Patient couch with an actuator hav a globoid worm gear

Abstract

A patient couch (1) has an actuator (2) which comprises a planetary gear (6) and a worm gear (10) connected downstream of the planetary gear (6). The worm gear (10) is a globoid worm gear.

Description

[0001] PATIENT COUCH WITH AN ACTUATOR CONTAINING A GLOBOID WORM GEAR

[0002] The invention relates to a patient bed equipped with an actuator according to the preamble of claim 1.

[0003] A patient couch of this type is known, for example, from DE 10 2012 215 016 A1. The known patient couch is intended for use in a medical diagnostic and / or treatment device and comprises at least two articulated couch sections that can be pivoted relative to each other by means of a motorized adjustment mechanism. The adjustment mechanism of the patient couch according to DE 10 2012 215 016 A1 can, in particular, comprise a planetary gear and a worm gear downstream thereof.

[0004] German patent application DE 10 2016 220 268 B4 relates to a patient table for a radiotherapy system. In this case, a positioning device allows the tabletop to be tilted. The tabletop is mounted on a lifting arm, which is designed as a linear unit, via a tilting mechanism. Details of the adjustment mechanisms, such as gear concepts, are not described in DE 10 2016 220 268 B4.

[0005] A patient positioning device described in DE 198 43 679 A1 comprises a patient table which is adjustable in both height and inclination relative to a reference system. Any change in height of a section of the table that occurs when the table is tilted is compensated for by a change in the height of the entire table. A program-controlled change in table height should be possible in such a way that a virtual axis can be located not only within the area of ​​the patient table but also outside of it.

[0006] The invention is based on the objective of further developing an adjustable patient bed compared to the aforementioned prior art, whereby a particularly favorable ratio between equipment effort, required installation space, required drive power and mechanical load capacity is sought.

[0007] This problem is solved according to the invention by a patient couch with the features of claim 1. In a basic concept known per se, the patient couch comprises an actuator, in particular in the form of an electromechanical actuator, which includes a planetary gear and a worm gear connected downstream of the planetary gear.

[0008] According to claim 1, the worm gear of the actuator is a globoid worm gear.

[0009] A globoidal worm gear differs from a cylindrical worm gear in general in that the worm of the gear describes the shape of a globoid, i.e., it is designed as a globoidal worm. Regarding possible designs of globoidal worm gears, reference is made to documents DE 1 296 466 A and DE 1 288 861 A. Methods for manufacturing globoidal worm gears are dealt with, for example, in DE 26 03 597 C1.

[0010] A first group of embodiments provides that the worm gear is designed as a spur-globoid worm gear. This means that the worm of the gear interacts directly with the spur gear teeth of another gear element, i.e., a gear. The spur-globoid worm gear is tolerant, to a limited extent, of displacements of the spur gear along its own axis of rotation.

[0011] A second group of embodiments provides for the worm gear to be designed as a double-globoid worm gear. In this case, the toothing of the gear meshing with the worm also describes a globoid shape. The power density of a double-globoid worm gear is comparable to that of a spur-gear globoid worm gear. Axial displacement of the gear driven by the worm is either nonexistent or, at most, minimal in a double-globoid worm gear.

[0012] With various profiling methods for the worm gear elements, the combination of planetary gear and worm gear provided by the actuator can be designed as a self-locking gear. This applies particularly to variants in which the worm gear alone is already self-locking. The planetary gear upstream of the worm gear further reduces efficiency, thus pushing it further into the self-locking range.

[0013] There are also embodiments in which the worm gear is a non-self-locking gear. This includes configurations in which a non-self-locking gear arrangement is formed by combining a planetary gear and a worm gear.

[0014] The planetary gear unit can be a single-stage or a multi-stage unit. Optionally, a compensating clutch and / or an overrun clutch, for example in the form of a detent clutch, can be integrated into the actuator.

[0015] Regarding the materials used to manufacture the elements of the globoid worm gear, generally known solutions can be employed. For example, the worm, as well as the gear (also referred to simply as the wheel), is made of metal. In particular, the worm can be made of steel and the wheel of cast iron. There are also embodiments in which a steel worm is combined with a wheel made of plastic, cast iron, or a non-ferrous metal alloy. Regardless of the materials used, the elements of the worm gear can be mounted, for example, by plain bearings or rolling bearings. Several exemplary embodiments of the invention are explained in more detail below with reference to a drawing. These drawings show, in some cases in a simplified form:

[0016] Fig. 1 schematically shows a patient bed with an electromechanical actuator comprising a globoid worm gear,

[0017] Fig. 2 Elements of the globoid worm gear of the arrangement according to Fig. 1 in side view,

[0018] Fig. 3 shows the arrangement according to Fig. 2 in a front view,

[0019] Figs. 4 and 5 show a modified variant of a globoid worm gear suitable for use in an actuator of a patient bed, in views analogous to Figs. 2 and 3.

[0020] Unless otherwise stated, the following explanations refer to both embodiments. Corresponding or essentially equivalent parts are marked with the same reference numerals in all figures.

[0021] A patient couch, designated by reference numeral 1 and only indicated in Fig. 1, comprises two couch sections 3, 4 which can be adjusted relative to each other by means of an electromechanical actuator 2. The patient couch 1 can be used, for example, in a medical imaging system or other medical technology system.

[0022] The actuator 2 comprises an electric motor 5, a planetary gear 6, and a worm gear 10 connected downstream of the planetary gear 6. The motor shaft of the electric motor 5 is designated 14. A shaft 13 represents the output shaft of the planetary gear 6 and simultaneously the input shaft of the worm gear 10. The planetary gear 6 is of a multi-stage design and, in the present case, comprises three gear stages 7, 8, 9.

[0023] Both embodiments, that is, both the embodiment according to Figures 1 to 3 and the embodiment according to Figures 4 and 5, operate with a globoid worm gear as the worm gear 10. This means that at least one worm 11 of the gear 10 describes a globoid shape. The worm 11 is rigidly connected to the shaft 13. An integral design of the worm 11 with the shaft 13 is also possible.

[0024] The worm 11 is a machine element made of steel. Unless it is formed by the shaft 13, the worm 11 can, for example, be pressed onto the shaft 13 or connected to the shaft 13 in some other way. An equalizing clutch and / or an overload clutch can be integrated into the actuator 2, though this is not shown.

[0025] In the embodiment shown in Figures 1 to 3, the worm gear 10 is designed as a spur gear-globoid worm gear. In this case, the gear directly interacting with the worm 11 is a spur gear. As indicated in Figure 3, this design allows at least slight axial displacements of the gear 12 without impairing the function of the worm gear 10.

[0026] In contrast, in the design according to Figures 4 and 5, as shown in Figure 5, the meshing tooth of the gear 12 with the worm 11 also describes a globoid shape, thus the worm gear 10 is designed as a double-globoid worm gear. The axial displacement of the gear 12 within the worm gear 10 is practically eliminated.

[0027] The worm gear 10 according to Figures 4 and 5 is also suitable for use in the patient couch 1 according to Figure 1. In the configuration shown in Figure 1, the pivot axis of the couch section 4 coincides with the central axis of the gear 12. Alternatively, the worm gear 10 can be coupled to the couch section 4 and / or to other components of the patient couch 1 via another transmission (not shown) in a manner not shown. For example, a synchronous mechanism operatively connected to the worm gear 10 can ensure that the couch sections 3 and 4 are adjustable synchronously in a defined manner.

[0028] In the present cases, the gear 12 is made of a cast iron alloy. Alternatively, non-ferrous metal alloys and plastics are suitable for the manufacture of the gear 12, which is driven by the shaft 13 via the gearbox 6.

[0029] Similarly, various materials, including steel or other metallic materials, are suitable for the manufacture of shaft 13. Shaft 13 can be a solid shaft, as sketched in Figures 2 to 5, or a hollow shaft.

[0030] List of reference signs

[0031] Patient bed

[0032] actuator

[0033] reclining section

[0034] reclining section

[0035] electric motor

[0036] planetary gear

[0037] gear stage

[0038] gear stage

[0039] gear stage

[0040] Worm gear

[0041] Snail

[0042] gear

[0043] Wave

[0044] Motor shaft

Claims

Patent claims 1. Patient couch (1) with an actuator (2) comprising a planetary gear (6) and a worm gear (10) downstream of the planetary gear (6), characterized in that the worm gear (10) is designed as a globoid worm gear.

2. Patient couch (1 ) according to claim 1 , characterized in that the worm gear (10) is designed as a spur gear globoid worm gear.

3. Patient couch (1 ) according to claim 1 , characterized in that the worm gear (10) is designed as a double globoid worm gear.

4. Patient couch (1 ) according to one of claims 1 to 3, characterized in that the combination of planetary gear (6) and worm gear (10) is designed as a self-locking gear.

5. Patient couch (1 ) according to claim 4, characterized in that the worm gear (10) alone is self-locking.

6. Patient couch (1 ) according to one of claims 1 to 3, characterized in that the worm gear (10) is designed as a non-self-locking gear.

7. Patient couch (1 ) according to claim 6, characterized in that the combination of planetary gear (6) and worm gear (10) is also not self-locking.

8. Patient couch (1 ) according to one of claims 1 to 7, characterized in that the planetary gear (6) is a multi-stage gear.

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