Patent Application
20130076043
The present invention is comprised in the technical field of energy accumulation and harnessing devices available in moving apparatuses or in surplus for another reason in an electrical system, delivering said energy in less time, i.e., with high power, such that it can be used in, for example, starting or regulating electrical systems, which are characterized by the demand of large amounts of energy in little time. The system is capable of absorbing said energy also in a short time span, i.e., at high power.
The accumulation of energy in electrical systems is very important because by means of the application thereof, starting processes are optimized to thereby reduce the power consumption of such processes.
It is therefore considered that optimizing starting processes by means of energy storage systems will entail considerable economic and environmental savings.
Storing energy with high energy and power densities together with high outputs is one of the main fields of research that is currently being conducted. The greatest possible accumulation of energy by means of the lowest weight and volume possible, together with loading and unloading times suited to each application, is sought.
The most common storage systems existing today are the following:
There are also elastic energy accumulation systems by means of using coil springs manufactured with composites, as described in patent application EP-A-2097655 (Elastodynamic Energy Accumulator-Regulator) with respect to electric wind generators, vehicles and non-stop power supply systems. The drawback of high consumption in starting processes is present in most electrical systems.
For example, starting up an electric machine in general entails a large consumption of electrical energy and the additional need of having to develop a high torque to overcome the resistant inertia in the motor in standby, consuming several times the nominal operating intensity during said period and causing the motor to overheat. There are starting systems with reduced voltage such as star-delta starters, auto-transformer starters, primary resistance starters or soft starters. Although said systems allow improving the aforementioned problems, the results are not the most favorable, low outputs, high consumptions, electric motor deterioration, control difficulty and excess cost added by introducing these systems being produced.
Another example would be emergency electric generation systems of large electrical installations: little time lapses from the time power is cutoff until auxiliary generators are started up, during which time there is no power supply. This can be a huge drawback in hospitals, airports, etc. A system capable of supplying a small amount of energy in a short time, without useless energy expenditures in starting electric motors, would solve this drawback.
The same occurs, for example, in vehicles: generally, a larger amount of energy is necessary during the start-up due to the necessary acceleration of the entire mass. Furthermore, if the vehicle is electric, the need for a larger amount of energy for starting the motor is combined with this effect.
Contributing to solve these problems would also make it possible to improve current energy regulation systems which provide energy when it is lacking in the system to which they are connected, and they absorb energy from it when there is a surplus therein: a simple and low-cost system such as that described, capable of delivering and absorbing an industrially significant amount of energy in short time spans, i.e., at high powers, has an immediate and advantageous application in regulation.
By using coil springs manufactured with a high elastic energy absorption and delivery capacity (for example, composites with a polymeric matrix and carbon, glass fiber reinforcement, etc., though more examples will be provided below), it is possible to transmit high mechanical torque for a considerable number of revolutions. This allows providing energy in the conditions necessary for start-up.
The energy accumulation systems described above have drawbacks, such as high cost, unfavorable energy efficiency, limited operating safety and/or a rather short service life.
The object of the present invention is to overcome the drawbacks of the state of the art described above by means of a storage system for storing energy useful in starting and regulating electrical systems, comprising
In view of the features described above, the invention provides a mechanical energy storage device by means of at least one coil spring, which can be formed by one spring or a set of springs arranged in series or in parallel and can be coupled to a motor to allow start-up thereof by means of unloading this previously stored mechanical energy. The spring of the system is compressed absorbing energy and being reloaded, accumulating mechanical energy which is subsequently used for starting the motor by means of the extension of the coil spring. The spring can be of the type described in patent application EP-A-2097655, different springs also being able to be used, such as coil springs with variable torque, springs the shape of which before being mounted in the casing or in the operating arrangement is defined with any type of spiral (Archimedean spiral, logarithmic spirals, etc.), the resistant section of the spring being able to have different configurations: hollow or solid monolithic section with different shapes, rectangular, circular, elliptical, etc.; sandwich section made up of skins on the outer faces and core in the central part, which can be, for example, foam, honeycomb, etc.; sandwich section with one skin having a different width than the other one, or laminated with sheets of different widths, and in all cases being able to vary along the length of the spring the resistant characteristics of the sections (shape, width, thickness, reinforcement, material). Furthermore, and for the purpose of increasing energy density, materials with an allowable tension—high Young modulus (like some engineered ceramic materials or elastomers) can be used. The use of spaces subjected to little mechanical stress, such as the core, for example, in sandwich sections or the hollow part in hollow monolithic sections, is also provided for arranging non-elastic storage systems, for example, batteries. Energy density can likewise be increased if piezoelectric, piezoresistive or electroactive materials (for example polymers), or recycled, organic materials, or composites thereof are placed in the areas of the spring that will experience greater deformation.
In one embodiment of the invention, the coil spring is attached to a central shaft and fixed to an outer casing and is driven by said shaft by means of the application of a twisting moment allowing the accumulation of energy in mechanical form for subsequent reuse thereof.
Once the energy is stored, is can be used to start the motor. For greater functionality, the system is preferably designed such that it is capable of storing sufficient mechanical energy to hot- and cold-start a certain number of times. As previously mentioned in the present specification, the coil spring can be formed by a set of springs arranged in series or in parallel for the purpose of reducing radial or longitudinal dimensions thereof. In another embodiment, springs arranged in separate shafts are provided for loading and unloading the storage system, the central shaft being the system loading shaft, and the outer casing being attached to a secondary shaft of the reduction gearing as the unloading shaft or vice versa.
When several springs are arranged in series, it is necessary to introduce attachment elements between them such that the rotation of each spring causes the rotation of the next spring, so each coil spring is attached at one end of the attachment element and at the opposite the end it is attached to the attachment element of the next spring. Likewise, several spirals offset by a certain angle contained in each attachment element can be introduced to optimize available space. That of said attachment elements located at one of the ends can be fixed and that of the opposite end can be integral with the drive shaft of the coil spring or it itself can act as a movement and torque transmission shaft. The different discs can be attached through adhesive, through a form fit mechanical connection or any fixing mechanism.
Particularly, in the series arrangement of several springs, each of the springs of the energy storage device is respectively arranged between two attachment elements which are arranged in the rotating shaft, and the attachment elements comprise a first end attachment element and a second end attachment element, and at least one intermediate attachment element susceptible to rotating about the rotating shaft. One of the end attachment elements is integral with the rotating shaft and rotates with the rotating shaft, and the other one is stationary and does not rotate with the rotating shaft, and each coil spring is attached at one of its ends to a central part of an attachment element and at its other end to a peripheral part of the adjacent attachment element.
In one embodiment of the series arrangement of several coil springs, each coil spring is arranged between a front surface and a rear surface of respective adjacent attachment elements and is peripherally surrounded by an annular body of an attachment element, the annular body comprising an open side, a side closed by a wall and an annular inner surface together forming an inner cavity in which the corresponding coil spring is housed.
At least one of the end attachment elements and each intermediate attachment element respectively have a central cylindrical projection with a diameter less than the annular body, emerging from the front surface and having an axial passage traversed by the rotating shaft. The first end of each coil spring is fixed to the cylindrical projection of one of the attachment elements, and the second end of each coil spring is fixed in the annular body of the adjacent attachment element. In turn, the attachment elements are immobilized with respect to one another, such that, when each coil spring is connected to two of the attachment elements, the rotation of the rotating shaft in said first direction successively tenses the coil springs arranged between the attachment elements, and the rotation of the rotating shaft in said second direction successively releases the coil springs arranged between the attachment elements. In turn, the stationary end attachment element can comprise a disc-shaped body from the front surface of which said cylindrical projection emerges.
At least one of the coil springs can comprise a first coil body and a second coil body arranged offset with respect to one another, each coil body being attached at one end to a first part of said central part of an attachment element and at the other end to a second part of said peripheral part of the adjacent attachment element, the respective coils of the coil bodies being arranged in an alternated and concentric manner. The offset of the coil bodies can be, for example, 180°.
The braking and holding element which allows fixing the spring in stationary conditions by means of locking is arranged attached to the rotating shaft. Locking can be done by means of using a braking device which can be, for example, a device with brake discs, shoes, an electromagnetic brake or locking brake or another similar device, and/or a ratchet or other mechanical locking or retention method. The braking and holding element can be driven by means of a preferably electromagnetic locking actuator, although it can also be electrical, pneumatic or hydraulic. When the braking and holding element is a ratchet mechanism, a braking device can additionally be arranged to apply a brake to the shaft once the necessary energy is unloaded. The braking device can be a device with brake discs, shoes, an electromagnetic brake or locking brake or another similar device. The braking device can be driven by means of a preferably electromagnetic braking actuator, although it can also be electrical, pneumatic or hydraulic.
It is inferred from the preceding description that the present invention overcomes the drawbacks of the systems of the state of the art by means of a simple and effective system.
The system can be used to absorb and deliver energy to an electric machine which is capable of acting like a motor and generator which, controlled by means of suitable power electronics, is capable of converting the energy stored in the spring mechanically into electrical energy, and vice versa. High electric power is thereby allowed for, for example, starting electric motors or regulating electrical systems or networks of another type.
In this application, the movement transmission shaft is connected to an electric machine capable of acting like both a motor and an electric generator, it sometimes being necessary to introduce between both systems a torque and rotation revolution varying element such that the operating conditions adapt to those demanded both by the storage system and by the electric machine used.
As a result of the release of the energy stored in the spring, the electric machine introduced therein starts operating, thereby generating electricity which can be used in starting or regulating electrical systems, such that the high consumption of the starting process comes from energy previously stored and obtained from energy not previously used.
Likewise, if the electric machine is supplied with electricity, it will be operating like a motor, the storage of energy in the springs thereby taking place as a result of the rotational movement reaching them.
The operation of the different states of the motor/generator is controlled through power electronics depending on the different states of the control variables of the system.
As a final complement of this description, it must be indicated that in certain applications a damping or absorption system for damping or absorbing vibrations, particularly twisting vibrations, in the event of very rapid loading or unloading, as well as a torque limiting system which could be mechanical, hydraulic, electrical, etc. . . . , preventing the problems derived from a very rapid loading or unloading, and provided that the control system had not acted due to that rapidness, may be necessary.
Aspects and embodiments of the invention are described below based on several drawings in which
When the load state of the springs 1 is high enough and electrical energy is to be generated, the electromagnetic actuator —7—acts on the braking and holding system —5—, causing the movement of the shaft —4—of the set of springs —1—. The reducing mechanism —6—adapts the operating conditions to those demanded by the motor/generator —9—, such that it produces electrical energy which is delivered to the network —11—in the necessary conditions as a result of the actuation of the power electronics —10—depending on the different control variables. To end the unloading process for unloading the set of springs —1—, the electromagnetic actuator —7—again puts the braking and holding system —5—in its initial position, causing the rotation of the shaft —4—of the set of coil springs —1—to stop.
To reload the set of coil springs —1—, the electronic power control element —10—establishes the conditions necessary for supplying power to the motor —9—as a result of the electrical energy taken from the electrical network —11—. The electromagnetic actuator —7—releases the braking and holding system —5—, so through the movement of the motor —9—and the actuation of the reducing mechanism —6—, the set of coil springs —1—is reloaded as a result of the movement of the shaft —4—. When the reloading process is to be stopped, the power electronics —10—stop supplying power to the motor —9—and the electromagnetic actuator —7—returns the retaining mechanism —5—to its initial position.
As can be seen, the springs —1—are arranged respectively between two attachment elements —12 —12′—, —12′—13—which are arranged in the rotating shaft (not shown in
Particularly, each coil spring —1—is arranged between a front surface and a rear surface of respective adjacent attachment elements —12—, —12′—, —13—, and is peripherally surrounded by an annular body —12a—, —12a′—of one of the attachment elements —12—, 12′—. The annular body —12—, —12′—comprises an open side, a side closed by a front wall —12c—, —12c′—and an annular inner surface —12b—, —12b′—together forming an inner cavity to house the corresponding coil spring —1—.
The attachment elements —12—, —12′—, —13—respectively have a central cylindrical projection —12d—, —12d′—, —13b—with a diameter less than the annular body —12a—, —12a′—, emerging from the front surface and having an axial passage —12e—, —12e′—, —13c—for the passage of the rotational shaft —4—. It can also be seen that the stationary end attachment element —13—comprises a disc-shaped body —13a—from the front surface of which said cylindrical projection —13b—emerges.
Each spring —1—is made up of two coil bodies —1A—, —1B—offset with one another by an angle of 180°, which can be seen in greater detail in
Since each coil spring —1—is connected to two of the attachment elements —12—, —12′—, —13—and since the second attachment element —13—is stationary, the rotation of the first attachment element —12—integral with the rotational shaft —4—in one direction successively tenses the coil springs —1—arranged between the attachment elements —12—, —12′—, —13—, whereas the rotation of the attachment element —12—in the opposite direction successively releases the coil springs —1—.
By introducing a rotation—A—in the shaft of the first coil spring 1—, the annular body will turn in direction—B—. If this annular body is attached to the annular body of a coil spring —1—wound in the opposite direction, the rotation—C—received by the latter will load that spring —1—and produce a rotation in the shaft —4—thereof in direction—D—.
Now by attaching the shaft —4—of this spring —1—with that of a third coil spring —1—, wound in the same direction as the first one, i.e., opposite the second one, the third spring —1—can also be loaded. The unloading operation occurs in a similar manner but in the reverse direction.
| Number | Date | Country | Kind |
|---|---|---|---|
| P201031069 | Oct 2009 | ES | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/ES2010/070653 | 10/8/2010 | WO | 00 | 12/10/2012 |
