A bypass circulation loop system

Abstract

The application discloses a bypass type circulating loop system and belongs to the technical field of bypass type circulating systems. The application comprises a control system, an accumulator and a centrifugal pump. The accumulator and the centrifugal pump are both installed on an integrated shell. An irregular flow channel is connected to the accumulator. A pressure sensor and a one-way valve are arranged on the irregular flow channel. The irregular flow channel and the pressure sensor are both installed in the integrated shell. After circulating outside through the centrifugal pump and the one-way valve, medium is returned to the inlet of the centrifugal pump through the irregular flow channel and the accumulator to form a closed bypass circulation. The integrated shell is adopted to greatly reduce the volume and weight of the equipment. The irregular flow channel composed of an arc and an ellipse solves the problem of flow channel plugging and liquid interruption after the accumulator diaphragm is in place, reduces fluid resistance and realizes uniform liquid filling in the inner cavity. The bypass circulation structure is suitable for various working conditions. The inlet and outlet pressures and the pump body temperature are synchronously collected to realize intelligent fault diagnosis. Double charging valves simplify the vacuum charging and medium emptying processes.

Description

Technical Field

[0001] This invention relates to the field of bypass circulation system technology, and in particular to a bypass circulation loop system. Background Technology

[0002] Hypersonic flight equipment and space orbital devices experience high thermal loads on their core heat-generating components during operation, requiring a closed-loop cooling system to continuously deliver coolant for active heat dissipation. Existing closed-loop cooling systems have the following drawbacks:

[0003] 1. The accumulator and pump inlet flow channel have a simple structure. When the accumulator diaphragm moves back and forth with the system pressure, it is easy to block the medium passage and cause the circulation to be interrupted.

[0004] 2. The pipelines, pump body, valves, and sensors are arranged separately, resulting in a large overall volume and weight. The numerous pipeline joints lead to significant pressure loss in the flow channel.

[0005] 3. The cooling pump has a single flow rate adjustment mode, which cannot adapt to the heat dissipation requirements of multiple operating conditions, and the inlet and outlet installation directions cannot be flexibly adjusted;

[0006] 4. Relying solely on a single pressure or temperature signal to monitor equipment operation status results in delayed fault identification and a lack of integrated intelligent diagnostic capabilities;

[0007] 5. Conventional circulation structures are difficult to adapt to vacuum filling conditions, and the internal working fluid of the system is not fully filled, affecting heat dissipation stability.

[0008] In summary, existing circulating cooling systems are inadequate in terms of integration, operational stability, monitoring capabilities, and ease of maintenance to meet the demanding operating conditions of hypersonic equipment and space orbital modules. There is an urgent need for an integrated, interruption-proof, multi-parameter synchronous monitoring bypass circulating loop system. Summary of the Invention

[0009] To address the shortcomings in the aforementioned background technology, this invention proposes a bypass circulation loop system, which solves the problems of easy flow channel blockage, low integration, poor adaptability to operating conditions, and imperfect fault monitoring in the prior art. It achieves continuous flow to the accumulator, high integration and lightweight design, adjustable multiple flow rates, combined temperature and pressure fault diagnosis, and adaptability to vacuum refueling and various aerospace heat dissipation scenarios.

[0010] The technical solution of the present invention is implemented as follows: a bypass circulation loop system includes a control system, an accumulator and a centrifugal pump. The accumulator and the centrifugal pump are both mounted on an integrated housing. An irregular flow channel is connected to the accumulator. A pressure sensor and a check valve are provided on the irregular flow channel. The irregular flow channel and the pressure sensor are both mounted inside the integrated housing. After the medium is circulated externally through the centrifugal pump and the check valve, it flows back to the inlet of the centrifugal pump through the irregular flow channel and the accumulator to form a closed bypass loop.

[0011] Further preferably, the accumulator has a side guide channel on its inner wall. This side guide channel is formed on the side shell of the accumulator diaphragm, extending in an arc shape and having a non-circular cross-section. This allows the working fluid to flow through the side guide channel into the accumulator inlet and the tiny gaps on the side, achieving uniform filling of the working fluid. The accumulator has a bottom discharge channel at its bottom. Both the side guide channel and the bottom discharge channel are connected to corresponding irregular flow channels. The bottom discharge channel is formed at the bottom shell of the accumulator, has an elliptical structure, and is fluidly connected to the side guide channel, thus providing a discharge channel for the working fluid when the diaphragm moves to its bottom limit position.

[0012] More preferably, the side guide channel is an arc-shaped flow channel. The bottom discharge channel is set on the accumulator to form an elliptical bottom flow channel, which is connected to the arc-shaped flow channel. The arc-shaped side flow channel can conform to the curvature of the diaphragm side, reducing fluid resistance and avoiding dead corners; the elliptical bottom flow channel can still retain sufficient flow area when the diaphragm is attached to the bottom, preventing the flow channel from being completely blocked by the diaphragm, thereby ensuring smooth drainage. During the filling stage, the side flow channel guides the working fluid into the gap to fill the working fluid; during the drainage stage, when the diaphragm descends to the bottom, the elliptical flow channel at the bottom plays the role of drainage.

[0013] More preferably, the irregular flow channel includes an inlet flow channel and an outlet flow channel, which are connected to the accumulator in a staggered manner, and a one-way valve is installed on the outlet flow channel. The irregular flow channel is an irregularly shaped flow guide channel structure, which is not a standard circular or rectangular cross-section, but a variable cross-section flow channel customized according to the internal space of the accumulator and the requirements of fluid dynamics.

[0014] More preferably, the inlet flow channel is provided with an inlet filling flow channel, and the inlet filling flow channel is provided with a filling / draining valve one. The outlet flow channel is provided with an outlet filling flow channel, and the outlet filling flow channel is provided with a filling / draining valve two.

[0015] More preferably, the accumulator is a diaphragm accumulator, and the accumulator is provided with an accumulator plug.

[0016] More preferably, the pressure sensor includes an outlet pressure sensor and an inlet pressure sensor, the outlet pressure sensor being disposed on the outlet pressure sensor flow channel and connected to the outlet flow channel, and the inlet pressure sensor being disposed on the inlet pressure sensor flow channel and connected to the outlet flow channel.

[0017] More preferably, the centrifugal pump is equipped with a temperature sensor, which is electrically connected to the control system.

[0018] The irregular flow channel of this invention is a non-circular flow channel structure, which is different from the standard circular and rectangular cross-section flow channels. It is customized into a combination of arc and elliptical variable cross-section structure according to the internal space and fluid dynamics requirements of the accumulator. The side flow channel is formed on the side shell of the diaphragm accumulator, and the arc non-circular cross-section structure guides the working fluid to fill the accumulator cavity evenly. The bottom discharge channel is formed on the bottom shell of the accumulator, is elliptical, and is connected to the side flow channel. When the diaphragm is pressed down to fit the bottom surface, it still retains an effective flow area and avoids complete blockage of the flow channel.

[0019] The integrated housing adopts a topology-optimized one-piece molding structure. The centrifugal pump, diaphragm accumulator, check valve, dual pressure sensors, and dual expansion and contraction valves are all installed with cartridge-type sealing. The entire flow channel is integrally molded inside the valve block, eliminating a large number of external pipeline joints and reducing the overall size, weight, and flow channel pressure drop. The centrifugal pump is equipped with multi-stage flow regulation function, and the bypass circulation layout can adjust the inlet and outlet orientation according to the needs of the installed equipment, adapting to various thermal management conditions. The control system synchronously collects inlet pressure, outlet pressure, and centrifugal pump temperature signals, and identifies and warns of faults such as pipeline blockage, pump overheating, diaphragm jamming, and check valve failure in real time.

[0020] The beneficial effects of this invention are as follows: Irregular flow channels are provided on the side and bottom of the accumulator, so that the medium passage will not be blocked when the accumulator diaphragm moves with the pressure piston, ensuring continuous and stable operation of the closed loop; at the same time, the inlet is connected from the side of the accumulator, which makes it easy for the working medium on the accumulator side to be completely filled, and is suitable for vacuum filling requirements.

[0021] The centrifugal pump, valves, sensors, and all internal flow channels are compactly integrated using a topology-optimized integrated housing, which significantly reduces the overall size and weight of the machine, while also reducing pipe bends and joints, effectively reducing flow channel pressure drop.

[0022] The matching controller can realize multi-stage flow regulation of centrifugal pumps, and the direction of the system inlet and outlet flow channels can be changed as needed, adapting to various installation spaces and heat dissipation conditions such as hypersonic aircraft and space orbit equipment.

[0023] It integrates inlet and outlet pressure and temperature acquisition functions, and the linkage of temperature and pressure data enables intelligent fault diagnosis of pump units. It can monitor the system operation status in real time and identify fault risks in advance.

[0024] With dual filling and discharging ports and a dedicated filling channel, closed-loop vacuum filling can be completed, ensuring that the inside of the channel is completely filled with cooling medium and improving the reliability of the heat dissipation system.

[0025] Membrane accumulators can dynamically adjust the back pressure inside the closed loop, stabilize the system circulation pressure, and prevent pressure fluctuations from affecting the stability of cooling flow. Attached Figure Description

[0026] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] Figure 2 This is a flow channel diagram of the integrated housing of the present invention;

[0029] Figure 3 This is a cross-sectional view of the present invention;

[0030] Figure 4 This is a schematic diagram of the flow channel between the accumulator and the impeller.

[0031] In the diagram: 1-Accumulator, 2-Inlet connector, 3-Plug, 4-Addition / exhaust valve one, 5-Integrated housing, 6-Inlet pressure sensor, 7-Centrifugal pump, 8-Outlet pressure sensor, 9-Addition / exhaust valve two, 10-Outlet connector, 11-Accumulator plug, 12-Check valve, 13-Side guide channel, 14-Bottom discharge channel, 15-Inlet flow channel, 16-Outlet flow channel, 17-Inlet pressure sensor flow channel, 18-Outlet pressure sensor flow channel, 19-Check valve flow channel. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] like Figure 1 , Figure 2 , Figure 3As shown in Embodiment 1, a bypass circulation loop system includes an external control system and an integrated housing 5. An accumulator 1 and a centrifugal pump 7 are fixedly installed on the integrated housing 5, and an impeller is installed inside the centrifugal pump 7. An irregular flow channel is integrally formed inside the integrated housing 5, which includes an inlet flow channel 15 and an outlet flow channel 16. A one-way valve 12 is installed inside the outlet flow channel 16, and the one-way valve 12 is located on a one-way valve flow channel 19, which is connected to the outlet flow channel 16. An inlet pressure sensor flow channel 17 and an outlet pressure sensor flow channel 18 are respectively formed inside the integrated housing 5. An inlet pressure sensor 6 is installed in the inlet pressure sensor flow channel 17, and an outlet pressure sensor 8 is installed in the outlet pressure sensor flow channel 18. All flow channels, detection elements, and valves are embedded inside the integrated housing 5, and there are no external connecting pipelines.

[0034] System medium circulation process: After the equipment is powered on, the control system drives the impeller inside the centrifugal pump 7 to rotate. The cooling medium is pressurized by the impeller and opens the one-way valve 12 in the outlet flow channel 16. It is then transported to the external heating module through the outlet connector 10 to complete heat exchange. The medium after heat exchange and cooling flows back to the inlet connector 2 of the integrated housing 5, enters the irregular flow channel along the inlet flow channel 15, and is diverted into the accumulator 1. Finally, it flows back to the inlet of the centrifugal pump 7, forming a complete closed bypass cycle. The accumulator 1 serves as a bypass pressure stabilizing branch, dynamically adjusting the overall back pressure of the circuit and buffering the pressure fluctuations of the centrifugal pump 7.

[0035] Combination Figure 4 A schematic diagram of the flow channel between the accumulator and the centrifugal pump impeller. The inner wall of the accumulator 1 is machined into an arc-shaped side guide groove 13. An elliptical bottom discharge groove 14 is opened at the bottom of the accumulator 1 housing. The arc-shaped side guide groove 13 and the elliptical bottom discharge groove 14 are interconnected and together form an irregular flow channel inside the accumulator 1, which is in fluid communication with the inlet flow channel 15 and the outlet flow channel 16 inside the integrated housing 5.

[0036] During the filling stage, the cooling medium flows evenly into the tiny gap between the diaphragm and the shell along the arc-shaped side guide groove 13, completely filling the inner cavity of the accumulator 1. The arc-shaped structure fits the outer curved surface of the diaphragm, eliminating fluid dead zones and reducing the flow resistance during filling.

[0037] During the drainage stage: When the system pressure change drives the diaphragm to move downward to the bottom limit position, the diaphragm completely adheres to the bottom surface of the housing, but the bottom elliptical discharge groove 14 still retains a continuous flow channel. The medium can continuously flow out through the elliptical groove without the problem of complete blockage of the flow channel or interruption of the loop, ensuring that the centrifugal pump 7 continuously feeds liquid and the circulation is uninterrupted; the accumulator 1 is equipped with an accumulator plug 11 at the end for assembly and maintenance sealing, and the integrated housing 5 is equipped with a plug 3 to achieve sealed assembly.

[0038] Flow channel and filling structure implementation: The irregular flow channel is divided into an inlet flow channel 15 and an outlet flow channel 16, which are connected to the accumulator 1 in a staggered manner. A one-way valve 12 is fixedly installed in the middle section of the outlet flow channel 16, allowing only unidirectional outward circulation of the medium to prevent backflow and pressure backflow. The inlet is located on the side of the accumulator. The irregular flow channels on the side and bottom of the accumulator help to fill the working medium on the diaphragm side, realizing normal flow of the working medium. In addition, the bypass circulation can change the inlet and outlet directions according to its own needs. The circulation pump can achieve multi-stage flow regulation through the controller, which is suitable for more scenarios.

[0039] The inlet flow channel 15 extends laterally to form an inlet filling flow channel, and a filling / draining valve 4 is installed at the end of the inlet filling flow channel; the outlet flow channel 16 extends laterally to form an outlet filling flow channel, and a filling / draining valve 9 is installed at the end of the outlet filling flow channel. During system vacuum filling, both sets of filling / draining valves can be opened simultaneously to quickly remove air from the circuit; during media maintenance and venting, individual valves can be opened separately to discharge the media from the flow channels in stages, making operation convenient.

[0040] Pressure and temperature monitoring implementation method: The inlet pressure sensor 6 is installed in the inlet pressure sensor flow channel 17 and connected to the inlet flow channel 15 to collect the inlet medium pressure of the circuit in real time; the outlet pressure sensor 8 is installed in the outlet pressure sensor flow channel 18 and connected to the outlet flow channel 16 to collect the outlet medium pressure of the circuit in real time.

[0041] A temperature sensor is installed inside the centrifugal pump 7. The temperature sensor, inlet pressure sensor 6, and outlet pressure sensor 8 are all electrically connected to the external control system via signal lines. The control system receives pressure and temperature data in real time. When the pressure exceeds the set threshold or the pump body temperature exceeds the standard, it automatically determines faults such as pipeline blockage, pump overheating, and accumulator failure, and outputs alarm signals to achieve intelligent fault diagnosis.

[0042] Integrated assembly method: The integrated housing 5 is formed by topology optimization one-piece casting. The centrifugal pump 7, accumulator 1, feed valve 1 4, feed valve 2 9 are all installed in the reserved mounting holes of the integrated housing 5 with a cartridge-type sealing structure. The medium is sealed by the sealing ring. The assembly structure is compact and easy to disassemble and maintain. The whole system has no scattered pipelines. The overall weight and volume are significantly reduced compared with the traditional split circulation system, which fully meets the lightweight mounting requirements of hypersonic aircraft and space orbit heat dissipation modules.

[0043] The complete working process of this embodiment is as follows: Medium filling stage: Open the filling and draining valve 1 4 and the filling and draining valve 2 9. The external vacuum equipment is used to evacuate the entire closed loop. After removing the air inside the pipeline, the cooling working medium is injected. After the medium fills all the flow channels, the two sets of filling and draining valves are closed to complete the sealed filling.

[0044] Normal circulation and heat dissipation stage: The control system starts the centrifugal pump 7, the impeller pressurizes and delivers the medium, the medium pushes open the one-way valve 12 and is delivered to the external heat-generating component for heat exchange through the outlet connector 10; after heat exchange, the medium flows back to the inlet connector 2, enters the irregular flow channel of the accumulator 1 along the inlet flow channel 15, and the arc-shaped side guide groove 13 evenly fills the inner cavity of the accumulator. Excess medium flows back to the inlet of the centrifugal pump 7 through the elliptical bottom discharge groove 14, and the closed circulation continues; the accumulator 1 dynamically stabilizes the pressure and buffers the pump body pressure pulsation; even if the diaphragm is pressed down to the bottom limit position, the bottom discharge groove 14 remains open, and there is no risk of the circuit being interrupted.

[0045] Real-time monitoring and fault handling: Inlet pressure sensor 6 and outlet pressure sensor 8 collect loop pressure in real time, and temperature sensor collects the operating temperature of centrifugal pump 7. The data is uploaded to the control system in real time. When the pressure and temperature parameters deviate from the normal range, the control system identifies the fault and issues an early warning, and can shut down the pump for maintenance.

[0046] During the maintenance and purging phase: Open valve 4 and valve 9 to drain the cooling medium inside the circuit, thus completing the equipment maintenance and medium replacement operations.

[0047] Example 2: A bypass circulation loop system, the core structure of which is an integrated housing with topology optimization molding. The centrifugal pump, diaphragm accumulator, check valve and two sets of pressure sensors are all fixed to the integrated housing by insert.

[0048] The integrated housing is molded as a single piece, encompassing all internal flow channels, including the pump head volute flow channel, accumulator flow channel, one-way valve flow channel, and pressure sensor dedicated flow channel; externally, inlet flow channel, outlet flow channel, and filling flow channel are provided, corresponding to filling and discharging port one and filling and discharging port two, respectively.

[0049] The diaphragm accumulator has irregularly connected flow channels on its sides and bottom, which connect the accumulator flow channel and the shell inlet flow channel to form a bypass circulation channel.

[0050] When the system is powered on, the centrifugal pump drives the cooling medium to pressurize. The medium pushes open the one-way valve and flows out of the shell through the outlet channel. After exchanging heat with the external heating module, the medium flows back to the shell inlet and re-enters the centrifugal pump inlet through the irregular flow channel of the accumulator, forming a complete closed bypass cycle.

[0051] The diaphragm accumulator adjusts the back pressure inside the closed loop in real time; when the system pressure changes, the diaphragm inside the accumulator moves in a piston-like reciprocating motion, and the irregular flow channels on the side and bottom always maintain the flow of the medium, so that the circulation channel will not be blocked due to diaphragm displacement.

[0052] In this embodiment, the integrated shell undergoes topology optimization design, resulting in a significantly reduced pressure drop in the flow channel compared to a split pipeline structure. This leads to a smaller overall size and weight, meeting the lightweight requirements of aerospace equipment. The dual filling and discharging ports, combined with the filling flow channel, enable vacuum filling of the entire closed loop, ensuring no air resistance within the flow channel.

[0053] This bypass circulation system is mainly used in the following scenarios: hypersonic flight systems and space orbit cooling modules. The bypass circulation system mainly uses a pump to drive the cooling medium to actively cool the heat-generating module, ensuring the safe and stable operation of its core components. By integrating components such as centrifugal pumps, one-way valves, and accumulators into the housing, the product achieves integrated design.

[0054] Example 3 adds an electrical control component to Example 2: a controller electrically connected to the centrifugal pump is configured. The controller can output multi-level control signals to adjust the output flow of the centrifugal pump and adapt to different heat dissipation requirements.

[0055] Temperature sensors are installed on both the controller body and the centrifugal pump body. The temperature signals collected by the sensors are transmitted to the controller, which can upload the temperature data to a PC for real-time display. At the same time, the inlet pressure sensor collects the pump inlet pressure and the outlet pressure sensor collects the pump outlet pressure. The controller integrates the temperature and pressure data to achieve intelligent fault diagnosis of the pump unit's operating status and promptly identify faults such as pump abnormalities and pipeline blockages.

[0056] In this embodiment, the installation direction of the inlet and outlet flow channels of the integrated housing can be flexibly adjusted according to the installation space requirements of the aircraft and orbital equipment, making it more versatile. The working principle is as follows: After the system is powered on, the circulating pump starts running after receiving a controller command. The medium is pressurized and pushes open the one-way valve, transmitting the medium to the outlet through the pipeline. It then circulates back to the inlet of the integrated housing, bypassing the pressure sensor and accumulator before entering the centrifugal pump inlet, thus completing one cycle of the medium. The pressure sensor collects the pump inlet and outlet pressure data based on the control signal. The accumulator is used to regulate the back pressure inside the closed system. This bypass circulation system is suitable for vacuum filling systems. When the system flow channels are filled with medium, the medium flows through the pressure sensor and accumulator, thus entering the centrifugal pump inlet. Therefore, irregular flow channels are designed on the sides and bottom of the accumulator. When the accumulator diaphragm moves piston-like due to internal pressure changes, the irregular flow channels prevent the medium from becoming blocked due to diaphragm movement, ensuring that the working fluid enters the centrifugal pump inlet normally, thus completing normal circulation.

[0057] Example 4: The bypass circulation loop system described in Example 2 or Example 3 is assembled into the hypersonic flight system and the space orbit heat dissipation module. The centrifugal pump continuously drives the cooling working fluid to flow through the heat-generating components. The heat is removed by the closed loop, and the core components are actively cooled to ensure the equipment can work stably for a long time.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bypass-type circulating loop system, comprising a control system, characterized in that: It also includes an accumulator (1) and a centrifugal pump (7). The accumulator (1) and the centrifugal pump (7) are both installed on the integrated housing (5). An irregular flow channel is connected to the accumulator (1). A pressure sensor and a check valve (12) are provided on the irregular flow channel. The irregular flow channel and the pressure sensor are both installed inside the integrated housing (5). After the medium circulates outside the centrifugal pump (7) and the check valve (12), it flows back to the inlet of the centrifugal pump (7) through the irregular flow channel and the accumulator (1) to form a closed bypass circulation.

2. The bypass loop system according to claim 1, characterized in that, The inner wall of the accumulator (1) is provided with a side guide groove (13) and the bottom of the accumulator (1) is provided with a bottom discharge groove (14). The side guide groove (13) and the bottom discharge groove (14) are both connected to the corresponding irregular flow channels.

3. The bypass loop system according to claim 2, characterized in that, The side guide groove (13) is an arc-shaped flow channel.

4. The bypass loop system according to claim 3, characterized in that, The bottom discharge groove (14) is set at the bottom of the accumulator (1) to form an elliptical bottom flow channel, which is connected to the arc flow channel.

5. The bypass loop system according to any one of claims 1 to 4, characterized in that, The irregular flow channel includes an inlet flow channel (15) and an outlet flow channel (16). The inlet flow channel (15) and the outlet flow channel (16) are connected to the accumulator (1) in a staggered manner. A one-way valve (12) is installed on the outlet flow channel (16).

6. The bypass loop system according to claim 5, characterized in that, The inlet flow channel (15) is provided with an inlet filling flow channel, and the inlet filling flow channel is provided with a filling and draining valve (4).

7. The bypass loop system according to claim 6, characterized in that, The outlet flow channel (16) is provided with an outlet filling flow channel, and the outlet filling flow channel is provided with a filling and draining valve two (9).

8. The bypass loop system according to any one of claims 1 to 4, 6, and 7, characterized in that, The accumulator (1) is a diaphragm accumulator, and the accumulator (1) is provided with an accumulator plug (11).

9. The bypass loop system according to claim 8, characterized in that, The pressure sensor includes an outlet pressure sensor (8) and an inlet pressure sensor (6). The outlet pressure sensor (8) is disposed on the outlet pressure sensor flow channel (18), which is connected to the outlet flow channel (16). The inlet pressure sensor (6) is disposed on the inlet pressure sensor flow channel (17), which is connected to the inlet flow channel (15).

10. The bypass loop system according to claim 9, characterized in that, The centrifugal pump (7) is equipped with a temperature sensor, which is electrically connected to the control system.

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