US3831942A - Portable exercise machine - Google Patents

Abstract

A light weight portable exercise machine is provided for maintaining cardiovascular tone and for rehabilitation of hospital patients confined to bed. Portability and versatility of the machine are enhanced by a mounting frame which is a part of the unit. Light but sustained exercise is accomplished through pedal operation by the feet and legs of the patient while holding the hands to bars on the frame. A number of permanent magnets are moved into exact juxtaposition opposite other magnets in progressive settings across a modified Faraday disc at a plurality of indented positions, and these magnets, with augmented inertia from a heavy rim, serve to achieve prescription exercise amounts for prescription exercise durations automatically terminated at set limits.

Description

[111 3,831,942 Aug. 27, 1974 PORTABLE EXERCISE MACHINE [75] Inventor: Bruce E. Del Mar, Los Angeles,

Calif.

[73] Assignee: Del Mar Engineering Laboratories,

Los Angeles, Calif.

[22] Filed: Feb. 13, 1973 [21] Appl. No.: 332,149

[52] U.S. Cl. 272/73, 310/105 [51] Int. Cl A63b 23/04 [58] Field of Search 272/73; 73/379, 380, 381; 188/158, 164; 192/84 PM; 310/74, 77, 78,

1,802,437 5/1970 Germany 272/73 Primary Examiner-Richard C. Pinkham Assistant Examiner-R. T. Stouffer Attorney, Agent, or Firm-Jessup & Beecher ABSTRACT A light weight portable exercise machine is provided for maintaining cardiovascular tone and for rehabilitation of hospital patients confined to bed. Portability and versatility of the machine are enhanced by a mounting frame which is a part of the unit. Light but sustained exercise is accomplished through pedal operation by the feet and legs of the patient while holding the hands to bars on the frame. A number of permanent magnets are moved into exact juxtaposition opposite other magnets in progressive settings across a modified Faraday disc at a plurality of indented positions, and these magnets, with augmented inertia from a heavy rim, serve to achieve prescription exercise amounts for prescription exercise durations automatically terminated at set limits.

6 Claims, 12 Drawing Figures 3.931.942 I v I PAIimtnmmn smanre swkza \LJZ//////////////////\T PAIENIEMsamu v 3,331,942

PORTABLE EXERCISE MACHINE BACKGROUND OF THE INVENTION Prolonged exercise has become a widely used method for maintaining and building health, as well as for rehabilitation purposes, by both laymen and professionals. Such exercise is used for the most part in cardiovascular conditioning, where muscular work done by large muscles of the body causes an increased load on the cardiovascular, respiratory and metabolic systems. To be effective, this work must require an appreciable fraction of the maximum power available from the body. Furthermore, the work must be of such a nature that it can be continued for many minutes. To be safe and effective, especially in the case of convalescent patients, and others with compromised physiological systems, the work load must be precisely repeatable and accurately quantified. Finally, since many patients are bedridden, the instrument by which the work is done must be compact and light enough to be carried from bed to bed in the hospital.

It has been found that once a patient becomes bedridden he rapidly loses the cardiovascular tone, and a loss in the normal flow of blood in the lower extremities of the body, the feet and legs. Even without disease, in-

fection, anesthesia, or operative shock, the inactive pa-- tient begins to lose his cardiovascular health, and he is soon unable to get up and walk without noting a great loss of his perambulatory work capability. If the patients perambulatory muscular and cardiovascular health is to be maintained, he needs a form of exercise that meets the requirements of his confinement and the physiological needs of his circulatory system. If his perambulatory muscular and cardiovascular health has become lost because of incapacitative illness or operation, then he needs effective rehabilitation.

Exercise applied to the calf muscles of the leg by exerting pressure thereon in alternating cycles by the patient, as during pedalling of a crank ergometer, pumps blood much as a heart assist. Such exercise is a reasonable and logical means of both avoiding deteriorating cardiovascular and muscular health and tone to the bedridden, and it serves an effective means of commencing rehabilitation of the patient early in the recovery to greatly accelerate his return to normal health and work capability. Such exercise is implemented by the instrument of the invention.

Specifically, the invention serves to meet the criteria set forth above. Although a wide variety of exercise machines and crank ergometers have been available for a number of years, all suffer from deficiencies of one type or another, and none meets all the aforesaid re quirements. Particularly, prior art crank ergometers are not convenient for use in bed by the patient lying on his back, nor are they compact or light enough to be easily carried from bed-to-bed. Although wheeled carts and pulley arrangements have been devised to allow inbed use of ergometer-type units, none of these is in any way practical.

There are several widely used forms of bicycle ergometers in the prior art which use the conventional handlebar and seat with a crank and pedal. One type of prior art bicycle ergometer uses a form of friction drag load which forces a roller against a pneumatic bicycle tire. Another prior art type uses a form of electric load, such as an electro-dynamic magnetic brake or an electric generator with a variable load or field current. The first type of prior art ergometer exhibits unstable load settings. The second type of prior art ergometer generates electric power which may be dangerous, particularly to hospitalized patients, who have implants or electrodes attached to their bodies. The second type of prior art ergometer is also unsatisfactory because it requires a high minimum pedal speed before it becomes effective.

Moreover, the measurement of the work done by the patient with the aforesaid prior art ergometers is subject to gross error. These errors include mechanical and electric generator losses which change with temperature, and a work load which is not readily repeatable by fixed settings. The exercise machine of the present invention is particularly constructed to impose known and measurable mechanical work loads on the users musclespLoading is based on the Faraday disc principle operating in conjunction with precision permanent magnets, the relative positions of which are adjustable by novel means to provide resistive forces of exact magnitudes.

It is an established fact that the capability to do work varies considerably among individuals depending, inter alia, upon their age, size, and physical condition. it is also well established that the crank speed of an ergometer which is most comfortable for prolonged exercising periods, likewise, varies among individuals. Therefore, the ability to introduce various work loads at reasonable but different crank rotational speed is a desirable feature in an exercise machine or ergometer to be used for therapeutic purposes. In the present invention, this is accomplished by incorporating calibrated position adjustments, which may be quickly moved to known locations thereby varying the resistive forces on the disc, and as a result, controlling the braking torque, associated with any given crank speed.

It has also been found, that there must be a certain ratio between the inertial and resistive forces in an ergometer for optimum efficiency insofar as the muscles being exercised are concerned. The exercise ergometer of the invention is constructed so that a particular high ratio of inertial to resistive forces is achieved for such optimum efficiency. Efficiency of muscular exercise is poor when a low ratio of inertial force is present. Also that efficiency becomes less if a very high ratio of inertial force to resistive force is attempted. Therefore, it may be stated that there is a range of inertial/resistive force ratios between a lower limit and an upper limit in which optimum efficiency is achieved. Since there is a range of ratios of inertial/resistive forces which achieve optimum efficiency, there is no need in the ergometer to exactly match the ratio with every load. In the present invention a high inertial mass is used to provide the desired ratio to resistive force at the lower limits for heavy force loads and to exceed the lower limit for the smaller force loads. This is accomplished by providing the load disc with a heavy rim.

The ability to accurately accomplish a prescribed exercise program and to repeat it at a later time for comparative purposes is a highly desirable feature. In order that this may be done without constant surveillance, a brake system is incorporated into the apparatus of the invention, whereby the exercise instrument is automatically stopped after the specified exercise program has been completed. This is accomplished by utilizing a mechanical clock mechanism to activate a brake on the loading wheel at the conclusion of the selected time period.

Other features reside in the shape and portability of the ergometer unit to be described, in its independence of external power requirements, its adaptability to utilization by a patient in a prone position, and its ability to be easily placed and to stay in place on the bed held by an adjustable rigid frame. Portability is assured by modular construction of the unit wherein the individual components are light weight and easily assembled together on a bed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of one embodiment of the exercise machine of the invention;

FIG. 2 is a cut-away elevational view of a disc and permanent magnet assembly in one relative position in the apparatus of FIG. 1 on a somewhat enlarged scale;

FIG. 2A is a further cut-away elevational view of the assembly of FIG. I with multiple pole permanent magnets installed;

FIG. 3 is a cut-away elevational view of the disc and the permanent magnet load assembly of FIG. 2 in another relative position;

FIG. 4 is a section of a component of the permanent magnet load assembly taken along the line 4-4 of FIG.

FIG. 5 is a curve useful in explaining the performance characteristics of the apparatus of FIG. 1;

FIG. 6 is a perspective cut-away view of another embodiment of a stationary permanent magnet assembly for use in the exercise machine;

FIG. 7 is a cut-away plan view of the stationary permanent magnet assembly of FIG. 6;

FIGS. 8 and 9 are operational representations of the embodiment of FIG. 6;

FIG. 10 is a perspective cut-away view of the clockdriven spring release mechanism for use in conjunction with the apparatus of FIG. 1; and

FIG. 11 is a perspective representation of one embodiment of the invention in which the ergometer unit of FIG. 1 is incorporated into a frame to be used on a hospital bed with the patient lying on his back.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS As mentioned above, the ergometer of the invention utilizes an energy absorption concept based on the Faraday disc principle. In the particular embodiment of FIG. I,pedals 10 are connected to apulley 12; thepulley 12 being coupled to apulley 16 on ashaft 18 by abelt 14. Pulleys l2 and 16 may be toothed andbelt 14 may also be toothed for a more positive drive.Disc assembly 20 is keyed toshaft 18, and a permanent magnet assembly is magnetically coupled todisc assembly 20 so as to form an eddy current brake. In the embodiment of FIG. I, the permanent magnet assembly comprisesstationary magnet sub-assembly 24, and arotatable magnet sub-assembly 26, the sub-assembly 26 providing a capability to adjust the restrictive forces on thedisc 20. Thedisc assembly 20 consists of acurrent conducting disc 28 andheavy metal rim 30 to provide sufficient mass to create an augmented flywheel effect.

It is desirable to use permanent magnets in the disc ergometer of the invention, not only because of their stability but also in order to avoid the need for external power supplies and wiring associated with electromagnets or generators. However, one major problem in the use of permanent magnets is to provide the capability to vary the load in a broad controllable manner particularly on a compact disc assembly. A magnet assembly arranged to provide a fixed flux field adjacent a Faraday disc can be moved radially outward to provide adjustment, but then there is at best a limited adjustment range and an ungainly size of disc. This problem is overcome in the present invention by incorporation of permanent magnet assemblies capable of being easily adjusted so as to provide varied flux field strengths at the disc. The permanent magnet assembly of the present invention can be such as to provide matching pairs of magnets with opposing poles preferably on opposite sides of the disc maintaining a fixed radial distance from the rotational center of the disc but varying the relative position of opposing magnets either by (a) rotational separation around the disc or .(b) by axial separation from the disc.

With reference to the first arrangement a suggested above for adjusting the flux field, the permanent magnet assembly shown in FIGS. 1, 2, 2A and 3 comprises astationary magnet sub-assembly 24, and an angularadjustable magnet sub-assembly 26. As shown, these magnet sub-assemblies are mounted on opposite sides of thedisc 20. In each of these sub-assemblies, a number of permanent magnets 27 (FIG. 2A) are firmly fixed on the same radius and positioned such that poles of the magnets in one sub-assembly are opposite from the poles in the other sub-assembly. In the examples of FIGS. 2 and 3, thepermanent magnets 27 in theadjustable magnet sub-assembly 26 are positioned such that the North poles are nearest theshaft 18, while in thestationary magnet sub-assembly 24, the permanent magnets are positioned such that the South poles are nearest theshaft 18.

While themagnet sub-assembly 24 is held stationary in its pre-selected position by a mounting to the frame structure, themagnet sub-assembly 26 is mounted onshaft 18 with a low friction bearing 32 and is free to be turned to selected angular positions about the shaft. Retention of theadjustable magnet sub-assembly 26 in a desired position is accomplished by including a spring loaded plunger 38 (FIG. 4) in theend portion 36 ofsub-assembly 26, and the incorporation on the frame of a locating device such as thedetent plate 34 shown in FIGS. 1, 2 and 3. The detent plate may be supported on the frame by any appropriate means. It has indentations 40 (FIG. 4) which cooperate with theplunger 38 for positive positioning. Details of one suitable arrangement are shown in FIG. 4 wherein the rotatable magnet sub-assembly is held in a desired position by the action of theplunger 38 contained in theplate 36 being held in one of theindentations 40 indetent plate 34 by a force of spring 42. The magnitude of the spring force is held to a nominal value so that application of a reasonable force onhandle 44 attached to plate 36 as shown in FIGS. 1, 3 and 3 and extending to the exterior of the units housing will result in the spring force being overcome,plunger 38 being moved out of theindentation 40 allowing for repositioning of themagnet subassembly 26 to another desired position.

} One desirable position of therotatable magnet subassembly 26 relative tostationary magnet sub-assembly 24 is a position whereby one and only one of the permanent magnets in each of thesub-assemblies 24 and 26 are aligned. This condition is shown in FIG. 2, and with the unlike poles of the two magnets opposite one another a certain magnetic field, the strength of which is dependent on among other things the size of the permanent magnets and the air gap between magnets, is established acrossdisc 20. Curve B on FIG. 5 is characteristic of the braking torque developed at various disc rotational speeds under this condition.

If themagnet sub-assembly 26 is rotated to the position shown in FIG. 3, two of the permanent magnets of the sub-assembly 26 are aligned with two of the pennanent magnets of the sub-assembly 24 and with unlike poles opposite, and an increased magnetic field strength across the disc is realized. This can be carried further with three or more permanent magnets in one sub-assembly being aligned with three or more permanent magnets in the other sub-assembly to produce increased torque to rotational speed relationships. As an example, curve C and curve D in FIG. 5 are representative of the braking torque to disc rotational speed relationship with two and threemagnets 27 in one subassembly aligned with two and threemagnets 27 in the other sub-assembly respectively. Likewise, curve A in FIG. 5 is representative of the braking torque to disc rotational speed relationship when therotatable magnet sub-assembly 26 is positioned such that none of the magnets are aligned with the minimum torque shown resulting from the stray magnetic field so established.

From FIG. 5, it can readily-be seen that with such an arrangement of permanent magnets, loads of differing magnitudes can be imposed for each rotational speed and conversely, any desired load can be achieved with one of several rotational speeds. In the ergometer of the present invention, these are accomplished by a simple adjustment to the relative position of the permanent magnets easily made by the application of hand movement onhandle 44 which also by its position provides an indication of the setting or relative position of the magnets.

Whereas at each magnet mounting location at one side of the disc simple two pole permanent magnets have been shown in the example, the permanent magnets at each mounting location could also have multiple poles as, for example, a pair at 90 to each other or three at 60 as shown in FIG. 2A. In either case, the magnets themselves form a highly efficient magnet circuit in which the magnets themselves provide the return magnetic path.

With reference to the embodiment of FIGS. 6 and 7 for adjusting the flux field strength supplied by pennanent magnets on a Faraday disc to thereby control the braking torque, there is herein shown the means for adjusting the air gap between opposing magnets in a permanent magnet assembly held near the rotating disc. Such an assembly can be as shown in FIGS. 6 and 7 wherein thepermanent magnets 49 are mounted for axial movement toward and away from the modifiedFaraday disc 28. These magnets are held in stationary support anns 51 and 59 on opposite sides of thedisc 20. In each of these support arms a number ofpermanent magnets 49 are installed at the same radial distance from the rotational center of the Faraday disc and these magnets are preferably positioned such that each magnetis directly opposite from a corresponding magnet in the other stationary magnet sub-assembly.

Each magnet is installed in the stationary support arms such that axial movement of the magnet can be effected to bring it close to the disc or far away. This axial movement of the individual permanent magnets can be accomplished with a rotating cam arrangement such as shown in FIG. 7 whereinmagnet 49 is fitted into a cylindrical recess drilled insupport arms 51 and 59.Magnet 49 may be keyed to akeyway 61 machined in the support arm thereby preventing rotational movement from the desired position.Compression spring 63 can be positioned into the cylindrical recess such that it will bear on both the base ofmagnet 49 and the support arm. Under the influence ofcompression spring 63,magnet 49 tends to be displaced closer to thecurrent conducting disc 28 ofdisc assembly 20.

The freedom of axial movement ofmagnet 49 is restricted by, and in fact the axial position ofmagnet 49 is controlled by, the presence of cooperatively engagedcams 65 and 67, the inner-most of which, orcam 65, being firmly fixed to one end ofshaft 69 having a fixed length.Cam 67 is firmly attached tomagnet 49 to prevent any relative movement between the two parts andshaft 69 passes through an appropriately drilled hole incam 67. The fixed length ofshaft 69 can be assured by insertion of asnap ring 71 into a groove machined intoshaft 69 at the appropriate dimension and this snap ring being brought to bear on a surface of the support arm by the force ofcompression spring 63.Shaft 69 can continue through an appropriately placed hole inexterior panel 73 of the basicexercise machine unit 112 and have attached on the exterior end a knob suitable forrotating shaft 69. Such a knob is shown in FIG. 7 with aknob 75 with aslot 77 included for insertion of some device such as a screwdriver or coin to provide the necessary torque to rotateshaft 69.

As shown in FIGS. 7 and 8,cam 65 andcam 67 are fully meshed allowingmagnet 49 to be fully extended by the force ofspring 63. Rotation ofshaft 69 in either a clockwise or counterclockwise direction causes a retraction ofmagnet 49 from the fully extended position due to the interaction of the rises on earns 65 and 67 (FIG. 9). With a rotation ofshaft 69 orknob 75,cam 65 is rotated such that the lands of this cam are positioned on the lands of the non-rotatable cam 67 (FIG. 9) and, as a result,magnet 49 is in a fully retracted position with the extent of axial movement equal to the rise of the cams.

In the invention as shown in FIG. 6 a multiplicity of permanent magnets are installed in each end of thesupport arms 51 and 59 at positions of equal radius from the center of disc rotation. Thesupport arms 51 and 59 are held stationary on opposite sides of thedisc 20, and they are preferably positioned such that each installedmagnet 49 of one is precisely in line with an installedmagnet 49 of the other. With the magnets installed in the support anns such that the poles of the magnets in one support arm are opposite from the poles of the magnets in the other support arm, it becomes readily apparent that the strength of the flux field through which the modifiedFaraday disc assembly 20 rotates can be widely varied by varying the air gap between the individual sets of permanent magnets.

With the opposing magnets in all of the multiplicity of sets fully retracted in support arms, a minimum strength flux field is established due to the relatively large air gap between opposing magnets existing with this condition. When theshafts 69 orknobs 75 on one set of opposing magnets are rotated 90 from the position of fully retracted magnets, the magnets become fully extended with the reduced air gap between magnets greatly increasing the flux field strength between the two magnets.

By establishing the minimum air gap between magnets in a progressive number of the remaining sets of opposing magnets, the total flux field strength through which the disc assembly rotates can be incrementally increased to the maximum attainable. Furthermore, by calibration and setting of the air gaps at each set of magnets to achieve a desired magnitude of field flux, the portable exercise machine can be rapidly set by the operation to achieve prescription exercise loads.

From the above, it can be readily seen that the present invention provides the capability of controlling the setting to known increments of workload, and that this can be accomplished by a simple positioning ofknobs 75. With aknob 75 such as shown in FIG. 7, wherein aslot 77 is provided at the exterior ofcase 73 to effect rotation of the knob and a 90 rotation of the knob is required to cause axial movement of the magnet from one extreme to the other, the angular positions of theslots 77 provide an easily discernable indication of the air gap existing between opposing magnets and therefore the load setting.

Now in order to achieve true therapeutic effect, exercise must be continued for a considerable period of time. To achieve this, the muscles must be presented with a load that is felt physically but one of such nature that rapid fatiguing does not occur. It can be shown that some relatively critical amount of inertia must be combined with a resistive load to allow reasonable mechanical efficiency to be achieved by a muscle. Specifically, in order to prevent fatigue of the muscle, it must be possible to apply forces during the most efficient portion of each cycle, and on a crank type ergometer, forces must be applied together with a sufficiently large amount of inertia to carry the crank over the next half cycle. To allow such efficiency, the moment of inertia must be large enough to match the greatest load. To avoid the large size heavy weight and poor inertia in the typical bicycle ergometer, for example, the mechanical design must be drastically improved. Since moment of inertia varies as the square of an increase in speed, that is gear ratio, the disc must be turned as rapidly as possible relative to input crank speed.

In the embodiment of the invention, such as shown in FIG. 1, the modified Faraday disc is formed, for example, of acopper disc 28 thin enough to allow a narrow air gap between the permanent magnets of the twosub-assemblies 24 and 26, and it is rimmed with asteel rim 30 so that the resulting inertia of thedisc 20 at any speed largely offsets the maximum resistance force generated by the permanent magnets. Copper is chosen for thedisc 20 to provide high load and efficiency because of its high electrical conductivity. Thedisc 20 is keyed toshaft 18 which also has thepulley 12 with thepositive drive belt 14, thedisc 20 is turned as the device is pedalled. By a judicious selection of pulley diameter ratio, the disc is driven at a relatively high speed with a reasonable crank rotational speed. Such an arrangement provides the desired high rotation speed of the disc and the desired high moment of inertia while maintaining size and weight at a minimum.

Another feature of the ergometer of the invention is its ability to display various essential parameters during its use. The displayed parameters are the rotational speed of theFaraday disc 20 in revolutions per minute and the accumulating number of crankv revolutions. As shown in FIG. 1, the rotational speed of thedisc 20 is determined by use of aconventional tachometer generator 46 appropriately supported such that its drive wheel is contacted by the disc and is therefore driven at a speed directly proportional to the speed of the disc. The information on disc rotational speed developed by the tachometer generator may be displayed on anindicator 54 incorporated in the present invention such as shown in FIG. 11.

A count of the number of revolutions of the crank can be easily established by incorporation of a simple mechanism such as a cam actuated lever. In such a mechanism as shown in FIG. 1, alever 52, positioned adjacent tocam 48 attached topulley shaft 50, is mounted onstructure 53 by pin 55 such that the lever is free to pivot about the pin 55. A force, developed bycompression spring 57 which is appropriately supported, is continuously applied to lever 52 to assure lever contact withcam 50 at all times. Thecam 50 is configured such that thelever 52 moves through one complete cycle for each revolution of thepedals 10. By suitable attachment of amechanical motion counter 56, such as a Veeder-Root counter or other summing device, to the other end oflever 52, the number of 'revolutions of the cank can be recorded and displayed.

To provide the capability of terminating the exercise program at a prescribed time or work level, a clock activated brake system has been included in the invention. This system consists of a braking device such as shown in FIG. 1, and a clock driven spring release device such as shown in FIG. 10.

In the clock release device of FIG. 10, a conventionalmechanical clock mechanism 58 is attached torear plate 60 with itsmain shaft 62 passing through appropriate holes inrear plate 60 andforward plate 64.Shaft 62 is supported in these plates by low friction bearings, such as bearing 66, thereby providing rotational freedom.Cam 68 is rigidly attached toshaft 62 intermediate its ends. Attached to the free end ofshaft 62 isknob 70 with which, by a clockwise rotation, the clock mechanism can be wound to a preselected time interval. This time interval can be read directly fromdial face 72 attached to forwardplate 64.

Asecond shaft 74 is installed betweenplate 60 andplate 64 and supported in a like manner by low friction bearings, such as bearing 76, to afford unrestricted freedom of rotation. Intermediate ends ofshaft 74 is attachedpawl 78 includingpin 80 as an integral part positioned such that it may be actuated bycam 68 and may engagenotch 82 machined inrod 84. A force developed bycompression spring 86, suitably attached toupper plate 88 and to pawl 78, assists in maintaining contact betweenpawl 78 androd 84. On one end,rod 84 is held in position bysleeve 90 onbase plate 92 while retaining its freedom for axial mvoement in a vertical direction.Rod 84 passes through an appropriately placed hole in theupper plate 88 and is attached toarm 92 positioned in a slot in its other end and held bypin 94.

Encompassing a portion of the upper end ofrod 84 and retained byplate 88 andarm 92 iscompression spring 96 developing a force which tends to moverod 84 in an upward direction or to raisearm 92. One end ofarm 92 is attached to plate 64 by use ofbracket 98 andpin 100. In such an arrangement, the movement ofarm 92 is thereby restricted to a pivotal action aroundpin 100.Arm 92 passes throughslot 102, machined inrear plate 60 to allow for vertical movement, and at the other end, has attachedhandle 104 which extends through the case housing the clock release device and may be used to manually positionarm 92. Pushrod 106 is attached by use ofpin 108 to this end ofarm 92 and extends upward through an appropriate hole in the exterior case of the unit.

When theclock release unit 110 of FIG. is assembled with the basicexercise machine unit 1 12 as shown in FIG. 1 1, pushrod 106 is passed through a hole in the exterior case of the exercise machine and comes into contact with lever 114 of the braking device shown in FIG. 1.Lever 1 14 is rigidly attached toshaft 116 which has its two ends supported in suitable structure by low friction bearing, such asbearing 118, thereby permitting rotation ofshaft 116. On one end oflever 118 is attachedtension spring 119 which develops a force tending to maintain contact betweenrod 106 and lever 114. Whereasrod 106 contacts lever 114 at a point somewhat removed from. the centerline ofshaft 116 toward the attachment point ofspring 119,belt 120 is firmly attached to the other end of lever 114 by some means, such asrivets 122 shown in FIG. 1. Lever 114 is positioned onshaft 116 such thatbelt 120 can be routed around disc assembly with the other end ofbelt 120 securely attached to a suitable structure by use of fitting 124 and rivets 126.

With the mechanism described above, it is apparent that whenrod 106 is fully extended as shown in FIG. 1, the force ofspring 119 is overcome and lever 114 is rotated into a position wherebybelt 120 is held taut thereby bringing a portion of the belt into contact with the exterior surface ofrim 30. With the proper belt tension and length of belt in contact withrim 30, adequate friction can be developed to prohibit continued rotation of thedisc 20 orpedals 10. In the converse situation, namely when the force ofspring 119 is not overcome byrod 106 due to its position, such as whenrod 106 is in its fully retracted position, the force developed byspring 119 rotates lever 114 in a direction such that slackness is created inbelt 120 and no contact between belt and rim results. In this condition, no impediment todisc 20 orpedal 10 rotation is introduced.

Therefore, the operational conditions of the unit of FIG. 1, whereby it is freely rotatable or locked, is dependent upon the position of thepush rod 106. Control over the position ofrod 106 is accomplished with the block release device previously described and shown in FIG. 10. As shown,rod 106 is in a fully retracted position and is held in this position by the interaction ofcam 78 and notch 82 inrod 84. As previously stated, this rod position results in aslack belt 120 and freedom for thepedals 10 to be rotated. The fully retracted position ofrod 106 can be achieved only by rotation ofknob 70 clockwise to some position other than zero thereby repositioning the lip oncam 68 such that no contact is made withpin 80 ofpawl 78 and then depressinghandle 104 until the action ofspring 86 forces pawl 78 intonotch 82 inrod 84. As stated before, rotation ofknob 70 in a clockwise directon winds themechanical clock mechanism 58 with the desired time interval for the clock mechanism to unwind being easily established by reference to dialface 72. As the clock unwinds,shaft 62 and the attachedcam 68 andknob 70 rotate in a counterclockwise direction when viewed from the front with the lip oncam 68 approaching contact with pin ofpawl 78 as the selected time interval nears completion or the index onknob 70 approaches the zero ondial face 72.

At the conclusion of the selected time interval, the lip oncam 68 engagespin 80 and causes movement such thatpawl 78 is rotated about the centerline ofshaft 74 overcoming the force ofspring 86 and is removed fromnotch 82 ofrod 84. With the removal of the pawl from the slot, the force ofspring 96 causesrod 84 to move in an upward direction. This vertical movement ofrod 84 is translated into the full extension ofpush rod 106 by the pivoting action ofarm 92 aboutpin 100. As previously explained,push rod 106 in the fully extended position acts on lever 114 to brake thedisc 20 and cause stoppage of rotation ofpedals 10.

In the assembly described above, the desired speed and number of rotations data are presented in a convenient and easily read manner. Utilizing this information, the actual work accomplished during any period may be readily determined by reference to charts provided with each ergometer and the exercise program can be terminated at the prescribed time interval or work load. In each instance, and as mentioned previously, the simply instrumentation, and the use of permanent magnets, renders the ergometer of the described embodimentof the invention completely independent of any external power requirement or external instrumentation, so that the ergometer may be safely used in a wide variety of locations and under a wide variety of conditions.

Also, with theclock release unit 110 and the basicexercise machine unit 112 fabricated as individual units, it becomes apparent that the units may be built as relatively small, self-contained packages which are rugged, light weight and as a result, easily portable. When assembled, the units provide sufficient instrumentation to monitor the subjects performance and the capability automatically to terminate the subjects activity at the conclusion of the prescribed exercise program with the necessary instruments and controls to accomplish this readily accessible. A latch mechanism betweenunits 110 and 112 is included to provide for easy assembly and disassembly of the two units. To enhance portability and stability of the exercise machine when utilized in bed, a light weight transverse frame such as shown in FIG. 11 is included as a separate unit.

In the embodiment shown in FIG. 11, theunits 110 and 112 are mounted in a frame of a shape appropriate for use in a hospital bed with the patient lying on his back. In such an assembly, theclock release unit 110 is permanently attached to a pair of cross bars 128, and themachine unit 112 is latched tounit 110 bylatches 111, or equivalent fasteners. Theclock release unit 110 provides elevation of thepedals 10 such that adequate foot clearance from the bed is realized. As an adjustment associated with the length of the subjects legs, the cross bars 128 slide longitudinally on the spaced and parallel bars offrame 130 to any desired position for leg reach, and are manually clamped into place byclamps 132. Theunit 112 may be removed from theunit 110 by releasing thelatches 111, andunit 112 may be conveniently carried by ahandle 113.

The vertical portion at one end of theframe 130 hasrubber pads 136 attached to it which rest against the uprights at the foot of a hospital bed giving resistance and stability to the leg action by the subject. Toward the head end of the bed, the parallel bars offrame 130 have their ends turned up to provide convenient andcomfortable handles 138 to be grasped by the subject in a reclining position with his feet on the pedals of the exercise machine.

The invention provides, therefore, an improved, simple and compact ergometer unit whereby desired work loads may be imparted to the body of a patient, or other subject over prolonged periods of time without excessive tiring. With the multiposition permanent magnet assemblies, the desired work load may be achieved at one of several crank speeds. With the novel braking system incorporated, the exercise program can be automatically terminated at the conclusion of a preselected time interval or work load. With the unique disc design and modular construction, a light weight and compact ergometer is possible resulting in a portable unit easily adapted to use by a patient in bed.

Although particular embodiments of the invention have been shown and described, modifications may be made. It is intended in the following claims to cover the modifications which come within the spirit and scope of the invention.

What is claimed is:

1. A portable exercise machineincluding: a rotatable disc of electrically conductive material; pedal means coupled to said disc to impart rotational motion to said disc; a stationary magnet support structure mounted on one side of said disc; an angularly adjustable magnet support structure mounted on the other side of said disc for angular movement about the axis of rotation of said disc; a first magnetic means mounted in said stationary support structure; and second magnetic means mounted in said adjustable magnet support structure, said first and second magnetic means providing a magnetic field across said disc, the strength of said magnetic field being dependent upon the angular position of said adjustable magnet support structure.

2. The portable exercise machine defined inclaim 1, in which said first and second magnetic means each comprises a plurality of permanent magnets.

3. The portable exercise machine defined inclaim 2, in which said magnets of said first plurality are positioned on said stationary magnet support structure at a particular radius from the axis of rotation of the disc, and said magnets of said second plurality are positioned on said adjustable magnet support structure at said particular radius from the axis of rotation of said disc.

4. The portable exercise machine defined in claim 3, in which said poles of the magnets of the first plurality are opposite from the poles of the magnets of the second plurality.

5. The portable exercise machine defined in claim 4, and which includes adetent assembly coupled to said adjustable support structure .to permit said adjustable magnet support structure to be turned to predetermined angular positions so as to permit varying numbers of the permanent magnets of the first and second plurality to be aligned with one another for varying the magnetic field strength across the disc.

6. The portable exercise machine defined in claim .1, in which the disc is formed of copper, and which includes a steel rim surrounding said disc and of high mass relative to the mass of the disc.

Claims (6)

1. A portable exercise machine including: a rotatable disc of electrically conductive material; pedal means coupled to said disc to impart rotational motion to said disc; a stationary magnet support structure mounted on one side of said disc; an angularly adjustable magnet support structure mounted on the other side of said disc for angular movement about the axis of rotation of said disc; a first magnetic means mounted in said stationary support structure; and second magnetic means mounted in said adjustable magnet support structure, said first and second magnetic means providing a magnetic field across said disc, the strength of said magnetic field being dependent upon the angular position of said adjustable magnet support structure.

2. The portable exercise machine defined in claim 1, in which said first and second magnetic means each comprises a plurality of permanent magnets.

3. The portable exercise machine defined in claim 2, in which said magnets of said first plurality are positioned on said stationary magnet support structure at a particular radius from the axis of rotation of the disc, and said magnets of said second plurality are positioned on said adjustable magnet support structure at said particular radius from the axis of rotation of said disc.

4. The portable exercise machine defined in claim 3, in which said poles of the magnets of the first plurality are opposite from the poles of the magnets of the second plurality.

5. The portable exercise machine defined in claim 4, and which includes a detent assembly coupled to said adjustable support structure to permit said adjustable magnet support structure to be turned to predetermined angular positions so as to permit varying numbers of the permanent magnets of the first and second plurality to be aligned with one another for varying the magnetic field strength across the disc.

6. The portable exercise machine defined in claim 1, in which the disc is formed of copper, and which includes a steel rim surrounding said disc and of high mass relative to the mass of the disc.

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