High-voltage tank for high-voltage generation, including a strain gauge for tank pressure measurement

Abstract

A housing for a high voltage tank has a boiler which is open on one side and a circuit board cover which closes the boiler. At least one strain gauge is arranged on or in the circuit board cover such that it is expanded or compressed with a pressure-induced deformation of the circuit board cover. A housing of this type is particularly suited as a high voltage tank for an x-ray emitter. An impermissible pressure in the housing for a high voltage tank can be determined easily and reliably.

Claims

1. A housing for a high voltage tank for high voltage generation, the housing comprising: a boiler being open on one side; a circuit board cover disposed to close said boiler; and at least one strain gauge disposed on or in said circuit board cover such that said at least one strain gauge is expanded or compressed with a pressure-induced deformation of said circuit board cover.

2. The housing according to claim 1, further comprising insulating oil contained on the inside of said housing.

3. The housing according to claim 1, wherein said boiler is a Gastronorm container.

4. The housing according to claim 1, further comprising a test circuit configured to detect changes in a resistance in said at least one strain gauge.

5. The housing according to claim 4, wherein said test circuit comprises a Wheatstone bridge circuit.

6. The housing according to claim 1, further comprising a safety circuit electrically connected to said test circuit and configured to switch off a high voltage generation upon detecting a change in resistance of said at least one strain gauge has reached a limit value.

7. A high voltage tank for high voltage generation, comprising: a housing according to claim 1; and a high-voltage transformer disposed in said housing.

8. A method for operating a high voltage tank, the method comprising: providing a housing according to claim 1 with a high-voltage transformer in the housing; generating high-voltages with the high-voltage transformer; and monitoring the strain gauge of the housing and, when an expansion or a compression of the strain gauge exceeds a predeterminable limit value, switching off the high voltage generation.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows an oblique view of a housing with strain gauges;

(2) FIG. 2 shows a cross-section of a housing with an arched circuit board cover with strain gauges; and

(3) FIG. 3 shows a block diagram of a circuit arrangement for determining a positive pressure in a housing and also indicates the transformer inside the housing.

DETAILED DESCRIPTION OF THE INVENTION

(4) Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a perspective view of a housing, or encasement, of a high voltage tank for high voltage generation. The housing has an upwardly open boiler 1 or vessel, which is sealed in a pressure-tight manner with a circuit board cover 2. Inside the housing, there is disposed a high voltage transformer in an insulating oil 3. A strain gauge 4 is glued to the circuit board cover 2 and is connected to a test circuit (not shown). FIG. 1 does not show an impermissible positive pressure in the housing. The circuit board cover 2 is flat and not arched or deformed. The compensation membranes 7 for pressure compensation are not stressed.

(5) FIG. 2 shows a cross-section taken through a housing according to FIG. 1. Here, the insulating oil 3 inside the boiler 1 is expanded by a rise in temperature and has already completely compressed the compensation membranes 7. The pressure on the inside of the housing is so large that the circuit board cover 2 is arched outwards and as a result expands the strain gauge 4. The change in resistance caused by the expansion can be determined with the aid of the test circuit.

(6) The basic state can be determined and changes detected and assessed by means of the test circuit, having AD converters/FPGA and associated software. Before damage-relevant deformations can occur, the high voltage generation can thus be switched off with the aid of the safety circuit. As a result, the temperature in the inside, which results inter alia in a higher pressure, can be reduced for instance. If a rare age-induced failure of the membranes occurs, this damage can be determined before the insulating oil can escape from the housing. This must be avoided at all costs due to the detrimental environment effects of the insulating oil 3.

(7) The deformation of the circuit board cover 2 and its determination with the strain gauge 4 has been detected experimentally for a 3.2 mm thick circuit board cover 2. In such cases a somewhat parabolic association is indicated between the expansion of the strain gauge 4 and force on the circuit board cover 2.

(8) FIG. 3 shows a block diagram of a circuit arrangement for determining a positive pressure in a housing of FIG. 1 and FIG. 2. The strain gauge 4 is electrically connected to a test circuit 5. The strain gauge 4 rests on the circuit board cover 2 of the housing. The test circuit may have a Wheatstone bridge for assessment. The test circuit 5 is connected to a safety circuit 6, which ensures that the high voltage generation is switched off if a predeterminable pressure in the boiler 1 is exceeded. As a result, the insulating oil can cool down and the pressure decreases. A high voltage transformer 8 is located inside the boiler 1. All in all it is part of a high voltage tank 9 for an x-ray emitter 10.

(9) The HVT typically also contains a sensor for the oil temperature. Since the pressure and temperature are inevitably associated after closing the boiler 1, the P-T curve (in other words the change in the strain gauge 4 as a function of the oil temperature) can be recorded in a calibration step (e.g. during the otherwise necessary testing of the boiler 1), and is continuously monitored during further operation. In this way it is not only an oil loss that can be detected by a leak in the HVT, (the pressure would be too low for the current temperature), but also a gas formation as a result of flashovers in the oil (due to the gas the pressure would be too high for the current temperature). These two problems were previously not detectable using conventional technology (temperature or pressure switch).

(10) Although the invention has been illustrated and described in detail by the preferred exemplary embodiments, the invention is not restricted by the examples given and other variations can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention.

(11) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 1 Boiler, vessel 2 Circuit board cover 3 Insulating oil 4 Strain gauge 5 Test circuit 6 Safety circuit 7 Compensation membrane 8 High voltage transformer 9 High voltage tank 10 X-ray emitter