Linear actuator for a medical technology facility and medical technology facility

Abstract

Linear actuator (8) for a medical device (1), comprising: - comprising a carrier component (9) having a fastening interface (10) for mechanical coupling of the linear actuating device (8) to the medical device (1), - a carriage (15) movable relative to the carrier component (9) along an actuating axis (14) with a coupling means (17) for the, in particular reversible, mechanical coupling of a patient couch (3) to the linear actuating device (8), - a drive unit (18) fixed to the carrier component (9) and - a spindle (19) rotatable by the drive device (18) and coupling the slide (15) to the drive device (18), wherein a position of the slide (15) relative to the support component (9) along the positioning axis (14) can be adjusted by rotating the spindle (19) by means of the drive device (18), characterized by the fact that the linear positioning device (8) can be pre-assembled, wherein the support component (9) is designed to hold all other components of the linear positioning device (8).

Description

[0001] The present invention relates to a linear actuator for a medical device. The invention also relates to a medical device.

[0002] Known linear actuators are described, for example, in the German patent application DE 101 40 862 A1 or the German utility model specification DE 20 2020 100 479 U1.

[0003] In the context of medical technology facilities, positioning a patient according to specific requirements is often crucial for examination and / or treatment. Depending on the type of examination and / or treatment, very precise patient positioning may be necessary. Linear positioning devices are typically used for this purpose, allowing a patient positioning platform, on which the patient lies or sits, to be moved or positioned along a linear axis.

[0004] Particularly in the field of radiation therapy, precise patient positioning is essential to ensure that the medical equipment can target only the specific tissue area that needs to be irradiated. During radiation treatment, it may also be necessary to reposition the patient several times to irradiate the target tissue from different angles according to one or more treatment plans.

[0005] Lateral positioning of the patient is also of particular relevance in radiotherapy and some other types of examination and / or treatment.

[0006] In the case of linear motors, which are typically used at least for the lateral positioning of the patient table, and thus the patient positioning plate, the stator or stator section is usually fixed to the medical device, with the active part coupled to the patient support. The latter can thus be moved relative to the medical device by the linear motor.

[0007] Of particular importance regarding the positioning of the patient or the patient table, especially in the lateral direction, is ensuring that the desired target position is maintained once reached, thus preventing any unintended changes in position. Linear motors inherently offer little or no protection against unintentional movement along their axis. They therefore have the disadvantage that they can be moved from the target position even by a relatively small force being applied. To prevent this, additional and adequately sized brake shoes are usually provided, which fix the patient table in the target position by applying additional braking force. The use of one or more friction brakes is particularly common. Depending on the application, the brake shoes can be very large and / or complex in design, making them comparatively expensive.This applies in particular if they are intended to be used to fix the patient bed against a particularly high axial force along the axis of adjustment.

[0008] The object of the present invention is therefore to provide an improved concept in connection with a linear positioning device for a medical technology device.

[0009] This task is solved in the present case by a linear actuator for a medical technology device, comprising: - comprising a support component with a mounting interface for mechanical coupling of the linear actuator to the medical device, - a slide movable relative to the support component along an actuating axis with a coupling means for the, in particular reversible, mechanical coupling of a patient bed to the linear actuating device, - a drive unit that is fixed to the carrier component and - a spindle rotatable by the drive device, coupling the carriage to the drive device, wherein a position of the carriage relative to the support component along the positioning axis can be adjusted by rotating the spindle by means of the drive device.

[0010] The linear positioning device according to the invention is designed to enable movement of the carriage along the positioning axis by means of the drive unit and the spindle. The position of the carriage relative to the support component along the positioning axis can be adjusted by appropriately controlling the drive unit. Preferably, it is infinitely adjustable, so that any position along the positioning axis within an adjustment range defined by the size of the linear positioning device can be set or reached by the carriage.

[0011] Regarding the operating principle and functionality of the linear actuator, the drive unit is designed to rotate the spindle and / or brake its rotation, in particular to lock it. The carriage is coupled to the spindle and mounted on the support component, for example by means of a linear guide, in such a way that rotation of the spindle results in movement of the carriage relative to the support component along the positioning axis. The spindle thus connects the drive unit to the carriage.

[0012] The coupling of the slide to the spindle converts the spindle's torque into an axial force acting on the slide along the axis of rotation. This force can be a driving force that moves the slide or a braking force that decelerates it. The slide is preferably coupled to the spindle by means of one or more spindle nuts. Due to the connection geometries of the spindle and the slide's spindle nut(s), a significantly higher force is required compared to the linear motor described above to unintentionally move the slide or the active part along the axis of rotation. Because of the coupling geometry between the spindle and the spindle nut, only a very small portion of the axial force acting on the slide along the axis of rotation is converted into a torque that sets the spindle in motion.In other words, the spindle provides a reduction in the drive mechanism from the slide. Furthermore, a large portion of the axial force presses the tooth flanks of the spindle nut and the spindle directly or indirectly against each other along the positioning axis, generating friction that counteracts the rotation required to move the slide. The linear positioning device therefore exhibits significantly higher self-locking than a linear motor. Consequently, the linear positioning device allows for particularly secure positioning of the slide along the positioning axis.

[0013] This advantage is particularly evident when the linear actuator is used to generate linear motion in a medical device. Here, it can be preferably rigidly coupled to the medical device via the mounting interface of the support component, meaning it is immovable relative to the medical device. A patient bed can also be coupled to the linear actuator's carriage, particularly reversibly, via this coupling device. By appropriately controlling the drive unit, the carriage with the patient bed can then be moved along the axis of motion relative to the support component fixed to the medical device. Thanks to the design of the linear actuator, unintentional movement of the patient bed along the axis of motion is, if at all, extremely difficult.For example, when positioning a patient on the treatment table, where comparatively high forces can act on the carriage, the system can increase safety against unintentional movement of the table. In general, linear actuators in medical devices offer enhanced positional stability when positioning the carriage, and thus the patient, along the axis of rotation. This is particularly true for lateral adjustments, where, compared to conventional linear drives, there is significantly greater protection against unintentional changes in the position of the treatment table, especially against the more frequent lateral impacts.

[0014] Regarding the design of the linear actuator, the support component can be understood as a base component to which the other components of the linear actuator are attached and / or mounted. Preferably, the support component has a plate-like design, i.e., at least essentially the shape of a plate, which makes it particularly space-saving. It is conceivable that the mounting interface is provided at least largely on a first side of the support component, with all other components of the linear actuator being attached and / or mounted on a second side of the support component opposite the first side.

[0015] The mounting interface of the support component is preferably designed such that the support component can be securely fixed to the medical device by means of additional fasteners, such as screws, bolts, or the like. The fastening can be achieved by positive locking and / or frictional locking. A material bond is also conceivable, provided that non-destructive disassembly of the support component is not required.

[0016] According to the invention, the linear actuator can be pre-assembled, with the support component designed to hold all other components of the linear actuator. The support component can thus be understood as a base part to which all other components of the linear actuator are attached. Preferably, the attachment is achieved with or without appropriate fasteners, either positively or frictionally. In principle, a material-bonded attachment, for example by welding, is also conceivable. This allows the linear actuator to be handled much more easily as a pre-assembled unit before final assembly on or in the medical device. Furthermore, a separation of pre-assembly and final assembly is possible, which enables process improvements, particularly increased efficiency, in manufacturing.

[0017] The carriage can be held by the support component. However, it is not fixed in position relative to the support component, but rather movable along the actuating axis. This is possible, for example, by a linear guide. Preferably, the linear actuating device has at least one guide rail to which the carriage is slidably coupled for guidance along the actuating axis. This allows for particularly precise and reliable guidance of the carriage. The at least one guide rail is preferably fixed to the support component, for example, by means of a screw connection. It is also conceivable that the support component is already designed in such a way that it has a projection forming the at least one guide rail.

[0018] The carriage can, in principle, be coupled to the at least one guide rail by any conceivable bearing arrangement. Preferably, a sliding bearing is provided for this purpose, as it is particularly inexpensive and offers low wear and noise. It is conceivable that the at least one guide rail has a recess running along the axis of rotation on one or two opposite sides, into which the carriage, or in particular a sliding bearing of the carriage, engages. The at least one guide rail can thus be gripped by the carriage or its sliding bearing, thereby securing it against "falling off" the at least one guide rail.

[0019] It is conceivable that the carriage has a bearing means on a first side, for example, projections encompassing the guide rail, by means of which it is coupled to the at least one guide rail, and that on a second side opposite the first side, it has the coupling means for the, in particular reversible, mechanical coupling of the patient bed. This coupling means can be configured to couple the patient bed to the carriage, in particular without additional fastening means, and to decouple it from the carriage again without damage. Preferably, the coupling means enables quick and easy coupling and decoupling of the patient bed to and from the carriage. The patient bed can also be permanently fixed to the carriage by means of the coupling means, for example, by a screw connection.

[0020] The mounting interface and / or coupling device can enable electrical coupling in addition to mechanical coupling. In other words, they can be configured to couple the linear actuator not only mechanically, but also for data transmission and / or power supply to the medical device and / or the patient bed. The electrical coupling can, in particular, occur synchronously, i.e., simultaneously, with the mechanical coupling.

[0021] The drive unit and the spindle are rigidly fixed to the support component. Suitable fasteners, such as screws, bolts, or the like, can be provided for this purpose. Any form-fit or material-fit fastening is also conceivable. While the drive unit is fixed against movement relative to the support component, the spindle is rotatably mounted to the support component along its longitudinal axis. For this purpose, the spindle is attached to the support component by means of a bracket. The bracket preferably has one or more bearings, for example, rolling bearings. It is advantageously designed such that it blocks translation of the spindle relative to the support component, while allowing rotation of the spindle about its longitudinal axis.

[0022] A threaded spindle, particularly a ball screw, is especially preferred. By appropriately selecting a thread pitch or a pitch of the tooth flanks of the spindle and the spindle nut(s), a reduction in gear ratio can be achieved, so that only a very small portion of an unintentional force acting on the slide along the positioning axis is converted into rotation of the spindle required to move the slide. Due to the gearing, a large portion of the unintentional force causes the tooth flanks of the spindle nut(s) to be pressed directly, or by means of at least one intermediate element (in the case of a ball screw, the balls), against the tooth flanks of the spindle along the positioning axis. This increases the friction between the tooth flanks or between the tooth flanks and the balls, which further counteracts rotation of the spindle.

[0023] In principle, any type of threaded spindle can be used, including, for example, a trapezoidal threaded spindle or a rolling screw spindle. However, the ball screw design is preferred because it is relatively inexpensive and requires little maintenance. It also allows for particularly quiet operation.

[0024] In a preferred embodiment, the drive unit for rotating the spindle comprises a motor with a rotor shaft and a brake acting on the rotor shaft for braking and / or locking the spindle's rotation. The motor can set the rotor shaft in rotation, and the brake can slow its rotation and / or lock it. A torque, in particular the drive and braking torque, can be transmitted directly or indirectly from the rotor shaft to the spindle. The drive torque and the braking torque act in opposition to each other.

[0025] The motor is preferably an electric motor comprising a rotor connected to the rotor shaft and a stator. The brake is preferably a friction brake acting on the rotor shaft. The drive unit may also include several such brakes. Additionally, if the motor is an electric motor, it may also include a motor brake by generating a magnetic field that opposes the rotation of the rotor shaft, thereby decelerating its rotation. Overall, the drive unit is preferably configured to apply both a driving torque and a braking torque to the rotor shaft. The drive unit is preferably fixed to the support component as a single unit by a suitable bracket.

[0026] The rotor shaft can, in principle, be directly connected to the spindle. In one embodiment, it can also be a part or section of the spindle, so that the motor and brake act directly on the spindle. Preferably, however, the drive unit has a torque transmission device configured to transmit the drive torque and / or the braking torque of the rotor shaft to the spindle, wherein the torque transmission device comprises a belt drive, in particular with a toothed belt, and / or a gearbox. The torque transmission device thus serves to couple the rotor shaft to the spindle. In this way, the spindle on the one hand and the motor with the brake or the drive unit on the other can each be provided as separate components, which simplifies the manufacture and maintenance of the linear actuator.

[0027] It is conceivable that the motor's rotor shaft is coupled to the spindle via the torque transmission device without a gearbox. In this case, one gear can be rotationally fixed to the rotor shaft and a second gear can be rotationally fixed to the spindle, with the spindle and the rotor shaft being coupled to each other by a belt, in particular a toothed belt, engaging both gears.

[0028] Preferably, the torque transmission device comprises a gearbox and a toothed belt. The gearbox can be interposed between the motor's rotor shaft and a drive shaft of the torque transmission device, allowing the drive shaft to be subjected to the drive torque via the gearbox and the rotor shaft. The spindle and the drive shaft can each have a gear, with the toothed belt engaging both gears. This creates a first gear reduction, preferably a reduction, of the drive and / or braking torque between the rotor shaft and the drive shaft. A second gear reduction, preferably a reduction, can then be created downstream via the belt drive, further adjusting the drive or braking torque acting on the spindle.In other words, the torque transmission device for transmitting torque from the rotor shaft to the spindle preferably has a gear stage provided by the gearbox and a belt stage provided by the toothed belt.

[0029] Instead of a timing belt, a V-belt, chain, or similar device could also be used. However, compared to a V-belt, a timing belt offers the advantage of being able to transmit higher torque, while the toothed design prevents slippage. Compared to a chain, a timing belt also allows for significantly quieter torque transmission. Furthermore, the cost and maintenance-free operation of a timing belt are also compelling reasons to choose one.

[0030] The spindle and / or the torque transmission device can thus provide or adjust a reduction ratio between the rotor shaft and the slide. This reduction ratio increases the braking torque generated by the brake, ultimately subjecting the slide of the linear actuator to a higher braking force and, as a result, better securing it against unintentional movement. As explained earlier, the spindle pitch already provides a reduction ratio between the spindle and the slide. This can be advantageously supplemented, i.e., increased, by one or more reduction ratios in the torque transmission device.

[0031] To achieve the highest possible reduction ratio using the torque transmission device, it is preferred that the torque transmission device comprises a gearbox and a toothed belt. A first reduction of the braking torque can be achieved by the gearbox stage, which can be provided, for example, between the rotor shaft and the drive shaft. A second reduction of the braking torque can then be achieved by the belt stage of the toothed belt, which is particularly located downstream of the gearbox stage, before the spindle is finally subjected to the reduced and thus significantly increased braking torque. The drive or braking torque at the spindle can therefore be increased by the torque transmission device compared to the drive or braking torque applied to the rotor shaft.The further (third) reduction between the spindle and the slide allows the braking force generated on the slide by the braking torque of the spindle to be increased even further.

[0032] The multiple reductions offer the advantage that a very high braking force or holding force can be exerted on the carriage, particularly with a comparatively small brake, along the actuating axis. This represents a significant advantage over the linear motors described earlier and the brakes required in that context. Due to the "amplification" of the braking torque or braking force by the reduction, a smaller brake is sufficient for decelerating and / or locking the carriage, according to the invention. Thus, the invention eliminates the need for costly (large) brake shoes, such as those required for linear motors.

[0033] The gear ratio can be fixed according to the selected components. Alternatively, it can be adjustable, for example, by changing the size or number of teeth of the gears on the drive shaft and the spindle, or similar means. Although this is preferred, the torque transmission device does not necessarily need to have an additional gearbox, so, for example, the rotor shaft can be coupled to the spindle by a toothed belt. For this purpose, both shafts can have a corresponding gear, fixed to the respective shaft in a rotationally fixed manner, into which the toothed belt can engage. In this case, only a gear reduction between the rotor shaft and the spindle via the torque transmission device and between the spindle and the slide is possible.

[0034] The linear positioning device is preferably designed such that a force for moving and / or braking, especially locking, the carriage can be transmitted from the drive unit to the carriage with virtually no slippage. In other words, the entire drive train of the linear positioning device is preferably designed with at least a virtually complete positive locking mechanism, so that no slippage can occur between the individual components. This improves the positioning accuracy of the carriage along the positioning axis. A target position can thus be reached more easily by the carriage. The positioning accuracy achieved in this way is particularly advantageous in dynamic applications where the position of the carriage along the positioning axis is changed rapidly, especially during changes of direction.

[0035] Slip-free operation requires that all components of the drive train are appropriately designed and interconnected. It is advantageous for the torque transmission device to incorporate a toothed belt. This belt can be made of rubber and pre-tensioned, ensuring slip-free coupling of the rotor shaft or, if present, the drive shaft to the spindle. The elasticity of the toothed belt can be utilized in this process. A suitable belt tensioner can be provided for tensioning the toothed belt. Furthermore, the previously described use of a ball screw and one or more screw nuts can also prevent slippage in the drive train when coupling the slide to the spindle. This advantage can, in principle, be achieved with any type of lead screw.

[0036] Furthermore, to prevent slippage, it is advantageous for the drive train components and their attachment to the support component to exhibit high rigidity. The support component, the drive unit and spindle mounts, the carriage, and / or the at least one guide rail are therefore preferably made of metal, particularly stainless steel or aluminum. The spindle is preferably made of stainless steel, particularly machine steel. It, like the at least one guide rail, is preferably a standard part, thus saving costs.

[0037] To position the carriage as precisely as possible along the positioning axis, the linear positioning device preferably includes a measuring device comprising a drive measuring element configured to measure the rotation angle of the rotor shaft of the drive unit. The drive measuring element can be a resolver or include one. Additionally or alternatively, the drive measuring element can be an encoder or include one. Thus, the rotation angle of the rotor shaft can be determined by the drive measuring element. Alternatively or additionally, if the torque transmission device includes a drive shaft as an intermediate stage, the drive measuring element is also configured to measure the rotation angle of the drive shaft.If the gear ratio of the drive train from the rotor shaft and / or the drive shaft to the carriage is known, the position of the carriage along the positioning axis can be calculated using the rotation angle of the rotor shaft and / or the drive shaft. The drive measuring device could be an incremental encoder or an absolute encoder, or it could include one. It could be mounted as part of the drive unit or separately on the support component.

[0038] Additionally or alternatively, the measuring device can include a slide measuring device configured to measure the position and / or the distance traveled by the slide along the actuating axis. This measuring device can be for detecting an absolute or a relative position of the slide along the actuating axis. In the latter case, a starting point is required to determine the actual position of the slide along the actuating axis, from which the actual absolute position of the slide can be determined using the determined relative position. At least one position sensor, in particular a light barrier, can be provided for this purpose. The position sensor can be mounted on the support component, on the slide, or on the at least one guide rail.It can be started up by appropriately controlling the drive unit at the beginning of operation of the linear positioning device, in particular once, in order to calibrate the slide measuring device.

[0039] Preferably, the measuring device comprises a drive measuring element and a slide measuring element. The resulting redundancy improves the reliability of the measuring device. This is particularly advantageous when the linear actuator requires highly precise positioning of the slide along the axis of rotation. For this purpose, the linear actuator can include a control unit that compares the measurement results of the drive measuring element with those of the slide measuring element and, based on this comparison, evaluates the functionality of the measuring device and / or the linear actuator. The internal control unit can be mounted on the support component.Additionally or alternatively, the linear actuator can be configured with an external control unit to perform a corresponding comparison of the measurement results and a corresponding evaluation of the functionality of the measuring device and / or the linear actuator. In this case, the linear actuator preferably has a suitable interface by which it can be connected to the external control unit. Such an external control unit could, for example, be a central computer of a medical device.

[0040] The term "measurement results" can be understood as the measurement data obtained using the drive and slide measuring devices. In the case of the drive measuring device, this means the rotation angle of the rotor shaft and / or the drive shaft, and in the case of the slide measuring device, the position and / or the distance traveled by the slide along the actuating axis. It is also conceivable that each "measurement result" refers to a predicted position of the slide along the actuating axis, determined based on this data—that is, a position where the slide should be if the data were correctly acquired.

[0041] The control unit, whether integrated into the linear actuator or connected to it externally, allows for a comparison of the measurement results from both measuring devices. If the measurement results match, the actual position of the carriage can be determined. If they do not match, an operational fault in the measuring device and / or the linear actuator can be detected. It is therefore advantageous if the control unit is also configured to control the drive unit. This allows the operation of the linear actuator to be stopped automatically upon detection of an operational fault, particularly by issuing a warning message.Such a warning message can be issued as a visual and / or audible indication on the medical device and / or on an operating system for the (especially external) operation of the medical device and / or a patient bed coupled to the linear actuator. The control unit can also be configured to issue a warning message even if it is not configured to control the drive unit.

[0042] As mentioned, the linear actuator preferably has at least one control interface configured for electrical power transmission and / or data transmission between the linear actuator and the medical device or the linear actuator and the patient bed. The linear actuator, in particular the drive unit and / or the measuring unit and / or the control unit, can thus be powered by the medical device. Additionally or alternatively, data exchange, especially of the aforementioned measurement results, is possible between the linear actuator and the medical device and / or the linear actuator and the patient bed. It is conceivable that the drive unit of the linear actuator can be controlled by an operator panel and / or a central computer of the medical device.It is also conceivable that the drive mechanism of the linear actuator can be controlled by a control panel on the patient bed.

[0043] In addition to the linear actuator according to the invention, the invention also relates to a medical device for the medical examination and / or treatment of patients, comprising a functional component and at least one linear actuator according to the invention. All features, embodiments, and advantages described in connection with the linear actuator according to the invention are transferable to the medical device according to the invention, including the functional component, and vice versa.

[0044] The functional component can be any component configured to achieve the purpose intended by the medical device. For example, a gantry or any component configured for medical imaging and / or irradiation is conceivable. Preferably, the functional component may be a component that includes a radiation generator for producing radiation, in particular photon and / or electron radiation of high intensity.

[0045] In particular, the linear positioning device according to the invention, as described above, is coupled to the functional component of the medical device by means of the mounting interface. It is conceivable, for example, that the support component of the linear positioning device has suitable bores to which it can be screwed onto or into the functional component.

[0046] It is further preferred that the medical device includes a patient bed for positioning a patient, wherein the patient bed is coupled or can be coupled to the carriage of the linear actuator by means of the coupling means. The patient bed can thus be coupled to the carriage of the linear actuator either permanently or reversibly by means of the coupling means. It is conceivable that the patient bed is a mobile patient bed that is coupled to the carriage of the linear actuator before the examination and / or treatment and is decoupled from the carriage again after the examination and / or treatment. For this purpose, the carriage and the patient bed can have a suitable coupling, in particular a magnetic and / or (electro-)mechanical one.

[0047] The patient table is preferably movable along the axis of movement by means of the linear actuator, the axis of movement being oriented perpendicular to a longitudinal axis of the patient table. The longitudinal axis of the patient table is understood to be the axis along which the patient table has its greatest extent. It is common practice for patients undergoing examination and / or treatment with medical equipment, such as a magnetic resonance imaging (MRI) scanner, to be moved in and out of the medical equipment along this longitudinal axis. If the axis of movement of the linear actuator is oriented perpendicular to the longitudinal axis of the patient table, particularly in the horizontal direction, then in addition to forward and backward movement along the longitudinal axis, lateral movement of the patient table to the left and right is also possible, thus providing greater freedom of movement.

[0048] The medical device is preferably a device for the medical irradiation of a patient, in particular a radiotherapy device. As mentioned above, the functional component may preferably comprise a radiation generator designed to produce radiation, in particular photon and / or electron radiation of high intensity. For example, the functional component may be or comprise a gantry in which the radiation generator is movably guided. In medical irradiation or radiotherapy, the precise positioning of the patient table, made possible by the linear positioning device according to the invention and secured against unintentional displacement, is of particular advantage.Here it is often necessary to position the patient bed at least once transversely to the longitudinal axis of the patient bed, i.e. laterally or sideways, during the treatment of the patient, for example in order to be able to irradiate a specific, non-central part of the patient's tissue.

[0049] Typically, a central computer in the radiotherapy unit calculates treatment plans that determine the patient's position relative to the target tissue. The central computer can be integrated into the functional component. The linear actuator is therefore preferably connected to the functional component, particularly its central computer, via a control interface. The drive mechanism of the linear actuator can then be controlled by the central computer according to the treatment plan(s). This allows the patient table to be moved to at least one position specified by the treatment plan(s).

[0050] In principle, the installation of the linear positioning device according to the invention is also conceivable in any other medical technology device in which a corresponding positioning of a patient bed perpendicular to its longitudinal axis is necessary or advantageous.

[0051] Further advantages and details of the present invention are explained below with reference to exemplary embodiments and the figures. These are schematic representations and show: Fig. 1 an embodiment of a medical device according to the invention comprising a functional component, a linear positioning device according to the invention and a patient bed, and Fig. 2 a sectional view through the medical device according to the invention Fig. 1 with regard to the linear positioning device according to the invention.

[0052] Fig. Figure 1 shows an embodiment of a medical device 1 according to the invention for examining and treating a patient. In this case, the medical device 1 is a radiotherapy device. It comprises a gantry 2 as a functional component. In other embodiments, any other functional component is conceivable instead of the gantry 2, provided it is configured to achieve the (treatment) goal or purpose of the medical device 1, such as imaging, radiotherapy, or similar. In addition to the gantry 2, the medical device 1 comprises a patient table 3 with a patient support plate 4 and a support surface 5 for positioning a patient. The patient table 3 is configured to move the patient support plate 4 along a longitudinal axis 6 of the patient table 3. Thus, the patient support plate 4 (with a patient) can be moved into and out of the tube 7.

[0053] The patient bed 3 is coupled to the functional component or gantry 2 of the medical device 1 by an embodiment of a linear actuating device 8 according to the invention. To illustrate the structure and function of the linear actuating device 8, the figure shows... Fig. 2 a sectional view through the medical technology facility 1 of the Fig. 1 with a view to the linear actuator 8.

[0054] Based on Fig. Figure 2 shows that the linear actuator 8 has a plate-like support component 9 with a mounting interface 10. The support component 9, and thus the linear actuator 8, is fixed to the gantry 2 by means of several bores 11 and screws 12 forming the mounting interface 10. The linear actuator 8 also has a guide rail 13, which is firmly screwed to the support component 9 and runs along an actuating axis 14. A slide 15 is mounted on this guide rail by means of a sliding bearing 16, or a sliding bearing element 16, so that it is slidable relative to the support component 9 along the actuating axis 14, such that the slide 15 can move along the actuating axis 14 relative to the gantry 2. The slide 15 in turn has a coupling element 17, which in this case comprises several bores 11 and screws 12, and through which the patient bed 3 is coupled to the slide 15. Fig.2 is the patient bed 3 in the area of ​​the coupling “cut off”.

[0055] The linear actuator 8 thus forms the link between the gantry 2 and the patient bed 3. The linear actuator 8 allows the lateral position of the patient bed 3 to be adjusted along the positioning axis 14, which is oriented perpendicular to the longitudinal axis 6. For this purpose, the linear actuator 8 has a drive unit 18 by which a spindle 19, in this case a ball screw, can be rotated. The carriage 15 is coupled to the spindle 19 by means of a spindle nut 20 such that its position along the positioning axis 14 can be continuously adjusted by rotating the spindle 19. The carriage 15 is guided on the guide rail 13.

[0056] Both the drive unit 18 and the spindle 19 are attached to the support component 9 by means of respective brackets 25, 26. The brackets 26 of the spindle 19 each include a rolling bearing 27, by which the spindle 19 is rotatably attached to the support component 9 about its longitudinal axis.

[0057] The drive unit 18 comprises an electric motor 21 with a rotor shaft. This rotor shaft is coupled to a drive shaft 23 by means of a gearbox 22 and a torque transmission device 28. Furthermore, the drive unit 18 includes a brake 24, in this case a friction brake, which acts on the rotor shaft of the electric motor 21 and is designed to apply a braking torque to the rotor shaft and, via the gearbox 22, also to the drive shaft 23, in order to decelerate or stop the movement of the carriage 15 along the positioning axis 14. The braking torque generated by the brake 24 at the drive shaft 23 is amplified by a reduction in the gearbox 22 between the rotor shaft and the drive shaft 23.

[0058] The drive torque and the braking torque of the rotor shaft are transmitted to the spindle 19 by the torque transmission device 28. In this case, the torque transmission device 28 comprises, in addition to the gearbox 22, a gear 29 fixedly connected to the drive shaft 23, a gear 30 fixedly connected to the spindle 19, and a toothed belt 31 whose teeth engage with the teeth of the two gears 29 and 30. The gears 29 and 30 are selected such that a further reduction occurs between the drive shaft 23 and the spindle 19, thereby further increasing the braking torque of the drive shaft 23 acting on the spindle 19.

[0059] Finally, the geometry of the spindle 19 and the spindle nut 20 further reduces the braking torque or braking force acting on the carriage 15 via the spindle 19. Overall, the braking torque that the rotor shaft of the electric motor 21 can be subjected to by the brake 24 is thus reduced several times along the drive train of the linear actuator 8. This allows the brake 24 to exert a very high holding force on the carriage 15, making it difficult or impossible to move it along the positioning axis 14. Due to the reduction in the braking torque of the brake 24 resulting from the drive train design, the position of the patient bed 3 along the positioning axis 14 is particularly well secured against unintentional movement.In particular, compared to conventional linear motors, the linear actuator 8 offers significantly more safety, while at the same time eliminating the need for large, expensive brake shoes.

[0060] In other configurations, the drive shaft 23 and the gearbox 22 can be omitted. In this case, the gear 29 can be directly attached to the rotor shaft of the electric motor 21, so that the rotor shaft is directly coupled to the spindle 19 via the toothed belt 31. However, this can affect the reduction ratio achievable with the drive train.

[0061] Several components of the linear actuator 8 are designed as standard components, in particular standard parts, resulting in simple and cost-effective manufacturing. Specifically, the spindle 19, the drive unit 18, the toothed belt 31, the guide rail 13, and the bearings 16 and 17 are provided as standard components or purchased parts.

[0062] The linear actuator 8 further offers the feature and advantage that the force for moving and braking, and in particular for locking, the carriage 15 along the positioning axis 14 can be transmitted from the drive unit 18, specifically the rotor shaft, to the carriage 15 with virtually no slippage. This makes it possible to position the carriage 15, and thus the patient bed 3, with exceptional precision along the positioning axis 14. This is particularly advantageous in dynamic applications with high movement speeds of the carriage 15.

[0063] The drive train of the linear actuator 8 is configured accordingly. In detail, the support component 8 and the brackets 25, 26 of the drive unit 18 and the spindle 19 are designed to be particularly rigid. The carriage 15 is also guided on the guide rail 13 with virtually no backlash. The use of the V-belt 31 for torque transmission also effectively prevents slippage when the rotor shaft or the drive shaft 23 is coupled to the spindle 19. The same applies to the coupling of the carriage to the ball screw 19 by means of the spindle nut 20.

[0064] To further improve the positional accuracy of the carriage 15 along the positioning axis 14, the linear positioning device 8 includes a measuring device 32. This comprises, on the one hand, a drive measuring device 33, in this case a resolver 34 or rotary encoder, which is configured to measure a rotation angle of the drive shaft 23. An encoder could also be used as the drive measuring device 33. The resolver 34 outputs the current rotation angle of the rotor shaft as the measurement result. In other embodiments, it would be conceivable, additionally or alternatively, that the drive measuring device 33 is configured to measure a rotation angle of the drive shaft 23 of the electric motor 21.

[0065] In addition, the measuring device 32 includes a slide measuring device 35, which is configured to output as a measurement result the distance traveled by the slide 15 along the actuating axis 14. The measuring device 32 further includes a position sensor 36, in this case a light barrier 37, by which a zero position or zero orientation of the slide 15 along the actuating axis 14 can be determined.

[0066] To control the drive unit 18 and to evaluate the measurement results of the measuring device 32, in particular the drive measuring device 33 and the carriage measuring device 35, the linear actuator has a control interface 38 by means of which it is connected to the gantry 2, specifically to a control unit 39 of the gantry 2, in this case a central computer 40. At the start of operation of the linear actuator 8, the control unit 39 moves the carriage 15 once over the light barrier 37 to calibrate the measuring device 32 and to establish the zero position of the carriage 15 along the positioning axis 14. During operation of the linear actuator 8, the control unit 39 is configured to compare the measurement results of the resolver 34 with those of the carriage measuring device 35. If these match, operation of the linear actuator 8 continues.However, if they do not match, operation is automatically interrupted with the display of a visual message on a control panel 41 of the gantry 2 and on an external computer 42, which is configured to control and monitor the medical device 1. An example of such a message is: "Error in the lateral adjustment of the patient table." An audible warning tone is also conceivable.

[0067] The linear actuator 8 is also powered via the control interface 38 through the gantry 2.

[0068] It should also be emphasized that the support component 9 is designed to hold all other components as well as parts of the linear actuator 8. This allows the linear actuator 8 to be pre-assembled as a module before being mounted to the gantry 2 at a later time using the mounting interface 10. This offers particular logistical and manufacturing advantages.

[0069] The linear positioning device according to the invention can generally be provided in any medical device, particularly in medical devices where precise linear movement, such as of a patient table, and / or a high degree of safety against unintentional displacement of the patient table are preferred. For example, it could be used in a magnetic resonance imaging (MRI) or computed tomography (CT) scanner.

[0070] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention.

[0071] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

[1] Linear actuator (8) for a medical device (1), comprising: - comprising a support component (9) having a fastening interface (10) for mechanically coupling the linear actuating device (8) to the medical device (1), - a carriage (15) movable relative to the carrier component (9) along an actuating axis (14) with a coupling means (17) for the, in particular reversible, mechanical coupling of a patient couch (3) to the linear actuating device (8), - a drive unit (18) fixed to the carrier component (9) and - a spindle (19) rotatable by the drive device (18) and coupling the slide (15) to the drive device (18), wherein a position of the slide (15) relative to the support component (9) along the positioning axis (14) can be adjusted by rotating the spindle (19) by means of the drive device (18), characterized by , that the linear positioning device (8) can be pre-assembled, wherein the support component (9) is designed to hold all other components of the linear positioning device (8). [2] Linear actuating device (8) according to claim 1, characterized by , that the spindle (19) is a threaded spindle, in particular a ball screw. [3] Linear actuating device (8) according to any one of the preceding claims, characterized by at least one guide rail (13) to which the carriage (15) is slidably coupled for guidance along the actuating axis (14). [4] Linear actuating device (8) according to any one of the preceding claims, characterized by , that the drive device (18) for rotating the spindle (19) has a motor (21) with a rotor shaft and for braking and / or stopping the rotation of the spindle (19) has a brake (24) acting on the rotor shaft. [5] Linear actuating device (8) according to claim 4, characterized by, that the drive device (18) has a torque transmission device (28) which is configured to transmit a drive torque and / or a braking torque of the rotor shaft to the spindle (19), wherein the torque transmission device (28) comprises a belt drive, in particular with a toothed belt (31), and / or a gearbox (22). [6] Linear actuating device (8) according to claim 4 or 5, characterized by , that a reduction between the rotor shaft and the slide (15) is specified or adjustable by the spindle (19) and / or the torque transmission device (28). [7] Linear actuating device (8) according to any one of the preceding claims, characterized by , that the linear positioning device (8) is designed such that a force for moving and / or braking, in particular locking, the carriage (15) can be transmitted from the drive device (18) to the carriage (15) at least substantially without slippage. [8] Linear actuating device (8) according to any one of the preceding claims, characterized by a measuring device (32), wherein the measuring device (32) comprises a drive measuring means (33), in particular a resolver (34), configured to measure an angle of rotation of one or the rotor shaft of the drive device (18) and / or a slide measuring means (35) configured to measure the position and / or a distance traveled by the slide (15) along the actuating axis (14). [9] Linear actuating device (8) according to claim 8, characterized by , that the linear positioning device (8) is equipped by means of a control device (39) of the linear positioning device (8) and / or by means of an external control device (39) to compare measurement results of the drive measuring device (33) with measurement results of the slide measuring device (35) and, depending on the comparison, to evaluate the functionality of the measuring device (32) and / or the linear positioning device (8). [10] Linear actuating device (8) according to any one of the preceding claims, characterized by at least one control interface (38) which is set up for electrical power transmission and / or data transmission between the linear actuator (8) and the medical device (1) or the linear actuator (8) and the patient bed (3). [11] Medical device (1) for medical examination and / or treatment of patients, comprising a functional component and at least one linear actuating device (8) according to one of the preceding claims, wherein the linear actuating device (8) is coupled to the functional component by means of the fastening interface (10). [12] Medical device (1) according to claim 11, characterized by, that the medical device (1) comprises a patient bed (3) for positioning a patient, wherein the patient bed (3) is coupled or can be coupled to the slide (15) of the linear positioning device (8) by means of the coupling means (17). [13] Medical device (1) according to claim 12, characterized by , that the patient bed (3) can be moved along the positioning axis (14) by means of the linear positioning device (8), wherein the positioning axis (14) is oriented perpendicular to a longitudinal axis (6) of the patient bed (3). [14] Medical device (1) according to any one of claims 11 to 13, characterized by , that the medical technology facility (1) is a facility for the medical irradiation of a patient, in particular a radiotherapy facility.

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