Adaptable damper

An adjustable damper includes a tube body, a driving rod to be displaced in the tube body and to engage a screw sleeve to drive a screw rod and further a fixed seat for rotation. The fixed seat has a plurality of permanent magnets surrounding for circular rotation and an operation element is driven by a rotating element for repeated linear displacement; a magnetic surface is further arranged on an inner periphery of an annular element of the operation element and an annular gap is arranged between the magnetic surface and the permanent magnets; therefore the displacing annular element is able to adjust a damping force of the driving rod by adjusting an overlapped area of the permanent magnets and a magnetic surface, and further adjust an eddy load formed thereby. The damper overcomes the problem of oil leakage and ensures the durability and quality with its adjustability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a linear damper, particularly to one that has a driving rod displacing linearly for a circular rotation operation of a plurality of permanent magnets, so as to adjust a damping force of the driving rod by controlling an overlapped area of the permanent magnets and a magnetic surface, and an eddy load formed thereby.

2. Description of the Related Art

In Indoor sports or rehabilitation equipment, some actuating mechanism such as rowing fitness and strength training machines must have load device or damping device. A foot sports equipment10as show inFIG. 1Ahas a seat11, two pedals12arranged on the seat11for stepping thereon, and a damping device13connected between the pedals12and the seat11. Due to the limitation of space, the damping device13is mostly a hydraulic cylinder as shown inFIG. 1Bin application to indoor sports equipment. Such hydraulic cylinder generally includes a cylinder131, a piston132being installed in the cylinder131and having a passage133arranged thereon and a piston rod134at an end thereof, and a predetermined quantity of hydraulic oil135filled in the cylinder131. When the piston rod134displaces linearly in the cylinder131subject to an axial force, the hydraulic oil135would pass through the passage133on the piston132to produce the damping effect.

The piston rod134of the conventional hydraulic damping device13has frequent frictions with an oil seal136due to the back and forth operation, resulting in an oil leakage problem fouling ground and equipment, and affecting the damping function of the device. Moreover, after a period of using the hydraulic oil, the viscosity of the hydraulic oil will change, and it is susceptible to high temperatures, causing an instability damping effect. Also, the hydraulic oil will have to flow from the piston to the other side during the operation; since the reaction speed of the exchanging path of the hydraulic oil is slow, the exercise equipment cannot be performed well.

The present inventor therefore has disclosed a linear damper in the U.S. patent application Ser. No. 14/105,829 as shown inFIG. 2. The main features of the linear damper is that a driving rod30is linearly displacing in a tube body20, rotating a fixed seat60by having a screw sleeve40driving a screw rod50for rotation; then a plurality of permanent magnets63arranged on the fixed seat60would be operated in circle rotation, forming a torque by an eddy current produced between the permanent magnets63and a magnetic surface73of a cover70, so as to provide a buffer and damping force. The subject invention has avoided problems of oil leakage and unstable damping effect, but the eddy current produced between the permanent magnets63and the magnetic surface73is unchanging; in other words, the device can only provide certain degree of the torque. However, for users of fitness equipment, an unchanging degree of damping force cannot meet the need of fitness training since different degree of the damping force is needed in different stages of the training. Therefore, the present inventor has been diligently working in a device with adjustable damping force for its users.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide an adjustable damper to solve a problem of oil leakage in the prior art and to ensure longer durability and better quality of the damper.

Another object of the present invention is to provide an adjustable damper that provides a stable damping force and reacts rapidly during operation to achieve better efficiency.

Yet another object of the present invention is to provide an adjustable damper for its user to easily change a torque needed in fitness training process, allowing different needs at different training stages.

To achieve the above objects, the present invention comprises a tube body having a first through hole at an end, a second through hole at the other end, and a first axial passage connecting through the first through hole and the second through hole; an engaging element having a first engaging portion at an end, a second engaging portion at the other end, and a second axial passage connecting through the first engaging portion and the second engaging portion; said second engaging portion having an outer threaded section and engaging in the second through hole of the tube body; a driving rod having a third axial passage arranged therein, an inner end to be engaged in the first and second axial passage, and an outer end stretching out from the first through hole and having a first pivot portion; a screw sleeve engaging the inner end of the driving rod for linear displacement in the first and second axial passage; a screw rod including a shaft section and a thread section to be screwed with the screw sleeve, said thread section being arranged in the third axial passage and the screw sleeve for the screw sleeve to displace linearly and for the screw rod to be rotatable; a fixed seat having a rotatable inner ring portion mounted on the shaft section to be driven to rotate and an outer ring portion having a plurality of permanent magnets encircling an outer surface thereof; a rotating element having a pushing surface and an inner threaded section to be screwed with the outer threaded section of the engaging element for the rotating element to rotate linearly along the engaging element by screwing; an operation element including an annular element having a magnetic surface arranged on an inner surface thereof and at least one pushing rod arranged at an end thereof to pass through a flange of the engaging element and to be driven by the pushing surface of the rotating element, for linear displacement of the annular element; said magnetic surface and the plurality of permanent magnets further having an annular gap arranged in-between; the permanent magnets and the magnetic surface thereby being in radially offset relationship relative to each other; a tubular cover having a first end engaging the first engaging portion of the engaging element and a second end engaging a cover with a second pivot portion; said cover having a seating arranged on the inner periphery thereof for engaging the shaft section of the screw rod and for the screw rod to be rotatable in the cover;

Whereby the driving rod displaces linearly in the first and second axial passage when the first pivot portion and the second pivot portion are subject to an axial force, driving the screw sleeve to rotate the screw rod and further driving the fixed seat for rotation, so that the permanent magnets are operating in a circular rotation motion; then a torque is produced by an eddy load formed between the permanent magnets and the magnetic surface and subject to repeated displacement of the annular element of the operation element, so as to adjust the damping force of the driving rod with linear displacement.

In addition, at least one spring is arranged between the engaging element and the annular element so that the annular element would move back to an original place before operation when the spring returns from stretching; and at least one engaging ditch is arranged on the surface of the engaging element for disposing the pushing rod and the spring so that the annular element of the operation element is able to stably perform linear displacement.

Furthermore, the permanent magnets are composed of a plurality of rubidium magnets. The magnetic surface is formed by an annular magnetic element fixed on an inner periphery of the annular element. The first pivot portion is an oil-bearing or a tube perpendicularly passing through the outer end of the driving rod; the cover further has a convex lug arranged aside, and the second pivot portion is an oil-bearing or tube perpendicularly passing through the convex lug. The screw sleeve is formed in one-piece on the inner periphery of the third axial passage.

Based on the features disclosed above, the present invention has the linear displacement of the driving rod driving the permanent magnets for circular rotation, so as to form a torque from an eddy load produced between the permanent magnets and the magnetic surface, solving the problem of oil leakage and ensuring durability and quality by replacing hydraulic oil by damping force. Also, without the defect of slow reaction in a conventional hydraulic cylinder, the present invention is able to react fast in either stretching or contracting status and provide a stable damping force in the operation, achieving better efficiency. Furthermore, the present invention can easily change a torque needed in fitness training process by adjusting an overlapped area of the permanent magnets and magnetic surface to provide different strength of damping force, allowing different needs in different training stages.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIGS. 3 to 6, in a preferred embodiment the present invention comprises a tube body20, a driving rod30, an engaging element80, a screw sleeve40, a screw rod50, a fixed seat60, a rotating element90, an operation element93, a tubular cover70, a second axial sleeve79, and a cover74.

The tube body20has a first through hole21at an end, a second through hole22at the other end, and a first axial passage23connecting through the first through hole21and the second through hole22. The driving rod30has an inner end31to be displaced in the tube body20, an outer end21stretching out from the first through hole21, and a third axial passage33connecting through the inner end31and the outer end21. In this embodiment, the first through hole21of the tube body20engages a first axial sleeve21A, and a bush21B is disposed in-between the inner periphery of the first axial sleeve21A and the driving rod30by a C ring21C. The driving rod30further has a first pivot portion321at the outer end32thereof, perpendicularly engaging through the outer end32of the driving rod30; the outer end is either an oil-bearing or a tube in the embodiment.

The engaging element80has a first engaging portion81and a flange82at an end, a second engaging portion84and an outer threaded section85at the other end, and a second axial passage83connecting through the first engaging portion81and the second engaging portion84. The second engaging portion84fixedly engages the second through hole22of the tube body20to connect the first axial passage23and the second axial passage83. Moreover, the engaging element80has four engaging ditches86arranged on the surface thereof in semicircle shape in this embodiment.

The screw sleeve40engages the inner end31of the driving rod30and has a fixing element43fixating the position thereof for linear displacement in the first axial passage33and the second axial passage83. In this embodiment, the screw sleeve40is a small element engaging in the inner end31; in another embodiment, the screw sleeve40is formed in one-piece on the inner periphery of the third axial passage33. The screw rod50includes a thread section51to be screwed with the screw sleeve40and a shaft section52, so that the screw rod50is driven by the linear displacement of the screw sleeve40for rotation.

The fixed seat60has a rotatable inner ring portion61mounted on the shaft section52to be driven to rotate and an outer ring portion62having a plurality of permanent magnets63encircling an outer surface thereof. In the embodiment, the permanent magnets63are composed of a plurality of rubidium magnets that have strong magnetic force with small volume, but the present invention is not limited to such application.

The rotating element90has a pushing surface91and an inner threaded section92to be screwed with the outer threaded section85of the engaging element80for the rotating element90to rotate linearly along the engaging element80by screwing. The operation element93includes an annular element931having a magnetic surface934arranged on an inner surface thereof to be arranged corresponding to the permanent magnets63of the annular element931; the permanent magnets63and the magnetic surface934further have an annular gap94arranged in-between. In this embodiment, the magnetic surface934includes two semi-circle copper pieces fixedly arranged on the inner periphery of the annular element931, but the present invention is not limited to such application. The annular element931further has at least one pushing rod932arranged at an end thereof to pass through a flange82of the engaging element80and to move along the engaging ditches86. The pushing rod932further has a contact end9321to contact the pushing surface91during operation. In this embodiment, two pushing rods932and two springs933are symmetrically and individually arranged to engage the engaging ditches86; the springs933has an end fixed at the end of the annular element931where the pushing rods932are arranged as well, and has the other end fixed at the far end of the engaging ditches86for operation.

With reference toFIG. 5A, when the rotating element90is rotated clockwise, the pushing surface91would contact the contact ends9321of the pushing rods932and push the pushing rods932to drive the annular element931of the operation element93for linear displacement, moving farther from the engaging element80, thus increasing the overlapped area of the magnetic surface934and the permanent magnets63and stretching the springs933; with reference toFIG. 6A, when the rotating element90is rotated counter-clockwise, the stretching springs933would contract and pull back the annular element931of the operation element93toward the engaging element80, thus decreasing the overlapped area of the magnetic surface934and the permanent magnets63.

The tubular cover70has a first end71, a second end72, and a fourth axial passage73connecting through the first end71and the second end72. The first end71engages the first engaging portion81of the engaging element80to connect the fourth axial passage73and the second axial passage83, and the fourth axial passage73has the space for disposing the fixed seat60and the magnetic surface934of the operation element93. The second axial sleeve79is fixedly disposed in the fourth axial passage73near the second end72of the tubular cover70. Two bearings75are mounted on the shaft section52of the screw rod50and fixed by a screw521. The cover74has a seating741arranged on the inner periphery thereof to be mounted with the second end72of the tubular cover70for the bearings75to be disposed between the seating741and the second axial sleeve79, so that the shaft section52of the screw rod50are fixed in position and the screw rod50is rotatable in the cover74. Further, the cover74has a second pivot portion76arranged at a far end from the tubular cover70. In this embodiment, the cover74further has a convex lug77arranged aside, and the second pivot portion76is an oil-bearing or tube perpendicularly passing through the convex lug77; a protective cover78is further mounted on the cover74, fixing the connecting form of the cover74and the tubular cover70.

Whereby the driving rod30and the screw sleeve40displace linearly in the first and second axial passage23,83when the first pivot portion321and the second pivot portion76are subject to an axial force, driving the screw sleeve40to rotate the screw rod50and further driving the fixed seat60of the shaft section52for rotation, so that the permanent magnets63are operating in a circular rotation motion; then a torque is produced by an eddy load formed between the permanent magnets63and the magnetic surface934and is subject to repeated displacement of the annular element931of the operation element93, so as to adjust the damping force of the driving rod30with linear displacement.

The structure of an adjustable damper disclosed above uses an eddy current resistance formed by position changes of a conductor in a magnetic field. It has the conductor moving in the magnetic field and the magnetic fields would react in accordance with the change, forming a magnetic force—an eddy current resistance. Moreover, according to Maxwell's Equation, the intensity of magnetic force is in direct proportion to the square of magnetic flux density. The magnetic force can be applied to fitness equipment for a supply for the buffer or damping load. In this embodiment, the present invention has an overlapped area between the permanent magnets63and the magnetic surface934to be the variable factor in changing the magnetic flux density and thus adjusting the damping force for fitness equipment.

FIGS. 5A to 5Care sectional views of the present invention with a maximum damping force. The rotating element90is rotated clockwise, causing the pushing surface91pushing the contact ends9321of the pushing rods932and also the pushing rods932to drive the annular element931of the operation element93for linear displacement, moving farther from the engaging element80, and thus increasing the overlapped area of the magnetic surface934and the permanent magnets63. When the magnetic surface934entirely leaves the permanent magnets63, the damping force reaches the maximum value.FIG. 5Bfurther shows the driving rod30being pulled to displace outward from the tube body20. Then the screw rod50is driven by the screw sleeve40for rotation in outward displacement to drive the fixed seat60rotating in counterclockwise direction.FIG. 5Cis a sectional view illustrating the driving rod30displacing back into the first and second axial passage23,83. By having the screw sleeve40driving the screw rod50for rotation, the fixed seat60is driven for rotation in clockwise direction for the permanent magnets63to be in circular rotation, and then a torque is produced by an eddy load formed between the magnetic surface934and the permanent magnets63. When the magnetic surface934entirely overlaps with the permanent magnets63, the damping force also reaches the maximum value. In other words, the displacement of the driving rod30decides the rotating direction of the fixed seat60.

FIGS. 6A to 6Care sectional views of the present invention with lessening damping force. Previously when the rotating element90is rotated clockwise, the springs933are stretched; then when the rotating element90is rotated counter-clockwise, the stretching springs933would contract and pull back the annular element931of the operation element93toward the engaging element80, thus decreasing the overlapped area of the magnetic surface934and the permanent magnets63. When the magnetic surface934entirely leaves the permanent magnets63, the damping force reaches the minimum value.FIG. 6Bfurther shows the driving rod30being pulled to displace outward from the tube body20. Then the screw rod50is driven by the screw sleeve40for rotation in outward displacement to drive the fixed seat60rotating in counterclockwise direction.FIG. 6Cis a sectional view illustrating the driving rod30displacing back into the first and second axial passage23,83. By having the screw sleeve40driving the screw rod50for rotation, the fixed seat60is driven for rotation in clockwise direction for the permanent magnets63to be in circular rotation; actually, whether the fixed seat60rotates in clockwise or counter-clockwise, the permanent magnets63will be driven in circular rotation, and then a torque is produced by an eddy load formed between the magnetic surface934and the permanent magnets63. When the magnetic surface934entirely leaves the permanent magnets63, the damping force also reaches the minimum value.

A conventional hydraulic cylinder has a problem of oil leakage from a piston to the other side during displacements. Besides, when exchanging the stretching path of the driving rod30, the equipment would not react until the hydraulic oil return; thus the reaction speed and the value of damping force would be obviously different. In contrast, the present invention does not need hydraulic oil for operation, thus avoiding the problem of oil leakage; and the damping force of the present invention is very stable because the eddy current—the damping—formed in the annular gap94between the permanent magnets63and magnetic surface934is a stable value, and the screw rod50with the screw sleeve40uses the spiral features to improve the lead. Therefore, the present invention is able to react fast and maintain a balanced damping force for better efficiency in operating fitness equipment.

Based on the features disclosed, the linear displacement of the driving rod30is converted into circular rotation of the permanent magnets63, and an eddy load is formed between the permanent magnets63and magnetic surface934to produce a torque in order to replace conventional hydraulic oil by magnetic resistance, so as to solve the problem of oil leakage and to provide a stable damping force for the fitness equipment. By adjusting the overlapped area of the permanent magnets63and magnetic surface934and displacement of the driving rod30, the present invention is able to provide different strength of damping force as a torque needed in fitness training, allowing different needs in different training stages.