Linear actuator for a medical device and medical device

Abstract

The invention relates to a linear actuator (8) for a medical device (1), comprising: - a carrier component (9) having a fastening interface (10) for mechanically coupling the linear actuator (8) to the medical device (1), - a carriage (15) movable relative to the support component (9) along an adjusting axis (14) with a coupling means (17) for, in particular reversibly, mechanical coupling of a patient bed (3) to the linear adjusting device (8), - a drive device (18) which is fixed to the carrier component (9) and - a spindle (19) rotatable by the drive device (18) and coupling the carriage (15) to the drive device (18), wherein a position of the carriage (15) relative to the carrier component (9) along the adjusting axis (14) can be adjusted by rotating the spindle (19) by means of the drive device (18).

Description

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

[0002] In the context of medical technology facilities, it is often important to position a patient according to specific requirements for examination and / or treatment. Depending on the type of examination and / or treatment, very precise patient positioning may be required. Linear actuators are typically used for this purpose, allowing a patient support plate, on which the patient is lying or sitting, to be moved or positioned along a positioning axis.

[0003] Particularly in the field of radiation therapy, precise patient positioning is required to ensure that the medical device can target only the part of the patient's tissue that actually 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 directions according to one or more treatment plans.

[0004] Lateral positioning of the patient is particularly relevant in radiotherapy and some other types of examination and / or treatment.

[0005] In the case of linear motors commonly used for at least the lateral positioning of the patient bed, and thus the patient support surface, the stator or stator section is usually firmly 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.

[0006] Of particular importance with regard to the positioning of the patient or patient support, even in the lateral direction, is that the desired target position is ensured once it has been reached, thus preventing any unintentional change in position. Linear motors inherently offer little or no protection against unintentional displacement along their actuating axis. They therefore have the disadvantage that they can be displaced from the target position even with the application of a relatively small amount of force. To prevent this, additional and sufficiently dimensioned brake shoes are usually provided, which fix the patient support in the target position by applying additional braking force. The use of one or more friction brakes is particularly not uncommon. Depending on the application, the brake shoes can be very large and / or complex, which makes them comparatively expensive.This applies in particular if they are to be used to fix the patient bed against a particularly high axial force along the adjustment axis.

[0007] The object of the present invention is therefore to provide an improved concept in connection with a linear actuator for a medical device.

[0008] This problem is solved by a linear actuator for a medical device, comprising: - a carrier component having a fastening interface for mechanically coupling the linear actuator to the medical device, - a carriage movable relative to the support component along an adjustment axis with a coupling means for, in particular reversibly, mechanical coupling of a patient bed to the linear adjustment device, - a drive device that is fixed to the carrier component and - a spindle rotatable by the drive device and coupling the carriage to the drive device, wherein a position of the carriage relative to the carrier component along the adjusting axis can be adjusted by rotating the spindle by means of the drive device.

[0009] The linear actuator according to the invention is configured to enable movement of the carriage along the adjustment axis by means of the drive device and the spindle. The position of the carriage relative to the support component along the adjustment axis can be adjusted by appropriately controlling the drive device. It is preferably continuously adjustable, so that any position along the adjustment axis that lies within an adjustment range predetermined by the size of the linear actuator can be adjusted or moved to by the carriage.

[0010] Regarding the operating principle or mode of operation of the linear actuator, the drive device is configured to rotate the spindle and / or to brake, in particular to block, its rotation. The carriage, in turn, 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 a movement of the carriage relative to the support component along the adjustment axis. The spindle thus connects the drive device to the carriage.

[0011] The coupling of the carriage to the spindle converts a torque of the spindle into an axial force acting on the carriage along the adjustment axis. This can be a driving force that moves the carriage or a braking force that brakes the carriage. The carriage is preferably coupled to the spindle by means of one or more spindle nuts. Due to the connecting geometries of the spindle and the spindle nut(s) of the carriage, a significantly higher force is required than with the linear motor described above to unintentionally move the carriage or the active part along the adjustment axis. Due to the coupling geometry between the spindle and the spindle nut, only a very small portion of an axial force acting on the carriage along the adjustment axis is converted into a torque that sets the spindle in rotation.In other words, the spindle preferably provides a reduction gear from the slide's drive mechanism. A large portion of the axial force also presses the tooth flanks of the spindle nut and the spindle together directly or indirectly along the adjustment axis, creating friction that counteracts the rotation required to move the slide. The linear actuator therefore has a significantly higher degree of self-locking than a linear motor. Therefore, the linear actuator allows for particularly secure positioning of the slide along the adjustment axis.

[0012] This advantage is particularly evident when the linear actuator is intended to generate a linear movement in a medical device. Here, it can be coupled to the medical device by means of the fastening interface of the support component, preferably firmly, i.e. immovably relative to the medical device. Furthermore, a patient support can be coupled, in particular reversibly, to the carriage of the linear actuator by means of the coupling means. By means of appropriate control of the drive device, the carriage with the patient support can then be moved along the adjustment axis relative to the support component fixed to the medical device. Thanks to the design of the linear actuator, unintentional displacement of the patient support along the adjustment axis is very difficult, if possible at all.For example, when positioning a patient on a patient table, where comparatively high forces can act on the slide, the safety against unintentional movement of the patient table can be increased. In general, the linear actuator in the context of medical technology devices enables increased positioning stability when positioning the slide and thus the patient along the adjustment axis. This is particularly true for lateral adjustment, where it offers significantly greater safety against unintentional changes in the position of the patient table compared to previously conventional linear drives, which are more frequently subject to lateral impacts.

[0013] With regard to the structure of the linear actuator, the support component can be understood as a base component to which the remaining components or parts of the linear actuator are fixed and / or mounted. Preferably, the support component has a plate-shaped design, i.e., at least substantially in the form of a plate, which makes it particularly space-saving. It is conceivable that the fastening interface is provided at least largely on a first side of the support component, with all other components of the linear actuator being fastened and / or mounted on a second side of the support component opposite the first side.

[0014] The mounting interface of the support component is preferably designed so that the support component can be firmly attached to the medical device using additional fastening elements, such as screws, bolts, or the like. The fastening can be achieved by positive and / or force-locking. A material connection is also conceivable, provided non-destructive disassembly of the support component is not required.

[0015] The linear actuator is preferably pre-assembled, with the support component being configured to hold all other components of the linear actuator. The support component can therefore be understood as a base part to which all other components of the linear actuator are fastened. Preferably, the fastening is carried out in a form-fitting and / or force-fitting manner, with or without appropriate fastening means. In principle, a material-to-material fastening, for example by welding, is also conceivable. This makes it significantly easier to handle the linear actuator as a pre-assembled unit prior to final installation on or in the medical device. Furthermore, a separation of pre-assembly and final assembly is possible, thereby enabling process improvements, in particular an increase in efficiency, in production.

[0016] The carriage can be held by the support component. However, it is not fixed in position relative to the support component, but is movable along the adjustment axis. This is possible, for example, using a linear guide. For this purpose, the linear adjustment device preferably has at least one guide rail, to which the carriage is slidably coupled for guidance along the adjustment axis. This enables particularly precise and secure guidance of the carriage. The at least one guide rail is preferably firmly fixed to the support component, for example by means of a screw connection. It is also conceivable for the support component to be designed in such a way that it has a projection forming the at least one guide rail.

[0017] The carriage can in principle be coupled to the at least one guide rail by any conceivable bearing. Preferably, a plain bearing means is provided for this purpose, as this is particularly inexpensive, low-wear, and low-noise. It is conceivable for the at least one guide rail to have a recess extending along the adjustment axis on one or two opposite sides, into which the carriage, in particular a plain bearing means of the carriage, engages. The at least one guide rail can thus be encompassed by the carriage or its plain bearing means, thereby securing it against "falling off" from the at least one guide rail.

[0018] It is conceivable for the carriage to have 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 the coupling means for the, in particular reversible, mechanical coupling of the patient support on a second side opposite the first side. This coupling means can be designed to couple the patient support 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 support to and from the carriage. However, the patient support can also be permanently fastened to the carriage by means of the coupling means, for example by means of a screw connection.

[0019] The mounting interface and / or the coupling means can enable not only mechanical coupling but also electrical coupling. In other words, they can be configured to couple the linear actuator to the medical device and / or the patient bed not only mechanically, but also for data transmission and / or power supply. The electrical coupling can, in particular, occur synchronously, i.e., simultaneously, with the mechanical coupling.

[0020] The drive device and the spindle are firmly fixed to the support component. Appropriate fastening means, such as screws, bolts or the like, can be provided for fastening. Any form-fitting or material-fitting fastening is also conceivable. However, while the drive device is fixed in relation to the support component, the spindle is rotatably mounted on the support component along its longitudinal axis. For this purpose, the spindle is attached to the support component by means of a holder. The holder preferably has one or more bearings, such as 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.

[0021] The spindle is particularly preferably a threaded spindle, in particular a recirculating ball screw. By appropriately selecting a thread pitch or a pitch of the tooth flanks of the spindle and the spindle nut(s), a reduction ratio can be achieved so that only a very small portion of any force unintentionally acting on the slide along the adjustment axis is converted into rotation of the spindle, which is required to move the slide. Due to the toothing, a large portion of the unintentionally acting force causes the tooth flanks of the spindle nut(s) to be pressed against the tooth flanks of the spindle along the adjustment axis, directly or by means of at least one intermediate part, the balls in the case of the recirculating ball screw. This increases the friction between the tooth flanks or the tooth flanks and the balls, which further counteracts rotation of the spindle.

[0022] In principle, any type of threaded spindle can be used, including trapezoidal thread spindles and roller thread spindles. However, the ball screw design is preferred, as it is comparatively inexpensive and requires little maintenance. It also enables particularly quiet operation.

[0023] In a preferred embodiment, the drive device comprises a motor with a rotor shaft for rotating the spindle and a brake acting on the rotor shaft for braking and / or locking the spindle's rotation. The rotor shaft can be set in rotation by the motor and braked and / or locked by the brake. A torque, in particular the drive and braking torque, can be transmitted directly or indirectly to the spindle from the rotor shaft. The drive torque and the braking torque counteract each other.

[0024] The motor is preferably an electric motor which, in addition to the rotor shaft, comprises a rotor connected to the rotor shaft and a stator. The brake is preferably a friction brake which engages the rotor shaft. The drive device can also have several such brakes. In addition, the motor, if it is an electric motor, can also have a motor brake, by means of which the rotational movement of the rotor shaft is decelerated by generating a magnetic field that counteracts the rotation of the rotor shaft. Overall, the drive device is therefore preferably designed to apply a drive torque and a braking torque to the rotor shaft. The drive device is preferably fixed as a unit to the support component by a suitable holder.

[0025] The rotor shaft can in principle be connected directly to the spindle. In one embodiment, it can also be a part or section of the spindle, so that the motor and the brake act directly on the spindle. However, it is preferred that the drive device has a torque transmission device designed 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 gear. The torque transmission device thus serves to couple the rotor shaft to the spindle. Thus, the spindle on the one hand and the motor with the brake or the drive device on the other hand can each be provided as separate components, which can simplify the manufacture and maintenance of the linear actuator.

[0026] It is conceivable that the rotor shaft of the motor is coupled to the spindle without a gearbox via the torque transmission device. In this case, one gear can be connected in a rotationally fixed manner to the rotor shaft and a second gear can be connected in a rotationally fixed manner to the spindle, with the spindle and the rotor shaft being coupled to each other by a belt, in particular a toothed belt, that engages both gears.

[0027] Preferably, however, the torque transmission device comprises a gear unit and a toothed belt. The gear unit can be interposed between the rotor shaft of the motor and a drive shaft of the torque transmission device, such that the drive shaft can be subjected to the drive torque via the gear unit through the rotor shaft. The spindle and the drive shaft can each have a gear, with the toothed belt engaging with the two gear units. In this way, a first transmission ratio, preferably a reduction ratio, of the drive and / or braking torque can be created between the rotor shaft and the drive shaft. The belt drive can create a second transmission ratio, preferably a reduction ratio, downstream of this, by means of which the drive or braking torque acting on the spindle can be further adjusted.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 gear and a belt stage provided by the toothed belt.

[0028] Instead of a timing belt, the use of a V-belt, a chain, or similar is also conceivable. Compared to a V-belt, however, a timing belt offers the advantage of being able to transmit greater torque, while the toothing prevents the belt from slipping. Compared to a chain, a timing belt also allows for significantly quieter torque transmission. Furthermore, the cost factor and the lack of maintenance also speak in favor of using a timing belt.

[0029] The spindle and / or the torque transmission device can thus predetermine or adjust a reduction ratio between the rotor shaft and the slide. This reduction ratio enables an increase in the braking torque generated by the brake, so that the slide of the linear actuator can ultimately be subjected to a higher braking force and, as a result, can be better secured against unintentional displacement. As explained at the beginning, the spindle pitch already provides a reduction ratio between the spindle and the slide. This can advantageously be supplemented, i.e., amplified, by one or more reduction ratios of the torque transmission device.

[0030] In order to achieve the greatest possible reduction by means of the torque transmission device, it is preferred that the torque transmission device comprises a gear unit and a toothed belt. The gear unit, which can be provided, for example, between the rotor shaft and the drive shaft, can achieve a first reduction in the braking torque. The belt unit of the toothed belt, in particular the unit downstream of the gear unit, can additionally achieve a second reduction in the braking torque before the spindle is finally subjected to the reduced and thus significantly increased braking torque. The drive or braking torque acting on the spindle can thus be increased by the torque transmission device compared to the drive or braking torque acting on the rotor shaft.The additional (third) reduction between the spindle and the carriage allows the braking force generated by the braking torque of the spindle on the carriage to be further increased.

[0031] The multiple reduction ratios have the advantage that a very high braking force or holding force can be exerted on the carriage along the actuating axis, especially even with a comparatively small brake. Compared to the linear motors described above and the brakes required in this context, this represents a significant advantage. Due to the "amplification" of the braking torque or braking force through the reduction ratio, a smaller brake is sufficient to decelerate and / or lock the carriage. This eliminates the need for costly (large) brake shoes, such as those required for linear motors.

[0032] The reduction ratio can be fixed depending on the selected components. Alternatively, it can be adjustable, for example, by adjusting the size or number of teeth of gears on the drive shaft and spindle, or similar. Even if this is preferred, the torque transmission device does not, in principle, require any additional gearing, so that, 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, non-rotatably attached to the respective shaft, into which the toothed belt can engage. In this case, only a reduction between the rotor shaft and the spindle is possible via the torque transmission device, and between the spindle and the carriage.

[0033] Particularly preferably, the linear actuating device is designed such that a force for moving and / or braking, in particular locking, the carriage can be transmitted from the drive device to the carriage at least substantially without slippage. In other words, the entire drive train of the linear actuating device is preferably designed to be at least substantially completely form-fitting, so that no slippage can occur between the individual components. This can improve the positioning accuracy of the carriage along the actuating axis. A target position can therefore be approached more easily by the carriage. The positioning accuracy achieved in this way is advantageous, especially in dynamic applications in which the position of the carriage along the actuating axis is changed quickly, in particular during changes of direction.

[0034] Slippage-free operation requires that all drive train components are appropriately designed and interconnected. It is advantageous for the torque transmission device to incorporate a toothed belt. This can be made of rubber and pre-tensioned so that the rotor shaft or, if present, the drive shaft is coupled to the spindle without slippage. The elasticity of the toothed belt can be utilized here. A suitable belt tensioner can be provided to tension the toothed belt. Furthermore, slippage in the drive train can be avoided even when coupling the carriage to the spindle by using a ball screw and one or more spindle nuts, as described above. In principle, this advantage can be achieved with any type of threaded spindle.

[0035] Furthermore, to prevent slippage, it is advantageous if the drive train components and their attachment to the support component are highly rigid. The support component, the mounts of the drive device and the spindle, the carriage, and / or the at least one guide rail are therefore preferably made of metal, in particular stainless steel or aluminum. The spindle is preferably made of stainless steel, in particular machine steel. Like the at least one guide rail, it is preferably a standard part, thus enabling cost savings.

[0036] To ensure the most precise positioning of the carriage along the positioning axis, the linear positioning device preferably has a measuring device comprising a drive measuring means configured to measure a rotational angle of the rotor shaft of the drive device. The drive measuring means can be or comprise a resolver. Additionally or alternatively, the drive measuring means can be or comprise an encoder. The rotational angle of the rotor shaft can therefore be determined by the drive measuring means. Alternatively or additionally, it is conceivable that the drive measuring means, if the torque transmission device has a drive shaft as an intermediate stage, is configured to measure a rotational angle of the drive shaft.If the transmission or reduction 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. It is conceivable that the drive measuring device is an incremental encoder or an absolute encoder, or includes one. It can be mounted as part of the drive system or separately on the support component.

[0037] Additionally or alternatively, the measuring device can comprise a slide measuring device configured to measure a position and / or a distance traveled by the slide along the adjustment axis. This can be a measuring device for detecting an absolute position or a relative position of the slide along the adjustment axis. In the latter case, a starting point is required to determine the actual position of the slide along the adjustment axis, from which starting point the actual absolute position of the slide can be determined using the determined relative position. For this purpose, at least one position sensor, in particular a light barrier, can be provided. The position sensor can be mounted on the carrier component, on the slide, or on the at least one guide rail.It can be started by appropriately controlling the drive device at the beginning of the operation of the linear actuator, in particular once, in order to calibrate the slide measuring device.

[0038] The measuring device preferably comprises a drive measuring device and a slide measuring device. The resulting redundancy can improve the fault tolerance of the measuring device. This is particularly advantageous when particularly precise positioning of the slide along the positioning axis is required with the linear actuating device. For this purpose, the linear actuating device can comprise a control device by means of which it is configured to compare measurement results of the drive measuring device with measurement results of the slide measuring device and, depending on the comparison, to evaluate the functionality of the measuring device and / or the linear actuating device. The internal control device can be mounted on the carrier component.Additionally or alternatively, the linear actuator can be configured by means of an external control device 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 means of which it can be coupled to the external control device. Such an external control device can be, for example, a central computer of a medical device.

[0039] "Measurement results" can be understood as the measurement data determined using the drive and slide measuring device. In the case of the drive measuring device, this means the angle of rotation of the rotor shaft and / or the drive shaft, and in the case of the slide measuring device, this means the position and / or the distance traveled by the slide along the adjustment axis. It is also conceivable that each "measurement result" refers to a probable position of the slide along the adjustment axis determined based on this data—i.e., a position at which the slide would have to be, assuming that the data was recorded correctly.

[0040] The control device, regardless of whether it is a component of the linear actuator or connected to the linear actuator as an external control device, enables a comparison of the measurement results from both measuring devices. If the measurement results match, the actual position of the slide can be determined based on the measurement results. If, however, they do not match, the presence of an operating error in the measuring device and / or the linear actuator can be detected. It is therefore advantageous if the control device is also configured to control the drive device. This allows the operation of the linear actuator to be stopped automatically upon detection of an operating error, in particular with the output of a warning message.Such a warning can be issued, for example, as a visual and / or acoustic signal on the medical device and / or on an operating system for, in particular, external operation of the medical device and / or a patient bed coupled to the linear actuator. The control device can also be configured to issue a warning even if it is not configured to control the drive device.

[0041] As mentioned, the linear actuating device can preferably have at least one control interface that is configured for electrical current transmission and / or data transmission between the linear actuating device and the medical device or between the linear actuating device and the patient bed. The linear actuating device, in particular the drive device and / or the measuring device and / or the control device, can thus be supplied with current by the medical device. Additionally or alternatively, data exchange, in particular of the aforementioned measurement results, is possible between the linear actuating device and the medical device and / or between the linear actuating device and the patient bed. It is conceivable in this case that the drive device of the linear actuating device can be controlled by a control panel and / or a central computer of the medical device.It is also conceivable that the drive device of the linear actuator can be controlled by a control panel on the patient couch.

[0042] 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.

[0043] The functional component can be any component configured to achieve the intended purpose of the medical device. For example, a gantry or any component configured for medical imaging and / or irradiation is conceivable. The functional component can preferably be a component that includes a beam generator for generating radiation, in particular photon and / or electron radiation of high radiation intensity.

[0044] In particular, the linear actuator according to the invention, as described above, is coupled to the functional component of the medical device by means of the fastening interface. It is conceivable, for example, that the support component of the linear actuator has suitable bores through which it can be screwed to or into the functional component.

[0045] Furthermore, it is preferred that the medical device comprises a patient support for supporting a patient, wherein the patient support is coupled or can be coupled to the carriage of the linear adjustment device by means of the coupling means. The patient support can therefore be coupled to the carriage of the linear adjustment device either permanently or reversibly by the coupling means. It is conceivable that the patient support is a mobile patient support that is coupled to the carriage of the linear adjustment device 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 support can have a suitable, in particular magnetic and / or (electro-)mechanical, coupling.

[0046] The patient bed is preferably movable along the adjustment axis by means of the linear adjustment device, wherein the adjustment axis is oriented perpendicular to a longitudinal axis of the patient bed. The longitudinal axis of the patient bed is understood to be the axis along which the patient bed has its greatest extent. It is common for patients to be pushed into and out of the medical device along this longitudinal axis during examination and / or treatment with a medical device, for example a magnetic resonance device. If the adjustment axis of the linear adjustment device is oriented perpendicular to the longitudinal axis of the patient bed, in particular in the horizontal direction, then in addition to the forward and backward movement along the longitudinal axis, a lateral movement of the patient bed to the left and right is also possible, thus providing more freedom of movement.

[0047] The medical device is preferably a device for medical irradiation of a patient, in particular a radiation therapy device. As mentioned above, the functional component can preferably comprise a radiation generator configured to generate radiation, in particular photon and / or electron radiation of high radiation intensity. For example, the functional component can be or comprise a gantry in which the radiation generator is movably guided. In medical irradiation or radiation therapy, the precise positioning of the patient bed, which is enabled by the linear adjustment device according to the invention and which is better secured against unintentional displacement, is particularly advantageous.Here, it is not uncommon to have to position the patient bed at least once during the treatment of the patient transversely to the longitudinal axis of the patient bed, i.e. laterally or to the side, for example in order to be able to irradiate a specific, non-central part of the patient's tissue.

[0048] Typically, a central computer of the radiotherapy facility calculates treatment plans that relate to the patient's position relative to the target tissue. The central computer can be provided as a component of the functional component. The linear actuator is therefore preferably coupled to the functional component, in particular its central computer, via a control interface. The drive device of the linear actuator can then be controlled by the central computer according to the treatment plan(s). This allows the patient bed to be moved to at least one position specified by the one or more treatment plans.

[0049] In principle, the linear adjustment device according to the invention can also be installed in any other medical device in which a corresponding positioning of a patient bed perpendicular to its longitudinal axis is necessary or advantageous.

[0050] Further advantages and details of the present invention are explained below using exemplary embodiments with reference to the figures. These are schematic representations and show: Fig. 1 an embodiment of a medical device according to the invention with a functional component, a linear actuator according to the invention and a patient bed, and Fig. 2 a sectional view through the medical device according to the invention of Fig. 1 with a view of the linear actuator according to the invention.

[0051] Fig. 1 shows an embodiment of a medical device 1 according to the invention for examining and treating a patient. In the present case, the medical device 1 is a radiation therapy device. It comprises a gantry 2 as a functional component. In other embodiments, any other functional component configured to achieve the (treatment) goal or purpose of the medical device 1, such as imaging or radiation treatment or the like, is conceivable instead of the gantry 2. In addition to the gantry 2, the medical device 1 comprises a patient bed 3 with a patient support plate 4 and a support surface 5 for supporting a patient. The patient bed 3 is configured to move the patient support plate 4 along a longitudinal axis 6 of the patient bed 3. The patient support plate 4 (with a patient) can thus be moved into and out of the tube 7.

[0052] The patient bed 3 is coupled to the functional component or gantry 2 by an embodiment of a linear actuator 8 according to the invention of the medical device 1. To illustrate the structure and function of the linear actuator 8, Fig. 2 a sectional view through the medical device 1 of the Fig. 1 with a view of the linear actuator 8.

[0053] Based on Fig. 2 it becomes clear that the linear actuator 8 has a plate-like support component 9 with a fastening interface 10. The support component 9, and thus the linear actuator 8, is fixed to the gantry 2 by means of several holes 11 and screws 12 forming the fastening 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 adjustment axis 14. A carriage 15 is mounted thereon by means of a sliding bearing 16 or a sliding bearing means 16, such that the carriage 15 is movable along the adjustment axis 14 relative to the support component 9. The carriage 15, in turn, has a coupling means 17, which in this case comprises several holes 11 and screws 12 and by means of which the patient support 3 is coupled to the carriage 15 (In Fig.2, the patient bed 3 is “cut off” in the area of ​​the coupling.

[0054] The linear adjustment device 8 thus represents the link between the gantry 2 and the patient support 3. The linear adjustment device 8 allows the position of the patient support 3 to be adjusted laterally along the adjustment axis 14 oriented perpendicular to the longitudinal axis 6. For this purpose, the linear adjustment device 8 has a drive device 18 by which a spindle 19, in this case a recirculating 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 adjustment axis 14 can be continuously adjusted by rotating the spindle 19. The carriage 15 is guided on the guide rail 13.

[0055] Both the drive device 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 comprise a rolling bearing 27, by which the spindle 19 is attached to the support component 9 so that it can rotate about its longitudinal axis.

[0056] The drive device 18 in this case comprises an electric motor 21 with a rotor shaft. This is coupled to a drive shaft 23 by means of a gear 22 of a torque transmission device 28. The drive device 18 further comprises a brake 24, in this case a friction brake, which engages the rotor shaft of the electric motor 21 and is configured to apply a braking torque to the rotor shaft and, via the gear 22, also to the drive shaft 23, in order to thereby decelerate or lock the movement of the carriage 15 along the actuating axis 14. By reducing the gear 22 between the rotor shaft and the drive shaft 23, the braking torque generated by the brake 24 on the drive shaft 23 is amplified.

[0057] 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 gear 22, a gear 29 connected in a rotationally fixed manner to the drive shaft 23, a gear 30 connected in a rotationally fixed manner to the spindle 19, and a toothed belt 31, the teeth of which mesh with the teeth of the two gears 29, 30. The gears 29 and 30 are selected such that a further reduction ratio is present between the drive shaft 23 and the spindle 19, which further amplifies the braking torque of the drive shaft 23 acting on the spindle 19.

[0058] Finally, the geometry of the spindle 19 and the spindle nut 20 results in a further reduction of the braking torque acting on the carriage 15 through the spindle 19, or the braking force acting on the carriage. Overall, the braking torque with which the rotor shaft of the electric motor 21 can be acted upon by the brake 24 is thus reduced several times along the drive train of the linear actuator 8. As a result, a very high holding force can be exerted on the carriage 15 by means of the brake 24, which makes it impossible or very difficult to move it along the adjustment axis 14. Due to the reduction of the braking torque of the brake 24 resulting from the design of the drive train, the position of the patient couch 3 along the adjustment axis 14 is particularly well secured against unintentional displacement.In particular, compared to conventional linear motors, the linear actuator 8 offers significantly greater safety, while at the same time eliminating the need for large, costly brake shoes.

[0059] In other designs, the drive shaft 23 and the gear 22 can also be omitted. In this case, the gear 29 can be attached directly 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 gear reduction achievable with the drive train.

[0060] Some components of the linear actuator 8 are provided as standard components, particularly standard parts, which results in simple and cost-effective production. Specifically, the spindle 19, the drive mechanism 18, the toothed belt 31, the guide rail 13, and the bearings 16, 17 are provided as standard components or purchased parts.

[0061] The linear actuator 8 further offers the property and advantage that the force for moving and braking, in particular for locking, the carriage 15 along the adjustment axis 14 can be transmitted from the drive device 18, specifically the rotor shaft, to the carriage 15 with at least substantially no slippage. This makes it possible to position the carriage 15, and thus the patient support 3, particularly precisely along the adjustment axis 14. This is particularly advantageous in dynamic applications with a high movement speed of the carriage 15.

[0062] The drive train of the linear actuator 8 is configured accordingly. In detail, the support component 8 as well as the mounts 25, 26 of the drive device 18 and the spindle 19 are designed to be particularly rigid. Furthermore, the carriage 15 is guided on the guide rail 13 with at least substantially no play. By using the V-belt 31 for torque transmission, slippage can be at least substantially avoided when coupling the rotor shaft or the drive shaft 23 to the spindle 19. The same applies to the coupling of the carriage to the ball screw 19 via the spindle nut 20.

[0063] To further improve the positioning accuracy of the carriage 15 along the actuating axis 14, the linear actuator 8 has 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 rotational angle of the drive shaft 23. An encoder could also be conceivable as the drive measuring device 33. The resolver 34 outputs the current rotational angle of the rotor shaft as the measurement result. In other embodiments, it would be conceivable, additionally or alternatively, for the drive measuring device 33 to be configured to measure a rotational angle of the drive shaft 23 of the electric motor 21.

[0064] In addition, the measuring device 32 comprises a slide measuring device 35, which is configured to output a distance traveled by the slide 15 along the adjustment axis 14 as a measurement result. The measuring device 32 further comprises a position sensor 36, in this case a light barrier 37, by which a zero position or zero position of the slide 15 along the adjustment axis 14 can be determined.

[0065] To control the drive device 18 and to evaluate the measurement results of the measuring device 32, in particular the drive measuring device 33 and the slide 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 device 39 of the gantry 2, in this case a central computer 40. At the start of operation of the linear actuator 8, the control device 39 moves the slide 15 once over the light barrier 37 in order to calibrate the measuring device 32 and establish the zero position of the slide 15 along the actuating axis 14. The control device 39 is configured to compare the measurement results of the resolver 34 with those of the slide measuring device 35 during operation of the linear actuator 8. If these match, operation of the linear actuator 8 continues.However, if they do not match, operation is automatically interrupted, with a visual warning being issued on a control panel 41 of gantry 2 and an external computer 42 configured to control and monitor medical device 1. An example of such a warning is: "Error in the lateral adjustment of the patient bed." An acoustic warning tone could also be issued.

[0066] The linear actuator 8 is also powered by the gantry 2 via the control interface 38.

[0067] It is also worth emphasizing that the support component 9 is designed to hold all other components and parts of the linear actuator 8. This allows the linear actuator 8 to be preassembled as a module before being mounted to the gantry 2 at a later time using the mounting interface 10. This has particular logistical and production-related advantages.

[0068] The linear actuator according to the invention can generally be provided in any medical device, particularly in medical devices where precise linear movement, such as that of a patient bed, and / or a high degree of security of the patient bed against unintentional displacement is preferred. Use in a magnetic resonance imaging or computed tomography device is conceivable, for example.

[0069] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0070] 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: - a carrier component (9) having a fastening interface (10) for mechanically coupling the linear actuator (8) to the medical device (1), - a carriage (15) movable relative to the support component (9) along an adjusting axis (14) with a coupling means (17) for, in particular reversibly, mechanical coupling of a patient bed (3) to the linear adjusting device (8), - a drive device (18) which is fixed to the carrier component (9) and - a spindle (19) rotatable by the drive device (18) and coupling the carriage (15) to the drive device (18), wherein a position of the carriage (15) relative to the carrier component (9) along the adjusting axis (14) can be adjusted by rotating the spindle (19) by means of the drive device (18). [2] Linear actuator (8) according to claim 1, characterized by that the spindle (19) is a threaded spindle, in particular a ball screw. [3] Linear actuator (8) according to one of the preceding claims, characterized by at least one guide rail (13) to which the carriage (15) is movably coupled for guidance along the adjusting axis (14). [4] Linear actuator (8) according to one of the preceding claims, characterized by that the drive device (18) has a motor (21) with a rotor shaft for rotating the spindle (19) and a brake (24) acting on the rotor shaft for braking and / or locking the rotation of the spindle (19). [5] Linear actuator (8) according to claim 4, characterized byin that the drive device (18) has a torque transmission device (28) which is designed 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 gear (22). [6] Linear actuator (8) according to claim 4 or 5, characterized by that a reduction between the rotor shaft and the carriage (15) is predetermined or adjustable by the spindle (19) and / or the torque transmission device (28). [7] Linear actuator (8) according to one of the preceding claims, characterized by that the linear adjusting 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 actuator (8) according to 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 traveled path of the slide (15) along the adjusting axis (14). [9] Linear actuator (8) according to claim 8, characterized by that the linear actuating device (8) is set up by means of a control device (39) of the linear actuating device (8) and / or by means of an external control device (39) to compare measurement results of the drive measuring means (33) with measurement results of the slide measuring means (35) and to evaluate a functionality of the measuring device (32) and / or the linear actuating device (8) depending on the comparison. [10] Linear actuator (8) according to one of the preceding claims, characterized by at least one control interface (38) which is designed for electrical current transmission and / or data transmission between the linear actuating device (8) and the medical device (1) or the linear actuating device (8) and the patient bed (3). [11] Linear actuator (8) according to one of the preceding claims, characterized by that the linear actuating device (8) can be pre-assembled, wherein the carrier component (9) is designed to hold all other components of the linear actuating device (8). [12] 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). [13] Medical device (1) according to claim 12, characterized by that the medical technology device (1) comprises a patient bed (3) for supporting a patient, wherein the patient bed (3) is coupled or can be coupled to the carriage (15) of the linear actuating device (8) by means of the coupling means (17). [14] Medical device (1) according to claim 13, characterized by that the patient bed (3) is movable along the adjusting axis (14) by means of the linear adjusting device (8), wherein the adjusting axis (14) is oriented perpendicular to a longitudinal axis (6) of the patient bed (3). [15] Medical device (1) according to one of claims 12 or 14, characterized by that the medical technology device (1) is a device for the medical irradiation of a patient, in particular a radiotherapy device.

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