Economical high-reliability helium compressor bypass structure and control method thereof

Abstract

The application discloses an economical high-reliability helium compressor bypass structure and a control method thereof. The bypass structure comprises a normally open electromagnetic valve and a normally closed electromagnetic valve connected in parallel between the high-pressure side and the low-pressure side of the compressor, and a control system electrically connected with both. The normally open electromagnetic valve is synchronized with the cold head power supply to realize passive bypass and pressure balance when the cold head starts and stops. The normally closed electromagnetic valve is independently controlled by the control system to realize active bypass and adjustment in operation under various control modes such as pressure regulation, pressure difference regulation, cold head abnormal protection and cold head-free test. The application uses general electromagnetic valves with low price and gives them the cooperative control logic of "passive + active", thereby greatly improving the safety, reliability and working condition adaptability of the system operation while significantly reducing the cost.

Description

Technical Field

[0001] This invention relates to a bypass structure for a compressor, and more particularly to an economical and highly reliable bypass structure for a helium compressor and its control method. Background Technology

[0002] Scroll compressors, as a type of efficient and reliable positive displacement compressor, are widely used in the refrigeration and cryogenic fields. In cryogenic refrigeration systems employing the Gifford-McMahon (GM) cycle, the helium compressor is the core power component, and its reliability directly affects the stable operation of the entire refrigeration system.

[0003] To ensure the safety of the helium compressor and its connected cold head (refrigeration unit), a bypass line and control valve are typically installed between the high-pressure discharge side and the low-pressure return side of the compressor. A common solution is to use a normally open solenoid valve as the bypass valve. During normal system operation, this valve is energized and closed; when the system is powered off or the cold head stops, the valve is de-energized and opens, allowing high-pressure gas to flow back to the low-pressure side, achieving pressure balance and providing passive protection.

[0004] However, this single normally open solenoid valve bypass solution has significant drawbacks. Due to limitations in its operating principle, the operating pressure differential (i.e., the minimum pressure difference between the inlet and outlet required for the valve to open reliably) of commonly available, economical normally open solenoid valves is usually small. When the internal pressure difference becomes too large due to system malfunctions or other reasons, the electromagnetic force may not be able to overcome the reverse force generated by this pressure difference, causing the valve to fail to open normally, the protection function to fail, and thus damaging the compressor or cold head. Although there are normally open solenoid valves for hydraulic applications that can meet higher pressure differential requirements, they are expensive and have limited model options, greatly increasing system costs and failing to meet the requirements of an economical design. Summary of the Invention

[0005] Purpose of the invention: The first purpose of the invention is to provide a bypass structure for a helium compressor that achieves active-passive coordinated bypass, effectively ensures the safe operation of the cold head, and significantly improves the reliability and economy of the system. The second purpose of the invention is to provide a control method that applies the bypass structure.

[0006] Technical Solution: The economical and high-reliability helium compressor bypass structure of the present invention includes a control system and a bypass circuit connecting the high-pressure exhaust side and the low-pressure return side of the helium compressor; the bypass circuit is provided with a normally open solenoid valve and a normally closed solenoid valve connected in parallel; the control system is electrically connected to the normally open solenoid valve and the normally closed solenoid valve, and is configured to: control the opening and closing state of the normally open solenoid valve to be synchronized with the start and stop state of the cold head driven by the helium compressor; and actively control the opening and closing of the normally closed solenoid valve according to the system pressure state, the cold head state, or external commands.

[0007] Preferably, the control system includes a control panel and a cold head relay; the normally open solenoid valve is connected to the output terminal of the cold head relay; and the control panel is connected to the normally closed solenoid valve.

[0008] Preferably, the control panel is configured to: when receiving an abnormal shutdown signal of the cold head or a remote control instruction to shut down the cold head, simultaneously control the normally closed solenoid valve to open while controlling the cold head relay to disconnect to shut down the cold head.

[0009] Preferably, the helium compressor bypass structure further includes a high-pressure sensor for detecting the high-pressure exhaust side pressure and a low-pressure sensor for detecting the low-pressure return side pressure.

[0010] Preferably, one end of the bypass circuit is connected to the pipeline between the oil separator and the adsorber of the compressor, and the other end is connected to the pipeline upstream of the buffer tank.

[0011] Preferably, the control panel is configured to: control the normally closed solenoid valve to open when the pressure is higher than a first set threshold, and control the normally closed solenoid valve to close when the pressure is lower than a second set threshold, based on the feedback signal from the high-pressure sensor, wherein the first set threshold is greater than the second set threshold.

[0012] Preferably, the control panel is configured to: control the normally closed solenoid valve to open when the pressure difference is higher than a third set threshold, and control the normally closed solenoid valve to close when the pressure difference is lower than a fourth set threshold, based on the feedback signal difference between the high-pressure sensor and the low-pressure sensor, wherein the third set threshold is greater than the fourth set threshold.

[0013] Preferably, the control panel is also configured to: when set to the no-cold-head test mode, control the normally open solenoid valve to be energized and closed, and control the opening and closing of the normally closed solenoid valve based on the signal from the high-pressure sensor to regulate the system pressure.

[0014] Preferably, a safety valve is installed on the pipeline between the oil separator and the adsorber.

[0015] The control method for the bypass structure of a helium compressor according to the present invention includes:

[0016] The steps for controlling the normally open solenoid valve are synchronized with the start and stop of the compressor-driven cold head;

[0017] And, based on the monitored system status, selectively execute corresponding control logic to operate the normally closed solenoid valve; wherein the system status includes at least one of: high pressure, high-low pressure difference, cold head operating status, and remote command.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) It realizes a dual safety mechanism of passive bypass when power is off and real-time adjustment during operation, which significantly improves the safety and reliability of the system; (2) It supports multiple working modes and can respond to remote commands and fault status, which enhances the flexibility and safety of the system in dealing with faults; (3) It utilizes a combination of low-cost general-purpose solenoid valves to achieve high working differential pressure capability and efficiency improvement while significantly reducing manufacturing costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0020] Figure 2 This is the abnormal protection control logic diagram of the present invention;

[0021] Figure 3 This is the pressure regulation and control logic diagram of the present invention;

[0022] Figure 4 This is the differential pressure regulation control logic diagram of the present invention;

[0023] Figure 5 This is the control logic diagram for the cold head-less test of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0025] As shown in the attached figure, this invention provides an economical and highly reliable helium compressor bypass structure and its control method. The helium compressor system mainly includes a gas circuit system, an independent lubricating oil circuit, a cooling water circuit, and an electrical control system.

[0026] I. System Hardware Configuration and Connections

[0027] 1. The flow chart of the gas path system is as follows:

[0028] After being discharged from the cold head 30, the low-pressure helium gas enters the system through the low-pressure inlet 24, flowing sequentially through the low-pressure sensor 23 and the buffer tank 14. The buffer tank 14 is used to stabilize the airflow. Subsequently, the low-pressure helium gas is drawn in through the suction port 3 of the helium vortex pressurizer 1.

[0029] Inside the helium vortex compressor 1, helium is compressed, increasing its temperature and pressure. The heated and pressurized high-temperature, high-pressure helium is discharged from exhaust port 4, passing sequentially through the third temperature sensor 13, heat exchanger 8, fourth temperature sensor 15, oil separator 18, high-pressure sensor 21, and adsorber 26. The heat exchanger 8 cools the helium, the oil separator 18 separates oil mist from the helium, and the adsorber 26 (such as an activated carbon filter) further adsorbs residual oil, ensuring the cleanliness of the helium entering the cold head. Finally, the clean, high-pressure helium is delivered to the cold head 30 via high-pressure exhaust port 25 for cooling.

[0030] This invention adds a bypass circuit with normally open and normally closed dual solenoid valves to the gas circuit system. The bypass circuit consists of a branch gas pipe extending from the high-pressure pipeline between the oil separator 18 and the adsorber 26. This gas pipe connects to a normally open solenoid valve 19 and a normally closed solenoid valve 20 connected in parallel, and then connects to the low-pressure pipeline upstream of the buffer tank 14. Furthermore, a safety valve 22 is installed on this high-pressure pipeline as a final overpressure protection device.

[0031] 2. The independent lubricating oil circuit includes:

[0032] Main oil return circuit: Under the action of gravity, the lubricating oil discharged from the bottom oil outlet 5 of the helium vortex press 1 flows through the heat exchanger 8 (cooled), the first filter 7 and the first throttling orifice 6 in sequence, and finally returns to the inside of the press 1 from the oil return port 2 to achieve circulation.

[0033] Oil replenishment circuit: The lubricating oil separated from the oil separator 18 is throttled by the second filter 17 and the second throttling orifice 16 in sequence, and then led back to the intake pipe downstream of the buffer tank 14 to replenish the oil volume circulating in the system.

[0034] 3. The cooling water circuit operates independently: Cooling water enters from the cooling water inlet 12, flows through the second temperature sensor 10, the heat exchanger 8 (where it exchanges heat with helium and lubricating oil to cool it), the first temperature sensor 9, and finally exits from the cooling water outlet 11.

[0035] II. Control System and Working Logic

[0036] The control system 27 includes a control panel 28 (such as a PCB circuit board) and a cold head relay 29. The control panel 28 receives signals from components such as the high-pressure sensor 21 and the low-pressure sensor 23, and issues control commands.

[0037] Control of the normally open solenoid valve 19: The normally open solenoid valve 19 is electrically connected to the output terminal of the cold head relay 29. Therefore, its state is completely synchronized with the cold head 30. When the control panel 28 issues a command to start the cold head 30, the cold head relay 29 is energized, the cold head 30 is powered on and running, and at the same time, the normally open solenoid valve 19 is energized and closed. When the cold head 30 is de-energized for any reason, the cold head relay 29 is de-energized, and the normally open solenoid valve 19 is also de-energized synchronously and immediately opens, forming a passive bypass to quickly balance the system pressure.

[0038] Control of the normally closed solenoid valve 20: It is directly controlled by the control panel 28. The control panel 28 actively controls its opening and closing according to the preset program logic, realizing active adjustment and protection during operation.

[0039] The following are some typical control logic implementation scenarios. Among them, for scenarios 2, 3, and 4 below, the "signal monitoring → judgment → action" logic runs continuously in a background loop in the actual system. The termination condition of this loop is that the control panel 28 receives a shutdown command for the entire machine.

[0040] Scenario 1: Cold block malfunction or remote control shutdown

[0041] The specific control logic is shown in the appendix. Figure 2 As shown.

[0042] (1) Normal start-up: The compressor is turned on, the control panel 28 controls the cold head relay 29 to engage, the cold head 30 runs, and the normally open solenoid valve 19 is energized and closed.

[0043] (2) Abnormality occurs: The control panel 28 detects abnormal fluctuations in the current of the cold head 30, or receives a remotely sent instruction that "the cold head stops while the compressor remains running".

[0044] (3) Protection action: The control panel 28 immediately sends a signal to disconnect the cold head relay 29. The cold head 30 stops, and at the same time, the normally open solenoid valve 19 is de-energized and opens.

[0045] (4) Active bypass: When an abnormality occurs, the control panel 28 sends a signal to disconnect the cold head relay 29 and simultaneously sends an "open" command to the normally closed solenoid valve 20 to energize and open it.

[0046] (5) This protection state will remain until the control panel 28 receives a fault reset or system restart command.

[0047] In this scenario, the normally open solenoid valve 19 and the normally closed solenoid valve 20 open simultaneously, forming two parallel bypass paths with greater flow capacity. High-pressure helium gas is fully bypassed back to the low-pressure side, maintaining the system pressure within a safe range. The compressor can continue to operate under no-load conditions in this state, awaiting troubleshooting of the cold head 30 or a remote restart command, thus protecting the cold head and improving the reliability of continuous system operation.

[0048] 2. Compressor operating pressure control

[0049] The specific control logic is shown in the appendix. Figure 3 As shown.

[0050] (1) Normal system operation: cold head relay 29 is engaged, cold head 30 is running, and normally open solenoid valve 19 is energized and closed.

[0051] (2) Pressure monitoring: The control panel 28 continuously reads the signal from the high pressure sensor 21.

[0052] (3) Logical judgment and action:

[0053] If the system pressure rises to the user-set upper limit value A MPa (e.g., 3.0 MPa), the control panel 28 will control the normally closed solenoid valve 20 to be energized and opened to release pressure.

[0054] When the pressure drops to the user-set lower limit value B MPa (e.g., 2.8 MPa), the control panel 28 controls the normally closed solenoid valve 20 to be de-energized and closed.

[0055] (4) This process will be repeated to stabilize the system pressure between B MPa and A MPa until the control panel receives the shutdown command for the whole machine.

[0056] If a shutdown command is received, the cold head relay 29 disconnects after receiving a signal from the control panel 28, the cold head 30 is de-energized, the normally open solenoid valve 19 is de-energized and opens, and the logic judgment ends; if no shutdown command is received, the control logic returns to "judging whether the maximum pressure is greater than A MPa", and a new round of cycle monitoring and adjustment begins.

[0057] 3. Differential Pressure-Based Operation Regulation

[0058] This mode is suitable for special operating conditions where there are strict requirements on the pressure difference between the compressor inlet and outlet. The specific control logic is shown in the attached figure. Figure 4 As shown.

[0059] (1) Normal system operation: cold head relay 29 is engaged, cold head 30 is running, and normally open solenoid valve 19 is energized and closed.

[0060] (2) Pressure difference calculation: The control panel 28 calculates the difference in readings between the high pressure sensor 21 and the low pressure sensor 23 in real time.

[0061] (3) Logical judgment and action:

[0062] If the pressure difference exceeds the user-set upper limit value C MPa, the normally closed solenoid valve 20 will be opened to release pressure.

[0063] When the differential pressure is less than the user-set lower limit value D MPa, the normally closed solenoid valve 20 is de-energized and closed.

[0064] (4) This process will be repeated to precisely control the system operating pressure difference within the range of D MPa to C MPa until the control panel 28 receives the shutdown command for the whole machine.

[0065] If a shutdown command is received, the cold head relay 29 disconnects after receiving a signal from the control panel 28, the cold head 30 is de-energized, the normally open solenoid valve 19 is de-energized and opens, and the logic judgment ends; if no shutdown command is received, the control logic returns to "judging whether the differential pressure is greater than the upper limit value C MPa", and a new round of cyclic monitoring and adjustment begins.

[0066] 4. No-cold-head bypass operation mode

[0067] This mode is used when the compressor operates with only basic operating conditions (such as power supply and cooling water) connected, but without the cooling block connected. The specific control logic is shown in the attached diagram. Figure 5 As shown.

[0068] (1) Mode setting: Set to "No cold head operation" through the control panel 28 to enable bypass operation mode.

[0069] (2) Initialization: When started in this mode, the control panel 28 controls the normally open solenoid valve 19 to open when de-energized, and the normally closed solenoid valve 20 to remain closed when de-energized.

[0070] (3) Logical judgment and action:

[0071] If the system pressure rises to the user-set upper limit value A MPa (e.g., 3.0 MPa), the control panel 28 will control the normally closed solenoid valve 20 to be energized and opened to release pressure.

[0072] When the pressure drops to the user-set lower limit value B MPa (e.g., 2.8 MPa), the control panel 28 controls the normally closed solenoid valve 20 to be de-energized and closed.

[0073] (4) This process is repeated to stabilize the system pressure between B MPa and A MPa until the control panel 28 receives the shutdown command for the whole machine.

[0074] If a shutdown command is received, the normally open solenoid valve 19 is de-energized and opened, and the compressor stops, ending the logic judgment. If no shutdown command is received, the control logic returns to "judging whether the maximum pressure is greater than A MPa" and begins a new round of cyclic monitoring and adjustment.

Claims

1. An economical and highly reliable helium compressor bypass structure, characterized in that, The system includes a control system (27) and a bypass circuit connecting the high-pressure exhaust side and the low-pressure return side of the helium compressor. The bypass circuit is provided with a normally open solenoid valve (19) and a normally closed solenoid valve (20) connected in parallel. The control system (27) is electrically connected to the normally open solenoid valve (19) and the normally closed solenoid valve (20) and is configured to: control the opening and closing state of the normally open solenoid valve (19) to be synchronized with the start and stop state of the cold head (30) driven by the helium compressor; and actively control the opening and closing of the normally closed solenoid valve (20) according to the system pressure state, the cold head (30) state or external commands.

2. The helium compressor bypass structure according to claim 1, characterized in that, The control system (27) includes a control panel (28) and a cold head relay (29); the normally open solenoid valve (19) is connected to the output terminal of the cold head relay (29); the control panel (28) is connected to the normally closed solenoid valve (20).

3. The helium compressor bypass structure according to claim 2, characterized in that, The control panel (28) is configured to: when receiving an abnormal shutdown signal of the cold head (30) or a remote control command to shut down the cold head (30), control the normally closed solenoid valve (20) to open while controlling the cold head relay (29) to disconnect so that the cold head (30) stops.

4. The helium compressor bypass structure according to claim 2 or 3, characterized in that, It also includes a high-pressure sensor (21) for detecting the high-pressure exhaust side pressure and a low-pressure sensor (23) for detecting the low-pressure return side pressure.

5. The helium compressor bypass structure according to claim 1, characterized in that, One end of the bypass circuit is connected to the pipeline between the oil separator (18) and the adsorber (26) of the compressor, and the other end is connected to the pipeline upstream of the buffer tank (14).

6. The helium compressor bypass structure according to claim 4, characterized in that, The control panel (28) is configured to: control the normally closed solenoid valve (20) to open when the pressure is higher than a first set threshold, and control the normally closed solenoid valve (20) to close when the pressure is lower than a second set threshold, based on the feedback signal from the high pressure sensor (21), wherein the first set threshold is greater than the second set threshold.

7. The helium compressor bypass structure according to claim 4, characterized in that, The control panel (28) is configured to: control the normally closed solenoid valve (20) to open when the pressure difference is higher than a third set threshold, and control the normally closed solenoid valve (20) to close when the pressure difference is lower than a fourth set threshold, based on the feedback signal difference between the high pressure sensor (21) and the low pressure sensor (23), wherein the third set threshold is greater than the fourth set threshold.

8. The helium compressor bypass structure according to claim 4, characterized in that, The control panel (28) is also configured to: when set to the no-cold-head test mode, control the normally open solenoid valve (19) to be energized and closed, and control the normally closed solenoid valve (20) to open and close based on the signal of the high-pressure sensor (21) to regulate the system pressure.

9. The compressor bypass structure according to claim 5, characterized in that, A safety valve (22) is installed on the pipeline between the oil separator (18) and the adsorber (26).

10. A control method for a helium compressor bypass structure as described in any one of claims 1-9, characterized in that, include: The steps of controlling the normally open solenoid valve (19) are synchronized with the start and stop of the compressor-driven cold head (30); And, based on the monitored system status, selectively execute the corresponding control logic to operate the normally closed solenoid valve (20); wherein the system status includes at least one of: high pressure, high-low pressure difference, cold head operating status and remote command.

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