CA2385481A1 - Portable load carrying device - Google Patents
Portable load carrying device Download PDFInfo
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- CA2385481A1 CA2385481A1 CA 2385481 CA2385481A CA2385481A1 CA 2385481 A1 CA2385481 A1 CA 2385481A1 CA 2385481 CA2385481 CA 2385481 CA 2385481 A CA2385481 A CA 2385481A CA 2385481 A1 CA2385481 A1 CA 2385481A1
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- Canada
- Prior art keywords
- load
- harness
- frame portion
- spring
- force
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- A—HUMAN NECESSITIES
- A45—HAND OR TRAVELLING ARTICLES
- A45F—TRAVELLING OR CAMP EQUIPMENT: SACKS OR PACKS CARRIED ON THE BODY
- A45F3/00—Travelling or camp articles; Sacks or packs carried on the body
- A45F3/04—Sacks or packs carried on the body by means of two straps passing over the two shoulders
Abstract
Disclosed herein is a portable load carrying device comprising a harness frame portion for carriage by a user, a load frame portion and a suspension portion joining the harness frame portion with the load frame portion, the suspension portion being operable to reduce dynamic forces exerted on the harness frame portion by the load frame portion during the user's gait.
Description
PORTABLE LOAD CARRYING DEVICE
BACKGROUND OF THE INVENTION
l . FIELD OF THE INVENTION
~f'Ihis invention relates in general to portable load carrying devices and more particularly, but not necessarily exclusively, to personal load carrying devices.
a!. DESCRIPTION OF THE RELATED ART
Personal Load Carriage Systems come in many different styles but all have two basic components a harness and a load. The harness i=ncludes shoulder straps and waist straps. The Load is typically supported by a "frame-sheet" and the harness is rigidly attached to a bag that ~ s 1-~olds the load.
>_iackpacks have traditionally been designed with padding and wide straps to distribute force over tlhe body during locomotion. Padding works to make wide straps more compliant to body contours, and this arrangement distributes load more evenly over the body, thereby reducing 2o contact pressures. Although this approach is effective, it does not reduce the contact pressures to an acceptable level under severe loading conditions. Discomfort, soreness and bruising are all common symptoms when using a backpack over an extended period of time. These symptoms are particularly noticeable when the backpack is heavy, and is being carried over rough terrain.
'JValking causes vertical oscillations as a person moves through the phases of gait. The body, and arty load it is carrying, must continuously rise and fall in order to move forward. Conventional personal load carriage systems keep the load tight to the body so that the load and the body are f;ssentially one mass. As the load accelerates up and down, oscillatory force is applied to the body that can be several times the magnitude of the static load'.
It is therefore an object of the present invention to mitigate the above mentioned disadvantages.
Briefly stated, the invention involves a portable load carrying device comprising a harness frame portion for carriage by a user, a load frame portion and a suspension portion joining the harness frame portion with the load frame portion, the suspension portion being operable to reduce t 5 dynamic forces exerted on the harness frame portion by the load frame portion during the user's gait.
Preferably, the suspension portion includes a pair of suspension members movable relative to one another, a first of the members being attached to the load frame portion and a second of the 20 members being attached to the harness frame portion, the suspension portion further including a 1 Kram, R. ( 1991 ) "Carrying loads with springy poles". .lournal q~ Applied Pf~ysiolo~ 72: I 119 - 1122.
dynamic force absorbing or reducing arrangement to control relative movement of the suspension members between a first position and a second position. In this case, the dynamic force absorbing arrangement includes at least one spring-like element operable to deliver the ~~uspension members to an intermediate: position between the first and second positions. In this case, the spring-like element may include spring-like elements such as compressed gases, fluids, resilient materials, and other energy storage media and the like, as well as springs such as coil springs.
Beneficially, in one embodiment, the spring-like element has characteristics defined by a force deflection curve having a first region in which the spring-like element has minimal deflection with increased force, a second transition region and a third region wherein the spring has minimal force increase with increased deflection. In this case, the force exerted in the first region corresponds generally to a rated maximum weight of a load to be supported by the load fame portion. Alternatively, means may be provided for adjusting the force at which the spring ~ 5 enters the second transition region. In other words, the dynamic force absorbing arrangement nnay be provided with an adjustable spring mechanism in order that the transitional force (namely tlhe force corresponding to the second region of t:he force deflection curve) may be adjusted according to the weight being carried, for example.
2o Preferably, the spring-like element includes a pair of coiled springs, each having an inner end and an outer end which are anchored to either the harness frame portion or the load frame portion.
1?referably, the harness frame portion further comprises a pair of stays positioned on opposite sides of a central axis, the stays being attached to a shoulder attachment and a waist attachment, the load frame portion further comprising a load support panel.
In one embodiment, the suspension members are provided in the form of a slide block member and a track member to receive the slide block member. One example provides two sets of slide block members and two corresponding sets of track members. The slide block members include an outer flanged portion to engage the track member and an anchor portion for attachment to the load support panel.
Preferably, an enclosure is attached to the load support panel to contain a load. The enclosure rnay be semi-rigid, such as a thin walled plastic container, or a bag-like structure formed from synthetic fabrics, cottons or other materials.
~ 5 In another of its aspects, there is provided a method for reducing dynamic forces in a back pack, comprising the steps of:
a) providing a harness frame portion for carriage by a user 20 b) providing a load frame portion;
c) providing a suspension portion between the harness frame portion and the load frame portion; and d) arranging the suspension portion to provide relative movement of the harness frame portion and the load frame portion between a first position and a second position along a central axis, and to reduce the transmission of dynamic forces between the load carrying portion and the harness frame portion during the user's gait.
Preferably, step c) includes the step of:
e) providing a plurality of displacement elements between the harness frame portion and the load frame portion.
~s Preferably, step e) includes the step of:
f) providing a number of sliding Mock elements, each of which travel along a corresponding track element between the first and second positions.
2o Preferably, step d) includes the steps of:
g) selecting a spring element whose characteristics are defined by a force deflection curve having a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring requires minimal force increase with increased deflection; and h) locating the spring element between the load frame portion and the harness portion.
I o In a preferred embodiment, the force exerted in the first region of step g) corresponds generally to a rated maximum weight of a load to be supported by the load frame portion.
Alternatively, the method may include the step of:
i) adjusting the force at which the spring enters the second transition region.
In another of its aspects, there is provided a portable load carrying device comprising a harness and a load support frame and a suspension arrangement therebetween, the suspension arrangement providing relative movement between the harness and the load support frame ~~etween a first position and a second position in a manner to control dynamic forces on the 2o harness from load oscillations during gait.
~Ci In still another of its aspects, there is provided a personal load carrying device comprising a harness and a load support frame and a suspension arrangement there between, the suspension ~~rrangement providing relative independent movement between the harness and the load support iFrame on either side of a central position between a first limit position and a second limit position, wherein the load support frame is operable to adopt a transient elevation at the central position while the harness moves in an undulating motion between the first and second limit positions during gait.
In yet another of its aspects, there is provided a back pack comprising a load support portion and a harness portion and control means for controlling displacement of the load support portion relative to the harness portion, the control means providing a path of travel of the load support portion relative to the harness portion, the load support portion being positionable at a central transient position along said path, the control means further controlling the displacement of the load support portion from the central transient position along said path in response to dynamic ~ 5 loads exerted thereon by the harness portion.
't'he teen 'dynamic forces' is intended to include those that can anise during the carrying of the device. These forces may be regular undulating forces exerted on the device by the user when he is walking at a steady pace or irregular undulating forces exerted on the device when the user 2o changes direction or speed. These forces may also include sudden impulse loads which can occur, for example, when the user steps or jumps to another ground elevation.
'Thus, the present invention is concerned with the control of dynamic forces generated during the ~;,arriage of a load. These dynamic f«rc:es may be exerted on the suspension portion by the user through the harness portion. Alternatively, these dynamic forces may be exerted on the >uspension portion by the load through the load frame portion. In effect, then, the forces are ~~ppearing at the suspension portion from either source and the suspension portion is capable of controlling those forces, more preferably reducing them, still more preferably minimizing them.
BRIEF DESCRIPTION OF THE DRAWINGS
~>everal preferred embodiments of the present invention will be provided, by way of examples only, with reference to the appended drawings, wherein, Figure 1 is a perspective view of a portable load carrying device;
t 5 Figure 2 is a fragmentary side view of a portion of the device shown in figure 1;
Figure 2a is a plot of force versus deflection for a portion of the device shown in figure l;
Figure 2b is a schematic view of a portion of an alternative load carrying device;
Figure 2c are two force displacement plots of the elements of the device shown in figure 2b;
Figure 3 is a fragmentary perspective view of another portion of the device shown in figure 1;
:Figure 4 is a sectional view taken one line 4-4 of figure 3;
lFigure 5 is a view of another portion of the device shown in figure 1;
1~igures 6a and 6b are schematic views of the device of figure I in two operative positions;
1~ figure 7 is a schematic view of a porti<»i of another load carrying device;
and 1i figure 8 is a schematic view of still another load carrying device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
~s Referring to the figures, there is provided a portable load carrying device 10, in the form of a backpack, having a harness frame portion 12 for carriage by a user, a load frame portion 14 and a suspension portion 16 joining the harness frame portion with the load frame portion. As will be dlescribed, the suspension portion 16 is operable to reduce dynamic forces exerted on the harness 2o frame portion by the load carrying portion during the user's gait.
'The harness frame portion 12 further comprises a pair of stays 18 positioned on opposite sides of .a central axis "c". The stays are semi-rigid and may typically be made of aluminum or molded ;plastics or the like. In this case, the stays are shaped to accommodate the contours of the back of nhe user and are attached to a shoulder attachment 20 and a waist attachment 22.
'rhe load frame portion 14 has a load support panel 24 which supports an enclosure 26. The latter is a bag-like structure formed from synthetic fabrics, cottons or other materials.
Preferably, the load support panel is fovned from semi rigid materials, for example polymer materials including polyethylenes, polyurethanes, or polypropylenes, although other materials may also be used.
rfhe suspension portion 16 includes a number of complementary displacement elements 40, which are coupled between the stays 18 and the load support panel 24, for providing relative movement therebetween along the central axis. The displacement elements 40 are, in this case, v 5 in the form of slide block members 42 which slide along track members 44.
The displacement elements 40 are divided into two groups, each on opposite sides of the central axis "c". As shown in figures 4 and 5, the slide bli>ck members 42 are mounted on the stays at regular locations and include an outer flanged portion 42a to engage the track member and an anchor portion 42b for attachment to the corresponding stay by way of threaded fasteners 42c.
>=ieneficially, the stays 18 are shaped to accommodate the contour of the back of the user. The slide block members are thus arranged, also, to accommodate the shape of the stays by adjusting the length of each anchor portion 42b according to the location of the slide block member. For example, the slide block member at the upper end of the stay has a relatively long anchor portion ~I2b, while the slide block member in the. central region of the stay has an anchor portion of essentially little or no extended length from the stay. The adjustment of the length of the anchor portions thus provides the outer flanged portions to lie in a substantially common suspension plane "D"
The suspension portion 16 further includes a dynamic force absorbing or reducing arrangement '.>0 which is operable between the stays 18 and the load support panel 24 for controlling movement of the slide block members relative to the corresponding track members between a first position (shown in solid lines in figure 2) and a second position (shown in dashed lines in figure 2). The dynamic force absorbing arrangement 50 includes a pair of spring elements 52 which biases, under a no load condition, the slide block members to the first position. In this ease, the spring elements 52 are constant force coiled springs, each spring 52 having an inner end ~ 5 '~2a and an outer end 52b. As shown in figure 5, each outer end 52b is anchored to a corresponding stay by way of a fastener 52c. Each inner end 52a is mounted to a transverse anchor bar 54 extending across the axis "C" and is mounted to the load support panel by way of a pair of split anchor blocks 56, although one split anchor block may be used if desired.
2o F;eferring to figure 2a, each of the spring elements 52 has a force deflection curve which includes a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring has minimal force increase with increased .deflection. In this case, the force exerted in the first region corresponds generally to a rated :maximum weight of a load to be supported by the load frame portion. If desired, however, the ~~ynamic force absorbing arrangement 'may be provided with an adjustable spring mechanism in birder that the transitional force (namely the force corresponding to the second region of the force ~~eflection curve) may be adjusted according to the weight being carried, for example.
;Figure 2b illustrates, schematically, a "linkage with spring" arrangement 60 which includes a rigid ann 62, a spring 64 and coaxial springs 66. The rigid ann 62 and spring 64 are provided ~,vith pivot points 68, 70 for attachment to the load support panel 24 or the stays 18. The coaxial 1 o springs include a number of springs of different length and in parallel.
As the coaxial springs are compressed initially, only one spring in the set is compressed. After a set amount of compression, a second spring begins to compress increasing the stiffness of the coaxial spring.
The spring rate of the coaxial spring, then, is determined by the number of springs placed in the coaxial spring. The force deflection curves for the linkage and a three spring coaxial spring I S arrangement is shown in figure 2c.
'the curve summing the curves a) and b) of figure 2c is the desired force-deflection curve of the embodiment shown in figure 2a. These characteristics are achievable using defonnable plastic elements or mechanical spring elements. The system may be tuned to the load being carried by 2o changing the distance between the two pin joints shown at 68 and 70, adjusting the position of the coaxial spring in the "y" direction {as shown in figure 2b), adjusting the length of the linage >2 or by adjusting the point along th-a link that the load is applied.
'The device 10 may be used as follows. First, load is installed in the enclosure. For this particular example, it will be assumed that the installed load has a weight which approximates the transitional force f«r the springs. T'he user then mounts the backpack on his back. Once the device is in its operative position, the load will exert the transitional force on the spring elements pausing them to move to their second transitional region. As a result, further forces exerted on ~:he springs, either from the harness portion or the load carrying portion, should cause the spring ~:o deflect. This will then have the effect of cau sing relative movement of the harness portion relative to the load car-r-ying portion.
1o Therefore, as the user walks, his gait will induce. a slight oscillatory or undulating motion on the harness portion, as shown in figure 6a in exaggerated fashion for illustrated purposes.
Beneficially, this undulating motion can then be seen in the slide block members traveling in an oscillatory motion in their associated track merrrbers. On the other hand, the track members can ~ 5 gravel relative to the slide block members depending on the changing orientation or forces that are exerted on the load as shown in figure 6b. This would occur, for instance, in a situation ~Nhere the user steps from an upper position to a lower position, causing the load to be exposed to a downward force. In this case, the load may then displace in an oscillatory fashion to accommodate the downward force and then return to its normal position.
l3 'Thus, the suspension an-angement of the device 10 is capable of providing relative movement between the harness and load support frame between a first and a second position in a manner to control dynamic forces on the harness from load oscillations during gait.
If desired, the suspension arrangement may be arranged to provide relative independent onovement between the harness portion and load support frame on either side of a central position between a first limit position and a second limit position, wherein the load support frame is operable to adopt a transient elevation at the central position while the harness moves an undulating motion between the first and second limit positions during gait. In this case, figure 6a illustrates the central position in solid lines and the first and second limit positions in dashed 1 fines.
l n some applications, the dynamic force control may alternatively be provided by a shock absorber (shown in dashed lines at 69 in figure l ), such as a gas charged shock absorber, which ~ 5 would dampen motion between the harness fi-ame portion and the load frame portion.
Figure 7 shows a portion of an alternative device. A harness frame panel 80 is attached to an outer sleeve portion 82 at its peripheries 82a to form a passage 84 to receive an inner load ~~upport panel 86. In this case, the panel 80 is attached to a foam panel 88 and is shaped to 20 accommodate the shape of the user"s back by way of an appropriate foam material. The load is shown schematically at 90 and is attached to the inner load support panel 86 by way of passages through the outer sleeve portion 82 (not shown).
l4 While the device 10 makes use of stays, they may instead be replaced by a single panel to which nhe shoulder and waste straps are attached. In this case, the single panel may be provided with a foam pad or similar padding which is shaped to conform to the user's back.
Similarly, while the stays in the device 10 are described as being adjustable to accommodate the shape of the user's hack, it will be understood that the stays may be made standard and padding may be provided on them to allow the device to be custom tailored to the user's back. While the suspension arrangement provided in the device 10 makes use of sliding blocks and tracks elements, other means may be used to achieve motion between harness frame portion and the load frame portion, such as by the use of wheels and bearings, lubricated sliding surfaces and two surfaces separated by a gas. In this case, the wheels could be added to the inner load support panel and run against the harness frame panel 80. Alternatively, the two could slide relative to one another.
'JVhile the device 10 makes use of a suspension having a track for sliding movement along a path, ~ 5 it is also contemplated that the suspension may be provided with a parallel link arrangement as ~,hown in figure 8. In this case, a harness portion shown at 90 and a load frame portion 92 are joined by a dynamic force control portion 94 which has a pair of anchor panels 96a, 96b to which a number of parallel links 98 are pivotally attached. In this case, displacement controllers, such avs a spring arrangement shown at I 00, control the motion of the parallel links allowing the 2o suspension to control dynamic forces and to permit the load to travel through an arcuate travel path F. The link arrangement may then establish a central transient position (denoted for .example, by the levers being in a "3 o'clock" position) between an upper limit position (for ~°xample, a "I o'clock" position) and a lower limit (for example, a "4-o'clock" position).
While the devices illustrated herein are intended to be used by a single user, the dynamic force controlling characteristics provided by the present invention may also be applied to portable carrying devices which involve two or more people, such as, for example, device having a back pack unit for each of two users where the back pack units include a support portion for carrying one end of a stretcher, a canoe, or multiple stretchers or canoes in tandem.
to 'While the load frame portion used herein is described in association with an enclosure 26 to contain a load, it will be understood th<zt the load frame portion may be provided in a number of different forms including a frame sheet, for example an L-shaped sheet for example, which together with straps or other restrains, anchors the load firmly thereto, as shown schematically in cashed lines in figure 6a.
'JVhile the devices disclosed herein are described as having dynamic force absorbing arrangements, such as that illustrated at 50 in figure 5, it will be understood that the force absorbing arrangement may be one which, in effect, reduces the transmission of dynamic forces from the harness portion to the load frame portion and vice versa while not completely absorbing 2o such forces.
While the present invention has been described for what are presently considered the preferred embodiments, the invention is not so limited. Tu the contrary, the invention is intended to cover ~~arious modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
BACKGROUND OF THE INVENTION
l . FIELD OF THE INVENTION
~f'Ihis invention relates in general to portable load carrying devices and more particularly, but not necessarily exclusively, to personal load carrying devices.
a!. DESCRIPTION OF THE RELATED ART
Personal Load Carriage Systems come in many different styles but all have two basic components a harness and a load. The harness i=ncludes shoulder straps and waist straps. The Load is typically supported by a "frame-sheet" and the harness is rigidly attached to a bag that ~ s 1-~olds the load.
>_iackpacks have traditionally been designed with padding and wide straps to distribute force over tlhe body during locomotion. Padding works to make wide straps more compliant to body contours, and this arrangement distributes load more evenly over the body, thereby reducing 2o contact pressures. Although this approach is effective, it does not reduce the contact pressures to an acceptable level under severe loading conditions. Discomfort, soreness and bruising are all common symptoms when using a backpack over an extended period of time. These symptoms are particularly noticeable when the backpack is heavy, and is being carried over rough terrain.
'JValking causes vertical oscillations as a person moves through the phases of gait. The body, and arty load it is carrying, must continuously rise and fall in order to move forward. Conventional personal load carriage systems keep the load tight to the body so that the load and the body are f;ssentially one mass. As the load accelerates up and down, oscillatory force is applied to the body that can be several times the magnitude of the static load'.
It is therefore an object of the present invention to mitigate the above mentioned disadvantages.
Briefly stated, the invention involves a portable load carrying device comprising a harness frame portion for carriage by a user, a load frame portion and a suspension portion joining the harness frame portion with the load frame portion, the suspension portion being operable to reduce t 5 dynamic forces exerted on the harness frame portion by the load frame portion during the user's gait.
Preferably, the suspension portion includes a pair of suspension members movable relative to one another, a first of the members being attached to the load frame portion and a second of the 20 members being attached to the harness frame portion, the suspension portion further including a 1 Kram, R. ( 1991 ) "Carrying loads with springy poles". .lournal q~ Applied Pf~ysiolo~ 72: I 119 - 1122.
dynamic force absorbing or reducing arrangement to control relative movement of the suspension members between a first position and a second position. In this case, the dynamic force absorbing arrangement includes at least one spring-like element operable to deliver the ~~uspension members to an intermediate: position between the first and second positions. In this case, the spring-like element may include spring-like elements such as compressed gases, fluids, resilient materials, and other energy storage media and the like, as well as springs such as coil springs.
Beneficially, in one embodiment, the spring-like element has characteristics defined by a force deflection curve having a first region in which the spring-like element has minimal deflection with increased force, a second transition region and a third region wherein the spring has minimal force increase with increased deflection. In this case, the force exerted in the first region corresponds generally to a rated maximum weight of a load to be supported by the load fame portion. Alternatively, means may be provided for adjusting the force at which the spring ~ 5 enters the second transition region. In other words, the dynamic force absorbing arrangement nnay be provided with an adjustable spring mechanism in order that the transitional force (namely tlhe force corresponding to the second region of t:he force deflection curve) may be adjusted according to the weight being carried, for example.
2o Preferably, the spring-like element includes a pair of coiled springs, each having an inner end and an outer end which are anchored to either the harness frame portion or the load frame portion.
1?referably, the harness frame portion further comprises a pair of stays positioned on opposite sides of a central axis, the stays being attached to a shoulder attachment and a waist attachment, the load frame portion further comprising a load support panel.
In one embodiment, the suspension members are provided in the form of a slide block member and a track member to receive the slide block member. One example provides two sets of slide block members and two corresponding sets of track members. The slide block members include an outer flanged portion to engage the track member and an anchor portion for attachment to the load support panel.
Preferably, an enclosure is attached to the load support panel to contain a load. The enclosure rnay be semi-rigid, such as a thin walled plastic container, or a bag-like structure formed from synthetic fabrics, cottons or other materials.
~ 5 In another of its aspects, there is provided a method for reducing dynamic forces in a back pack, comprising the steps of:
a) providing a harness frame portion for carriage by a user 20 b) providing a load frame portion;
c) providing a suspension portion between the harness frame portion and the load frame portion; and d) arranging the suspension portion to provide relative movement of the harness frame portion and the load frame portion between a first position and a second position along a central axis, and to reduce the transmission of dynamic forces between the load carrying portion and the harness frame portion during the user's gait.
Preferably, step c) includes the step of:
e) providing a plurality of displacement elements between the harness frame portion and the load frame portion.
~s Preferably, step e) includes the step of:
f) providing a number of sliding Mock elements, each of which travel along a corresponding track element between the first and second positions.
2o Preferably, step d) includes the steps of:
g) selecting a spring element whose characteristics are defined by a force deflection curve having a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring requires minimal force increase with increased deflection; and h) locating the spring element between the load frame portion and the harness portion.
I o In a preferred embodiment, the force exerted in the first region of step g) corresponds generally to a rated maximum weight of a load to be supported by the load frame portion.
Alternatively, the method may include the step of:
i) adjusting the force at which the spring enters the second transition region.
In another of its aspects, there is provided a portable load carrying device comprising a harness and a load support frame and a suspension arrangement therebetween, the suspension arrangement providing relative movement between the harness and the load support frame ~~etween a first position and a second position in a manner to control dynamic forces on the 2o harness from load oscillations during gait.
~Ci In still another of its aspects, there is provided a personal load carrying device comprising a harness and a load support frame and a suspension arrangement there between, the suspension ~~rrangement providing relative independent movement between the harness and the load support iFrame on either side of a central position between a first limit position and a second limit position, wherein the load support frame is operable to adopt a transient elevation at the central position while the harness moves in an undulating motion between the first and second limit positions during gait.
In yet another of its aspects, there is provided a back pack comprising a load support portion and a harness portion and control means for controlling displacement of the load support portion relative to the harness portion, the control means providing a path of travel of the load support portion relative to the harness portion, the load support portion being positionable at a central transient position along said path, the control means further controlling the displacement of the load support portion from the central transient position along said path in response to dynamic ~ 5 loads exerted thereon by the harness portion.
't'he teen 'dynamic forces' is intended to include those that can anise during the carrying of the device. These forces may be regular undulating forces exerted on the device by the user when he is walking at a steady pace or irregular undulating forces exerted on the device when the user 2o changes direction or speed. These forces may also include sudden impulse loads which can occur, for example, when the user steps or jumps to another ground elevation.
'Thus, the present invention is concerned with the control of dynamic forces generated during the ~;,arriage of a load. These dynamic f«rc:es may be exerted on the suspension portion by the user through the harness portion. Alternatively, these dynamic forces may be exerted on the >uspension portion by the load through the load frame portion. In effect, then, the forces are ~~ppearing at the suspension portion from either source and the suspension portion is capable of controlling those forces, more preferably reducing them, still more preferably minimizing them.
BRIEF DESCRIPTION OF THE DRAWINGS
~>everal preferred embodiments of the present invention will be provided, by way of examples only, with reference to the appended drawings, wherein, Figure 1 is a perspective view of a portable load carrying device;
t 5 Figure 2 is a fragmentary side view of a portion of the device shown in figure 1;
Figure 2a is a plot of force versus deflection for a portion of the device shown in figure l;
Figure 2b is a schematic view of a portion of an alternative load carrying device;
Figure 2c are two force displacement plots of the elements of the device shown in figure 2b;
Figure 3 is a fragmentary perspective view of another portion of the device shown in figure 1;
:Figure 4 is a sectional view taken one line 4-4 of figure 3;
lFigure 5 is a view of another portion of the device shown in figure 1;
1~igures 6a and 6b are schematic views of the device of figure I in two operative positions;
1~ figure 7 is a schematic view of a porti<»i of another load carrying device;
and 1i figure 8 is a schematic view of still another load carrying device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
~s Referring to the figures, there is provided a portable load carrying device 10, in the form of a backpack, having a harness frame portion 12 for carriage by a user, a load frame portion 14 and a suspension portion 16 joining the harness frame portion with the load frame portion. As will be dlescribed, the suspension portion 16 is operable to reduce dynamic forces exerted on the harness 2o frame portion by the load carrying portion during the user's gait.
'The harness frame portion 12 further comprises a pair of stays 18 positioned on opposite sides of .a central axis "c". The stays are semi-rigid and may typically be made of aluminum or molded ;plastics or the like. In this case, the stays are shaped to accommodate the contours of the back of nhe user and are attached to a shoulder attachment 20 and a waist attachment 22.
'rhe load frame portion 14 has a load support panel 24 which supports an enclosure 26. The latter is a bag-like structure formed from synthetic fabrics, cottons or other materials.
Preferably, the load support panel is fovned from semi rigid materials, for example polymer materials including polyethylenes, polyurethanes, or polypropylenes, although other materials may also be used.
rfhe suspension portion 16 includes a number of complementary displacement elements 40, which are coupled between the stays 18 and the load support panel 24, for providing relative movement therebetween along the central axis. The displacement elements 40 are, in this case, v 5 in the form of slide block members 42 which slide along track members 44.
The displacement elements 40 are divided into two groups, each on opposite sides of the central axis "c". As shown in figures 4 and 5, the slide bli>ck members 42 are mounted on the stays at regular locations and include an outer flanged portion 42a to engage the track member and an anchor portion 42b for attachment to the corresponding stay by way of threaded fasteners 42c.
>=ieneficially, the stays 18 are shaped to accommodate the contour of the back of the user. The slide block members are thus arranged, also, to accommodate the shape of the stays by adjusting the length of each anchor portion 42b according to the location of the slide block member. For example, the slide block member at the upper end of the stay has a relatively long anchor portion ~I2b, while the slide block member in the. central region of the stay has an anchor portion of essentially little or no extended length from the stay. The adjustment of the length of the anchor portions thus provides the outer flanged portions to lie in a substantially common suspension plane "D"
The suspension portion 16 further includes a dynamic force absorbing or reducing arrangement '.>0 which is operable between the stays 18 and the load support panel 24 for controlling movement of the slide block members relative to the corresponding track members between a first position (shown in solid lines in figure 2) and a second position (shown in dashed lines in figure 2). The dynamic force absorbing arrangement 50 includes a pair of spring elements 52 which biases, under a no load condition, the slide block members to the first position. In this ease, the spring elements 52 are constant force coiled springs, each spring 52 having an inner end ~ 5 '~2a and an outer end 52b. As shown in figure 5, each outer end 52b is anchored to a corresponding stay by way of a fastener 52c. Each inner end 52a is mounted to a transverse anchor bar 54 extending across the axis "C" and is mounted to the load support panel by way of a pair of split anchor blocks 56, although one split anchor block may be used if desired.
2o F;eferring to figure 2a, each of the spring elements 52 has a force deflection curve which includes a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring has minimal force increase with increased .deflection. In this case, the force exerted in the first region corresponds generally to a rated :maximum weight of a load to be supported by the load frame portion. If desired, however, the ~~ynamic force absorbing arrangement 'may be provided with an adjustable spring mechanism in birder that the transitional force (namely the force corresponding to the second region of the force ~~eflection curve) may be adjusted according to the weight being carried, for example.
;Figure 2b illustrates, schematically, a "linkage with spring" arrangement 60 which includes a rigid ann 62, a spring 64 and coaxial springs 66. The rigid ann 62 and spring 64 are provided ~,vith pivot points 68, 70 for attachment to the load support panel 24 or the stays 18. The coaxial 1 o springs include a number of springs of different length and in parallel.
As the coaxial springs are compressed initially, only one spring in the set is compressed. After a set amount of compression, a second spring begins to compress increasing the stiffness of the coaxial spring.
The spring rate of the coaxial spring, then, is determined by the number of springs placed in the coaxial spring. The force deflection curves for the linkage and a three spring coaxial spring I S arrangement is shown in figure 2c.
'the curve summing the curves a) and b) of figure 2c is the desired force-deflection curve of the embodiment shown in figure 2a. These characteristics are achievable using defonnable plastic elements or mechanical spring elements. The system may be tuned to the load being carried by 2o changing the distance between the two pin joints shown at 68 and 70, adjusting the position of the coaxial spring in the "y" direction {as shown in figure 2b), adjusting the length of the linage >2 or by adjusting the point along th-a link that the load is applied.
'The device 10 may be used as follows. First, load is installed in the enclosure. For this particular example, it will be assumed that the installed load has a weight which approximates the transitional force f«r the springs. T'he user then mounts the backpack on his back. Once the device is in its operative position, the load will exert the transitional force on the spring elements pausing them to move to their second transitional region. As a result, further forces exerted on ~:he springs, either from the harness portion or the load carrying portion, should cause the spring ~:o deflect. This will then have the effect of cau sing relative movement of the harness portion relative to the load car-r-ying portion.
1o Therefore, as the user walks, his gait will induce. a slight oscillatory or undulating motion on the harness portion, as shown in figure 6a in exaggerated fashion for illustrated purposes.
Beneficially, this undulating motion can then be seen in the slide block members traveling in an oscillatory motion in their associated track merrrbers. On the other hand, the track members can ~ 5 gravel relative to the slide block members depending on the changing orientation or forces that are exerted on the load as shown in figure 6b. This would occur, for instance, in a situation ~Nhere the user steps from an upper position to a lower position, causing the load to be exposed to a downward force. In this case, the load may then displace in an oscillatory fashion to accommodate the downward force and then return to its normal position.
l3 'Thus, the suspension an-angement of the device 10 is capable of providing relative movement between the harness and load support frame between a first and a second position in a manner to control dynamic forces on the harness from load oscillations during gait.
If desired, the suspension arrangement may be arranged to provide relative independent onovement between the harness portion and load support frame on either side of a central position between a first limit position and a second limit position, wherein the load support frame is operable to adopt a transient elevation at the central position while the harness moves an undulating motion between the first and second limit positions during gait. In this case, figure 6a illustrates the central position in solid lines and the first and second limit positions in dashed 1 fines.
l n some applications, the dynamic force control may alternatively be provided by a shock absorber (shown in dashed lines at 69 in figure l ), such as a gas charged shock absorber, which ~ 5 would dampen motion between the harness fi-ame portion and the load frame portion.
Figure 7 shows a portion of an alternative device. A harness frame panel 80 is attached to an outer sleeve portion 82 at its peripheries 82a to form a passage 84 to receive an inner load ~~upport panel 86. In this case, the panel 80 is attached to a foam panel 88 and is shaped to 20 accommodate the shape of the user"s back by way of an appropriate foam material. The load is shown schematically at 90 and is attached to the inner load support panel 86 by way of passages through the outer sleeve portion 82 (not shown).
l4 While the device 10 makes use of stays, they may instead be replaced by a single panel to which nhe shoulder and waste straps are attached. In this case, the single panel may be provided with a foam pad or similar padding which is shaped to conform to the user's back.
Similarly, while the stays in the device 10 are described as being adjustable to accommodate the shape of the user's hack, it will be understood that the stays may be made standard and padding may be provided on them to allow the device to be custom tailored to the user's back. While the suspension arrangement provided in the device 10 makes use of sliding blocks and tracks elements, other means may be used to achieve motion between harness frame portion and the load frame portion, such as by the use of wheels and bearings, lubricated sliding surfaces and two surfaces separated by a gas. In this case, the wheels could be added to the inner load support panel and run against the harness frame panel 80. Alternatively, the two could slide relative to one another.
'JVhile the device 10 makes use of a suspension having a track for sliding movement along a path, ~ 5 it is also contemplated that the suspension may be provided with a parallel link arrangement as ~,hown in figure 8. In this case, a harness portion shown at 90 and a load frame portion 92 are joined by a dynamic force control portion 94 which has a pair of anchor panels 96a, 96b to which a number of parallel links 98 are pivotally attached. In this case, displacement controllers, such avs a spring arrangement shown at I 00, control the motion of the parallel links allowing the 2o suspension to control dynamic forces and to permit the load to travel through an arcuate travel path F. The link arrangement may then establish a central transient position (denoted for .example, by the levers being in a "3 o'clock" position) between an upper limit position (for ~°xample, a "I o'clock" position) and a lower limit (for example, a "4-o'clock" position).
While the devices illustrated herein are intended to be used by a single user, the dynamic force controlling characteristics provided by the present invention may also be applied to portable carrying devices which involve two or more people, such as, for example, device having a back pack unit for each of two users where the back pack units include a support portion for carrying one end of a stretcher, a canoe, or multiple stretchers or canoes in tandem.
to 'While the load frame portion used herein is described in association with an enclosure 26 to contain a load, it will be understood th<zt the load frame portion may be provided in a number of different forms including a frame sheet, for example an L-shaped sheet for example, which together with straps or other restrains, anchors the load firmly thereto, as shown schematically in cashed lines in figure 6a.
'JVhile the devices disclosed herein are described as having dynamic force absorbing arrangements, such as that illustrated at 50 in figure 5, it will be understood that the force absorbing arrangement may be one which, in effect, reduces the transmission of dynamic forces from the harness portion to the load frame portion and vice versa while not completely absorbing 2o such forces.
While the present invention has been described for what are presently considered the preferred embodiments, the invention is not so limited. Tu the contrary, the invention is intended to cover ~~arious modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
Claims (24)
1. A portable load carrying device comprising a harness frame portion for carriage by a user, a load frame portion and a suspension portion joining the harness frame portion with the load frame portion, the suspension portion being operable to reduce dynamic forces exerted on the harness frame portion by the load frame portion during the user's gait.
2. A device as defined in claim 1 wherein the suspension portion includes a pair of suspension members movable relative to one another, a first of the members being attached to the load frame portion and a second of the members being attached to the harness frame portion, the suspension portion further including a dynamic force reducing arrangement to control relative movement of the suspension members between a first position and a second position.
3. A device as defined in claim 2 wherein the dynamic force reducing arrangement includes at least one spring-like element operable to deliver the suspension members to an intermediate position between the first and second positions.
4. A device as defined in claim 3 wherein the spring element has characteristics defined by a force deflection curve having a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring has minimal force increase with increased deflection.
5. A device as defined in claim 4 wherein the force exerted in the first region corresponds generally to a rated maximum weight of a load to be supported by the load frame portion.
6. A device as defined in claim 4 further comprising means for adjusting the force at which the spring enters the second transition region.
7. A device as defined in claim 4 wherein the spring-like element includes one or more coiled springs, each having an inner end and an outer end which are anchored to either the harness frame portion or the load frame portion.
8. A device as defined in claim 7 wherein the suspension members include a slide block member and a track member to receive the slide block member.
9. A device as defined in claim 8, further comprising two sets of slide block members and two corresponding sets of track members.
10. A device as defined in claim 9 wherein the harness frame portion includes a pair of stays, each slide block member further includes an outer flanged portion to engage the track member and an anchor portion for attachment to a corresponding stay.
11. A device as defined in claim 10, further comprising a transverse anchor bar mounted to load support portion and to the inner end of each coiled spring.
12. A method for reducing dynamic forces in a back pack, comprising the steps of:
a) providing a harness frame portion for carriage by a user;
b) providing a load frame portion;
c) providing a suspension portion between the harness frame portion and the load frame portion; and d) arranging the suspension portion to provide relative movement of the harness frame portion and the load frame portion between a first position and a second position along a central axis, and to reduce the transmission of dynamic forces between the load carrying portion and the harness frame portion during the user's gait.
a) providing a harness frame portion for carriage by a user;
b) providing a load frame portion;
c) providing a suspension portion between the harness frame portion and the load frame portion; and d) arranging the suspension portion to provide relative movement of the harness frame portion and the load frame portion between a first position and a second position along a central axis, and to reduce the transmission of dynamic forces between the load carrying portion and the harness frame portion during the user's gait.
13. A method as defined in claim 12, wherein step c) includes the step of:
e) providing a plurality of displacement elements between the harness frame portion and the load frame portion.
e) providing a plurality of displacement elements between the harness frame portion and the load frame portion.
14. A method as defined in claim 13 wherein step e) includes the step of:
f) providing a number of sliding block elements; each of which travel along a corresponding track element between the first and second positions.
f) providing a number of sliding block elements; each of which travel along a corresponding track element between the first and second positions.
15. A method as defined in claim 12 wherein step d) includes the steps of:
g) selecting a spring-like element whose characteristics are defined by a force deflection curve having a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring requires minimal force increase with increased deflection; and h) locating the spring element between the load frame portion and the harness portion.
g) selecting a spring-like element whose characteristics are defined by a force deflection curve having a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring requires minimal force increase with increased deflection; and h) locating the spring element between the load frame portion and the harness portion.
16. A method as defined in claim 15 wherein the force exerted in the first region of step g) corresponds generally to a rated maximum weight of a load to be supported by the load frame portion.
17. A method as defined in claim 15, further comprising the step of i) adjusting the force at which the spring enters the second transition region.
18. A personal load carrying device comprising a harness and a load support frame and a suspension arrangement there between, the suspension arrangement providing relative movement between the harness and the load support frame between a first position and a second position in a manner to control dynamic forces on the load from oscillations by the harness during gait.
19. A portable load carrying device comprising a harness and a load support frame and a suspension arrangement there between, the suspension arrangement providing relative independent movement between the harness and the load support frame on either side of a central position between a first limit position and a second limit position, wherein the load support frame is operable to adopt a transient elevation at the central position while the harness moves in an undulating motion between the first and second limit positions during gait.
20. A back pack comprising a load support portion and a harness portion and control means for controlling displacement of the load support portion relative to the harness portion, the control means providing a path of travel of the load support portion relative to the harness portion, the load support portion being positionable at a central transient position along said path, the control means further controlling the displacement of the load support portion from the central transient position along said path in response to dynamic loads exerted thereon by the harness portion.
21. A back pack as defined in claim 20 wherein the control means includes a pair of suspension members movable relative to one another, a first of the members being attached to the load support portion and a second of the members being attached to the harness portion and at least one spring-like element operable to deliver the load support portion to the central transient position.
22. A device as defined in claim 21 wherein the spring-like element has characteristics defined by a force deflection curve having a first region in which the spring element has minimal deflection with increased force, a second transition region and a third region wherein the spring has minimal force increase with increased deflection.
23. A device as defined in claim 22 wherein the force exerted in the first region corresponds generally to a rated maximum weight of a load to be supported by the load support portion.
24. A device as defined in claim 23 further comprising means for adjusting the force at which the spring enters the second region transition region.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29040701P | 2001-05-14 | 2001-05-14 | |
| US60/290,407 | 2001-05-14 | ||
| US35248302P | 2002-01-30 | 2002-01-30 | |
| US60/352,483 | 2002-01-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2385481A1 true CA2385481A1 (en) | 2002-11-14 |
Family
ID=26966169
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2385481 Abandoned CA2385481A1 (en) | 2001-05-14 | 2002-05-08 | Portable load carrying device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2385481A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7391123B2 (en) | 2003-03-17 | 2008-06-24 | Lightning Packs Llc | Backpack for harvesting electrical energy during walking and for minimizing shoulder strain |
| EP2094126A2 (en) * | 2006-12-14 | 2009-09-02 | Lightning Packs LLC | Suspended load ergonomic backpack |
| US7851932B2 (en) | 2007-03-29 | 2010-12-14 | Lightning Packs, Llc | Backpack based system for human electricity generation and use when off the electric grid |
| US10413045B2 (en) | 2017-11-15 | 2019-09-17 | Valerie CRISP | Hard shell backpack |
-
2002
- 2002-05-08 CA CA 2385481 patent/CA2385481A1/en not_active Abandoned
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7391123B2 (en) | 2003-03-17 | 2008-06-24 | Lightning Packs Llc | Backpack for harvesting electrical energy during walking and for minimizing shoulder strain |
| US7931178B2 (en) | 2003-03-17 | 2011-04-26 | Lighting Packs, LLC | Suspended load ergonomic backpack |
| EP2094126A2 (en) * | 2006-12-14 | 2009-09-02 | Lightning Packs LLC | Suspended load ergonomic backpack |
| EP2094126A4 (en) * | 2006-12-14 | 2012-10-03 | Lightning Packs Llc | Suspended load ergonomic backpack |
| US7851932B2 (en) | 2007-03-29 | 2010-12-14 | Lightning Packs, Llc | Backpack based system for human electricity generation and use when off the electric grid |
| US10413045B2 (en) | 2017-11-15 | 2019-09-17 | Valerie CRISP | Hard shell backpack |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| FZDE | Dead |