Gas dosing unit for gas supply to cryoinstrument

Abstract

To provide a gas dosing unit capable of operating a cryoinstrument after starting with desired cooling power without delay even when the temperature of a gas storage is low.SOLUTION: A gas dosing unit 10 is configured to adjust a desired gas flow and includes a pressure control module having a pressure reduction device. In a case of a normal room temperature, a control device controls the pressure reduction device for adjusting a desired pressure or a desired gas stream. If the room temperature and / or the temperature of the connected gas storage 12 is lower and accordingly, the gas pressure applied at an inlet connection 15 of the gas dosing unit is insufficient for the correct operation of the pressure control module, the control device activates a compressor arranged in a gas path, which increases the pressure upstream of the pressure control module to a value appropriate for the correct operation of the pressure control module. In doing so, a cryoinstrument 11 can be correctly activated and used independent of the room temperature and the pressure inside the pressure storage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas input unit configured for gas supply of a cryoinstrument, as well as to a combination of a gas input unit, a gas storage device and a cryoinstrument, which can be used, for example, for biopsies or for other medical purposes, such as cryoablation. [Background technology]

[0002] The gas input unit according to the invention supplies the freezing device with a gaseous coolant, in particular CO 2 , N 2 The cryoinstrument serves to deliver O, or another gas suitable for cryogenic production, in particular at least a triatomic gas. The cryoinstrument operates according to the freezing principle, according to which the instrument tip, which is in contact with the living tissue, is cooled, whereby the tissue freezes and adheres to the instrument tip. In this way, the tissue attached to the instrument tip can be extracted from the patient by the instrument, for example for further examination or for other purposes.

[0003] For the supply of cryoablation devices, US 2022 / 0068929 A1 discloses a gas supply device having a compression vessel with a flexible wall dividing its interior into two compartments, where application of pressure to one compartment allows the medium present in the other compartment to be pressurized and supplied to a gas consumer.

[0004] For supplying compressed gas to a freezing tool and for cooling its tip by the Joule-Thomson effect, WO 2004 / 064914 discloses a gas input unit in which gas returning back from the tool under low pressure is compressed by a compressor and then supplied again at high pressure to the tool via a so-called flow regulator.

[0005] In addition, EP 3854334 A1 discloses a gas input unit for the gas supply of a freezing appliance. The input unit comprises an inlet connection for a gas storage device and an outlet connection for the appliance. A pressure control module is arranged between the inlet and outlet connections. It comprises a pump, which can be configured for example as a double-acting piston pump, which is configured to supply gas from the pressure storage device into the buffer vessel. The buffer vessel is assigned a temperature regulation device which serves to heat or cool the buffer vessel. In addition, the pressure control module comprises a pressure control valve for supplying gaseous coolant from the buffer vessel to the outlet connection and thus to the appliance in a specific and controlled manner. The control device is thereby configured to detect the pressure and / or temperature in the buffer vessel and to control its temperature regulation.

[0006] Especially when using a freezing instrument during a biopsy, a very rapid activation of the probe is often desired in order to keep the time required for the biopsy short. For example, since a typical application of a biopsy probe lasts only 3-5 seconds, the freezing power at the instrument tip after activation of the gas injection unit should be provided as immediately as possible.

[0007] The gas serves primarily as a coolant for operating cryo-instruments that exhibit a strong Joule-Thomson effect and therefore a distinct cryogenic evolution upon expansion. Such gases include CO 2 or N 2 O. Other triatomic or polyatomic gases also work well, especially those with polar molecules.

[0008] Typically, such gas is taken from a pressure storage device, such as a gas bottle, where the gas is supplied in liquefied form under pressure. Typically, this gas is supplied to the freezing instrument via a pressure control module, which shows that the freezing power of the freezing instrument may start to delay after activation if, for example, the temperature of the gas storage device falls below the temperature limit due to low room temperature or for other reasons. For example, at room temperatures below about 18°C, the freezing power of the freezing instrument may start with a delay or remain below the required power. Finally, this may extend the required application period or make application impossible, which is rejected by the therapist. Particularly, this is of concern for instruments that are significantly long and thin. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Application Publication No. 2022 / 0068929 [Patent Document 2] International Publication No. 2004 / 064914 [Patent Document 3] European Patent Application Publication No. 3854334 Summary of the Invention [Problem to be solved by the invention]

[0010] In view of the above, an object of the present invention is to provide a gas input unit that allows the freezing tool to operate with the desired cooling power after startup without delay even when the temperature of the gas storage device is low. [Means for solving the problem]

[0011] This object is solved by a gas dosing unit as claimed in claim 1.

[0012] The gas input unit according to the invention comprises a pressure control module arranged between an inlet connection and an outlet connection. A gas storage device can be connected to the inlet connection and a freezing appliance can be connected to the outlet connection. The pressure control module is configured to direct the gas from the inlet connection to the outlet connection, whereby the gas flows through the pressure reducing device. At least one pressure sensor is arranged upstream of the pressure reducing device to measure the gas pressure of the gas supplied to the pressure reducing device and to compare it with a limit value Pmin. The control device is configured to start the compressor to increase the pressure of the gas supplied to the pressure reducing device above the limit value Pmin if the pressure of the gas from the gas storage device falls below the limit value Pmin.

[0013] The compressor is connected to and driven by a motor, the motor being connected to a control device that operates the motor at a variable rotational speed set by the control device, whereby the control device, coupled simultaneously to the at least one pressure sensor, is configured to cause the compressor to increase a sufficiently high pressure so that the pressure reducing device provides a desired amount of controlled gas flow to the freezing appliance.

[0014] Furthermore, the control device can be configured to drive the motor and the compressor together, i.e. start, only when a start switch, which is located on the instrument or separate from the instrument and is connected to the control device, is activated. In doing so, it can be ensured that the compressor only runs to start the instrument, but does not start during the downtime. This allows the buffer volume between the compressor and the downstream valve (start valve) to be omitted and also the line volume present therein to be minimized. This, on the other hand, allows a more rapid pressure rise to be achieved when the compressor starts. This also contributes to noise reduction and thus quieter in the patient. In addition, examples of compressors that run particularly smoothly are preferred, in which case they have at least two or more pistons. It has been shown that a compressor that runs slowly, with a maximum rotational speed of less than 300 rpm, runs particularly smoothly, which has an approximately square bore-to-stroke ratio and whose connecting rod is at least 5 times, better 7-8 times, longer than the crank radius of its crankshaft. The crank radius is identical to the eccentricity of the crank pin of its crankshaft.

[0015] In a preferred embodiment, the freezing tool comprises a gas feedback line connected to a gas input unit. The gas input unit comprises a gas path for the fed back gas, in which a mass flow sensor is arranged. The gas path is preferably connected to a pressure control module for adjusting the pressure of the gas fed back to the freezing tool to a value that matches the desired mass flow value. The control device of the pressure control module is configured to compare the desired mass flow rate with the actual measured mass flow rate and to increase or decrease the pressure of the gas supplied to the tool to establish a desired equivalence between the desired mass flow rate and the measured mass flow rate. In particular for very thin and / or very long tools, the pressure required for this purpose may be significantly higher than the pressure provided by the gas storage device. In this case, the control device is configured to start the compressor.

[0016] In another possible embodiment, the pressure control module comprises a first pressure sensor between the inlet connection and the compressor and a second pressure sensor between the compressor and the pressure reducing device. Both pressure sensors are preferably connected to the control device. Furthermore, the pressure reducing device may have a controllable valve, the actuator of which is connected to the control device.

[0017] The flow measurement device can be located between the valve and the outlet connection or in the gas feedback line as described above. For example, the flow measurement device can comprise a throttle and pressure sensors located upstream and downstream of the throttle. Other configurations are possible, such as impeller, ultrasonic or thermal measurement. For example, one of the pressure sensors can be located between the valve and the throttle and the other pressure sensor can be located between the throttle and the outlet connection. Both pressure sensors can be connected to a control device. The control device can be configured to adjust the valve so that there is a desired pressure drop across the throttle and therefore a desired mass flow rate to feed the freezing tool.

[0018] The valve controlled by the control device may have a closed position and an open position, and preferably intermediate control positions where the valve throttles more or less the gas stream flowing therethrough, such that the valve is configured to keep the mass flow rate of gas towards the instrument constant, thereby eliminating pressure pulsations that result or may result from operation of the compressor.

[0019] The control device can have different operating modes. After start-up, by activation of the start-up switch, the control device can first check whether the pressure upstream of the valve exceeds a minimum pressure. This pressure can be detected by the first pressure sensor or possibly also by the second pressure sensor. The control device can be configured to operate the compressor motor first at a preset, preferably highest possible, rotation speed if the pressure falls below the minimum pressure Pmin. The control device can be configured to be in this operating mode for a defined time phase, for example 1 or 2 seconds. However, it is also possible to exit this operating mode and change to a second operating mode as soon as the pressure monitored by a second pressure sensor in the line between the compressor and the pressure reducing device reaches a maximum pressure Pmax. While the motor speed is maintained at a specific value in the first operating mode, the control device can be configured to control the motor speed in the second operating mode depending on the desired pressure in the line between the compressor and the pressure reducing device. In doing so, a sufficient pressure is always provided to the pressure reducing device in order to supply the required mass flow rate of gaseous cryogenic fluid to the freezing appliance.

[0020] The control device can be configured to operate in a third operating mode in which the motor is not driven and the compressor is stationary. The control device can use the pressure detected by the first and / or second pressure sensor for this purpose. If the pressure of the gas supplied by the gas storage device is between the minimum pressure Pmin and the maximum pressure Pmax, a sufficient output pressure for the correct operation of the pressure reducing device is provided. The gas flow can then flow through the working space of the inoperative compressor (whose piston is therefore immovably stationary) or through a bypass unblocked for this purpose to the valve, by which the control device then controls the desired gas stream.

[0021] Further details of embodiments of the invention are the subject of the drawings as well as the associated description or dependent claims.

[0022] The drawings show embodiments of the invention. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a schematic diagram of a gas input unit with a freezing tool connected thereto. [Diagram 2] FIG. 2 is a schematic diagram of a gas input unit. [Diagram 3] 11A and 11B are diagrams for explaining the operation of components of a gas supply unit. [Figure 4] FIG. 2 is a schematic diagram of a portion of the compressor and pressure reducing device. [Diagram 5] FIG. 13 shows an alternative configuration of a gas input unit according to the invention; [Figure 6] FIG. 13 is another diagram showing an alternative configuration of a gas input unit according to the present invention. [Figure 7] FIG. 13 is another diagram showing an alternative configuration of a gas input unit according to the present invention. [Figure 8] FIG. 13 is another diagram showing an alternative configuration of a gas input unit according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In Fig. 1, a gas input unit 10 is shown which serves to supply a freezing tool 11 with gas from a gas storage device 12. The gas storage device 12 can be, for example, a gas bottle in which the gas serving to supply the tool 11 is provided liquefied under pressure. A typical gas for this purpose is CO2, which has a boiling point significantly below 0°C. 2 , N 2 O or other polyatomic gas. The pressure present in the gas storage device 12 is typically between 40 and 60 bar.

[0025] The gas storage device 12 comprises a connection 13, preferably without an intermediate pressure reducing valve connection, through which a line 14 leads to an inlet connection 15 of the gas input unit 10. The gas input unit 10 additionally comprises an outlet connection 16 to which the freezing tool 11 is connected, via which the latter is supplied with gas for the cryogenic cooling of its tip 17.

[0026] In particular, the freezing instrument 11 is an elongated flexible instrument having a probe hose that is closed at its tip 17 by an end piece, typically made of metal, where a capillary opens out from which the gas supplied by the gas input unit 10 emerges, thereby expanding and thus cooling the tip 17 of the freezing instrument 11 from the inside by the Joule-Thomson effect. This allows temperatures well below 0° C. to be reached so that the tissue can freeze and adhere strongly to the tip 17.

[0027] The outer diameter of the freezing instrument 11 may be less than 2 mm. The lumens provided therein and the capillaries arranged therein are therefore narrowed. The length of the freezing instrument 11 may significantly exceed 1 m. Also, outer diameters less than 1 mm and / or lengths greater than 2 m are possible, the gas pressure of the supplied gas must be sufficiently high to overcome the resulting flow resistance. A freezing instrument having a length of at least 1.5 m, 2 m or up to 2.50 m or more is suitable for extracting tissue samples (biopsies) in the bile duct of a patient, especially if it has an outer diameter less than 2 mm or less than 1 mm. The invention also extends to carrying out such a biopsy with the freezing instrument 11 and gas input unit 10 of the above-mentioned configuration. Such a freezing instrument 11 may be adapted to pump CO at a sufficient pressure that may exceed the pressure of the gas storage device 12. 2 (or another suitable gas) to operate particularly advantageously with a gas input unit 10 of the described configuration, which is particularly suited to overcome the increased internal flow resistance due to the length and small diameter of the cryoinstrument 11 and to achieve a cooling effect at its tip 17. Such an elongated cryoinstrument 11 can also be used for biopsies at other locations of a patient's body in other narrow body cavities.

[0028] For a reliable gas supply of the freezing device 11, a gas input unit 10 is provided, the basic configuration of which is clear from Fig. 2. The gas input unit comprises a pressure control module 18 shown in Fig. 2, in which a gas path 19 is formed, which runs from the inlet connection 15 to the outlet connection 16, so that gas passes through the gas path from the inlet connection 15 to the outlet connection 16. The gas path 19 comprises a compressor 20 and, in the flow direction after the compressor, a pressure reducing device 21.

[0029] The compressor is preferably a piston compressor, more preferably a multi-piston compressor, as shown diagrammatically in Fig. 4. Its two cylinders 22, 23 house pistons connected via connecting rods 24, 25 to the crank pins of a crankshaft 26, which can be driven in rotation at a variable rotational speed by a motor 27. The eccentricity of the crank pins of the crankshaft 26 is therefore preferably small compared to the length of the connecting rods 24, 25, which preferably means less than one fifth or one eighth of their length. However, it should be noted that instead of a piston compressor, other compressors can also be used, such as rotary positive displacement pumps, gear pumps or rotary piston pumps.

[0030] The two pistons limit the displacement volume, which can be 1-3 cubic centimeters in total. The adjacent volume V1 of the gas path 19 is shown separately in FIG. 4 by the pressure storage symbol 19'. The volume V1 is at most 5 times the displacement volume of the compressor 20, preferably at most 3 to 4 times. In doing so, it is ensured that the volume V1 is filled and has the required pressure within a few revolutions of the crankshaft 16.

[0031] As is evident from FIG. 2, a number of pressure sensors S1 to S4 are arranged in the gas path 19. A first pressure sensor S1 is arranged between the inlet connection 15 and the compressor 20 and provides a signal characterizing a first pressure P1. A second pressure sensor S2 is arranged between the compressor 20 and the pressure reducing device 21 and provides a signal characterizing a second pressure P2. A third pressure sensor S3 can be arranged in the pressure reducing device between a valve 28 arranged therein and a downstream throttle 29 and provides a signal characterizing a third pressure P3. To determine the mass flow rate, the throttle 29 can be arranged aft and a fourth pressure sensor S4 can be arranged between the throttle 29 and the outlet connection 16. The fourth pressure sensor S4 provides a signal characterizing a fourth pressure P4. The pressure difference P3-P4 determines the mass flow rate. TIFF2025058945000002.tif4169 (hereinafter referred to as m). The valve 28, the throttle 29 and the two pressure sensors S3, S4 are part of the pressure reducing device in this embodiment.

[0032] Valve 28 may be configured as a two-port / two-way valve and may include an actuator 30 for different throttling positions between a closed and an open position, and functions as an actuation valve for unblocking or stopping gas flow.

[0033] The pressure sensors S1-S4 are connected to a control device 31, further configured to control the motor 27 and the actuator 30. The control device 31 can be a computer, a microcontroller or another digital or analog control circuit consisting of one or more units. In addition, the control device can be connected to a display device 32 (FIG. 1) and one or more input means 33, which can be arranged on the housing of the gas dosing unit. Via the display device 32 and the input means 33, the operating conditions can be displayed and pre-set.

[0034] Additionally, the control device 31 is connected to an activation switch 34 (FIG. 2), which may be located on the housing of the input unit 10 as a separate switch, e.g., a foot switch, or may be located on the instrument. On-instrument location is particularly likely when the instrument is provided as a handheld instrument for open surgical applications. In typical use, however, the freezing instrument 11 is provided and configured as an elongated flexible probe for endoscopic use.

[0035] The gas input unit 10 described thus far operates in cooperation with the freezing tool 11 and the gas storage device 12 as follows.

[0036] To set up the gas input unit 10, a first gas storage device 12 is connected to the inlet connection 15, for example by a line 14, and the gas input unit 10 is ready for operation. The gas input unit can thereby be configured as a separate device or as part of a larger device.

[0037] After connecting the gas storage device 12 to the gas input unit 10, gas flows from the gas storage device 12 into the gas path 19 to the closed valve 28 until the pressure P1 detected by the gas sensor S1 substantially corresponds to the internal pressure of the gas storage device 12. In addition, gas can also reach the valve 28 through the check valve of the compressor 20, which is shown diagrammatically in FIG. 4 by a small circle, so that the pressure sensor S2 also detects the respective gas pressure P2 and outputs a respective signal to the control device 31. The gas input unit 10 is now ready to operate.

[0038] For a biopsy or another treatment, the freezing instrument 11 is connected to the outlet connection 16 and guided with its tip 17 to the surgical site. By activating the activation switch 34, the freezing instrument 11 is activated, i.e. it starts to cool. In detail, after receiving an activation signal from the activation switch 34, the control device 31 first checks the pressure P2 at the pressure sensor S2. If this pressure is higher than the minimum pressure Pmin required for the correct operation of the decompression device 21 and the freezing instrument 11, the compressor 20 remains stopped, i.e. the control device 31 does not rotate the motor 27. The control device also outputs a signal to the actuator 30 to open the valve 28. Now the gas flows through the throttle 29 towards the freezing instrument 11 (and from there back or into the environment via an outlet not shown). The pressure sensors S3 and S4 thereby provide signals characterizing the respective pressures P3, P4, from which the control device 31 determines the differential pressure P3-P4 on the throttle 29. To ensure a certain gas flow (liters / minute) to the freezing tool, the control device 31 influences the actuator 30, which in turn gradually opens and closes the valve 28 further. The control device 31, in conjunction with the pressure sensors S3 and S4 and the actuator 30, operates, for example, as a closed loop PID control with the compressor 20 stationary.

[0039] Another operating state exists when the gas pressure P1 and / or P2 at the sensors S1 and / or S2 falls below the minimum pressure Pmin due to a very low temperature in the operating room or in particular the temperature of the gas storage device 12. This operating state is illustrated in FIG. 3. Immediately after initiating the start of the operation by activating the start switch 34, the control device 31 determines that the current gas pressure is below the minimum pressure Pmin by checking the pressure P1 and / or P2 at the sensors S1 and / or S2. The control device 31 is then configured to operate the motor 27 at the maximum rotation speed. In this operating phase, the control device 31 does not operate as a closed-loop PID control as in the other case, but only monitors the pressure P2 at the sensor S2 and thereby does not reduce the motor rotation speed. However, as soon as the pressure at the sensor S2 reaches the maximum pressure Pmax or, for example, a pressure slightly lower than the pressure Pdes sufficient for the operation of the pressure control, the control device 31 ends the operating phase A and transitions to a feedback control of the pressure P2 according to the desired pressure Pdes. This causes the control device 31 to reduce the motor rotation speed and control this speed to operate as a closed loop PID control.

[0040] Since the volume V1 enclosed between the compressor 20 and the valve 28 is relatively small compared to the displacement of the compressor, the pressure fluctuations around the desired value Pdes are still relatively high, as also shown in FIG. 3. However, the control device 31 is configured to adjust these pressure fluctuations by means of the actuator 30 in a second closed control loop. The control device 31 thus forms a first closed control loop for the pressure, for which the compressor rotation speed is controlled. The control device also forms a second closed control loop for the valve 28 for balancing the resulting pressure fluctuations. The time constant of the second closed control loop is preferably significantly shorter than the time constant of the first closed control loop. This results in a smooth pressure progression without fluctuations generated by the compressor 20, the downstream valve 28 at the pressure sensor S3. A constant gas mass flow rate m is thus generated, which means a constant gas flow rate. Also, the rotation speed rpm of the motor 27 and thus of the compressor 20 remains relatively constant.

[0041] In the combination of the operating phases A and B, the instrument 11 is supplied with a gas stream suitable for the application immediately after the start-up of the freezing instrument 11, i.e. after activation of the start-up switch 34, independently of the environmental temperature and independently of the pressure in the gas storage device 12. This allows a precise biopsy and also a fast response of the freezing instrument 11 in the case of very elongated biopsy probes. This is achieved in particular without the need to operate a compressor before the start-up or during the rest phase and without the need to keep the buffer vessel under pressure, so to speak as a precaution. In this way, the noise generation and the energy consumption as well as the weight and volume of the instrument are minimized.

[0042] In the embodiment described above, the compressor 20 is switched on when the pressure P1 applied by the pressure sensor S1 is less than the minimum pressure Pmin and is switched off when the pressure P1 is equal to or greater than the maximum pressure Pmax. If the pressure P1 is intermediate at the beginning of start-up, flow passes through the compressor 20 in that the pressure of gas from the gas storage device 12 is sufficient to open the valve of the compressor 20.

[0043] However, the embodiments described below (FIGS. 5-8) avoid the pressure losses that occur across these valves in that individual bypass channels 35 are each provided for this mode of operation.

[0044] For this purpose, on the basis of all the reference numbers introduced so far and on the basis of the associated explanations, figure 5 shows an embodiment in which a bypass channel 35 bypasses the compressor 20. A valve, in particular a two-port / two-way valve 36, is arranged in this bypass channel 35, which can be put into a closed or open position by means of an actuator 37. For this purpose, the actuator 37 is connected to a control device 31. The control device is configured to stop the motor 27 and to open the two-port / two-way valve 36 by means of the actuator 37 if and as long as the pressure P1 at the pressure sensor S1 exceeds a minimum pressure Pmin.

[0045] Another variant is shown in Fig. 6, where the bypass channel 35 is realised inside the valve 28. The valve is configured for this purpose as a 3-port / 3-way valve, where in a first valve position there is a complete closing of the gas path 19, and in a second valve position the bypass channel 35 is part of the gas path. In a third valve position (shown in Fig. 6) the compressor 20 is part of the gas path.

[0046] Apart from that, the above description applies where appropriate on the basis of the reference signs already introduced.

[0047] A modified embodiment of the gas input unit 10 according to the invention is shown in FIG. 7. The gas input unit 10 is almost identical to the gas input unit 10 according to FIG. 5. The above description therefore applies on the basis of the following: The sensor S4 is configured as a mass flow sensor, which is not necessarily based on the detection of a pressure difference. Other measurement principles of the flow sensor can be used. A second difference is provided in the bypass valve 36, which is configured here as a 3-port / 2-way valve and is arranged between the gas storage device 12 and the compressor 20. This forms a switch that directs the gas flow coming from the gas storage device 12 towards the compressor 20 or via a bypass 35 around the compressor. The valve 36 is controlled by the control device 31. Regarding the functioning of this gas input unit 10, reference is made to the description of the embodiment according to FIG. 5, which applies accordingly.

[0048] Another embodiment of the gas input unit 10 is evident from FIG. 8. The gas input unit 10 shown there is based on the gas input unit according to FIG. 7, the description of which applies here accordingly. However, unlike the gas input unit described above, this gas input unit comprises a feedback channel 38 to which the feedback line 16a of the instrument 11 can be connected. Between the pressurized line leading to the outlet connection 16 and the gas feedback channel 38, a vent valve 39 can be provided, which can be controlled by a control device 38 similar to all other actuators. The sensor S4 can be a mass flow sensor arranged in the feedback line 38, which differs from the embodiment described above. At least optionally, the feedback line can also comprise an additional sensor S4'. Both pressure sensors S4, S4' can be connected to the control device 31. In addition, a sound absorber 40 can be provided in the feedback line 38 leading to the gas outlet.

[0049] Such a gas feedback flow path can also be used in all of the other embodiments according to Fig. 2, 5, 6 or 7. In addition, it is rational to thermostat, in particular heat, the components following the compressor 20, in particular the lines and valves 28, 39, and if necessary the valve 36, to avoid condensation of the compressed gas. For this purpose, a heating device surrounding the respective component can be provided. With or without a thermostat, finally, a gas input unit 10 is provided which can ensure correct operation also in case of low temperature gas bottles, low environmental temperatures, almost empty gas bottles, as well as when using very elongated and / or very long freezing instruments. Such freezing instruments can have lengths of up to 2.55 m or more and diameters of only 1.1 mm to 0.9 mm, or even less, the gas input unit 10 according to the invention being able to reliably overcome the increased flow resistance. Such a probe is particularly suitable also for biopsies or for the treatment of tissues in urology, for example for biopsies, for the diagnosis of suspicious tissues in the upper urinary tract, and also in the field of pneumonia. This is suitable for example for small bronchoscopes with a working channel with a clearance of only 1.2 mm. The invention therefore also relates to the overall arrangement consisting of the instrument 11 and the gas injection unit 10 and to its medical use for biopsies in the field of urology and / or pneumonia.

[0050] The gas input unit 10 according to the invention is adapted to receive a desired gas flow m (in particular CO 2The freezing tool 11 comprises a pressure control module 18 configured to adjust the desired pressure or the desired gas stream and having a pressure reducing device 21. In case of normal room temperature, the control device 31 controls the pressure reducing device 21 to adjust the desired pressure or the desired gas stream. In case of low room temperature and / or low temperature of the connected gas storage device 12, and therefore the gas pressure applied to the inlet connection 15 of the gas input unit 10 is insufficient for the correct operation of the pressure control module, the control device starts the compressor 20 arranged in the gas path, which increases the pressure upstream of the pressure control module 18 by a value suitable for the correct operation of the pressure control module 21. In doing so, the freezing tool 11 can be correctly started and used independently of the room temperature and independently of the pressure inside the pressure storage device 12. Operational limitations that would otherwise be present are avoided. [Explanation of symbols]

[0051] 10 Gas input unit 11 Freezing equipment 12 Gas storage equipment 13 Gas storage device connections 14 Line 15 Inlet connection 16 Outlet Connection 16a Feedback Connection 17 Tip 18 Pressure Control Module 19,19' Gas route Vl is the volume of the gas path between the compressor 20 and the valve 28 20 Compressor 21 Pressure Reducing Device 22,23 Cylinder 24,25 Connecting rod 26 Crankshaft 27 Motor S1~S4 Pressure sensor S4' P1~P4 Pressure at pressure sensors S1...S4 28 Valves 29 Throttle 30 Actuator 31 Control Device 32 Display Devices 33 Input Method 34 Start switch Pmin Minimum pressure Pmax Maximum pressure Pdes Desired pressure m mass flow rate 35 Bypass Channel 36 2 port / 2 way valve 37 Actuator 38 Gas Feedback Channel 39 Vent valve 40 Sound absorber

Claims

1. A gas input unit (10) for the gas supply of a freezing device (11), comprising: an inlet connection (15) to which a gas storage device (12) can be connected; an outlet connection (16) to which a freezing device (11) can be connected; a pressure control module (18) arranged between the inlet connection (15) and the outlet connection (16), characterised in that the pressure control module (18) comprises a compressor (20), a pressure reducing device (21) arranged downstream of the compressor (20) and a control device (31) configured to start up the compressor (20) when a pressure (P2) measured by the pressure reducing device (21) falls below a limit value (Pmin), Gas injection unit.

2. characterised in that the compressor (20) is driven by a motor (27) connected to the control device (31), the control device (31) being configured to drive the motor (27) at a variable rotation speed set by the control device (31).

2. A gas input unit according to claim 1.

3. a first pressure sensor (S1) is arranged between the inlet connection (15) and the compressor (20) and is connected to the control device (31), the control device (31) being configured to monitor a pressure (P1) in a connected gas storage device (12), 2. A gas input unit according to claim 1.

4. a pressure sensor (S2) is arranged between the compressor (20) and the pressure reducing device (21) and is connected to the control device (31), 2. A gas input unit according to claim 1.

5. characterised in that the control device (31) is configured to operate in a controlled operating mode for driving the motor (27) at a preset rotational speed (rpm) and for preset time phases or at least until the pressure (P2), measured between the compressor (20) and the pressure reducing device (21), exceeds a preset minimum pressure (Pmin) and preferably reaches a maximum pressure (Pmax), A gas input unit according to claim 4.

6. the control device (31) is configured to operate in a closed-loop control mode to control the rotational speed (rpm) of the motor (27) according to the pressure (P2) measured by the pressure sensor (S2) in a feedback control manner, A gas input unit according to claim 4 or 5.

7. characterised in that the pressure reduction device (21) comprises a valve (28) arranged between the compressor (20) and the outlet connection (16), 2. A gas input unit according to claim 1.

8. The valve (28) includes an actuator (30) and an open position and a closed position. A gas input unit according to claim 7.

9. the valve (28) and the actuator (30) are configured to assume intermediate positions between the open and closed positions in response to an actuator signal of the control device (31), A gas input unit according to claim 8.

10. the control device (31) is connected to an activation switch (34) and configured to stop the compressor (20) and move the valve (28) to the closed position if the activation switch (34) is not activated. A gas dosing unit according to any one of claims 7 to 9.

11. a third pressure sensor (S3) for detecting a third pressure (P3) and a mass flow sensor (S4) are arranged downstream of the valve (28), the mass flow sensor (S4) being connected to the control device (31), the control device (31) being configured to control the valve (28) in such a way that the mass flow rate (m) at the outlet connection (16, 16a) has a predetermined value, A gas dosing unit according to any one of claims 7 to 9.

12. the control device (31) is configured to stop the compressor (20) when the first pressure (P1) detected by the first pressure sensor (S1) is at least as high as a maximum pressure (Pmax); and / or the control device (31) is configured to stop the compressor (20) when a second pressure (P2) measured by the second pressure sensor (S2) is at least as high as a maximum pressure (Pmax), 2. A gas input unit according to claim 1.

13. the control device is configured to bypass the compressor (20) by means of a bypass channel (35) if the pressure (P1) measured by the first pressure sensor (S1) is higher than a minimum pressure (Pmin); and / or the control device (31) is configured to bypass the compressor (20) by the bypass channel (35) when the pressure (P2) detected by the second pressure sensor (S2) is higher than a minimum pressure (Pmin). A gas dosing unit according to claim 1 or 12.

14. The compressor (20) comprises at least two cylinders (22, 23) having pistons moving in opposite directions.

2. A gas input unit according to claim 1.

15. the compressor (20) has a displacement volume (VK), a line (19') having a line volume (V1) is provided between the compressor (20) and the pressure reducing device (21), and the ratio of the displacement volume (VK) to the line volume (V1) is greater than 1:5, 15. A gas dosing unit according to claim 1 or 14.

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