Magneto-rheological fluid rotary resistance device

A resistance device applied to relative rotations between a flywheel and an axis includes an inner stator, an outer rotor, a conductive wire and a magneto-rheological fluid. The inner stator is fixedly joined with the axis and includes an accommodating space surrounding the axis at a position away from the axis. The outer rotor, fixedly joined with the flywheel, encloses and rotates relative to the inner stator. An accommodating gap is formed between the outer rotor and the inner stator at a position away from the axis. The conductive wire is wound in the accommodating space, and generates a magnetic line passing the accommodating gap when applied by an electric current. The magneto-rheological fluid is filled in the accommodating gap. Thus, the outer rotor is disposed at the outer most region of the resistance device to increase the braking torque, and the magneto-rheological fluid is away from the axis to increase the braking moment.

FIELD OF THE INVENTION

The present invention relates to a rotary resistance device, and particularly to a magneto-rheological fluid rotary resistance device.

BACKGROUND OF THE INVENTION

A spinning bicycle is a type of exercise bicycle. A difference of a spinning bicycle from a common exercise bicycle is that, a spinning bicycle is designed to simulate an on-road bicycle, and not only brings better workout effects but also effectively boosts cardiopulmonary performance. Thus, a spinning bicycle is considered an ideal alternative solution for modern people who cannot conduct actual on-road rides. Further, a user of a spinning bicycle is allowed to carry out simulation trainings and thus obtain better results when the user actually rides on-road. In a spinning bicycle, a programmable and controllable continuous braking system is installed between a flywheel and an axis to simulate the feel of actually riding on-road. A conventional braking resistance system is a touch resistance brake, and resistance may be gradually lost due to abrasion with a braking contact plane over an extended period of use. Further, the above conventional braking resistance system provides unstable resistance and requires periodical maintenance and replacement that lead to high maintenance fees. Further, there are devices that employ an electromagnet as a resistance source. Such device, although featuring an advantage of readily adjustable resistance, is quite power consuming. Further, a resistance device employing conventional magnets lacks adjustment flexibilities although being free from the issue of power consumption.

Therefore, there is a resistance source of a resistance device in a brake that uses a magneto-rheological fluid for assisting braking. The above resistance source offers advantages of having stable resistance, no wearable consumables, readily adjustable resistance and low power consumption. The magneto-rheological fluid is a composite fluid, and includes minute magnetic particles, which has high magnetic permeability and a low hysteresis property, and a non-magnetic permeable liquid. The magneto-rheological fluid is filled in a binding gap of a rotor and a stator. When a magnetic line passes the magneto-rheological fluid, the magnetic particles are caused to be arranged and bound in a predetermined direction, in a way that the viscosity of the magneto-rheological fluid is significantly increased to brake the relative rotation between the rotor and the stator. The magneto-rheological fluid is extremely high in performance and produces almost no abrasion and replacement issues. For example, the U.S. Pat. No. 8,397,885 B2, “Magneto-Rheological Fluid Brake”, discloses a magneto-rheological brake resistance device. However, the above disclosure designed with an inner rotor has unsatisfactory torque utilization efficiency and includes multi-polar magnetic coils. As a result, the above disclosure has a complicated structure, gaps present between the multi-polar magnetic coils, poor distribution of magnetic lines and inadequate magnetic permeability efficiency, hence failing to meet application requirements.

SUMMARY OF THE INVENTION

Therefore, it is a primary object of the present invention to disclose a magneto-rheological fluid rotary brake resistance device with a high braking torque.

To achieve the above object, the present invention provides a magneto-rheological rotary brake resistance device that provides a resistive force upon a relative rotation between a flywheel and an axis. The magneto-rheological rotary brake resistance device includes an inner stator, an outer rotor, a conductive line and a magneto-rheological fluid. The inner stator is fixedly joined with the axis, and is provided with an accommodating space that surrounds the axis at a position away from the axis. The outer rotor is fixedly joined with the flywheel, encloses the inner stator, and rotates relative to the inner stator. An accommodating gap is formed between the outer rotor and the inner stator at a position away from the axis. The conductive line is winded in the accommodating space, and generates a magnetic line passing the accommodating gap when applied by an electric current. The magneto-rheological fluid is filled in the accommodating gap.

With the incorporation of the outer rotor and the inner stator, the position of the outer rotor that generates the resistive force is located at outermost to provide a greater braking torque moment. Further, in the present invention, the accommodating gap is located at a position away from the axis; that is, the magneto-rheological fluid is away from the axis. Thus, when the magneto-rheological fluid exercises a viscous effect under the influence of the magnetic line and brakes the relative rotation between the flywheel and the axis, a greater braking torque moment is generated to provide a better braking effect.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Details and technical features of the present invention are given with the accompanying drawings below.

FIG. 1,FIG. 2andFIG. 3show a perspective appearance diagram, a section structural diagram and a partial perspective section structural diagram according to a preferred embodiment of the present invention. Referring toFIG. 1toFIG. 3, the present invention provides a magneto-rheological fluid rotary resistance device applied to brake a relative rotation between a flywheel (not shown) and an axis20. The magneto-rheological fluid rotary resistance device includes an inner stator30, an outer rotor40, a conductive line50and a magneto-rheological fluid60. The inner stator30is fixedly joined with the axis20, and is provided with an accommodating space31that surrounds the axis20at a position away from the axis20.

In practice, the inner stator30may include a fixed portion32and a fastening portion33. The fixed portion32is fixedly joined with the axis20. The fastening portion33is fixed to the fixed portion32using at least one fastening element34. The accommodating space31is formed between the fixed portion32and the fastening portion33. As such, the inner stator30may be formed as an assembly to reduce manufacturing complications.

The outer rotor40encloses the inner stator30, and rotates relative to the inner stator30. More specifically, the outer rotor40is directly connected to a curved crank (not shown) that a user pedals, and is driven by the rotational force as the user pedals. Alternatively, the outer rotor40is driven to rotate through an indirect connection means of a chain or a linked band. Similarly, for manufacturing possibilities, the outer rotor40may include a first disc41and a second disc42. The first disc41and the second disc42cover and enclose at the two sides of the inner stator30and are fixedly joined. Further, the first disc41includes a screw fastening structure43, through which the first disc41may be directly connected to the curved crank (not shown) that a user pedals, such that the outer rotor40is driven to rotate by the rotational force as the user pedals. Alternatively, the outer rotor40may be driven to rotate through an indirect connection means of a chain or a linked band.

At a position away from the axis20, an accommodating gap70is formed between the outer rotor40and the inner stator30, and the magneto-rheological fluid60is filled in the accommodating gap70. The conductive line50is winded in the accommodating space31, and generates a magnetic line51(as shown inFIG. 5) that encircles in the accommodating gap70when applied by an electric current. In practice, the conductive line50may be implemented by an enamel insulated wire, which is winded in the accommodating space31with respective to the axis20.

Away from the axis20, the accommodating space31is provided with an opening35in communication with the accommodating gap70. A magnetic baffle plate80for sealing the opening35is disposed at the opening35. To enlarge an effective range of the magnetic line51, the width of the magnetic baffle plate80may be larger than the width of the conductive line50, so as to force the magnetic line51to bypass the magnetic baffle plate80to increase the region where the magnetic line51encircles the accommodating gap70. Thus, the magnetic line51is prevented from choosing a shortest route instead of passing the position of accommodating gap70, hence eliminating the issue that the magneto-rheological fluid may fail to fully exercise the magnetic force for generating a resistive force. Further, when the inner stator30is assembled from the fixed portion32and the fastening portion33, each of the fixed portion32and the fastening portion33may include a notch36. Through the opening35, the fixed portion32and the fastening portion33may fasten and position the magnetic baffle plate80, while contact areas of the fixed portion32, the fastening portion33and the magnetic baffle plate80may be increased to securely seal the opening35of the accommodating space31and to prevent the magneto-rheological fluid60from seeping into the accommodating space31via the accommodating gap70.

To prevent the magneto-rheological fluid60from seeping out and to allow the outer rotor40with a good degree of freedom for rotation, two sides of the inner stator30and between the inner stator30and the outer rotor40may be disposed with a spacing ring90and a sealing member91sealing the accommodating gap70, respectively. The spacing ring90maintains the gap between the inner stator30and the outer rotor40, and further prevents an issue of relative displacement between the inner stator30and the outer rotor40with respective to the axial direction. The sealing member91prevents the magneto-rheological fluid60from seeping out. Further, a bearing92may be disposed between each of the two sides of the outer rotor40and the axis20. The bearing92allows the outer rotor40to freely rotate relative to the axis20.

Referring toFIG. 4andFIG. 5, before the present invention takes effect, the flywheel (not shown) rotates relative to the axis20; that is, the outer rotor40is in a rotating state (as shown inFIG. 4). To apply the brake, the conductive line50is applied by an electric current to generate the magnetic line51(as shown inFIG. 5). The magnetic line51passes the accommodating gap70, and the magneto-rheological fluid60then becomes orderly arranged under the influence of the magnetic line51to generate a viscosity property. As such, the outer rotor40receives a resistive force. In order to overcome this resistive force, the user is required to apply a larger pedaling force through the pedal (not shown); that is, the feel of riding uphill is simulated. The size of the resistive force may be changed along with the magnetic flux of the magnetic line51. That is to say, by controlling the value of the electric current of the conductive line50, the resistive force may be controlled to simulate conditions of different terrains. Further, the present invention may also be applied as a brake control mechanism of common wheel motions, so as to prevent issues of abrasion caused by physical contact and periodic replacement of related consumables.

In conclusion, as opposed to the prior art, the present invention provides at least following advantages.

1. With the incorporation of the outer rotor and the inner stator, the outer rotor is disposed at the outermost to provide a larger braking torque.

2. By locating the accommodating gap at a position away from the axis, when magneto-rheological fluid exercises a viscous effect under the influence of the magnetic line, a larger moment is generated to provide a better braking effect.

3. Through the magnetic baffle plate, the magnetic line is better distributed to increase an effective region of the magneto-rheological fluid and to enhance the braking effect.

4. By sealing the opening with the magnetic baffle plate, the magneto-rheological fluid is prevented from seeping into the accommodating space.