DE3014283A1 - Suspension mechanism with weight counterbalancing - has spring-supported device working in curved track coupled to arm spindle - Google Patents

Abstract

The suspension mechanism (10) with a hinging supporting arm is particularly for counterbalancing the weight of medical or surgical appts. It comprises a device sliding along a curved track and supported by a spring, positively coupled to the arm pivot spindle. The complete mechanism can be round and enclosed in a tubular housing which is fully sealed. There can be a tubular spring guide body inserted and fixed in the tubular arm spindle. A spring round the body is pressed against it by a thrust ring in the axial direction, to a degree dependent on the arm position.

Description

Comments on the invention proposal

"Suspension device with torque compensation" The aim of the invention the compensation of the torque caused by a load on a swivel arm is caused.

A practical application is the weight compensation during vertical movement of the lamp body of surgical lights.

With the previously used mechanical torque compensation principles the main feature is a spring counterforce that is applied to the axis of the swivel arm eccentric rotary motion is initiated (see DBP 1036787 and US Pat. No. 4,107 769).

The principle underlying the invention according to claim 1 is used In contrast to this, a cam ring which is centric to the pivot axis and on which a pair of rollers depending on the position of the support arm (synchronous to the swivel axis) a defined spring counterforce and thus a defined counter torque according to Hooke's law and the wedge principle generated. Further developments of the invention are contained in the subclaims.

Exemplary embodiments can be found in the drawings.

The functional principle is shown in FIG. Main part of the rotationally symmetrical built-up compensation device is the cam ring 1, which is fixed to the housing 2 is connected.

A rotation on the pivot axis 3 causes a rotation in the same direction the pull rod 4. Part 4 is displaceable but not rotatable with part 3 tied together. An axial deflection takes place in accordance with the position of the pair of rollers 5 the pull rod 4 and thus a change in the force of the spring.

By appropriately coordinating spring force 8 and curve inclination the counter-torque characteristics required for the specific application achieved.

For a swivel arm loaded with weight force, the following the functional dependency between the inclination of the curve, the spring force and the amount to be compensated Torque shown.

Figure 2 shows the balance of forces on the swivel arm the following equation for the torque characteristic to be compensated from 1) Md = RG are Figure 3 shows the balance of forces for torque compensation, which is realized by the wedge principle (inclination of the cam ring). To clarify of the physical principle, friction forces do not need to be taken into account for the time being to become.

In addition, these can be kept relatively small by means of roller bearings for the moving parts. The equilibrium conditions apply: 2) MG = MK # RG. G. sinα = RK. FK 3) FK = FFtanα FF = SCF The following results for the required spring deflection: 4) S = #### #### S = f (#, #) The production of the cam ring on a numerically controlled machine tool allows the specification in sections the height of the curve or the required spring travel w. FIG. 4 shows the development of the curve in steps. The curve height can then be calculated as follows: 5) Sn = 5n-1 +. tan'fn Inserted this equation in 4 gives: 6) tan² # n + ## tan # n - ###### sinα = 0 For the individual sections, / and S can then be determined as follows: Because of the required one-sided direction of the counter-torque: no negative distortion is permitted at the root.

One possible form of practical execution; of the principle described is to be explained below with reference to FIG.

The rotationally symmetrical components of the device are in the tubular housing 11, which is closed by the Dekcplatten 22 and 23, arranged. By the Connecting pipe 21 indicates the attachment of the housing.

The cam ring 13 (see also Fig. 6) is inserted in the housing 11 and is through a fitting screw 33 secured against rotation. The connection of the spring guide body 14 rrlit the pivot axis 12 takes place on the thread side through the support disk 19 and at the other end through the Abschlubund 36. As a connection for the swivel arm is the Coupling 15 is provided, which is secured with a screw connection 31.

If a rotary movement is now initiated via the coupling 15, the pivot axis 12, the spring guide body 14, the pressure disk 16 and the two Disk bolts 20 are moved in the same @ dimensions. The rotary movement is made possible by the deep groove ball bearing 26 and the angular contact ball bearing 29. The ball bearings 28 at the end of the Disc bolts 20 accordingly run on the cam track of the stationary cam ring 13 and cause the thrust washer 16 to move axially.

Two longitudinal slots 55 at the end of the pivot axis 12 lead the benbolzen 20 with their axial movement. The frictional forces occurring there are caused by the Ball bearing 27 toned down.

Corresponding to the axial movement of the thrust washer 16, the counter torque becomes generating spring force built up by the disk spring assembly 30. To adjust the The clamping nut 17, which is secured by the lock nut 18, is used for spring force is.

Feeds for the electrical power supply can through the Bore in the spring guide body 14 and the openings 34 in the cam ring 13 and the housing 11 can be relocated.

The main advantages of the suspension device according to the invention are: a) in the large swivel range of the swivel arm. With a favorable design of the Bearing 28 and the cam ring 13 can be achieved a pivot angle of 180 °.

b) in the simple development of a size-graded series c) in the easy assembly d) in the easy adjustability e) in the low cost of required manufacturing tools

Claims (6)

"Suspension device with torque compensation" P a t e n t a n s p r ü c h e 1. Suspension device with rotatably mounted support arm, in particular for Weight compensation on medical devices, characterized by one over one Spring supported on a curved track displaceable device with the support arm axis is positively and positively connected. 2. Suspension device according to claim 1, characterized in that the entire device is constructed rotationally symmetrical, from a tubular Housing is enclosed, which is completely closed. 3. Suspension device according to claim 1 or 2, characterized in that that a tubular spring guide body is firmly inserted into the tubular support arm axis is on which a pressure ring is dependent on the pressure spring arranged around the spring body more or less axially compresses from the support arm position 4. Suspension device according to one or more of the preceding claims, characterized in that two drive pins are radially embedded in the thrust ring, which at their free Ends each have two rolling bearings, of which the outer one on the track The cam ring fixed to the housing run, while the inner in two longitudinal slots open at the end of the support arm axis are guided. 5. Suspension device according to one or more of the preceding Claims, characterized in that the mounting of the support arm axis is on the connection side by a deep groove ball bearing arranged in the housing as a fixed bearing, while the storage on the closed side of the housing is taken over by an angular contact ball bearing that at the same time transmits the axial force from the spring tension. 6. Suspension device according to one or more of the preceding Claims that the adjustment of the compensation device takes place by tightening a nut on the spring guide body.