LOAD-RELIEVING ARRANGEMENT

Abstract: A load-relieving arrangement for use in connection with seated or standing work comprises a support element (5) intended to act upon the forearm area of the user, which support element is capable on the one hand of movement in essentially horizontal directions, and on the other hand of movement downwards against the effect of a spring (15-17) which fully or partly relieves the weight of the user's arm. The spring consists of a pneumatic spring, the maximum stroke volume of which is so insignificant in relation to the space (17) containing the gas providing the spring action that the pneumatic spring exerts essentially the same spring force irrespective of the vertical position of the support element (5).

Description: Load—re I i e ing arrangement The present invention relates to a load-relieving arrangement for use in connection with seated or standing work of a kind which comprises a support element intended to act upon the forearm ares of the user, which support element is capable on the one hand of movement in essentially horizontal directions, and on the other hand of movement downwards against the effect of a spring which fully or partly relieves the weight of the user's arm. Arrangements of the aforementioned kind are used to reduce the stress on the musculature, especially in the neck and the shoulders, due, inter alia, to the weight of the arms, in conjunction with work involving long periods without movement or work which requires only small movements of the body, for example certain types of assembly work or work at a cash register or a computer terminal. A previously disclosed arrangement of the aforementioned kind consists of a sling suspended by means of a line in a so-called balance block, in which sling at least a part of the forearm, possibly including an adjacent part of the wrist or elbow, is supported to a degree which can be determined by adjustment of the balance block. This previously disclosed arrangement requires the availability of considerable height and is rather noticeable, for which reason its use is found to be embarrassing by certain individuals, as a result of which there is a risk of it being used only once damage due to wear and tear, which it is actually intended to prevent, has already occurred. The previously disclosed arrangements make use of mechanical springs, which means that the load—relieving forces exerted by them will vary depending on the level at which the supported parts of the user's arm are present at any given time. One object of the present invention is to propose a novel and improved load—rel ev ng arrangement of the kind described by way of introduction, which takes up little space and can be executed very discreetly, so that it can be readily accepted by everybody, and which provides a supporting effect which is essentially unaffected by the arm movements of the user. For the aforementioned purpose the arrangement in accordance with the invention is characterized essentially in that the spring is a pneumatic spring of a kind already familiar from the prior art, in that the pneumatic spring has a piston, the maximum stroke volume of which is negligible in relation to the space containing the gas providing the spring action, which means that the pneumatic spring will exert essentially the same spring force irrespective of the vertical position of the support element, and in that the pressure of the gas providing the spring action is adjustable by means of an adjustment device capable of operation by the user. Further characterizing features and advantages of the invention are indicated in the subsidiary Claims and can be appreciated from the following description of an embodiment of the invention shown in the accompanying drawing, but selected only as an illustrative example. Fig. 1 is a partial front view of a chair fitted with a load— —relieving arrangement in accordance with the invention. Fig. 2 is a side view on an enlarged scale of the load—relieving arrangement in accordance with Fig. 1. Fig. 3 is a view from the rear of the load-relieving arrangement in accordance with Fig. 1. Fig. 4 is an axial sectional view on an enlarged scale through a lower part of the load—rel eving arrangement in accordance with Figs. 1—3. Fig. 5 is an axial sectional view on an enlarged scale through an upper part of the load—relieving arrangement in accordance with Figs. 1—3. Fig. 1 shows a chair with a seat 1, illustrated here in part only, a leg structure 2 and a backrest 3. Arranged on one side of the seat is a load—relieving arrangement indicated generally by the designation 4, comprising a support element 5 carried by an upright assembly consisting of the parts 6 and 7. The upright assembly 6, 7 is connected at a considerable distance beneath the support element 5 via a universally articulated device 8 to a bracket 9 mounted on the chair at the side of the seat. The bracket 9 can thus be executed in such a way that the universally articulated device 8 is capable of being attached to it in different positions, viewed in the sense of the depth of the seat 1 of the chair. The universally articulated device 8 permits pivoting of the upright assembly 6, 7 both about a horizontal axis 10, that is to say forwards and backwards in Fig. 1, and about axes running essentially perpendicularly to it, that is to say to one side and the other, as shown by the arrows 11 in Fig. 1. The universally articulated device 8 is preferably spring—loaded towards a neutral position indicated in Fig. 1. An upright assembly 6, 7 with its associated support element 5 is shown in more detail in Figs. 2—5. The parts 6 and 7 of the upright assembly are supported in such a way as to be capable of longitudinal displacement or of telescoping relative to one another, in conjunction with which one part 6 exhibits a fastening lug 12 via which it is secured in a detachable fashion to the universally articulated device 8 by means of a screw 13. This screw 13 passes through an essentially vertical slot 14 arrranged in the fastening lug 12, which slot permits the part 6 to be secured to the universally articulated device 8 at different positions of height and inclination relative to the chair seat 1. The upright component 7 and with it the support element 5 are capable of being displaced downwards against the effect of a pneumatic spring consisting of a piston 15, which is mounted in a guide 16 in such a way as to be capable of pivoting and of axial displacement, so as to permit movement into a space 17 filled with the gas providing the spring action, for example air, under positive pressure. The maximum stroke volume of the piston 15 is selected for this purpose so as to be so insignificant in relation to the space 17 containing the gas providing the spring action that the pneumatic spring exerts essentially the same spring force irrespective of the vertical position of the support element 5. In the example shown the pneumatic spring piston 15 consists of a cylindrical, essentially vertical rod, the lower end of which is rigidly connected via a socket 18 to the lower end of the upright component 6 executed as a straight tube. The piston 15 projects upwards through the upright component 6 and is mounted in a gas—tight fashion in the guide 16, which is rigidly attached inside a lower, straight part of the similarly tubular upright component 7. On pushing down the support element 5, and with it the upright component 7, the guide 16 and the lower part of the upright component 7 surrounding it thus slide downwards on the piston 15 and into the upright component 6. The piston 15 is fitted at a point close to the socket 18 with a radially projecting pin 19, in conjunction with which the downward movement of the support element 5 is restricted through the engagement between that pin 19 and the lower end of the guide 16. Also executed in the lower end of the guide 16 is an angled groove 20, in which the pin 19 can be accommodated by pushing down and turning the guide 16, so that it retains the guide 16, and with it the upright component 7 and the support element 5, in a detachable fashion in a lower ineffective position. There extends diametrically through the upper end of the piston 15 a further pin 21, and a 'U'—shaped recess 22 is executed in the upper end of the guide. Through its engagement with the upper end of the guide 16, the pin 21 restricts the extent to which the upright components 6, 7 can be moved apart by the effect of the pneumatic spring 15-17, and in so doing determines the uppermost position of the support element 5. In this position the pin 21 has been displaced to the bottom of the recesss through interaction with the walls of the 'U 1 —shaped recess 22. By initially selecting the rotated position of the piston 15 in relation to the upright component 6, and the rotated position of the guide 16 in relation to the upright component 7, it is accordingly possible to ensure that the support element 5, when in its initial upper position in which it is not under any load, is always facing in the desired sense, usually parallel with the side edge of the seat 1. In order to permit working at a certain distance in front of the edge of a table, the upright component 7 exhibits, as may be appreciated from Fig. 2, an essentially 'C 1 —shaped rearward—curved part 23 in the area immediately beneath the support element 5. The support element 5 in the embodiment illustrated here is essentially of 'U'—shaped cross—section and is pivotal ly mounted about a shaft 24 passing across same. The support element 5 benefits from its small thickness measured in the vertical sense. It is situated on the side of the 'C—shaped part 23 of the upright component 7 facing towards the user, and its underside is situated level with or below the top part of the part 23. The element 5 exhibits at its rear end an upward—inclined base 25 (Fig. 2), such that, by engaging with the user's elbow, unintentional sliding of the forearm towards the rear is prevented. In order to achieve the necessary large volume of the space 17 for the gas providing the spring action, without this having a detrimental influence on the appearance of the arrangement, use is made in the illustrative example shown here of the inside of the tubular upright component 7 as the space for the gas providing the spring effect, which is sealed for this purpose at its opposite ends. For the purpose of setting any desired spring pressure, an adjuster device is provided in the form of a pump built into the upper end of the 'C—shaped part 23 and a valve 26, 27 (Fig. 5). The valve comprises a screw 26 capable of being operated by the user, which screw is installed in a valve pipe 27 running between the space 17 and the surrounding atmosphere, with a valve orifice capable of being opened and closed by means of the screw 26. The pump comprises a pump piston 28 with a handle 29 capable of operation by the user. The pump piston 28 is mounted in such a way as to be capable of axial displacement inside a pump cylinder 20, which communicates with the space 17 via a non—return valve 31. The scope of the invention nevertheless permits the alternative arrangement of a pressurized gas cartridge, for example, in place of the pump 28—31. The invention is thus not restricted to the embodiment described above and illustrated in the drawing, but can be realized in any manner within the scope of the idea of invention described in the Claims. For example, the universally articulated device heed not necessarily spring back into position, but may exhibit a small amount of inherent friction, so that the upright component 6 will, in the absence of lateral forces acting on same, maintain its direction relative to the chair 1—3, whilst the support element 5 and the upright component 7 will change their position relative to the upright component 6. The load—relieving arrangement can also be applied to a work table or a work bench.

Claims: Patent Claims 1. Load-relieving arrangement for use in connection with seated or standing work of a kind which comprises a support element (5) intended to act upon the forearm area of the user, which support element is capable on the one hand of movement in essentially horizontal directions, and on the other hand of movement downwards against the effect of a spring (15—17) which fully or partly relieves the weight of the user's arm, c h a r a c t e r— i z e d in that the spring (15—17) is a pneumatic spring of a kind already familiar from the prior art, in that the gas spring has a piston (15), the maximum stroke volume of which is negligible in relation to the space (17) containing the gas providing the spring action, which means that the pneumatic spring exerts essentially the same spring force irrespective of the vertical position of the support element (5), and in that the pressure of the gas providing the spring action is adjustable by means of an adjustment device (26—31) capable of operation by the user. 2. Load—relieving arrangement according to Claim 1, c h a r a c t e r¬ i z e d in that the gas providing the spring action is air, and in that the aforementioned adjustment device consists of a pump (28—31) for the purpose of pumping air from the surrounding atmosphere into the space (17) containing the gas providing the spring action, and a valve (26, 27) for the purpose of discharging air from the aforementioned space to the surrounding atmosphere. 3. Load—relieving arrangement according to Claims 1 or 2, c h a i— a c t e r i z e d in that the support element (5) is attached to the upper end of an upright unit (6, 7), which, for a considerable distance beneath the support element, is capable of being connected, preferably in any desired vertical position, to a bracket (9) intended for the attachment of the load—relieving arrangement to a support for same consisting preferably of a work chair (1—3) via a universally articulated device (8 ) permitting the aforementioned movement in essentially horizontal positions and preferably capable of springing back to a neutral position. 4. Load—relieving arrangement according to Claim 3, c ha r a c te r¬ i z e d in that the upright unit comprises two upright components (6, 7) supported in such a way as to be capable of longitudinal displacement relative to one another, and appropriately capable of telescoping into one another, of which one carries the universally articulated device (8) and the other carries the support element (5), in conjunction with which the pneumatic spring (15—17) acts between the upright components, and in conjunction with which the upright components are preferably capable of being locked together (19, 20) in a telescoped position. 5. Load—relieving arrangement according to Claim 4, c h a ra c te r¬ i z e d in that one of the upright components ( 6) comprises a pneumatic spring piston (15) lying essentially vertically in the aforementioned neutral position and rigidly attached to same, whereas the other upright component (7) exhibits a sealing guide (16) for the piston (15) and a reservoir (17) for the gas providing the spring action which is in contact with the active end of the piston (15). 6. Load—relieving arrangement according to Claim 5, c ha ra c t e r¬ i z e d in that the pneumatic spring piston (15) constitutes a part of the upright component (6) supporting the universally articulated device (8), whereas the aforementioned guide (16) is executed in a lower part of the other upright component (7), in conjunction with which the other upright component (7) consists of a tubular element, the inside of which has a considerable volume and forms the space (17) containing the gas providing the spring action. 7. Load—relieving arrangement according to any of the Claims 4—6, c h a r a c t e r i z e d in that the upright component (7) carrying the support element (5) exhibits an essentially *C—shaped, rearward-curved part (23) in the area immediately beneath the support element, which is preferably pivotally mounted about a horizontal shaft (24) passing across same. 8. Load—relieving arrangement according to Claim 7, c h a r a c t e r¬ i z e d in that the support element (5) exhibits only a small thickness measured in the vertical sense, and is situated on the side of the 'C—shaped part (23) of the upright component facing towards the user, in conjunction with which the support element (5), which is preferably of 'U'—shaped cross—section, has its underside situated level with or below the top of the 'C—shaped part (23) of the upright component. 9. Load—relieving arrangement according to any of the Claims 1—8, c h a r a c t e r i z e d in that the support element (5) is pivotally mounted about an essentially vertical shaft ( 15), in conjunction with which an arrangement (21, 22) is provided for the purpose of returning the support element to a predetermined neutral position when the support element (5) is not under load.

Inventors: SAGERMAN BJOERN, SAGERMAN, BJOERN
Applicants: LUNDGREN LARS, SAGERMAN BJOERN, LUNDGREN, LARS, SAGERMAN, BJOERN
Application year: 1989
Main classification: A47C7
IPC codes: A47C1, A47C9, A47C15