WO2005115091A2

WO2005115091A2 - Mechanical energy storage and release device

Info

Publication number: WO2005115091A2
Application number: PCT/IN2005/000167
Authority: WO
Inventors: Ankit Mehta; S. Pasumarthy Seshu
Original assignee: Indian Institute Of Technology, Bombay
Priority date: 2004-05-31
Filing date: 2005-05-26
Publication date: 2005-12-08
Also published as: WO2005115091A3

Abstract

A mechanical energy storage and release device comprises wound energy storage element (1), an arbor (2), a casing (3) and a means of charging. The energy storage element (1) is connected at one end to the arbor and at another to the casing (3). The energy storage element (1) is wound helically layer layer by layer with each layer connected to the other at one end thus leading to a high energy density and mechanical efficiency configuration, since a larger number of turns can be accommodated in the system. One of the applications of the device is as a rechargeable battery. The electrical generator (9) connected to the output end of the configuration produces electric energy by the virtue of the drive from the wound energy storage element (1).

Description

A NOVEL MECHANICAL ENERGY STORAGE AND RELEASE DEVICE Field of Invention

The invention relates to an improved mechanical energy storage and release device comprising of wound energy storing element(s) Background of the Invention Mechanical energy storage and release devices are capable of being recharged anywhere, anytime repeatedly, thereby extending the usability of their products. These devices use energy storing element in the form of strip commonly known as spring. Number of turns in a spring is defined as the number of circular turns taken by the strip in the configuration. Springs as energy storage devices have been extensively used in clocks, wind up toys, retractable measuring tapes, seatbelts, etc. Clockwork motors in the form of energy release device are traditionally used as the drives for the wind up clocks and wind up toys. CN1121562: Describes an energy accumulator consisting of energy input, storage and output three parts of construction. The method connects several energy accumulators in series on the square frame support; the torque is delivered from two spiral power springs to drive the pinwheel and belt pulley to do work continuously. The energy accumulator can also be retrieved repeatedly to charge energy and utilize. This design of the energy-storage engine suggests the use of a conventional clockwork spring. One of the shortcomings of this invention is that the configuration involves complex arrangement of pawls and ratchets on each spring causing an ineffective utilization of the volume. GB2352335: Describes a battery replacement in the form of electro-mechanical generator.

In this case an electro- mechanical battery capable of providing electrical energy from stored potential mechanical energy and used to replace or supplement conventional batteries/cells, the internal components being adapted to suit standard battery cases such as A, AA, "Lantern" type etc. The terminals are supplied from a generator via a zenner diode, capacitor acting to smooth the electrical output and store some electricity. A clockwork motor and step up gearbox supply mechanical power via a shaft, forms part of the main outer casing of the battery and winding is achieved, using a key or by rotating section of the case. The operating time of such a configuration is very less because of the less number of turns that can pack in the configuration. US5982577: Describes a batteryless, spring-powered portable cassette player. The system simultaneously provides mechanical motion driven by a rotatable drive shaft rotating at a continuous predetermined desired speed, to generate voltage output by an electrical generator having a rotor that rotates at a continuous predetermined desired speed, the rotatable drive shaft being non-concentric with, being laterally-spaced-apart from, and being parallel to the rotor. The system includes a prime mover, which comprises a windable driving spring, which, in turn, includes an interconnecting drive train for separately drivably connecting the driving spring both to the rotatable drive shaft and to the rotor of the electrical generator. The interconnecting drive train comprising a gear train, which has a driving section which is connected to the driving spring means and which is common for driving both the rotatable drive shaft and the rotor at the electrical generator. It also includes two driven sections that are laterally spaced from one another and which extend in parallel from the driving section. One of the driven sections is drivably connected to the rotatable drive shaft. The other one of the driven sections is drivably connected to the rotor of the electrical generator. A speed governor is included for controlling unwinding of the driving spring so as to cause the driving spring to drive both the rotatable drive shaft and the rotor of the electrical generator at the respective continuous predetermined desired speeds. US3354383: Describes a spring powered and regulated generator. This invention relates to low-power electric generators of spring powered or wind up type adapted for use in remote areas for demolitions and other ignition spark supply, radio and communication, limited lighting, and the like. These are therefore self energized and can release kinetic energy and generate electricity for instant use, without standby battery power. US2524005: Describes a spring powered electric generator that is specifically made for the use in airplanes for the pilots to start of the process of the escape of the pilot during emergency. US5839817: Describes a dynamo-powered torch that is operative without a power supply in the form of a battery. The dynamo-powered torch includes a cylindrical hollow body and a dynamo housed in the cylindrical hollow body. The cylindrical hollow body has a knob disposed at a rear end thereof. The knob has an axle centrally mounted on a face of the knob and a spiral power spring mounted around the axle. A clamp is mounted on the axle of the knob and driven by the spiral power spring. A gear train, which includes a first gear, a second gear, a drive shaft, a third gear and a forth gear, is provided for driving the dynamo. Two conductor strips extend from the dynamo to a bulb, which is lit by current passing from the dynamo to the bulb via the conductor strips. DE3906861 : Describes a power supply unit as a replacement for a standard battery or a standard accumulator for small loads, especially test sets. The unit is of modular construction and has the standard dimensions and standard connections of monocells, batteries or small accumulators, so that it can be used instead of these devices, the spring-mechanism store is a mechanical clockwork device, the generator is a rotating generator whose rotation speed is controlled by the movement of the clock mechanism and is kept largely constant. The drawings of the patent do not suggest anything about the configuration of used springs. The prior art is replete with examples that implement energy storage and release using the clockwork motor to store energy and drive an electric generator to produce electrical energy with varying application and the outer design of the products. The number of turns obtained is very less from conventional clockwork motors. The gear train necessary to drive the output device (for example a generator), from a high torque spring decreases the efficiency of the system. The energy storage and release devices listed in the prior art suffer from following drawbacks:

1. Less energy density: The energy density of such configurations is too low for these motors to be used for energy storage or for generating motive power for extended periods of time. The number of turns that can be accommodated in the existing mechanisms is very less and thus the mechanical efficiency of such systems is low owing to the necessary use of a gearbox box for most of the applications.

2. Operating speeds are very low: The operating speeds of the conventional motor have to be kept low, in order that the motor can be operated for extended period of time. This is detrimental to good mechanical efficiency of the system, as more number of gears is used for the drive train.

3. Very high torque: The high torque characteristics lead to difficulties in handling and maintenance of such systems.

Summary of the invention The main object of the invention is to provide improved mechanical energy storage and release device comprising of wound energy storing element(s) Another object of the invention is to provide more number of turns of wound energy storing element(s) in the same volume thereby increasing energy density of the mechanical energy storage and release device. Yet another object of the invention is to improve mechanical efficiency of the mechanical energy storage and release device. Yet another object of the invention is to enhance operating speed of the energy storage and release device. Yet another object of the invention is to provide energy storing element(s) with flat torque curve. Yet another object of the invention is to provide energy storage and release device, which can also be used as rechargeable battery Yet another object of the invention is to provide energy storage and release device capable of being configured for use in various applications/uses substantially as herein described and illustrated with reference to the accompanying figures. Thus in accordance with the invention the energy storage and release device comprises of:

• Wound energy storing element (s)

• Arbor

• Casing • Optional electric generator Key Detailed Description of the Invention

Features and advantages of this invention will become apparent in the following detailed description and the preferred embodiments with reference to the accompanying drawings. Figure 1 : Mechanical energy storage/release device Figure 2: Exploded view of the device used as battery Figure 3: Winding configuration The drawings illustrate specific embodiment of the invention and variations may be made within the meaning of this invention. Fig. 1 shows the mechanical energy storage and release device. A strip (1) wound in helically layer by layer, with each layer connected to the other at one end, a cylindrical solid or hollow arbor (2) with straight, stepped or curved shape and a cylindrical solid or hollow casing (3) with straight, stepped or curved shape. The energy storing element(s) in the form of a strip (1) material is wound axially over an arbor and after reaching the end of the arbor (2) the spring is wound again on the same arbor

(2) over the first layer of the spring, repeating the process to obtain the desired number of layers. The arbor (2) and the casing (3) may be cylindrical solid or hollow shaft that is made straight, stepped or curved, depending on the application. The shape of the arbor (2) and casing

(3) depends on the configuration for a specified application we use the spring in. In one of the embodiments, mechanical energy storage/release device is used to drive the electric generator to function as a mechanically rechargeable battery as shown in (Figures 2 & 3). A energy storing element(s) in the form of a strip (1) wound in helically layer by layer, with each layer connected to the other at one end, a straight cylindrical hollow arbor (2) with straight retaining strips (6) acting as a straight cylindrical hollow casing. The strip (1) material is wound axially over the arbor (2) and after reaching the end of the arbor (2) the spring is wound again on the same arbor (2) over the first layer of the spring, repeating the process to obtain the desired number of layers. The shape of the arbor (2) is hollow and fitted with a slot (10). The hollow shape facilitates to encase the electric generator (9) within arbor (2). The generator (9) is retained by a hollow keyed retaining cylinder (7), which is fixed on a support plate (5). The engaging and disengaging of the generator (9) from the arbor (2) is ensured by a sliding motion of the generator (9) in a keyed retaining cylinder (7) due to which the generator input shaft moves in and out of the slot (10). The engaging and disengaging of the generator (9) is done by the insertion of the key (11) in the slot (10), when the key (11) is removed the backing spring (8) pushes the generator (9) input shaft back into the arbor slot (10). The supporting plate (4) and (5) are welded onto the retaining strips (6) to make a closed structure. The arbor (2) is used for both input and output. The input is given using a key (11 ). The input to the device is a manual cranking effort spent in winding the spring (1) on the arbor (2) and the electrical output obtained by the unwinding of the strip (1 ) from the arbor (2) onto the casing (6). The strip (1) is wound on the arbor (2) by rotating the arbor (2) or the casing (3) in a specific direction using a key, which can be manually or electrical motor operated. The strip (1) when is fully wound on the arbor is fully charged. The energy can be released by the system via both the arbor (2) and the casing (3), depending on the torque applied to each end. The end where the external torque acting is less than the strip configuration torque then that end is releasing energy and the end where the torque is more is storing energy in the configuration. Both these operations can be performed simultaneously. And any of the arbor (2) or casing (3) can be used for energy input or release. The output can be given to the system directly or via a gearbox. In another embodiment the energy storing element is wound not over a straight cylindrical arbor but a stepped or curved one, leading to customized response curves from the energy- storing element. In one of the embodiments a variable thickness energy-storing element made of a single variable width element or joining of two or more such elements is used. In another embodiment the casing and the arbor are of any suitable shape depending on the end use. In one of the embodiments energy storing element is of the cross sections such as trapezoidal, triangular, square rectangular and there like. In another embodiment the device can be charged by external means such as to function as a motor the output of which is in the form of mechanical motion thereby simultaneously functioning as an energy storage element. In another embodiment the device functions as a motor, which is in the form of a thick hollow cylinder. In yet other embodiments the same configuration is used for the other configurations of a conventional planar spring. E.g. B-motor, twin spool configurations and there like. Example 1 : The following example illustrates how the novel energy storage and release device results in enhancement in the energy density because of more number of turns as against conventional devices. The specifications of the device used as a battery replacement in a commercially available windup radio, as obtained from the prior art:

1. Overall dimensions: 30X320X210 mm3 (approx.)

2. Output power: 55 mW

3. Output voltage: 3 V

4. Operating time, maximum (on full charge): 30 mins 5. Gearbox reduction ratio: 1000:1 (6 stage gearbox used)

6. Number of spring turns: 60

7. Spring configuration: B-Motor

8. Hand cranked charging

The spring dimensions used in the implementation are: Length, L = 10m

Width, b = 30mm

Thickness, t = 0.2mm Spring unwinding rate = 2rpm

Thus the volume energy density of the energy storage and release mechanism is ~ 317.6 Whr/m3, and the over all efficiency, considering the generator efficiency as 60% and the efficiency of each stage at gearbox as 95%, is 44%.

Specifications of a device designed based on an embodiment of the invention disclosed above, keeping the length of the spring case as 30 mm.

1. Overall dimensions: Φ50X30 mm3 (Cylindrical construction) 2. Output power: 55 mW

3. Output voltage: 3 V

4. Operating time, maximum (on full charge: approx): 45 mins

5. Gearbox reduction ratio: 44.4:1 (3 stage gearbox needed)

6. Number of spring active turns: 2000 7. Spring configuration: conventional power spring

8. Hand cranked charging

Spring configuration details:

Length, L = 660m

Width, b = 0.15mm Thickness, t = 0.5mm

Case diameter, D = 50mms Arbor diameter, d = 20mm Case length, I = 30mm Spring unwinding rate = 45rpm Thus the volume energy density of the energy storage and release configuration is ~ 1860 Whr/m3, and the overall efficiency, with the generator and the gears remaining the same, is 51%. Including a gearbox at the casing side of the battery to allow rapid charging can do the winding of the battery. Including less number of gears leads to lower cost configurations. The spring used in my idea is very easily made by drawing a round spring wire from a die made of required dimensions. Comparing the two configurations:

Thus it is evident from this example that the novel configuration results in more number of turns in the same or less (as in the above case) volume as compared to the conventional devices resulting in the substantial increase in the energy density and overall efficiency of the energy storage and release device.

Claims

1. A mechanical energy storage device comprising: a woundable energy storing element; an arbor means adapted for winding thereon of said woundable element for storing of the energy, said wounding adapted for high energy density and mechanical efficiency of the storage and release energy comprising wounding of said woundable energy storing element helically layer by layer to form at least two layers with each layer connected to the other at one end; a casing means adapted to retain the woundable energy storing element during said storing and releasing operations, one end of said woundable element operatively connected to said casing and the other to said arbor and a means to charge the device.

2. A mechanical energy storage device as claimed in claim 1 wherein said woundable energy storing element comprise a woundable strip means.

3. A mechanical energy storage device as claimed in anyone of claims 1 or 2 comprising selective repeat number of turns of wound energy storing element(s) in selective volume for selectively varying power density of the mechanical energy storage and release capacity.

4. A mechanical energy storage device as claimed in anyone of claims 1 to 3 wherein said woundable energy storing element is wound axially over the arbor means and after reaching the end of the arbor the said woundable energy storing element is wound again on the same arbor over the first layer of the said woundable energy storing element and repeated wound in such desired number of layers.

5. A mechanical energy storage device as claimed in anyone of claims 1 to 4 wherein said woundable energy storing element comprise a metal strip element wound helically layer by layer over said arbor means, each layer connected to the other at one end.

6. A mechanical energy storage device as claimed in anyone of claims 1 to 5 wherein said arbor means comprise a substantially cylindrical solid, thick or hollow arbor with straight, stepped or curved surface portion.

7. A mechanical energy storage device as claimed in anyone of claims 1 to 6 wherein said casing comprise substantially cylindrical, solid, thick or hollow casing with straight, stepped or curved surface portion.

8. A mechanical energy storage device as claimed in anyone of claims 1 to 7 wherein the shape of the arbor and casing are selected based on the configuration of its application/use.

9. A mechanical energy storage device as claimed in anyone of claims 1 to 8 wherein the energy is released via both the arbor and/or the casing depending upon the torque applied to each end, the end where the external torque acting is less than the strip configuration torque then that end is releasing energy and the end where the torque is more is adapted to store energy in the configuration.

10. A mechanical energy storage device as claimed in anyone of claims 1 to 9 wherein it is charged by external means and adapted to function as a motor the output of which is in the form of mechanical energy thereby simultaneously functioning as an energy storage element.

11. A mechanical energy storage device as claimed in anyone of claims 1 to 10 adapted for^' use for other configurations of conventional planer spring including B-motor, twin spool configurations and the like.

12. A mechanical energy storage device as claimed in anyone of claims 1 to 11 wherein the energy storing strip is wound on a stepped and/or curved arbor and adapted for customized response curves from the energy storing element.

13. A mechanical energy storage device as claimed in anyone of claims 1 to 12 wherein said energy storing strip element is selected from a single variable width element or by joining two or more elements.

14. A mechanical energy storage device as claimed in anyone of claims 1 to 13 wherein the casing and the arbor are of any suitable shape depending on the end use.

15. A mechanical energy storage device as claimed in anyone of claims 1 to 14 wherein said woundable energy storing element is of a suitable cross-section such as oval, flat oval, trapezoidal, triangular, square, rectangular and the like.

16. A mechanically rechargeable battery comprising a mechanical energy storage device comprising a woundable energy storing element; an arbor means adapted for winding thereon of said woundable element for storing of the energy, said wounding adapted for high energy density and mechanical efficiency of the storage and release energy; a casing means adapted to retain the woundable energy storing element during said storing and releasing operations, one end of said woundable element operatively connected to said casing and the other to said arbor and key means to charge the device.

17. A mechanically rechargeable battery as claimed in claim 16 wherein said mechanical energy storing device comprise anyone of claims 1 to 15.

18. A mechanically rechargeable battery as claimed in anyone of claims 16 or 17 adapted for use to drive an electric generator.

19. A mechanically rechargeable battery as claimed in claim 18 comprising an electric generator; said mechanical energy storage device comprising a woundable energy storing element; said arbor means is hollow and fitted with slot, said hollow shape adapted to encase the electric generator within said arbor, the said generator retained by a hollow keyed retaining cylinder which is fixed on a support plate, the engaging and disengaging of the generator from the arbor is ensured by a sliding motion of the generator in said keyed retaining cylinder whereby the generator input shaft is adapted to move in and out of the slot, the engaging and disengaging of the generator is done by the insertion of the key in the slot when the key is removed the backing spring is adapted top push the generator input shaft back into the arbor slot, said wounding of the energy storing element adapted for high power density of the storage and release energy; and a casing means adapted to retain the woundable energy storing element during said storing and releasing operations.

20. A mechanically rechargeable battery as claimed in claim 19 wherein said casing comprise of retaining strips and support plates welded at the ends thereof to define a closed structure.

21. A mechanically rechargeable battery as claimed in anyone of claims 16 to 20 wherein said arbor is adapted for use as both the input and output of the rechargeable system.

22. A mechanically rechargeable battery as claimed in claim 19 wherein said key means to charge the device comprise a manual cranking effort to wind the strip element on the arbor and the electrical output is through unwinding of the strip from the arbor onto the casing.

23. A mechanically rechargeable battery as claimed in anyone of claims 1 to 22 comprising a key means for winding the strip element on the arbor by rotating the arbor or the said casing.

24. A mechanically rechargeable battery as claimed in claims 1 to 23 wherein the key means is manual or electrical motor operated including I.C. engine, steam turbine and any prime mover as charging means.

25. A mechanically rechargeable battery as claimed in anyone of claims 16 to 24 wherein the energy is released via both the arbor and/or the casing depending upon the torque applied to each end, the end where the external torque acting is less than the strip configuration torque then that end is releasing energy and the end where the torque is more is adapted to store energy in the configuration.

26. A mechanically rechargeable battery as claimed in anyone of claims 16 to 25 wherein the output is direct and/or via gear box system.

27. A mechanically rechargeable battery as claimed in anyone of claims 16 to 26 wherein the energy storing strip is wound on a stepped and/or curved arbor and adapted fro customized response curves from the energy storing element.

28. A mechanically rechargeable battery as claimed in anyone of claims 16 to 27 wherein said energy storing strip element is selected from a single variable width element or by joining two or more elements.

29. A mechanically rechargeable battery as claimed in anyone of claims 16 to 28 wherein the casing and the arbor are of any suitable shape depending on the end use.

30. A mechanically rechargeable battery as claimed in anyone of claims 16 to 29 wherein said energy storing device is of a suitable cross-section selected from trapezoidal, triangular, square, rectangular and the like.

31. A mechanical energy storage device and its various applications/uses substantially as herein described and illustrated with reference to accompanying figures.