Braking system for an X-ray examination device

Abstract

Electromechanical braking system for an X-ray examination device (1), comprising a clamping device (7) designed for direct interaction with a C-arm (5) of the X-ray examination device (1), and an energy-generating unit (19) provided for its operation and spatially separated from it, characterized in that the energy-generating unit (19) has a planetary roller gear (23).

Description

[0001] The invention relates to a braking system provided for braking and / or clamping a C-arm in an X-ray examination device. Furthermore, the invention relates to an X-ray examination device with a braking system, in particular an emergency braking system.

[0002] In X-ray examination devices designed as C-arm systems, an adjustable C-arm carries an X-ray source and an associated detector, particularly a semiconductor detector. In principle, C-arm X-ray systems can be used for both projection images and cross-sectional images, i.e., computed tomography. In this context, reference is made to the following publication: J. Rieber et al.: Cardiac Application of C-Arm Computed Tomography, Radiology 2009, Springer Medizin Verlag 2009, DOI 10.1007 / s00117-009-1869-0

[0003] A C-arm of an X-ray examination device, such as a computed tomography system, is typically motor-driven and braked. EP 0 430 338 B1, for example, discloses an X-ray examination apparatus with a friction roller for moving or locking a C-shaped support, i.e., a C-arm.

[0004] Another C-arm X-ray device is known, for example, from DE 10 2011 077 086 A1. A drive unit is provided for driving or braking bearing rollers, by means of which the C-arm of the X-ray device is mounted for movement.

[0005] DE 298 09 676 U1 discloses a hydraulic braking system for a mobile medical device, in particular for a medical X-ray diagnostic device, with a multiply adjustable C-arm. The hydraulic braking system comprises an electric hydraulic pump and hydraulic cylinders in which the hydraulic pressure at the location of a brake, for example, a drum brake, is converted into a mechanical force.

[0006] DE 88 12 768 U1 discloses a mobile X-ray diagnostic device with an adjustable C-arm and locking devices for various adjustable components. The locking devices can be activated either via a central switch or via individual control switches. Electromagnetic brakes are proposed as locking devices, which are closed by spring force when de-energized and can be opened by energizing an electromagnet.

[0007] US Pat. No. 6,113,265 A shows another embodiment of a C-arm device with a C-arm locking mechanism. In this case, a braking device comprises a compressible brake shoe. The braking device is actuated by means of a screw drive.

[0008] A C-arm device with counterweight compensation is known from DE 10 2004 001 460 B4. This assumes that additional components are attached to the C-arm, which, together with the C-arm, exert a torque on the C-arm. To at least partially compensate for this torque, a counterweight is coupled to the C-arm via a gear mechanism. This means that a locking brake exerting only a small force should be sufficient to lock the C-arm in place. Even slight frictional forces, for example, in a gear mechanism designed to adjust the C-arm, should keep the C-arm stable in any position, even without an additional brake.

[0009] The invention is based on the object of providing a braking system for a C-arm X-ray system which is further developed compared to the cited prior art and is particularly suitable as an emergency braking system.

[0010] This object is achieved according to the invention by an electromechanical braking system having the features of claim 1. The electromechanical braking system can be used in an X-ray examination device according to claim 9. The object is further achieved by a method for operating such an electromechanical braking system according to claim 10. The embodiments and advantages of the invention explained below in connection with the devices, i.e., the braking system and the examination device, also apply mutatis mutandis to the operating method, and vice versa.

[0011] The braking system has at least one clamping device designed for direct interaction with a C-arm of an X-ray examination device. In particular, the X-ray examination device is a medical imaging device. In principle, the X-ray examination device can also be used for other purposes, in particular for non-destructive material testing. In any case, an energy-generating unit is provided to operate the clamping device of the electromechanical braking system, which is spatially separated from the clamping device.

[0012] Depending on the design of the X-ray examination device, the spatial separation between the energy-generating unit and the clamping device has, among other advantages, that several clamping devices for different axes of the X-ray examination device can be operated by means of a single energy-generating unit and / or the moving masses of the X-ray examination device are minimized.

[0013] The C-arm of the X-ray examination device is not necessarily rigid. Rather, the C-arm-shaped axis, which is to be braked or clamped using the clamping device, can be designed, for example, as a telescopic unit. The clamping device can be attached to a stationary or to a movable, particularly rotatable, machine part, for example, to another C-arm. The C-arm, which can be locked using the clamping device, is driven by a drive device that is mechanically independent of the clamping device. This makes the electromechanical braking system particularly suitable as an emergency braking system. A toothed belt drive, for example, can be used to drive and regularly brake the C-arm. In the event of a toothed belt break or a power failure, the electromechanical braking system acts as a redundant system, capable of braking the C-arm to a standstill.

[0014] The energy-generating unit of the electromechanical braking system is preferably an electrohydraulic actuator, in particular a hydraulic pump, which is operated, for example, with a silicone oil as the pressure medium. A low-viscosity silicone oil is particularly suitable, as it has favorable aging properties, for example, with regard to resinification.

[0015] The electrohydraulic actuator, to which the at least one clamping device is connected, has a gear that converts rotation into linear motion with a high gear ratio. This is a planetary roller gear. For the design of a planetary roller gear, reference is made to DE 10 2009 040 606 A1.

[0016] The use of a planetary roller gear in the energy-generating unit has the advantage that a sufficiently high hydraulic pressure, for example a pressure of 40 bar, can be generated even with a low drive torque. Despite the integration of a high-ratio gear into the energy-generating unit, the clamping device, in a preferred embodiment, can be used in an even smaller installation space than the energy-generating unit. One possible design of a clamping device, which, with regard to its basic concept, is suitable for use in the electromechanical braking system, is disclosed in DE 198 05 449 A1. However, the braking device known from DE 198 05 449 A1 is not intended for braking an elongated, curved object such as a C-arm, but for braking a support body on a straight guide rail.

[0017] A multi-way valve, in particular a 3 / 3-way valve, is preferably connected between the energy-generating unit of the braking system on the one hand and a clamping device or an arrangement of several clamping devices on the other. The multi-way valve can be combined with the hydraulic pump to form a single structural unit. Likewise, the multi-way valve can be spatially separated from both the hydraulic pump and the at least one clamping device.

[0018] An oil reservoir is preferably connected to the multi-way valve. An emergency position of the multi-way valve is created by applying a force independent of external energy supply, in particular by means of a compression spring. As soon as this emergency position is assumed in the event of a failure of the power supply to the multi-way valve and also of the energy-generating unit, hydraulic medium flows from the clamping device(s) via the multi-way valve into the oil reservoir. At the same time, the at least one clamping device assumes its clamping state, i.e., it fixes the C-arm. A clamping device designed as a spring-loaded brake that can be released by hydraulic pressure against the spring force is particularly suitable for this function.

[0019] The clamping device preferably has exactly one inner brake shoe and exactly one outer brake shoe, with the friction surface of the inner brake shoe being convex and the friction surface of the outer brake shoe being concave. Using a set of different brake shoes, clamping devices for C-arms with different radii can be provided in a modular system. The different brake shoes of one and the same clamping device preferably have different radii of curvature, which adapt them to the geometry of a C-arm.

[0020] The electromechanical braking system preferably operates with a single energy-generating unit, to which several, for example three, clamping devices are connected and controlled in an identical manner. With minimal equipment effort, an emergency braking system can be implemented that simultaneously stops all axes of a C-arm X-ray system in the event of a power failure.

[0021] Overall, the following features can be realized when operating the X-ray examination device with the help of the electromechanical braking system: - Before starting regular operation of the examination device, i.e. before acquiring image data by means of an adjustable arrangement of X-ray source and X-ray detector, a clamping device of the brake system designed as a spring-loaded brake, optionally a plurality of such clamping devices, is released by applying pressure with a pressure medium, in particular hydraulic oil, - during the subsequent regular operation of the examination device, at least one C-arm, which can be braked and blocked by the clamping device, is adjusted by means of a preferably electrically operated drive and guide unit while keeping the clamping device open, - In the event of a power failure, in particular a power failure affecting the drive and guide unit, the clamping device is automatically closed due to its spring force load and the C-arm is thus stopped due to the inevitable, simultaneous loss of power supply to the clamping device, which means a drop in pressure in the pressure medium supply.

[0022] An embodiment of the invention is explained in more detail below with reference to a drawing. In the drawings: Fig. 1 a schematic representation of a computer tomography system designed as a C-arm X-ray system, Fig. 2 in a schematic sectional view of a clamping device of an electromechanical braking system of the computer tomography system, Fig. 3 the clamping device according to Fig. 2 and other components of the electromechanical braking system.

[0023] A computer tomography system, designated overall by reference numeral 1, i.e., an X-ray examination device, is designed as a C-arm X-ray system. The isocenter of the computer tomography system 1 is located between an X-ray source 2 and a detector 3, which are held by a C-arm 5. Furthermore, Fig. 1 a patient bed 4 is indicated.

[0024] The C-arm 5 is adjustably guided by a drive and guide unit 6. In a manner not shown, the C-arm 5 is driven and braked as needed via a toothed belt drive, which is part of the drive and guide unit 6. Additionally, a clamping device 7 is provided, which serves as an emergency braking device for stopping the C-arm 5.

[0025] With regard to the structure of the clamping device 7, reference is made below to the Fig. 2. In a housing 8 of the clamping device 7, there are two brake shoes 9, 10, namely an inner brake shoe 9 and an outer brake shoe 10. An inner friction surface 11 of the inner brake shoe 9 and an outer friction surface 12 of the outer brake shoe 10 are adapted to the shape of the C-arm 5 and interact directly with it. While the inner friction surface 11 is convexly curved, the outer friction surface 12 is concavely curved. The radius of curvature of the inner friction surface 11 is smaller than the radius of curvature of the outer friction surface 12. An inner wedge 13 and an outer wedge 14 are provided for displacing the brake shoes 9, 10 within the housing 8. Pressure chambers 15, 16, which are delimited by components of the clamping device 7 fixed to the housing and by the wedges 13, 14, enable the displacement of the wedges 13, 14 and thus also of the brake shoes 9, 10 with the aid of a pressure medium, namely hydraulic oil.In a manner not shown, the brake shoes 9, 10 are preloaded by spring force in such a way that they are pressed against the C-arm 5 without pressure being applied and thus prevent any movement of the C-arm 5.

[0026] The integration of several clamping devices 7 into a single electromechanical braking system is Fig. 3. A pressure line 18 is connected to a connection opening 17 on the housing 8 of the clamping device 7. In a manner not shown, two further clamping devices 7, the structure of which is also similar to the clamping device 7 according to Fig. 2, connected to the pressure line 18.

[0027] The supply of the electromechanical braking system according to the Fig. 1 to 3 with hydraulic oil is carried out with the aid of an oil pump 19, generally referred to as an energy-generating unit. The oil pump 19 has a pump housing 20, in which, among other things, an electric motor 21 is located. The motor shaft of the electric motor 21, designated 24, introduces a torque via a coupling 25 into a planetary roller gear 23, which is also arranged within the pump housing 20. An axial bearing 30 is provided, among other things, for supporting the motor shaft 24. On the output side, the planetary roller gear 23, which converts the rotation of the motor shaft 24 into a linear movement, is coupled to a piston 22, which is designed as an annular piston and builds up pressure in a likewise annular pressure chamber 26 within the pump housing 20. The oil pump 19 is located at a location separate from all clamping devices 7. For example, this can be a machine cabinet, which is in Fig. 1 is not shown.

[0028] A multi-way valve 27, namely a 3 / 3-way valve, is connected between the pressure chamber 26 and the pressure line 18, which is connected to the clamping devices 7.

[0029] In the switching position of the multi-way valve 27 after Fig. 3, the pressure chamber 26 of the oil pump 19 is connected to the pressure line 18, so that the connected clamping devices 7 are open, i.e. they do not brake the C-arm 5. The switching position according to Fig.3 can only be maintained as long as the 3 / 3-way valve 27 is supplied with electrical power. If the power supply fails, a compression spring 29 of the multi-way valve 27 immediately assumes a different switching position of this 3 / 3-way valve 27, in which hydraulic oil flows from the pressure line 18 back into an oil reservoir 28. This process is accompanied by a blocking of the clamping devices 7, i.e., an emergency braking of the C-arm 5. By pressurizing the pressure line 18, the clamping of the clamping devices 7 can be released at any time. List of reference symbols 1 X-ray examination device 2 X-ray tubes 3 Detector 4 patient beds 5 C-arms 6 Drive and guide unit 7 clamping device 8 housings 9 Inner brake shoe 10 Outer brake shoe 11 Inner friction surface 12 Outer friction surface 13 Inner wedge 14 Outer wedge 15 Printing room 16 Printing room 17 Connection opening 18 pressure line 19 Oil pump, energy generating unit 20 pump housings 21 Electric motor 22 pistons 23 planetary roller gears 24 Motor shaft 25 Clutch 26 Printing room 27 Multi-way valve 28 Oil reservoir 29 compression spring 30 thrust bearings

Claims

[1] Electromechanical braking system for an X-ray examination device (1), comprising a clamping device (7) designed for direct interaction with a C-arm (5) of the X-ray examination device (1), and an energy-generating unit (19) provided for its operation and spatially separated therefrom, characterized by that the energy-generating unit (19) has a planetary roller gear (23). [2] Braking system according to claim 1, characterized by that the energy-generating unit (19) is designed as an electro-hydraulic actuator. [3] Braking system according to claim 2, characterized by that the energy-generating unit (19) is filled with a silicone oil as a pressure medium. [4] Braking system according to one of claims 1 to 3, characterized by a multi-way valve (27) connected between the energy-generating unit (19) and the clamping device (7) and coupled to an oil reservoir (28). [5] Braking system according to one of claims 1 to 4, characterized by that the clamping device (7) is designed as a spring-loaded brake. [6] Braking system according to claim 5, characterized by that the clamping device (7) comprises an inner brake shoe (9) with a convex friction surface (11) and an outer brake shoe (10) with a concave friction surface (12). [7] Braking system according to claim 6, characterized by that the convex friction surface (11) has a different radius of curvature from the concave friction surface (12). [8] Braking system according to one of claims 1 to 7, characterized by that a plurality of clamping devices (7) are connected to the energy generating unit (19). [9] X-ray examination device (1) with an electromechanical braking system according to claim 1. [10] Method for operating an electromechanical braking system according to claim 1, having the following features: - At least one clamping device (7) of the brake system designed as a spring-loaded brake is released by applying pressure with a pressure medium, in particular hydraulic oil, the pressure being applied by means of an energy-generating unit (19) which has a planetary roller gear (23), - a C-arm (5) of an X-ray examination device (1) which can be braked and locked by means of the at least one clamping device (7) is adjusted by a drive and guide unit (6), - in the event of a power failure affecting the drive and guide unit (6), the clamping device (7) is automatically closed due to the loss of power supply and the C-arm (5) is thus stopped.

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