U.S. patent number 3,831,942 [Application Number 05/332,149] was granted by the patent office on 1974-08-27 for portable exercise machine.
This patent grant is currently assigned to Del Mar Engineering Laboratories. Invention is credited to Bruce E. Del Mar.
United States Patent |
3,831,942 |
Del Mar |
August 27, 1974 |
PORTABLE EXERCISE MACHINE
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.
Inventors: |
Del Mar; Bruce E. (Los Angeles,
CA) |
Assignee: |
Del Mar Engineering
Laboratories (Los Angeles, CA)
|
Family
ID: |
23296915 |
Appl.
No.: |
05/332,149 |
Filed: |
February 13, 1973 |
Current U.S.
Class: |
482/72; 482/5;
74/527; 74/567; 310/105 |
Current CPC
Class: |
A63B
21/015 (20130101); A63B 22/0694 (20130101); A63B
21/0051 (20130101); A63B 22/0605 (20130101); Y10T
74/20636 (20150115); A63B 2208/0252 (20130101); Y10T
74/2101 (20150115) |
Current International
Class: |
A63B
21/005 (20060101); A63B 21/012 (20060101); A63B
21/015 (20060101); A63B 22/08 (20060101); A63B
22/06 (20060101); A63b 023/04 () |
Field of
Search: |
;272/73 ;73/379,380,381
;188/158,164 ;192/84PM ;310/74,77,78,103,105 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
120,015 |
|
Aug 1970 |
|
NO |
|
1,802,437 |
|
May 1970 |
|
DT |
|
Primary Examiner: Pinkham; Richard C.
Assistant Examiner: Stouffer; R. T.
Attorney, Agent or Firm: Jessup & Beecher
Claims
What is claimed is:
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.
Description
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, infection, anesthesia, or operative shock, the
inactive patient 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 patient's 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 requirements. 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 in-bed 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 user's muscles. Loading 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. 1 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. 3;
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 clock-driven 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. 1, pedals 10 are connected to a
pulley 12; the pulley 12 being coupled to a pulley 16 on a shaft 18
by a belt 14. Pulleys 12 and 16 may be toothed and belt 14 may also
be toothed for a more positive drive. Disc assembly 20 is keyed to
shaft 18, and a permanent magnet assembly is magnetically coupled
to disc assembly 20 so as to form an eddy current brake. In the
embodiment of FIG. 1, the permanent magnet assembly comprises
stationary magnet sub-assembly 24, and a rotatable magnet
sub-assembly 26, the sub-assembly 26 providing a capability to
adjust the restrictive forces on the disc 20. The disc assembly 20
consists of a current conducting disc 28 and heavy 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 a stationary magnet sub-assembly 24,
and an angular adjustable magnet sub-assembly 26. As shown, these
magnet sub-assemblies are mounted on opposite sides of the disc 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,
the permanent magnets 27 in the adjustable magnet sub-assembly 26
are positioned such that the "North" poles are nearest the shaft
18, while in the stationary magnet sub-assembly 24, the permanent
magnets are positioned such that the "South" poles are nearest the
shaft 18.
While the magnet sub-assembly 24 is held stationary in its
pre-selected position by a mounting to the frame structure, the
magnet sub-assembly 26 is mounted on shaft 18 with a low friction
bearing 32 and is free to be turned to selected angular positions
about the shaft. Retention of the adjustable magnet sub-assembly 26
in a desired position is accomplished by including a spring loaded
plunger 38 (FIG. 4) in the end portion 36 of sub-assembly 26, and
the incorporation on the frame of a locating device such as the
detent 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 the plunger 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 the plunger 38 contained in the
plate 36 being held in one of the indentations 40 in detent 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
on handle 44 attached to plate 36 as shown in FIGS. 1, 3 and 3 and
extending to the exterior of the unit's housing will result in the
spring force being overcome, plunger 38 being moved out of the
indentation 40 allowing for repositioning of the magnet
sub-assembly 26 to another desired position.
One desirable position of the rotatable magnet sub-assembly 26
relative to stationary magnet sub-assembly 24 is a position whereby
one and only one of the permanent magnets in each of the
sub-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 across disc 20.
Curve B on FIG. 5 is characteristic of the braking torque developed
at various disc rotational speeds under this condition.
If the magnet 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 permanent magnets of the sub-assembly 24
and with unlike poles opposite, and an increased magnetic field
strength across the disc 20 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 three magnets 27 in one sub-assembly
aligned with two and three magnets 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 the
rotatable 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 on handle 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.degree. to each other
or three at 60.degree. 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 permanent 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 the permanent
magnets 49 are mounted for axial movement toward and away from the
modified Faraday disc 28. These magnets are held in stationary
support arms 51 and 59 on opposite sides of the disc 20. In each of
these support arms a number of permanent 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 magnet is 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 wherein magnet 49 is fitted
into a cylindrical recess drilled in support arms 51 and 59. Magnet
49 may be keyed to a keyway 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 of magnet 49 and the
support arm. Under the influence of compression spring 63, magnet
49 tends to be displaced closer to the current conducting disc 28
of disc assembly 20.
The freedom of axial movement of magnet 49 is restricted by, and in
fact the axial position of magnet 49 is controlled by, the presence
of cooperatively engaged cams 65 and 67, the inner-most of which,
or cam 65, being firmly fixed to one end of shaft 69 having a fixed
length. Cam 67 is firmly attached to magnet 49 to prevent any
relative movement between the two parts and shaft 69 passes through
an appropriately drilled hole in cam 67. The fixed length of shaft
69 can be assured by insertion of a snap ring 71 into a groove
machined into shaft 69 at the appropriate dimension and this snap
ring being brought to bear on a surface of the support arm by the
force of compression spring 63. Shaft 69 can continue through an
appropriately placed hole in exterior panel 73 of the basic
exercise machine unit 112 and have attached on the exterior end a
knob suitable for rotating shaft 69. Such a knob is shown in FIG. 7
with a knob 75 with a slot 77 included for insertion of some device
such as a screwdriver or coin to provide the necessary torque to
rotate shaft 69.
As shown in FIGS. 7 and 8, cam 65 and cam 67 are fully meshed
allowing magnet 49 to be fully extended by the force of spring 63.
Rotation of shaft 69 in either a clockwise or counterclockwise
direction causes a retraction of magnet 49 from the fully extended
position due to the interaction of the rises on cams 65 and 67
(FIG. 9). With a 90.degree. rotation of shaft 69 or knob 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 the support arms 51 and 59 at
positions of equal radius from the center of disc rotation. The
support arms 51 and 59 are held stationary on opposite sides of the
disc 20, and they are preferably positioned such that each
installed magnet 49 of one is precisely in line with an installed
magnet 49 of the other. With the magnets installed in the support
arms 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 modified Faraday 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 the shafts 69 or knobs
75 on one set of opposing magnets are rotated 90.degree. 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 of knobs 75. With a knob 75 such as shown in
FIG. 7, wherein a slot 77 is provided at the exterior of case 73 to
effect rotation of the knob and a 90.degree. rotation of the knob
is required to cause axial movement of the magnet from one extreme
to the other, the angular positions of the slots 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 20 is formed, for example, of a copper disc
28 thin enough to allow a narrow air gap between the permanent
magnets of the two sub-assemblies 24 and 26, and it is rimmed with
a steel rim 30 so that the resulting inertia of the disc 20 at any
speed largely offsets the maximum resistance force generated by the
permanent magnets. Copper is chosen for the disc 20 to provide high
load and efficiency because of its high electrical conductivity.
The disc 20 is keyed to shaft 18 which also has the pulley 12 with
the positive drive belt 14, the disc 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 the Faraday disc 20 in
revolutions per minute and the accumulating number of crank
revolutions. As shown in FIG. 1, the rotational speed of the disc
20 is determined by use of a conventional 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 an
indicator 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, a lever 52,
positioned adjacent to cam 48 attached to pulley shaft 50, is
mounted on structure 53 by pin 55 such that the lever is free to
pivot about the pin 55. A force, developed by compression spring 57
which is appropriately supported, is continuously applied to lever
52 to assure lever contact with cam 50 at all times. The cam 50 is
configured such that the lever 52 moves through one complete cycle
for each revolution of the pedals 10. By suitable attachment of a
mechanical motion counter 56, such as a Veeder-Root counter or
other summing device, to the other end of lever 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 conventional mechanical
clock mechanism 58 is attached to rear plate 60 with its main shaft
62 passing through appropriate holes in rear plate 60 and forward
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 to shaft 62 intermediate its ends.
Attached to the free end of shaft 62 is knob 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
from dial face 72 attached to forward plate 64.
A second shaft 74 is installed between plate 60 and plate 64 and
supported in a like manner by low friction bearings, such as
bearing 76, to afford unrestricted freedom of rotation.
Intermediate ends of shaft 74 is attached pawl 78 including pin 80
as an integral part positioned such that it may be actuated by cam
68 and may engage notch 82 machined in rod 84. A force developed by
compression spring 86, suitably attached to upper plate 88 and to
pawl 78, assists in maintaining contact between pawl 78 and rod 84.
On one end, rod 84 is held in position by sleeve 90 on base plate
92 while retaining its freedom for axial mvoement in a vertical
direction. Rod 84 passes through an appropriately placed hole in
the upper plate 88 and is attached to arm 92 positioned in a slot
in its other end and held by pin 94.
Encompassing a portion of the upper end of rod 84 and retained by
plate 88 and arm 92 is compression spring 96 developing a force
which tends to move rod 84 in an upward direction or to raise arm
92. One end of arm 92 is attached to plate 64 by use of bracket 98
and pin 100. In such an arrangement, the movement of arm 92 is
thereby restricted to a pivotal action around pin 100. Arm 92
passes through slot 102, machined in rear plate 60 to allow for
vertical movement, and at the other end, has attached handle 104
which extends through the case housing the clock release device and
may be used to manually position arm 92. Push rod 106 is attached
by use of pin 108 to this end of arm 92 and extends upward through
an appropriate hole in the exterior case of the unit.
When the clock release unit 110 of FIG. 10 is assembled with the
basic exercise machine unit 112 as shown in FIG. 11, push rod 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 114 is rigidly attached to shaft 116 which
has its two ends supported in suitable structure by low friction
bearing, such as bearing 118, thereby permitting rotation of shaft
116. On one end of lever 118 is attached tension spring 119 which
develops a force tending to maintain contact between rod 106 and
lever 114. Whereas rod 106 contacts lever 114 at a point somewhat
removed from the centerline of shaft 116 toward the attachment
point of spring 119, belt 120 is firmly attached to the other end
of lever 114 by some means, such as rivets 122 shown in FIG. 1.
Lever 114 is positioned on shaft 116 such that belt 120 can be
routed around disc assembly 20 with the other end of belt 120
securely attached to a suitable structure by use of fitting 124 and
rivets 126.
With the mechanism described above, it is apparent that when rod
106 is fully extended as shown in FIG. 1, the force of spring 119
is overcome and lever 114 is rotated into a position whereby belt
120 is held taut thereby bringing a portion of the belt into
contact with the exterior surface of rim 30. With the proper belt
tension and length of belt in contact with rim 30, adequate
friction can be developed to prohibit continued rotation of the
disc 20 or pedals 10. In the converse situation, namely when the
force of spring 119 is not overcome by rod 106 due to its position,
such as when rod 106 is in its fully retracted position, the force
developed by spring 119 rotates lever 114 in a direction such that
slackness is created in belt 120 and no contact between belt and
rim results. In this condition, no impediment to disc 20 or pedal
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 the push rod 106. Control over the position of rod 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 of cam 78
and notch 82 in rod 84. As previously stated, this rod position
results in a slack belt 120 and freedom for the pedals 10 to be
rotated. The fully retracted position of rod 106 can be achieved
only by rotation of knob 70 clockwise to some position other than
zero thereby repositioning the lip on cam 68 such that no contact
is made with pin 80 of pawl 78 and then depressing handle 104 until
the action of spring 86 forces pawl 78 into notch 82 in rod 84. As
stated before, rotation of knob 70 in a clockwise directon winds
the mechanical clock mechanism 58 with the desired time interval
for the clock mechanism to unwind being easily established by
reference to dial face 72. As the clock unwinds, shaft 62 and the
attached cam 68 and knob 70 rotate in a counterclockwise direction
when viewed from the front with the lip on cam 68 approaching
contact with pin 80 of pawl 78 as the selected time interval nears
completion or the index on knob 70 approaches the zero on dial face
72.
At the conclusion of the selected time interval, the lip on cam 68
engages pin 80 and causes movement such that pawl 78 is rotated
about the centerline of shaft 74 overcoming the force of spring 86
and is removed from notch 82 of rod 84. With the removal of the
pawl from the slot, the force of spring 96 causes rod 84 to move in
an upward direction. This vertical movement of rod 84 is translated
into the full extension of push rod 106 by the pivoting action of
arm 92 about pin 100. As previously explained, push rod 106 in the
fully extended position acts on lever 114 to brake the disc 20 and
cause stoppage of rotation of pedals 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 embodiment of 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 the clock release unit 110 and the basic exercise
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 subject's performance and
the capability automatically to terminate the subject's activity at
the conclusion of the prescribed exercise program with the
necessary instruments and controls to accomplish this readily
accessible. A latch mechanism between units 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, the units 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, the clock
release unit 110 is permanently attached to a pair of cross bars
128, and the machine unit 112 is latched to unit 110 by latches
111, or equivalent fasteners. The clock release unit 110 provides
elevation of the pedals 10 such that adequate foot clearance from
the bed is realized. As an adjustment associated with the length of
the subject's legs, the cross bars 128 slide longitudinally on the
spaced and parallel bars of frame 130 to any desired position for
leg reach, and are manually clamped into place by clamps 132. The
unit 112 may be removed from the unit 110 by releasing the latches
111, and unit 112 may be conveniently carried by a handle 113.
The vertical portion at one end of the frame 130 has rubber 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 of
frame 130 have their ends turned up to provide convenient and
comfortable 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.
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