Rotary resistance device

A rotary resistance device providing resistance to rotary object includes a magnetic field generating assembly having a magnetizable main body, an even number of magnetizable extended bodies, magnetizable coils and separators, two first caps, and two shaft sections; a magnetizable outer cylinder enclosing the magnetic field generating assembly therein and rotatably connected to the shaft sections; and a magnetorheological fluid filled in a space formed between the magnetic field generating assembly and the magnetizable outer cylinder. The magnetizable extended bodies have the magnetizable coils wound thereon and are radially equally spaced on the magnetizable main body; the separators are respectively connected to between two adjacent magnetizable extended bodies; the first caps are closed onto two ends of the assembled magnetizable main body, magnetizable extended bodies and separators to seal the magnetizable coils in the magnetic field generating assembly; and the shaft sections are fixedly connected to the first caps.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 103106664 filed in Taiwan, R.O.C. on Feb. 27, 2014, the entire contents of which are hereby incorporated by reference.

FIELD OF TECHNOLOGY

The present invention relates to a resistance device, and more particularly to a rotary resistance device that utilizes magnetorheological fluid to provide a resistance to a rotary object.

BACKGROUND

A magnetorheological fluid (MRF) is a rapidly developing smart material. When the MRF is subjected to a magnetic field, solid magnetic particles within the MRF are caused to align themselves with the direction of the magnetic lines of force between the N pole and the S pole and accordingly form a plurality of particle chains between the two poles. The formation of the particle chains in the magnetorheological fluid produces an effect of anti-shear stress.

Among the conventional resistance devices that employ the MRF, there is a type of internal rotary resistance device, which mainly includes an outer cylinder, an inner magnetizable body, and a magnetorheological fluid. The outer cylinder encloses the inner magnetizable body therein. A plurality of magnetizable bars is circumferentially arranged on the inner magnetizable body, and each of the magnetizable bars has a coil wound thereon to serve as an applied magnetic field. The magnetizable bars with the coils wound thereon respectively have two ends outward extended through the outer cylinder. When the coils are supplied with a voltage or an electric current, a magnetic field is generated. The inner magnetizable body is rotatable relative to the outer cylinder. And, the magnetorheological fluid is filled in a space formed between the outer cylinder and the inner magnetizable body.

The manner in which the conventional internal rotary resistance device provides the resistance is described below. When the inner magnetizable body rotates about and relative to the outer cylinder, a voltage or an electric current can be supplied to the coils to generate a magnetic field. At this point, magnetic particles in the magnetorheological fluid located within the acting area of the magnetic field would align with the direction of the magnetic lines of force extended between the North and the South pole of the magnetic field to form particle chains between the two poles, which in turn produces an effect of anti-shear stress on an outer surface of the inner magnetizable body and an inner surface of the outer cylinder, preventing the inner magnetizable body from rotating relative to the outer cylinder, so as to achieve the purpose of providing a resistance.

With the structural arrangements of the conventional internal rotary resistance device, an increased resistance can be provided only when the space formed between the outer cylinder and the inner magnetizable body is increased to allow for more contact areas with the magnetorheological fluid. In this case, the internal rotary resistance device would have a disadvantageously expanded volume.

SUMMARY

To solve the above disadvantage of the conventional internal rotary resistance device, it is a primary object of the present invention to provide a rotary resistance device that has minimized volume and weight due to a good internal structural arrangement enabling optimal space utilization.

To achieve the above and other objects, the rotary resistance device according to the present invention includes a magnetic field generating assembly, a magnetizable outer cylinder, and a magnetorheological fluid. The magnetic field generating assembly includes a magnetizable main body, an even number of magnetizable extended bodies, an even number of magnetizable coils, an even number of separators, two pieces of first caps, and two shaft sections. The magnetizable extended bodies are radially spaced on an outer surface of the magnetizable main body at equal angular intervals; the magnetizable coils are respectively wound on one of the magnetizable extended bodies; the separators are respectively connected to between two adjacent ones of the magnetizable extended bodies; the first caps are closed onto two opposite ends of the assembled magnetizable main body, magnetizable extended bodies and separators to seal the magnetizable coils in the magnetic field generating assembly; and the shaft sections are fixedly connected to the first caps. The magnetizable outer cylinder encloses the magnetic field generating assembly therein and is rotatably connected to the two shaft sections. The magnetorheological fluid is filled in a space formed between the magnetic field generating assembly and the magnetizable outer cylinder.

In an embodiment of the present invention, the magnetizable extended bodies respectively include a bar-shaped magnetizable neck portion and a curved magnetizable top portion; the magnetizable coils are respectively wound on one of the bar-shaped magnetizable neck portions; and the separators are respectively connected to between two adjacent ones of the curved magnetizable top portions.

In an embodiment of the present invention, any two adjacent ones of the curved magnetizable top portions have magnetic fields of two opposite directions.

In an embodiment of the present invention, the shaft sections are formed of a rotary shaft that axially extends through the first caps and the magnetizable main body.

In an embodiment of the present invention, the magnetic field generating assembly further includes two pieces of first washers, and the first washers are respectively fitted between one first cap and one end of the magnetizable extended bodies and the separators.

In an embodiment of the present invention, the magnetizable outer cylinder includes a magnetizable cylindrical shell and two pieces of second caps. The second caps are separately connected to two opposite ends of the magnetizable cylindrical shell. The magnetizable main body, the magnetizable extended bodies, the magnetizable coils, the separators and the first caps are located in the cylindrical shell, and the shaft sections are rotatably connected to the second caps.

In an embodiment of the present invention, the magnetizable outer cylinder further includes two pieces of second washers; and the second washers are respectively fitted between one second cap and one end of the magnetizable cylindrical shell.

In an embodiment of the present invention, the magnetizable main body is in the form of a round bar, the magnetic field generating assembly has a configuration like a round bar, and the magnetizable outer cylinder is in the form of a hollow cylindrical member.

With the magnetic field generating assembly, the magnetizable outer cylinder and the magnetorheological fluid arranged in the above manner to form the rotary resistance device of the present invention, the magnetizable outer cylinder can rotate about and relative to the magnetic field generating assembly, and the magnetic fields produced by the magnetic field generating assembly can act on the magnetorheological fluid, which causes the solid magnetic particles in the magnetorheological fluid to align themselves with the direction of the magnetic lines of force between the N pole and the S pole and accordingly form a plurality of particle chains between the two poles. The formation of the particle chains in the magnetorheological fluid produces an effect of anti-shear stress and accordingly provides a resistance to the magnetizable outer cylinder

DETAILED DESCRIPTION

The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.

Please refer toFIGS. 1 to 4, in whichFIG. 1is an exploded perspective view of a rotary resistance device1according to a preferred embodiment of the present invention,FIGS. 2 and 3are partially and fully assembled views, respectively, of the rotary resistance device ofFIG. 1, andFIG. 4is an assembled cross-sectional view of the rotary resistance device ofFIG. 1.

As shown inFIG. 1, the rotary resistance device1includes a magnetic field generating assembly11, a magnetizable outer cylinder12, and a magnetorheological fluid13(seeFIG. 4).

The magnetic field generating assembly11includes a magnetizable main body111, an even number of magnetizable extended bodies112, an even number of magnetizable coils113, an even number of separators114, two pieces of first caps115, and two shaft sections116a.

In the illustrated preferred embodiment, the magnetizable main body111is a round bar in shape. However, in other operable embodiments, the magnetizable main body111can be a rectangular cuboid, a triangular prism or any other suitable polygonal prism in shape.

The magnetizable extended bodies112are spaced at equal angular intervals on an outer surface of the magnetizable main body111. That is, the magnetizable extended bodies112are radially evenly spaced on the outer surface of the magnetizable main body111. More specifically, in the illustrated preferred embodiment, there are four magnetizable extended bodies112radially equally spaced on the outer surface of the magnetizable main body111at 90-degree angular intervals. In the case of having two magnetizable extended bodies112, they are radially spaced on the outer surface of the magnetizable main body111at 180-degree angular intervals. Or, in the case of having six magnetizable extended bodies112, they are radially spaced on the outer surface of the magnetizable main body111at 60-degree angular intervals. Accordingly, the arrangement of the magnetizable extended bodies112on the outer surface of the magnetizable main body111depends on the number of the magnetizable extended bodies112. In principle, the magnetizable extended bodies112are radially evenly spaced on the outer surface of the magnetizable main body111. The purpose of the above-described arrangements of the magnetizable extended bodies112is to evenly generate magnetic fields around the magnetizable main body111and accordingly have evenly distributed magnetic lines of force. In the present invention, the magnetizable extended bodies112can be integrally formed with the magnetizable main body111, or be assembled to the magnetizable main body111by way of snap-fitting, gluing, welding or screwing.

The magnetizable coils113are separately wound on the magnetizable extended bodies112. More specifically, the magnetizable coils113are respectively immovably arranged at a position between the outer surface of the magnetizable main body111and a top portion of one magnetizable extended body112, such that a combination of each magnetizable extended body112and the magnetizable coil113wound thereon forms an electromagnet. In other words, the electromagnets will respectively produce a magnetic field having a north pole (N pole) and a south pole (S pole) when an electric current flows through the magnetizable coils113. Further, the number of turns of the magnetizable coils113can be determined according to actual need.

The separators114are respectively connected to between two adjacent magnetizable extended bodies112. More specifically, the separators114can be respectively connected to between two adjacent magnetizable extended bodies112by way of gluing or snap-fitting. As can be seen inFIG. 4, by arranging the separators114and the magnetizable extended bodies112in the above manner, the magnetic fields produced between any two adjacent combinations of the magnetizable extended body112and the magnetizable coil113can form loops passing through the magnetorheological fluid13.

The first caps115are closed onto two opposite ends of the assembled magnetizable main body111, magnetizable extended bodies112and separators114, so as to seal the magnetizable coils113in the magnetic field generating assembly11. More specifically, the first caps115can be closed onto the two opposite ends of the assembled magnetizable main body111, magnetizable extended bodies112and separators114by way of screwing, gluing, welding, snap-fitting, or other functionally equivalent ways, so as to seal the magnetizable coils113in the magnetic field generating assembly11.

As can be seen fromFIG. 2, the shaft sections116acan be connected to the first caps115by way of screwing, gluing, welding, snap-fitting and the like.

The magnetizable outer cylinder12encloses the magnetic field generating assembly11therein, and is rotatably connected to the shaft sections116a. Further, the magnetizable outer cylinder12can be rotatably connected at two opposite ends to the shaft sections116avia two bearing structures, so as to rotate about and relative to the magnetic field generating assembly11.

The magnetorheological fluid13is filled in a space formed between the magnetic field generating assembly11and the magnetizable outer cylinder12. Being stopped by the separators114, the top portions of the magnetizable extended bodies112and the first caps115, the magnetorheological fluid13is limited to flow only in the space between the magnetic field generating assembly11and the magnetizable outer cylinder12without flowing into a sealed space in the magnetic field generating assembly11. In this manner, the magnetorheological fluid13would not affect the magnetizable extended bodies112and the magnetizable coils113from generating magnetic fields.

Please refer toFIGS. 3 and 4. When two inverse voltages are separately applied to any two adjacent magnetizable coils113, a plurality of magnetic field loops passing through the magnetorheological fluid13is formed between the two magnetizable extended bodies112on which the two adjacent magnetizable coils113are wound. These magnetic field loops can exist at the same time to achieve an increased magnetic field performance. Further, since the resistance provided by the rotary resistance device1is applied to the magnetizable outer cylinder12, it means the rotary resistance device1provides an arm of resistance and a moment of resistance larger than those of the conventional internal rotary resistance device, and can therefore provide a larger resistance than a conventional internal rotary resistance device of the same volume.

In the above-described rotary resistance device1, the magnetizable extended bodies112respectively include a bar-shaped magnetizable neck portion112aand a curved magnetizable top portion112bextended from a radially outer end of the neck portion112a, such that each of the magnetizable extended bodies112has a substantially T-shaped configuration. The neck portions112aof the magnetizable extended bodies112are radially spaced on the outer surface of the magnetizable main body111at equal angular intervals. The magnetizable coils113are respectively wound on one of the bar-shaped magnetizable neck portions112a, and the curved magnetizable top portions112brespectively provide an increased magnetic field actuation area.

The magnetizable coils113are wound on the bar-shaped magnetizable neck portions112a, so that the combination of each magnetizable extended body112and the magnetizable coil113wound thereon forms an electromagnet. In other words, the electromagnets will respectively produce a magnetic field having an N pole and an S pole when an electric current flows through the magnetizable coils113. Further, the number of turns of the magnetizable coils113can be determined according to actual need.

The separators114can be respectively connected to between the curved magnetizable top portions112bof two adjacent magnetizable extended bodies112by way of gluing or snap-fitting. As can be seen inFIG. 4, by arranging the separators114and the curved magnetizable top portions112bin the above manner, the magnetic fields produced between any two adjacent combinations of the magnetizable extended body112and the magnetizable coil113can form loops passing through the magnetorheological fluid13.

In the above-described rotary resistance device1, any two adjacent electromagnets can be so arranged that their magnetic fields have two opposite directions. In this manner, the magnetic fields can have increased action areas. InFIG. 4, two N poles and two S poles are indicated outside the magnetizable outer cylinder12. It is noted these N poles and S poles are alternately arranged, so that the magnetic lines of force can extend from one electromagnet to another adjacent electromagnet to thereby increase the distribution area of the magnetic lines of force.

In the rotary resistance device1of the present invention, as shown inFIGS. 1 and 2, the shaft sections116acan be formed of a rotary shaft116that axially extends through the first caps115and the magnetizable main body111. More specifically, the rotary shaft116can be provided with a raised key (not shown) for engaging with a slot formed in a bore of the magnetizable main body111, so that the rotary shaft116is tightly fitted in the magnetizable main body111. In other words, the rotary shaft116and the magnetizable main body111rotate synchronously.

According to the rotary resistance device1of the present invention, the magnetic field generating assembly11can further include two pieces of first washers117, each of which is fitted between the first cap115and one end of the magnetizable extended bodies112and the separators114. More specifically, each of the first caps115is provided on an inner side with a first annular groove115a. The first washers117are respectively partially fitted in one first annular groove115aand partially protruded from the first annular groove115a. And, the portions of the first washers117that are protruded from the first annular grooves115aare in tight contact with the magnetizable extended bodies112and the separators114.

According to the rotary resistance device1of the present invention, the magnetizable outer cylinder12includes a magnetizable cylindrical shell121and two pieces of second caps122. The second caps122are separately connected to two opposite open ends of the magnetizable cylindrical shell121, so that the magnetizable main body111, the magnetizable extended bodies112, the magnetizable coils113, the separators114and the first caps115all are located in the cylindrical shell121. The shaft sections116aare rotatably connected to the second caps122. The shaft sections116acan be formed of a rotary shaft116that axially extends through the first caps115and the magnetizable main body111. More specifically, the second caps122can be connected to the two opposite ends of the magnetizable cylindrical shell121by way of screwing, gluing, welding, snap-fitting and so on.

According to the rotary resistance device1of the present invention, the magnetizable cylindrical shell121can further include two pieces of second washers123, each of which is fitted between the magnetizable cylindrical shell121and one of the second caps122. More specifically, each of the second caps122is provided on an inner side with a second annular groove122a. The second washers123are respectively partially fitted in one second annular groove122aand partially protruded from the second annular groove122a. And, the portions of the second washers123that are protruded from the second annular grooves122aare in tight contact with the magnetizable cylindrical shell121.

According to the rotary resistance device1of the present invention, the magnetizable main body111can be in the form of a round bar, and the magnetic field generating assembly11can have a configuration like a round bar, and the magnetizable outer cylinder12can be in the form of a hollow cylindrical member. Therefore, the fully assembled rotary resistance device1can work with an external structure having a round configuration.

In conclusion, with the magnetic field generating assembly, the magnetizable outer cylinder and the magnetorheological fluid arranged in the above manner to form the rotary resistance device of the present invention, the magnetizable outer cylinder can rotate about and relative to the magnetic field generating assembly, and the magnetic fields generated by the magnetic field generating assembly can act on the magnetorheological fluid, which causes the solid magnetic particles in the magnetorheological fluid to align themselves with the direction of the magnetic lines of force between the N pole and the S pole and accordingly form a plurality of particle chains between the two poles. The formation of the particle chains in the magnetorheological fluid produces an effect of anti-shear stress and accordingly provides a resistance to the magnetizable outer cylinder. Further, the provision of the first washers and on the magnetic field generating assembly and the second washers on the magnetizable outer cylinder also prevents the magnetorheological fluid from easily leaking out of the rotary resistance device.