CA1237152A - Spring system having a variable spring characteristic - Google Patents
Spring system having a variable spring characteristicInfo
- Publication number
- CA1237152A CA1237152A CA000467273A CA467273A CA1237152A CA 1237152 A CA1237152 A CA 1237152A CA 000467273 A CA000467273 A CA 000467273A CA 467273 A CA467273 A CA 467273A CA 1237152 A CA1237152 A CA 1237152A
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- Canada
- Prior art keywords
- spring
- springs
- housing part
- spring system
- housing
- 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.)
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Links
- 230000008878 coupling Effects 0.000 claims abstract description 5
- 238000010168 coupling process Methods 0.000 claims abstract description 5
- 238000005859 coupling reaction Methods 0.000 claims abstract description 5
- 238000007906 compression Methods 0.000 claims description 22
- 230000006835 compression Effects 0.000 claims description 21
- 238000006073 displacement reaction Methods 0.000 description 4
- 230000007246 mechanism Effects 0.000 description 4
- 238000013459 approach Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000000605 extraction Methods 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 230000005483 Hooke's law Effects 0.000 description 1
- 206010043268 Tension Diseases 0.000 description 1
- 241000011102 Thera Species 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000036316 preload Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
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Abstract
ABSTRACT
A spring system for providing an elastic force between two objects, is disclosed, including a housing with two parts, the first part adapted for attachment to the first object and the second part adapted for attachment to the second object.
Within the housing are two coil springs, the first spring having one of its ends attached to the first housing part and its other end attached, via a coupling piece, to one end of the second spring. The other end of the second spring is attached to the second housing part. The first housing part is dimensioned to encase the first spring, and is provided with at least one opposed pair of substantially transversely extending slits. A
fork-shaped member is insertable in the pair of slits and between adjacent coils of the first spring, to vary the effective length of the first spring.
A spring system for providing an elastic force between two objects, is disclosed, including a housing with two parts, the first part adapted for attachment to the first object and the second part adapted for attachment to the second object.
Within the housing are two coil springs, the first spring having one of its ends attached to the first housing part and its other end attached, via a coupling piece, to one end of the second spring. The other end of the second spring is attached to the second housing part. The first housing part is dimensioned to encase the first spring, and is provided with at least one opposed pair of substantially transversely extending slits. A
fork-shaped member is insertable in the pair of slits and between adjacent coils of the first spring, to vary the effective length of the first spring.
Description
:~Z~'715~
The invention relates to a spring system compr~sing at least two mainly parallel, e.g. concentric, springs, wherein at least one spring, having a variable spring characteristic, is connected at its one end with one of B 5 two ~ , between which an elastic force is to be in-troduced, and at least one othe~r ~ring is connected at its one end with the other ~r~.
It is known that the spring characteristic of a spring, i.e. the travel of the spring as a function o 10 the elastic force, can be changed by altering the number of the effective turns of the spring, e.g. by means of a clamp which fixes a number of the spring's turns in relation to each other. The elastic force corresponding to a given travel of the spring can thereby be varied, 15 e.g. in a mechanism in which a spring acting as a power spring actuates two parts to move a certain distance towards or away from each other at different loads, i.e.
by exerting various spring forces, or in a spring sus-pension system in which various loads are absorbed, the 20 travels of the spring being unchanged.
If, for example, the same spring is in this way to be made to exert different elastic forces within a predetermined interval, e.g. 50-1~00 kp, with a constant, likewise predetermined, spring travel, a fairly long and 25 bulky spring must be used, which both permits the defor-mation corresponding to the desired spring travel at the small force, e.g. 50 kp, and by reduction of the number of effective turns limits the deformation to the~
same value at the large force, e.g. 100 kp. At the elastic force interval of 50-100 kp chosen as example the slope of the spring characteristic must thus be changed by a factor of 2j and the free spring length, i. e. the total length of the-spring without load will be somewhat more than twice`the desired spring travel.
This means that a solution such as this is often not feasible owing to considerations of space.
: .
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Fro~n the U.S. Paten-t Spec:ification No. 973,641 a spring system i~ known with two concentric spring~, between which a tubular member is provided t:he ends of which are in mesh between the turns on the innermost and outermost spring, respectively.
By turning the tubular member one can increase or diminish the elastic force of the two springs at the same time, but unless other manipulations are made, this also increases or diminishes the resulting elastic force of t-he system in the initial position, which is often disadvantageous.
A purpose of the present invention is to produce a spring system which in connection with a simple and compact structure and without replacement of the spring permits a particularly large variation in the spring characteristic, i.e.
a considerable increase or decrease of the elastic force within a predetermined interval at a predetermined spring travel and with unchanged elastic force in the initial position.
One broad aspect of the preaent invention relates to a spring system for lmparting an elastic force between two objects comprising a housing comprised of a first part adapted for attachment to the first ob~ect and a second part adapted for attachment to the second object, first and second coil springs, said first spring having one of lts ends attached to said first houslng part and the other of its ends attached to one end of said second spring via a coupling piece, the other end of said second spring being attached to sald second housing part, characterized in that the said first housing part is dimensioned to encase said first spring, and is provided wlth at least one
The invention relates to a spring system compr~sing at least two mainly parallel, e.g. concentric, springs, wherein at least one spring, having a variable spring characteristic, is connected at its one end with one of B 5 two ~ , between which an elastic force is to be in-troduced, and at least one othe~r ~ring is connected at its one end with the other ~r~.
It is known that the spring characteristic of a spring, i.e. the travel of the spring as a function o 10 the elastic force, can be changed by altering the number of the effective turns of the spring, e.g. by means of a clamp which fixes a number of the spring's turns in relation to each other. The elastic force corresponding to a given travel of the spring can thereby be varied, 15 e.g. in a mechanism in which a spring acting as a power spring actuates two parts to move a certain distance towards or away from each other at different loads, i.e.
by exerting various spring forces, or in a spring sus-pension system in which various loads are absorbed, the 20 travels of the spring being unchanged.
If, for example, the same spring is in this way to be made to exert different elastic forces within a predetermined interval, e.g. 50-1~00 kp, with a constant, likewise predetermined, spring travel, a fairly long and 25 bulky spring must be used, which both permits the defor-mation corresponding to the desired spring travel at the small force, e.g. 50 kp, and by reduction of the number of effective turns limits the deformation to the~
same value at the large force, e.g. 100 kp. At the elastic force interval of 50-100 kp chosen as example the slope of the spring characteristic must thus be changed by a factor of 2j and the free spring length, i. e. the total length of the-spring without load will be somewhat more than twice`the desired spring travel.
This means that a solution such as this is often not feasible owing to considerations of space.
: .
~L23~7~L5~
Fro~n the U.S. Paten-t Spec:ification No. 973,641 a spring system i~ known with two concentric spring~, between which a tubular member is provided t:he ends of which are in mesh between the turns on the innermost and outermost spring, respectively.
By turning the tubular member one can increase or diminish the elastic force of the two springs at the same time, but unless other manipulations are made, this also increases or diminishes the resulting elastic force of t-he system in the initial position, which is often disadvantageous.
A purpose of the present invention is to produce a spring system which in connection with a simple and compact structure and without replacement of the spring permits a particularly large variation in the spring characteristic, i.e.
a considerable increase or decrease of the elastic force within a predetermined interval at a predetermined spring travel and with unchanged elastic force in the initial position.
One broad aspect of the preaent invention relates to a spring system for lmparting an elastic force between two objects comprising a housing comprised of a first part adapted for attachment to the first ob~ect and a second part adapted for attachment to the second object, first and second coil springs, said first spring having one of lts ends attached to said first houslng part and the other of its ends attached to one end of said second spring via a coupling piece, the other end of said second spring being attached to sald second housing part, characterized in that the said first housing part is dimensioned to encase said first spring, and is provided wlth at least one
- 2 -:B~ :
, opposed pair of sllbstantially transver3f31y extending sJits, there being provided a movable stop inser-table in said pair of slits between ad~acent coils of said first sprirly to vary the effective length of said first spring.
~ second broad aspect of the present invention relates to a spring system for imparting an elastic force between two objects comprising a housing comprised of a first part adapted for attachment to the first object and a second part adapted for attachment to the second object, at least two coil springs, a first spring having one of its ends attached to said first housing part and a second spring having one of its ends attached to said second housing part, the other springs connected end to end between said first and second springs via coupling pieces, characterized in that the said first housing part is dimensioned to encase said first spring, and i5 provided with at least one opposed pair of substantially transversely extending slits, there being provided a member insertable in said pair of slits and between adjacent coils of said first sprins to vary the effective length of said first spring.
Aa: a result of the mutual position and lnterconnection of the springs, the resulting spring travel for the spring system equals the sum of the travels of at least two springs, and as at least ~one cf these has a variable characteristic~ a very considerable range of variation for the slope of the system's spring characteristic can be obtained depending on the choice of spring. The total obtainable sprlng travel that can~
be made to approach or even exceed the length of the spring system in the initial position also depends on B 2a -,.,,. ., ~,, ' .
~ ' : : . .. ' . : ~
~L~3~S2 the choice of sprin~. Moreover, a constant elastic force is obtained in the initial position, if the distance B between the- ~ actuated by the spring system ls always the same in the initial position.
In principle, in a spring system according to the invention, an arbitrary number of springs can be used, but in many cases it is sufficient to have two springs, which can be two tension springs, two compression springs or one tension and one compression spring, and of which one has a variable characteristic and preferably in the unloaded initial position is weaker than the other spring A spring system according to the invention having, e.g. two springs with identical characteristics, will in the initial position with an unregulated characteris-tic for the variable spring have a resultant systemcharacteristic with a slope corresponding to twice the slope of the characteristic of the individual springs, because a force acting on one of the springs is transferred to the other spring via the connection between the springs, and the springs are deformed to an equal extent. However, if the number of effective turns of the variable spring is diminished, the slope of the characteristic of this spring and thereby also the slope of the characteristic of the system decreases. If, for example, the number of efective turns in the variable spring is reduced to ~ero, the slope of the spring characteristic of the system decreases to half of the starting value. This possibility of variation is obtai-ned at a comparatively small length of the spring system in comparison to the resultant spring travel, because this is equal to the sum of the travels of the individual springs.
:
. .... . .
::
`
' A greater variation in the slope of the characterlstic of the system can however be obtained, if springs with different characteristics are used in the system, that is, for example, two springs, one of which, preferabl~
5 the spring with a variable number of effective turns, is weaker and has a 5teeper characteristic curve than the other spring. The strong spring can, if desired, have a certain initial tension.
When a spring system such as this is acted on by a 10 gradually increasing load, the weak spring will be deformed most, and if the strong spring has an initial tension, to begin with only the weak spring is deformed, and its characteristic will then be practically the sole determining factor of the spring characteristic for the 15 spring system as a whole. In that case the system characteristic will have a breaking-point at the load e a ~ ~ e s p O ~ q A -~H~e~p}}at~ to the initial tension, at which load the strong spring begins to be deformed and thereby contri-bute to the total spring travel,~which of course is 20 again equal to the sum of the travels of the individual springs, in this case the two individual springs.
Again a variable system characteristic with a comparatively large spring travel in relation to the length of the spring system has been obtained, and by 25 the use of a strong spring with a preload the breaking-point in the characteristic produced by this can be moved by alteration of the number of effective turns in the weak spring.
In both cases the load corresponding to a given 30 total spring travel or total deformation of the indivi-dual springs depends on the proportion in which the deformation is divided between the springs, and this proportion can be adjusted by variation of the number of effective turns of the - at least in the initial 35 position - weaker spring. If this number is large, a given total travel corresponds to a comparatively small load, and if the number of effective turns in the weak ~, `:
, :
.. . . .
~'7~52 spring is low or perhaps zero, the given total travel corresponds to a greater load, because the strong spring then performs a greater part of or even the whole of the total travel of the system.
This applies if, for example, the spring system is constituted by two tension springs or two compression springs and - particularly as regards the tension springs - is loaded only within the range in which Hooke's law applies. This can be ensured, for instance, by restricting the travel of a tension spring by means of a stop.
In a suitable embodiment of the invention the spring system is constituted by tension springs and compression springs, e.g. two springs, the weak spring being a compression spring and the strong spring being a tension spring.
In the case of a gradually increasing load of the spring system in this embodiment it is also first and foremost the weak spring, i.e. the compression spring, that is deformed, and the system characteristic corre-sponds in essentials to the characteristic of this spring with an initial slope corresponding to its slope, particularly if the stronger tension spring has an initial tension. After a certain deformation of the compression spring, deformation of the stronger tension spring begins to appear, and the two springs jointly determine the system characteristic, which also in this case may have a breaking-point and has now a steeper course. When the load is further increased the compres-sion spring may at some point become completely compres-sed, and no longer contribute to the deformation or travel of the spring system. The system characteristic gets a new breaking-point and is then less steep, the slope being determined by the strong spring and thus being less than the initial slope. The systemcharacteris-tic and thereby the load corresponding to a given travel may also here be adjusted by variation of the number of effective turns of the weak spring. If this number IS lo~, the .
.
:~ .
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, 7~5;~
strong spring will comparatively quickly come to deter-mine the course of the system characteristic, and a given travel will correspond to a comparatively grea~
A load on the spring system.
In all~ cases a variation of the characteristic of the spring system is permitted in connection with the spring system as a whole having a comparatively short length in relation to the spring travel, because the travels of the separate springs comprised in the system and situated vis a vis each other, e.g. concentric springs, are added together. The range of variation can be made greatest when the spring system is constituted by a combination of tension and compression springs/
because the latter can be subjected to a more conside-rable load than tension springs and in the present - context do not lose their effect because they are completely compressed. This means, for instance, that a compression spring with a variable number of effective turns can be combined with a considerably stronger tension spring having a very flat spring characteristic.
The resultant system characteristic will then take a very progressive course. Yet, it should be mentioned that in this context a compression spring may be equated to a tension spring having a deformation-restricting stop, e.g. a drawing cable in the spring connecting the first and last turn of the spring and having a length corresponding to the maximal spring length.
A spring system according to the invention can be realized with very simple means, and can suitably be constructed with ordinary coil springs.
By the terms "weaker" and "stronger" spring is here meant the spring~ whose characteristic at a given free spring length, i.e. length in unloaded condition, has respectively the greatest and the least slope.
The invention is explained below on the basis of a few examples of embodiments with reference to the drawing, where ~ ;
:
`~ :
, - : '' ':' ' . . ~
;, Fig. 1 shows ~ practical enlbotlimellt of a spring system in a housillg, Fig. 2 is a sectional view along the line II-II in ~ig. 1, ~ ig. 3 depicts an adjusting clamp for the spring system sllown in Figs. 1 and 2, Fig. 4 depicts various reali~ations of a spring system according to the inventioll with different combinatiolls of con~pression and tension sprinKs, and Fig. 5 depicts an example of use of a system according to the invention.
Pig. 2 shows two concentric coil springs in the form of a tension spring 2 and a compression spring 3 in a joint housing 1.
Of these two springs the tension spring 2 has by way of example the greatest elastic force, and it may have an initial tension.
The spring 2 is accommodated in a tuoe 4, at the bottom of which it is attached by one of its ends, e.g. by mealls of a plug 5 screwed into the spring, through which plug ex-tellds a bolt 6, wh.ich also extends through the bottom of the tube and outside this bears, for instance, a drawing eyelet 7 ~hat is screwed on. Inside the bolt 6 is fixed to the plug 5 by means of a couple o~ nuts 3 .
At the opposite end of the spring 2 a plug ~ is also screwed in, and this plug has a radial flallge 10, via whic!l tha spring 2 is connected at the said end with one end of the spring 3, which extends in the ring-s!laped space between the tube 4 and the housing 1 and at its opposite end abuts against a ring 11 serving as a stop, the said ring being attached to the inner wall of the housing.
~3~ 2 B c~b jcct:~
The~ two p~rt~ which rll'~ to bc conn~cte(l wi-th each othHr via the spring system are connected, respectlvely, with the housing 1, e.g. by means Oe a couple Oe pins 12 attached extHrnally to th:l~
~b~ts housing, and wlth the drawing eyelet 7, whereby the two ~t~, which are no-t _ 7(a~ -A
:: : :
` ;. .
.
.
~3L 2d~ :~3 71 S ~
shown but merely indicated by A and B, are connected to one end of elther one of the spr.ings 2 and 3, name-ly, the right end in Fig. 2, these springs being connected to each other at their other ends ~ia the plug 9.
When the spring system shown in Fig. 2, which is a tension spring system, is subjected.to a load, e.g. by the drawing eyelet 7 being subjected to tension towards the right in Fig. 2, the spring 3, which as stated is iII this case the weaker of the two springs, is deformed first and mostly, and under compression o the spring 3 the tube 4 is moved a corresponding distance out of the housing 1. When the load has reached a certain size, e.g. when the turns of the spring 3 fit tightly against each other or shortly before depending on whether or not thera is an initial tension in the spring 2, the deformation of the stronger spring 2 begins, and the extraction of the tube 4 from the housing 1 continues, the plug 9, which with its flange 10 abuts against and is held by the compressed spring 3, keeping the end of the spring 2, into which it is screwed.
During the first part of the e~traction of the part 7 the spring characteristic for -the spring system as a whole has a course corresponding to the characteris~ic for the spring 3, as will directly be seen, whereas the characteristic of the system during the last part of the extraction movement, where the spring 3 can be wholly compressed, has a course determined by the characteristic of the spring 2 and thereby less steep, if the spring travel is plotted along the axis of ordinates and the spring force along the axis of the abscissa. The resu.lting spring travel for the spring system is equal to the sum of the travels of the two~
separate springs, whereas the length of the housing does not appreciably exceed the length of each of the two springs.
.
:~2~
It can be seen ~rom Fig. 1 that the sprinq system's housing 1 has slits 14 alony two opposite sides.
These slits lie in pairs opposite each other, a connec-ting line between two slits in a pair Eorming an angle corresponding to the pitch of the turns of the spring
, opposed pair of sllbstantially transver3f31y extending sJits, there being provided a movable stop inser-table in said pair of slits between ad~acent coils of said first sprirly to vary the effective length of said first spring.
~ second broad aspect of the present invention relates to a spring system for imparting an elastic force between two objects comprising a housing comprised of a first part adapted for attachment to the first object and a second part adapted for attachment to the second object, at least two coil springs, a first spring having one of its ends attached to said first housing part and a second spring having one of its ends attached to said second housing part, the other springs connected end to end between said first and second springs via coupling pieces, characterized in that the said first housing part is dimensioned to encase said first spring, and i5 provided with at least one opposed pair of substantially transversely extending slits, there being provided a member insertable in said pair of slits and between adjacent coils of said first sprins to vary the effective length of said first spring.
Aa: a result of the mutual position and lnterconnection of the springs, the resulting spring travel for the spring system equals the sum of the travels of at least two springs, and as at least ~one cf these has a variable characteristic~ a very considerable range of variation for the slope of the system's spring characteristic can be obtained depending on the choice of spring. The total obtainable sprlng travel that can~
be made to approach or even exceed the length of the spring system in the initial position also depends on B 2a -,.,,. ., ~,, ' .
~ ' : : . .. ' . : ~
~L~3~S2 the choice of sprin~. Moreover, a constant elastic force is obtained in the initial position, if the distance B between the- ~ actuated by the spring system ls always the same in the initial position.
In principle, in a spring system according to the invention, an arbitrary number of springs can be used, but in many cases it is sufficient to have two springs, which can be two tension springs, two compression springs or one tension and one compression spring, and of which one has a variable characteristic and preferably in the unloaded initial position is weaker than the other spring A spring system according to the invention having, e.g. two springs with identical characteristics, will in the initial position with an unregulated characteris-tic for the variable spring have a resultant systemcharacteristic with a slope corresponding to twice the slope of the characteristic of the individual springs, because a force acting on one of the springs is transferred to the other spring via the connection between the springs, and the springs are deformed to an equal extent. However, if the number of effective turns of the variable spring is diminished, the slope of the characteristic of this spring and thereby also the slope of the characteristic of the system decreases. If, for example, the number of efective turns in the variable spring is reduced to ~ero, the slope of the spring characteristic of the system decreases to half of the starting value. This possibility of variation is obtai-ned at a comparatively small length of the spring system in comparison to the resultant spring travel, because this is equal to the sum of the travels of the individual springs.
:
. .... . .
::
`
' A greater variation in the slope of the characterlstic of the system can however be obtained, if springs with different characteristics are used in the system, that is, for example, two springs, one of which, preferabl~
5 the spring with a variable number of effective turns, is weaker and has a 5teeper characteristic curve than the other spring. The strong spring can, if desired, have a certain initial tension.
When a spring system such as this is acted on by a 10 gradually increasing load, the weak spring will be deformed most, and if the strong spring has an initial tension, to begin with only the weak spring is deformed, and its characteristic will then be practically the sole determining factor of the spring characteristic for the 15 spring system as a whole. In that case the system characteristic will have a breaking-point at the load e a ~ ~ e s p O ~ q A -~H~e~p}}at~ to the initial tension, at which load the strong spring begins to be deformed and thereby contri-bute to the total spring travel,~which of course is 20 again equal to the sum of the travels of the individual springs, in this case the two individual springs.
Again a variable system characteristic with a comparatively large spring travel in relation to the length of the spring system has been obtained, and by 25 the use of a strong spring with a preload the breaking-point in the characteristic produced by this can be moved by alteration of the number of effective turns in the weak spring.
In both cases the load corresponding to a given 30 total spring travel or total deformation of the indivi-dual springs depends on the proportion in which the deformation is divided between the springs, and this proportion can be adjusted by variation of the number of effective turns of the - at least in the initial 35 position - weaker spring. If this number is large, a given total travel corresponds to a comparatively small load, and if the number of effective turns in the weak ~, `:
, :
.. . . .
~'7~52 spring is low or perhaps zero, the given total travel corresponds to a greater load, because the strong spring then performs a greater part of or even the whole of the total travel of the system.
This applies if, for example, the spring system is constituted by two tension springs or two compression springs and - particularly as regards the tension springs - is loaded only within the range in which Hooke's law applies. This can be ensured, for instance, by restricting the travel of a tension spring by means of a stop.
In a suitable embodiment of the invention the spring system is constituted by tension springs and compression springs, e.g. two springs, the weak spring being a compression spring and the strong spring being a tension spring.
In the case of a gradually increasing load of the spring system in this embodiment it is also first and foremost the weak spring, i.e. the compression spring, that is deformed, and the system characteristic corre-sponds in essentials to the characteristic of this spring with an initial slope corresponding to its slope, particularly if the stronger tension spring has an initial tension. After a certain deformation of the compression spring, deformation of the stronger tension spring begins to appear, and the two springs jointly determine the system characteristic, which also in this case may have a breaking-point and has now a steeper course. When the load is further increased the compres-sion spring may at some point become completely compres-sed, and no longer contribute to the deformation or travel of the spring system. The system characteristic gets a new breaking-point and is then less steep, the slope being determined by the strong spring and thus being less than the initial slope. The systemcharacteris-tic and thereby the load corresponding to a given travel may also here be adjusted by variation of the number of effective turns of the weak spring. If this number IS lo~, the .
.
:~ .
' : ~
, 7~5;~
strong spring will comparatively quickly come to deter-mine the course of the system characteristic, and a given travel will correspond to a comparatively grea~
A load on the spring system.
In all~ cases a variation of the characteristic of the spring system is permitted in connection with the spring system as a whole having a comparatively short length in relation to the spring travel, because the travels of the separate springs comprised in the system and situated vis a vis each other, e.g. concentric springs, are added together. The range of variation can be made greatest when the spring system is constituted by a combination of tension and compression springs/
because the latter can be subjected to a more conside-rable load than tension springs and in the present - context do not lose their effect because they are completely compressed. This means, for instance, that a compression spring with a variable number of effective turns can be combined with a considerably stronger tension spring having a very flat spring characteristic.
The resultant system characteristic will then take a very progressive course. Yet, it should be mentioned that in this context a compression spring may be equated to a tension spring having a deformation-restricting stop, e.g. a drawing cable in the spring connecting the first and last turn of the spring and having a length corresponding to the maximal spring length.
A spring system according to the invention can be realized with very simple means, and can suitably be constructed with ordinary coil springs.
By the terms "weaker" and "stronger" spring is here meant the spring~ whose characteristic at a given free spring length, i.e. length in unloaded condition, has respectively the greatest and the least slope.
The invention is explained below on the basis of a few examples of embodiments with reference to the drawing, where ~ ;
:
`~ :
, - : '' ':' ' . . ~
;, Fig. 1 shows ~ practical enlbotlimellt of a spring system in a housillg, Fig. 2 is a sectional view along the line II-II in ~ig. 1, ~ ig. 3 depicts an adjusting clamp for the spring system sllown in Figs. 1 and 2, Fig. 4 depicts various reali~ations of a spring system according to the inventioll with different combinatiolls of con~pression and tension sprinKs, and Fig. 5 depicts an example of use of a system according to the invention.
Pig. 2 shows two concentric coil springs in the form of a tension spring 2 and a compression spring 3 in a joint housing 1.
Of these two springs the tension spring 2 has by way of example the greatest elastic force, and it may have an initial tension.
The spring 2 is accommodated in a tuoe 4, at the bottom of which it is attached by one of its ends, e.g. by mealls of a plug 5 screwed into the spring, through which plug ex-tellds a bolt 6, wh.ich also extends through the bottom of the tube and outside this bears, for instance, a drawing eyelet 7 ~hat is screwed on. Inside the bolt 6 is fixed to the plug 5 by means of a couple o~ nuts 3 .
At the opposite end of the spring 2 a plug ~ is also screwed in, and this plug has a radial flallge 10, via whic!l tha spring 2 is connected at the said end with one end of the spring 3, which extends in the ring-s!laped space between the tube 4 and the housing 1 and at its opposite end abuts against a ring 11 serving as a stop, the said ring being attached to the inner wall of the housing.
~3~ 2 B c~b jcct:~
The~ two p~rt~ which rll'~ to bc conn~cte(l wi-th each othHr via the spring system are connected, respectlvely, with the housing 1, e.g. by means Oe a couple Oe pins 12 attached extHrnally to th:l~
~b~ts housing, and wlth the drawing eyelet 7, whereby the two ~t~, which are no-t _ 7(a~ -A
:: : :
` ;. .
.
.
~3L 2d~ :~3 71 S ~
shown but merely indicated by A and B, are connected to one end of elther one of the spr.ings 2 and 3, name-ly, the right end in Fig. 2, these springs being connected to each other at their other ends ~ia the plug 9.
When the spring system shown in Fig. 2, which is a tension spring system, is subjected.to a load, e.g. by the drawing eyelet 7 being subjected to tension towards the right in Fig. 2, the spring 3, which as stated is iII this case the weaker of the two springs, is deformed first and mostly, and under compression o the spring 3 the tube 4 is moved a corresponding distance out of the housing 1. When the load has reached a certain size, e.g. when the turns of the spring 3 fit tightly against each other or shortly before depending on whether or not thera is an initial tension in the spring 2, the deformation of the stronger spring 2 begins, and the extraction of the tube 4 from the housing 1 continues, the plug 9, which with its flange 10 abuts against and is held by the compressed spring 3, keeping the end of the spring 2, into which it is screwed.
During the first part of the e~traction of the part 7 the spring characteristic for -the spring system as a whole has a course corresponding to the characteris~ic for the spring 3, as will directly be seen, whereas the characteristic of the system during the last part of the extraction movement, where the spring 3 can be wholly compressed, has a course determined by the characteristic of the spring 2 and thereby less steep, if the spring travel is plotted along the axis of ordinates and the spring force along the axis of the abscissa. The resu.lting spring travel for the spring system is equal to the sum of the travels of the two~
separate springs, whereas the length of the housing does not appreciably exceed the length of each of the two springs.
.
:~2~
It can be seen ~rom Fig. 1 that the sprinq system's housing 1 has slits 14 alony two opposite sides.
These slits lie in pairs opposite each other, a connec-ting line between two slits in a pair Eorming an angle corresponding to the pitch of the turns of the spring
3 with the longitudinal axis of the housing 1. In each such pair of slits a U-shaped clamp or fork, fvr example, can be inserted, as shown in Fig. 3, where it is designated as 13. The internal distance between the legs of the clamp is slightly greater than the diameter of the tube ~j such that the clamp 13 can be inser-ted over this tube.
With this clamp 13 one can vary the spring characteristic for the spring 3 and thereby for the spring system as a whole, as one can thereby vary the effective length of the spring 3. The insertion of the clamp 13 corresponds to moving the stop at 11 towards the left. The closer to the linking point 9, 10 between the two springs 2 and 3, i.eO the further to the left in Figs. 1 and 2 the clamp 13 is placed, the shorter becomes the effective length of the spring 3, and the earlier t:he spring 2 comes to determine the characteristic of the system. Thus, the slope of this characteristic can be reduced by insertion of the clamp 13 further to the left in Figs. 1 and 2 and the slope can be increased by the clamp being moved to the -r`ight, until the maximum steepness is obtained when the clamp 13 is removed completely.
As stated, the spring system in Fig. 2 is made up of a tension spring 2 and a compression spring 3. If the flange 10 on the plug 9 is removed, the left end of the spring 3 in Fig. 2 is attached to the end wall of the housing 1, and the left end turn of the spring 2 is firmly connected to the right end of the spring 3, and the stop ring 11 is removed, the spring 3 can also be a tension spring, and the effective part of the spring will lie to the right of the clamp 13, but , . ..
'. , .
,~ r,~ J3 the shown co~ination of a tension and a compression spring is simpler both ~rom the point of view of construction and installation. An example of a system with tension springs alone is indicated schema-tically 5 in Fig. 4b.
In the embodiment shown in Figs. 1 and 2 a displacement of the clamp 13 gives rise to a displace-ment of the effective point of co~nection between the B spring 3 and the spring-actuated ~ A, and if the 10 spring 13 could similarly co-operate with slits in the internal tube 4 and could thus fix a variable part of the turns of the spring 3 in relation to this tube 4, a displacement of the clamp 13 wo~ld give rise to a displacement of the effective point of connection 15 between the spring 3 and the spring 2. An embodiment corresponding to the latter alternative is not shown, but in relation to Fig. 2, beyond slits in the tube 4, only a reduction of the diameter of the flange 10 will have to be effected, so ~hat the flange 10 co-operates 20 with the end of the tube 4, and the spring 2 must be able to be drawn out of the tube 4 at the right end o~
the latter in Fig. 2.
~ spring system according to the invention will, for example, in many cases be able to be used as a 25 prime mover for the raising alld lowering mechanism in a piece of furniture of the kind having a seat that can swing up and down, in particular for handicapped pPr-sons. An example o~ such mechanism, which-is described in the Danish patent specification No. 146 223, is shown 30 schematically at a-c in Fig. 5. Other raising and lowering mechanisms ~or the stated purpose arej for example, described in the U.S. patent publications Nos. 3.479.086 and 4.185.335.
In the example of a seat lift shown in Fig. 5, in 35 which a spring system according to the invention can be used as prime mover, the seat itself is designated as E.
.
.' ~
3~Lrj~
From the one end position shown by a in Fiy. 5, where the seat E is horizontal, the seat is moved via the position shown by b to the other end position shown by c, where the seat inclines downwards so that the user S can more easily leave it. The movement is obtained by means of a prime mover I, e.g. an electric mot~r with a worm drive, which when raising the seat E exerts tension on a spindle L, which via a hin~e point H is co ~ c-ted.to an arm G, which thereby turns a bearing arm A
around the point 1. The bearing arm A is both connected to the rear edge o~ the seat E and in a point D,D1, D2 connected to another bearing arm B, which at one end is connected to the front edge of the seat E and at its opposite end at K is connected to the housing of the prime mover I. Under the influence of the prime mover I the points K and H are thus made to approach each other when raising the seat E, whereas they move away from one another when lowering the seat.
. IE instead of, e.g. an electric motor as the prime mover I a spring system is used according to the invention, e.g. in the form shown in Fig. 2, this spring system in the initial position of the seat E as shown by a in Fig. 5~ in which the power requirement is large, will exercise a very great tension between the points K and H, when the user releases a lock which arrests the seat in the lowered horizontal position, and a somewhat weaker tension when the seat approaches the other end position shown by c. The tension exerted by the spring system between the points K
and H can be adjusted and adapted according to the weight of various users by means of the U-shaped clamp.
With the spring system as prime mover the chair is not dependent on the existence of a source of energy, e.g. a battery or an electric socket.
However, there are also other uses for a spring system according to the invention, and the use in a seat l1ft described above is only an example. Thus, in many : : ' 12 ~LX3~L5~
cases it will also be possible to use a spring system according to the invention instead of a variable counterweight, e.g. in connection with cranes.
Also in apparatus or constructions in which a constant elastic force is desired between two parts at a variable movement or mutual distance a spring system elaborated according to the present invention will be able to be used.
Fig. 4 shows schematically three examples o~ spring systems according to the invention. All three examples involve a system with three parallel springs, placed vis a vis each other, and in each of these systems either the middle spring or the two exterior springs may have a variable spring characteristic. Moreover, it holds good for each of the three systems that the two exterior springs can be replaced by a single spring, which then preferably surrounds and is concentric with the middle spring.
At a in Fig. 4 is shown a system with two exterior compression springs and a tension spring~between them.
This system is both from the point of view of construc-tion and function analogous to the embodiment shown in Fig. 2.
At b in Fig. 4 is shown a system with three ten-sion springs analogous to the one suggested in connec-tion with the explanation of Fig. 2.
While a and b in Fig. 4 show tension spring systems, c in Fig. 4 shows a compression spring system involving three-compression springs.
With this clamp 13 one can vary the spring characteristic for the spring 3 and thereby for the spring system as a whole, as one can thereby vary the effective length of the spring 3. The insertion of the clamp 13 corresponds to moving the stop at 11 towards the left. The closer to the linking point 9, 10 between the two springs 2 and 3, i.eO the further to the left in Figs. 1 and 2 the clamp 13 is placed, the shorter becomes the effective length of the spring 3, and the earlier t:he spring 2 comes to determine the characteristic of the system. Thus, the slope of this characteristic can be reduced by insertion of the clamp 13 further to the left in Figs. 1 and 2 and the slope can be increased by the clamp being moved to the -r`ight, until the maximum steepness is obtained when the clamp 13 is removed completely.
As stated, the spring system in Fig. 2 is made up of a tension spring 2 and a compression spring 3. If the flange 10 on the plug 9 is removed, the left end of the spring 3 in Fig. 2 is attached to the end wall of the housing 1, and the left end turn of the spring 2 is firmly connected to the right end of the spring 3, and the stop ring 11 is removed, the spring 3 can also be a tension spring, and the effective part of the spring will lie to the right of the clamp 13, but , . ..
'. , .
,~ r,~ J3 the shown co~ination of a tension and a compression spring is simpler both ~rom the point of view of construction and installation. An example of a system with tension springs alone is indicated schema-tically 5 in Fig. 4b.
In the embodiment shown in Figs. 1 and 2 a displacement of the clamp 13 gives rise to a displace-ment of the effective point of co~nection between the B spring 3 and the spring-actuated ~ A, and if the 10 spring 13 could similarly co-operate with slits in the internal tube 4 and could thus fix a variable part of the turns of the spring 3 in relation to this tube 4, a displacement of the clamp 13 wo~ld give rise to a displacement of the effective point of connection 15 between the spring 3 and the spring 2. An embodiment corresponding to the latter alternative is not shown, but in relation to Fig. 2, beyond slits in the tube 4, only a reduction of the diameter of the flange 10 will have to be effected, so ~hat the flange 10 co-operates 20 with the end of the tube 4, and the spring 2 must be able to be drawn out of the tube 4 at the right end o~
the latter in Fig. 2.
~ spring system according to the invention will, for example, in many cases be able to be used as a 25 prime mover for the raising alld lowering mechanism in a piece of furniture of the kind having a seat that can swing up and down, in particular for handicapped pPr-sons. An example o~ such mechanism, which-is described in the Danish patent specification No. 146 223, is shown 30 schematically at a-c in Fig. 5. Other raising and lowering mechanisms ~or the stated purpose arej for example, described in the U.S. patent publications Nos. 3.479.086 and 4.185.335.
In the example of a seat lift shown in Fig. 5, in 35 which a spring system according to the invention can be used as prime mover, the seat itself is designated as E.
.
.' ~
3~Lrj~
From the one end position shown by a in Fiy. 5, where the seat E is horizontal, the seat is moved via the position shown by b to the other end position shown by c, where the seat inclines downwards so that the user S can more easily leave it. The movement is obtained by means of a prime mover I, e.g. an electric mot~r with a worm drive, which when raising the seat E exerts tension on a spindle L, which via a hin~e point H is co ~ c-ted.to an arm G, which thereby turns a bearing arm A
around the point 1. The bearing arm A is both connected to the rear edge o~ the seat E and in a point D,D1, D2 connected to another bearing arm B, which at one end is connected to the front edge of the seat E and at its opposite end at K is connected to the housing of the prime mover I. Under the influence of the prime mover I the points K and H are thus made to approach each other when raising the seat E, whereas they move away from one another when lowering the seat.
. IE instead of, e.g. an electric motor as the prime mover I a spring system is used according to the invention, e.g. in the form shown in Fig. 2, this spring system in the initial position of the seat E as shown by a in Fig. 5~ in which the power requirement is large, will exercise a very great tension between the points K and H, when the user releases a lock which arrests the seat in the lowered horizontal position, and a somewhat weaker tension when the seat approaches the other end position shown by c. The tension exerted by the spring system between the points K
and H can be adjusted and adapted according to the weight of various users by means of the U-shaped clamp.
With the spring system as prime mover the chair is not dependent on the existence of a source of energy, e.g. a battery or an electric socket.
However, there are also other uses for a spring system according to the invention, and the use in a seat l1ft described above is only an example. Thus, in many : : ' 12 ~LX3~L5~
cases it will also be possible to use a spring system according to the invention instead of a variable counterweight, e.g. in connection with cranes.
Also in apparatus or constructions in which a constant elastic force is desired between two parts at a variable movement or mutual distance a spring system elaborated according to the present invention will be able to be used.
Fig. 4 shows schematically three examples o~ spring systems according to the invention. All three examples involve a system with three parallel springs, placed vis a vis each other, and in each of these systems either the middle spring or the two exterior springs may have a variable spring characteristic. Moreover, it holds good for each of the three systems that the two exterior springs can be replaced by a single spring, which then preferably surrounds and is concentric with the middle spring.
At a in Fig. 4 is shown a system with two exterior compression springs and a tension spring~between them.
This system is both from the point of view of construc-tion and function analogous to the embodiment shown in Fig. 2.
At b in Fig. 4 is shown a system with three ten-sion springs analogous to the one suggested in connec-tion with the explanation of Fig. 2.
While a and b in Fig. 4 show tension spring systems, c in Fig. 4 shows a compression spring system involving three-compression springs.
Claims (14)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:-
1. A spring system for imparting an elastic force between two objects comprising: a housing comprised of a first part adapted for attachment to the first object and a. second part adapted for attachment to the second object, first and second coil springs, said first spring having one of its ends attached to said first housing part and the other of its ends attached to one end of said second spring via a coupling piece, the other end of said second spring being attached to said second housing part, characterized in that the said first housing part is dimensioned to encase said first spring, and is provided with at least one opposed pair of substantially transversely extending slits, there being provided a movable stop insertable in said pair of slits between adjacent coils of said first spring to vary the effective length of said first spring.
2. A spring system as claimed in claim 1 wherein said first and second springs are substantially parallel.
3. A spring system as claimed in claim 1 wherein said movable stop acts to vary the effective point of connection between said first spring and said first housing part.
4. A spring system as claimed in claim 1 wherein said movable stop acts to vary the effective point of connection between said first spring and said second spring.
5. A spring system as claimed in claim 1 characterzed in that in the initial position the ends of said first and second springs which are attached to said first and second housing parts respectively, have a constant distance from each other in the spring direction.
6. Spring system according to claim 1, characterized in that it is constituted by two compression springs, two tension springs or one compression spring and one tension spring.
7. Spring system according to claim 3, characterized in that the first spring is, at least in the initial state, weaker than the second spring.
8. Spring system according to claim 4, characterized in that the first spring is a compression spring, and it surrounds the second spring which is a tension spring that, at least in its initial position, is stronger than the compression spring.
9. A spring system as claimed in claim 1 in which the slits in the first housing part are oblique.
10. A spring system as claimed in claim 1 in which the movable stop comprises a fork-shaped member.
11. A spring system as claimed in claim 9 in which the internal distance between the legs of said fork-shaped member is slightly greater than the diameter of said first housing part.
12. A spring system as claimed in claims 1, 9 or 11 wherein a regularly spaced series of said pairs of slits are provided in said first housing part.
13. A spring system as claimed in claim 1 in which said second spring has an initial tension.
14. A spring system for imparting an elastic force between two objects comprising a housing comprised of a first part adapted for attachment to the first object and a second part adapted for attachment to the second object, at least two coil springs, a first spring having one of its ends attached to said first housing part and a second spring having one of its ends attached to said second housing part, the other springs connected end to end between said first and second springs via coupling pieces, characterized in that the said first housing part is dimensioned to encase said first spring, and is provided with at least one opposed pair of substantially transversely extending slits, there being provided a member insertable in said pair of slits and between adjacent coils of said first spring to vary the effective length of said first spring.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000467273A CA1237152A (en) | 1984-11-07 | 1984-11-07 | Spring system having a variable spring characteristic |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000467273A CA1237152A (en) | 1984-11-07 | 1984-11-07 | Spring system having a variable spring characteristic |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1237152A true CA1237152A (en) | 1988-05-24 |
Family
ID=4129103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000467273A Expired CA1237152A (en) | 1984-11-07 | 1984-11-07 | Spring system having a variable spring characteristic |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1237152A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112483353A (en) * | 2020-11-25 | 2021-03-12 | 长虹华意压缩机股份有限公司 | Compressor supporting structure |
-
1984
- 1984-11-07 CA CA000467273A patent/CA1237152A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112483353A (en) * | 2020-11-25 | 2021-03-12 | 长虹华意压缩机股份有限公司 | Compressor supporting structure |
| CN112483353B (en) * | 2020-11-25 | 2022-06-24 | 长虹华意压缩机股份有限公司 | Compressor supporting structure |
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