the EME capacitance from maximum to minimum, and therefore will have a larger capacity.

There can be a lot of options for such a sectorial structure of the electrodes, for example, sectors can be not only strips, but also have complex geometry, they can be located at different angles to the sides of the rotor or stator, and so on. In a generalized definition, this structure of electrodes can be described as follows: each electrode is divided into many sectors of conductive material, alternating with sectors of dielectric material, and sectors of conductive material can be combined into one or more groups of sectors, each of which has its own separate connection to a power source or load.

An important additional positive property of EMEs with shear tension electrodes is that the rotor of such EMEs may not have switching to the power supply or load, charges on the rotor electrodes can be formed by electrostatic induction under the influence of the electric fields of the stator electrodes.

Additional embodiments of the invention.

Since it is essential that the movement of the electrodes of the EME claimed here, transmitted or received from an external mechanical drive, is reciprocating, the following additional technical solutions, described below, may be important for EME.

Firstly, an important additional solution for the declared EMEs is combining two or more EMEs sequentially one after another in one device so that the stator (or rotor) of each EME is kinematically connected with the rotor (or stator) of the previous or next EME. This combination allows you to increase the amplitude of the translational-backward movement of the EME transmitted or received from an external mechanical drive.

Secondly, an important additional solution for the declared EMEs is the combination of two or more EMEs in one device in which individual EMEs are kinematically coupled and operate either in turn, or in antiphase, or with a different phase shift relative to each other, that is, all combined EMEs have a kinematic connection with a common mechanical drive, and at any moment of the EME working cycle, the distances between the contact surfaces of one of the EMEs differ from similar distances of the other EME. As a result, when one EME is in the C _max position, the other EME can be in the C _m j _n position, or a different position. This combination of EMEs allows for continuous operation of the device, and also allows you to average the operating characteristics of EMEs, since the dependence of the EME capacitance on the distance between the interacting electrodes is non-linear.

Thirdly, an important additional solution may be the inclusion of an elastic return mechanism in the EME in order to return the EME to its original state for the start of the next working cycle. Given return elastic the mechanism must have such elastic strength and energy stored during the active phase of the EME working cycle when the energy conversion necessary for the user occurs so as not to block this active phase, but be sufficient to return the EME to its original state at the beginning of the working cycle.

Fourth, in order to suppress stray transient processes leading to unnecessary voltage and current fluctuations in the power supply circuit or EME load, and also to eliminate currents reverse to the power supply or EME charging currents, it is useful to include an electric valve (rectifier) in the EME power circuit ), for example, a diode, in such a way as to exclude or minimize the current in the direction opposite to the supply or charging current of the EME. Otherwise, parasitic fluctuations in voltage and current will occur in the electric circuit of the power supply or the EME load, caused by transient dynamic processes, at least reducing the power and efficiency of the EME.

Fifth, in order to reduce or completely prevent sticking of the electrodes in the C _max position, it is useful to additionally place a release agent or coating on the electrode contact surface that has dielectric properties

Achievable technical results.

The technical results achieved by the solutions claimed in the present invention are to increase the power and specific power and other power characteristics of electrostatic converters - EMEs with tension electrodes.

Claims

CLAIM

1. Capacitive electric machine with tension electrodes (EME), consisting of at least two electrodes containing conductive material and dielectric material, intended for electrostatic interaction with each other, by any combination of the following: or by changing the distance between the electrodes or their parts ; or by shifting one electrode relative to another; or by completely or partially replacing one dielectric material between EME electrodes with a dielectric material with a different dielectric constant or with a conductive material;

characterized in that at least two EME electrodes designed to interact with each other, both fully or partially made in the form of either a tape, or a film, or wires, which are in a state of constant tension and are fixed in a tensioned state or in the construction of the EME, or inside its electrode section, which is the rotor or stator of the EME, or in its own frame of rigidity.

2. Capacitive electric machine with tension electrodes (EME) according to claim 1, characterized in that it further comprises at least one tape or film made of a dielectric material, which are in a constant tension state and are fixed in a tensioned state or in a structure EME, either inside its section of electrodes, which is the rotor or stator of the EME, or in its own frame of rigidity.

3. Capacitive electric machine with tension electrodes (EME) according to claim 1, characterized in that it contains two sections of plane-parallel electrodes, one of which is a rotor and the other is a stator, each section consists of a section frame and a set of plane-parallel or tapes, or films , or wires stretched in the frame of the section so that the electrodes are arranged sequentially one after another with the formation between the adjacent stator electrodes of the slot space, the width of which is equal to or close to the width of one or all electrodes p torus, and to form between adjacent electrodes rotor slot space width of which is equal to or close to the width, or one or all electrodes of the stator and the electrodes rototira and stator completely or partially placed in these slit spaces of each other so that those elements of the rotor frame and the stator to which the section electrodes are attached are shifted relative to each other at a right angle or another angle relative to the axis perpendicular to the plane of the surfaces of the rotor and stator electrodes and do not interfere with the shift rotor electrodes relative to the stator electrodes.

4. Capacitive electric machine with tension electrodes (EME) according to claim 3, characterized in that at least one pair of adjacent rotor and stator electrodes made in the form of a stretched tape or film are distinguished by the following design feature: each electrode is divided into many sectors from conductive material alternating with sectors of dielectric material, and sectors of conductive material can be combined into one or more groups of sectors, each of which has the ability to separate CONNECTIONS to the power supply or load.

5. Capacitive electric machine with tension electrodes (EME) according to any one of paragraphs. 3 - 4, characterized in that it consists of several EMEs, connected sequentially one after another in one device so that the stator of each EME is kinematically connected to the rotor of the previous and / or next EME, and the rotor of each EME is kinematically connected to the stator of the previous and / or the next EME.

6. Capacitive electric machine with tension electrodes (EME) according to any one of paragraphs. 3 to 4, characterized in that it consists of several EMEs combined in one device in which individual EMEs are kinematically coupled and operate either in turn, or in antiphase, or with a different phase shift relative to each other.

7. Capacitive electric machine with tension electrodes (EME) according to any one of paragraphs. 3 to 4, characterized in that it further comprises an elastic return mechanism kinematically connecting the rotor and the EME stator to each other in such a way as to ensure the return of the rotor to its original state inside the EME duty cycle.

8. Electric capacitive machine with tension electrodes (EME) according to any one of paragraphs. 3 to 4, characterized in that it further comprises at least one an electric valve or rectifier included in the circuit for supplying electric power to the EME electrodes in such a way as to minimize or make impossible the current in the direction opposite to the current of the power source.

9. Capacitive electric machine with tension electrodes (EME) according to any one of paragraphs. 3 to 4, characterized in that at least one electrode on the contact surface further comprises a release adhesive lubricant or coating having dielectric properties.