DE2448650A1 - Support arm with tension spring balancing mechanism - has common fixed axis for two independent levers - Google Patents

Abstract

A double lever support arm such as used for desk lamps, has a third lever attached to its free end. Tension elements acting over pulleys transmit the turning moment of the outer lever to the pivot point of the middle lever. A similar arrangement connects the turning moment of this axis to an anchor point on the fixed axis of the inner lever. The short arm of the inner arm is maintained in a horizontal position, regardless of the angular position of the other two levers.

Description

Double lever spring weight compensation with outside the action triangle misplaced springs In X-ray technology and in other equipment construction are simple Known spring balancings, as already mentioned, for example, in the German patent specification No. 936,966. There it is also explained in particular which means one must provide for the spring outside the triangle, formed from: load application point, kinematic reducer suspension point and lever pivot point. (This is regarding ir sizing of neither is often crucial). To a later one The point in time was published in Issue 1, 1960, of the magazine E and X, Springer-Verlag, Vienna, on the occasion of the explanation of a logarithmic peder compensation for the sake of completeness the lever spring balancing is briefly mentioned again, and there are also certain letter designations were introduced, especially for the distance between the fulcrum and the fixed position Cederkraftungspunkt the letter "e", which is here in dervig. 2 as eI and eII found, as well as for the point of application of neither the moving load lever system the distance a from the fulcrum, which is shown here as al and aTT also in Fig. 2 shows.

The publications mentioned only deal with the hall, that the total excursion of the load is made possible by a single lever and therefore it is only circular. on the other hand are numerous practical Versions known to enlarge the excursion or sweep a two spring-balanced lever systems lined up in a row have, which work independently of one another with regard to the compensation and at which peder compensations are used, whose compensating springs are not outside of the functional triangle load application point, lever pivot point and spring suspension point " are housed (e.g. for writing.

table-3-door lights and the like). Do you want this system for heavier Loads and longer lever arms, for example for X-ray machines that are up to 20 or 30 kg tube load have to carry, then one arrives at structures that are mechanically constructed because of the dimensioning of the springs and their space requirements for a practical implementation ~ are hardly suitable.

For the purposes of the invention, it is therefore proposed that the two per se to combine known design options to form a double lever compensation system, which has the advantage of a large excursion area (see office desk lamp) with the housing advantages of bringing out the otherwise difficult to accommodate Compensating springs combined according to the first-mentioned, long-known system (#Ps 936.966).

The double lever spring weight balance which solves this problem and forms the subject of the invention is characterized in that the redergewichtsausgleichsystem for two against each other lined up, but acting independently of one another, load levers via a single geometrical one Axis are guided, preferably via the fixed geometric axis of the overall system.

Fig. 1 shows in principle the purely kinematic excursion possibilities a double lever system with freely rotatable lever I as the basic lever, one on it subsequent lever II, which in principle also assume any position independently of I. can, and a horizontal spacing stalk h the the Load is hanging (e.g. an X-ray tube unit with complete accessories).

Fig. 2 shows schematically an embodiment of the invention. That Lever system I corresponds without further ado to the principles of German Ps no. 936.966. According to the invention a similar system II is now coupled at the end of system I, with the load torque on the top axle by means of a traction mechanism transmission zil into the lever bearing axle of the system 1 is transmitted. The geometric support axis of the system 1 is stationary and the load torque transmitted via zII is based on the same principle, like the load moment of lever I, namely balanced according to the principle of Dtfs 936.966. It should be noted that the at the extreme end of the entire lever system is vertical acting load remains the same also in the node between I and II, while the The load torque generated there is fed to the stationary axis of system I.

A mutual influence of the two systems I and II can therefore do not enter.

Since an X-ray machine (X-ray stand) also has the task of a position-invariable reference direction at the end of the movable mounting system to secure, there is still a lever h in the two figures (in this case for "horizontal") drawn.

It is known that this transmission is very easy with a load lever to realize parallel guide levers, but depending on the balance of power the distance between these two levers can be considerable and obstruct the construction can lead. Here n-an is suggested, also this reference direction by one each Train means transfer hl, h2 from the end point of the lever system over the inot point to drive away to the stationary axis of the system I and there mechanically to be determined.

The implementation of such a system shows that one can advantageously Use relatively slim and long levers I and II and thus extremely large excursion areas can spread. In order to minimize the space required by the balancing springs themselves to hold, the tension springs do not simply grab at the end points of the load lever al and all on, but in a manner known per se (Dt.Ps No.

936.966) their power-transmitting traction means guided over pulleys, such that the spring axis remains unchanged when the entire system is moved. With regard to the dimensioning of the spring then of course no longer applies Distance of the end point of the compensating lever a from the fixed suspension point and it turns out that the so-called eccentricity e in the moment equation of the compensation system. On the other hand, it is also the length for the Pure spring space can be freely selected, as far as the system itself is spatially permitted. In a further development of the invention, the two springs provided can through Interposition of mechanical means can also be arranged concentrically.

When manipulating the two levers i and II can be in such positions come that to overcome possible friction of or # dead spots too much force is required for the excursion movement of the X-ray tube, especially when the Lever I arrives in positions that deviate little from the horizontal.

Particularly unfavorable in this sense is that in Fig. 1 with I ", II", h denoted days of the overall lever system. To eliminate this disadvantage too, it is proposed to use the self-balanced system with small motors Gear, e.g.

in the manner shown in Fig. 2 to move. In principle, this can be done in every node, but the cheapest is undoubtedly the fixed one Axis of the lever system 1. A spur gear is shown as an example, however is when the system (e.g. for reasons of safety or the oscillation of the load-balancing springs) should become more rigid, at this point a self-locking one Use gear.

Depending on the installation location of such a self-locking gear This also results in an increase in the security against spring breakage on the one hand and against breakage of the traction mechanism on the other hand.

Patent Claims \ Öri. Double lever spring weight compensation, thereby characterized in that the veder weight compensation systems for two are strung together but independently acting load levers on a single geometric axis are performed, preferably via the fixed geometric axis of the overall system.

2. Spring compensation according to claim 1, characterized in that the necessary torque transmissions take place via traction means known per se, if necessary also those moment transmissions that serve to move from the stationary geometric Axis to ensure a reference direction at the end of the second independent lever system.

3. Federaus1 # calibration according to claim 1 or 2, characterized in that that to avoid swiveling the balance springs their force-transmitting Traction means are guided over pulleys, such that when moving the compensation system the main axes of the springs remain.

Claims (1)

4. Spring compensation according to claim 1, 2 or 3, characterized in that that an electromotive auxiliary drive system at the axle bearing points of the levers is provided, preferably by means of torque transmission to the geometrical fixed axis.