PASSIVE PUMP SWITCHING

Abstract

A thermal management system comprises several, normally isolated thermal subsystems, each managing its own equipment. The thermal subsystems can automatically connect to one another in response to local pressure within the subsystems. When connected, one or more components (e.g., a pump) of a subsystem can affect the equipment managed by each of the connected subsystems. However, the isolation of the subsystems can be actively enforced if a leak is detected in one of them.

Description

BACKGROUND

[0001] Thermal management systems provide cooling for various types of heat-generating equipment. For example, thermal management can be used in an aircraft propulsion system. Generally, a thermal management system includes a coolant (e.g., water, ethylene glycol, etc.) that is circulated by a pump through pipes between a heat exchanger and the equipment to be cooled. SUMMARY

[0002] One task to be solved is to provide an improved thermal management concept. This task is solved by the subject matter of the independent claim. Developments are the subject matter of the dependent claims.

[0003] For example, a thermal management system comprises a first thermal subsystem configured for the thermal control of a first piece of equipment and a second thermal subsystem configured for the thermal control of a second piece of equipment that is different from the first. The thermal management system is configured to automatically switch between a normal operating state, a first assistance state, and a second assistance state. The first and second thermal subsystems are isolated from each other when the thermal management system is configured in the normal operating state. The thermal subsystems are interconnected to regulate the first and second pieces of equipment in each of the assistance states. Specifically, the second thermal subsystem controls the coolant flow in the first assistance state, and the first thermal subsystem controls the coolant flow in the second assistance state.

[0004] In certain embodiments, each thermal subsystem includes a pump configured to deliver coolant along a specific local path to the respective equipment. A first cross-connection path links the local paths downstream of the pumps, and a second cross-connection path links the local paths upstream of the pumps. Accordingly, if the other pump experiences a malfunction (e.g., stops working, no longer operates at the required system pressure, etc.), either pump can circulate the coolant through both sets of local paths. This ability of one subsystem to assume responsibility for the equipment in other subsystems provides redundancy and thereby increases the reliability of the system.

[0005] In certain embodiments, a passive valve arrangement allows the thermal management system to automatically transition from normal operation to assisted operation when the pressure in one of the systems drops. For example, when both thermal subsystems are operating normally, the pressure within the subsystems exerts a largely equal pressure on the passive valve arrangement. However, if the pressure in one thermal subsystem drops, the passive valve arrangement allows flow from the higher-pressure subsystem through the lower-pressure subsystem. Similarly, the passive valve arrangement automatically returns the thermal management system to normal operation once the faulty pump has been repaired. This transition between states, without the need for active components, further enhances the reliability of the thermal management system.

[0006] The thermal management system can be supplemented with an active valve arrangement to isolate local paths in the event of a leak. The active valve arrangement can, for example, be controlled by a control unit that receives input from one or more sensors within the system to detect the presence of a leak.

[0007] A multitude of further inventive aspects are set forth in the following description. These inventive aspects may relate to individual features or combinations thereof. It is understood that both the preceding general description and the following detailed description are merely exemplary and illustrative in nature and do not limit the broad inventive concepts on which the embodiments disclosed herein are based. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are included in and form part of the description, illustrate various aspects of this revelation. A brief description of the drawings is as follows: Fig. Figure 1 is a schematic representation of an example of a thermal management system configured in a normal operating state, wherein the thermal management system comprises thermal subsystems interconnected by cross-connection paths and a passive valve arrangement. Fig. 2 shows the thermal management system Fig. 1, which is configured in a first assistance state in which a pump of the second subsystem pumps fluid between all interconnected subsystems. Fig. 3 shows the thermal management system Fig. 1, which is configured in a second assist state in which a pump of the first subsystem pumps fluid between all interconnected subsystems. Fig. Figure 4 shows an embodiment of a valve arrangement suitable for use in the passive valve from the Fig. 1 to 3 is suitable. Fig. 5 adds to the thermal management system Fig. 1. Add an active valve arrangement, wherein the active valve arrangement is configured in an open state. Fig. Figure 6 shows the passive valve arrangement of the thermal management system. Fig. 5, which is configured in the first assist state, while the active valve arrangement is configured in the open state. Fig. 7 shows the thermal management system Fig. 6, while the active valve assembly is configured in an isolated state. DETAILED DESCRIPTION

[0009] Detailed reference will now be made to exemplary aspects of the present revelation, which are illustrated in the accompanying drawings. Wherever possible, the same reference symbols are used throughout the drawings to refer to identical or similar parts.

[0010] A thermal management system 100 comprises several thermal subsystems 110, 120, each operating independently to thermally regulate respective equipment 112, 122. While two thermal subsystems 110, 120 are shown in the figures, it is understood that the thermal management system 100 could include additional thermal subsystems. Each thermal subsystem 110, 120 includes a respective pump 114, 124 configured to deliver coolant along a corresponding path 115, 125 to the respective equipment 112, 122.

[0011] According to certain aspects of the disclosure, the thermal management system 100 is configured to switch between a normal operating state, a first assistance state, and a second assistance state. The first and second paths 115, 125 are isolated from each other when the thermal management system 100 is configured in the normal operating state. The first pump 114 supplies coolant to both the first equipment 112 and the second equipment 122 when the thermal management system 100 is configured in the first assistance state. The second pump 124 supplies coolant to both the first equipment 112 and the second equipment 122 when the thermal management system 100 is configured in the second assistance state.

[0012] In certain embodiments, the transition between states occurs automatically upon failure of one of the subsystems 110, 120. For example, the transition is not controlled by active valves. In certain embodiments, the transition is implemented using a passive valve arrangement 130. The passive valve arrangement 130 isolates the first and second paths 115, 125 during normal operation. During a component failure, the passive valve arrangement 130 allows flow from one of the first and second paths 115, 125 with higher pressure to one of the first and second paths 115, 125 with lower pressure, resulting in a change to one of the assisted states.

[0013] In certain examples, the thermal subsystems 110, 120 are interconnected via a first and a second cross-connection path 136, 138. For example, a first cross-connection path 136 can connect the first path 115 at a first point 140 downstream of the first pump 114 with the second path 125 at a second point 142 downstream of the second pump 124. A second cross-connection path 138 connects the first path 115 at a third point 144 upstream of the first pump 114 with the second path 125 at a fourth point 146 upstream of the second pump 124.

[0014] The passive valve arrangement 130 comprises a first valve arrangement 132, which is arranged along the first cross-connection path 136, and a second valve arrangement, which is arranged along the second cross-connection path 138. If the pressure within the first and second paths 115, 125 is approximately equal, the flow from each path 115, 125 to the first valve arrangement 132 is approximately equal, thus exerting approximately the same pressure on the first valve arrangement 132. Accordingly, the first valve arrangement 132 prevents the flow from each of the thermal subsystems 110, 120 into the other. However, if the pressure within one of the paths 115, 125 is greater than that of the other, for example in the event of a pump failure in one of the thermal subsystems 110, 120, the valve arrangements 132, 134 allow flow from the system with higher pressure along the respective cross-connection paths 136, 138 into the system with lower pressure.

[0015] For example, it shows Fig. 2 the thermal management system configured in the first assistance state 100. In Fig. 2. Pump 114 of the first thermal subsystem 110 has ceased operation. Consequently, the coolant pressure within the first thermal subsystem 110 drops to a value lower than the pressure in the second thermal subsystem 120, which still has a functioning pump 124. Therefore, some of the coolant pressurized by pump 124 in the second thermal subsystem 120 bypasses the coolant of the first thermal subsystem 110 at the first valve assembly 132 and flows along the first cross-connection path 136 to join the first path 115. Another portion of the coolant pressurized by pump 124 continues to flow along the second path 125.

[0016] Furthermore, the second pump 124 draws coolant towards itself along the second path 125, while the first pump 114 has ceased drawing coolant. Accordingly, the second valve assembly 134 senses a greater suction from the second thermal subsystem 120 and opens to allow flow from point 144 upstream of the first pump 114 along the second cross-connection path 138 to point 146 upstream of the second pump 124, forming a combined path 148. All the coolant in both subsystems 110, 120 circulates along the combined path 148 in a first direction back to the second pump 124. Accordingly, the coolant pumped by the second pump 124 flows through each piece of equipment 112, 122 in the subsystems 110, 120.

[0017] In certain examples, the fluid from the second pump 124 flows into Fig. The two coolants are also conveyed through or past both heat exchangers 116 and 126. Including both heat exchangers 116 and 126 in the combined path 148 helps to balance the load generated by the equipment 112 and 122. In the example shown, the first cross-connection path 136 connects the first and second paths 115 and 125 at points upstream of the heat exchangers 116 and 126. In other examples, however, the first cross-connection path 136 could connect the first and second paths 115 and 125 at points downstream of the heat exchangers 116 and 126.

[0018] Fig. Figure 3 shows the thermal management system 100 configured in the second assistance state. In particular, it shows Fig. 3. The second pump 124 is in a non-operational state, while the first pump 114 remains operational. In such a system, the coolant pressure within the second thermal subsystem 120 drops to a value lower than the pressure in the first thermal subsystem 110, causing the first and second valve arrangements 132, 134 to experience a flow in the reverse direction compared to the Fig. 2. Accordingly, the pump 114 of the first thermal subsystem 110 drives a first part of the coolant along the local path 115 and a second part of the coolant via the first cross-connection path 136 to the second path 125. The second cross-connection path 138 allows the second part of the coolant to recirculate back to the first pump 114.

[0019] Fig. Figure 4 shows an embodiment of a valve arrangement 150 suitable for use as a valve arrangement 132, 134 along the cross-connection paths 136, 138. Fig. The valve arrangement 150 comprises a first check valve 152 and a second check valve 154. The first check valve 152 opens only when the pressure from a first side 156 overcomes the pressure on the opposite second side 158. The second check valve 154 opens only when the pressure from the second side 158 overcomes the pressure on the first side 156. The first and second check valves 152, 154 are arranged parallel to each other. For example, the cross-connection path 136, 138 can split into a first path section 160 and a second path section 162, which run parallel to each other before merging again. When open, the first check valve 152 allows flow in a first direction from the first side 156 to the second side 158 along the first path section 160.The second check valve 154, when open, allows flow in a second direction from the second side 158 to the first side 156 along the second path section 162. The check valves 152 and 154 remain closed when the pressure on both sides 156 and 158 is equal or approximately equal.

[0020] With reference to the Fig. 5 to 7, an active protection can be added to the thermal management system 100 to prevent the subsystems 110 and 120 from being linked together if a leak causes a local pressure loss. For example, an active valve arrangement 164 can be arranged along the first and second cross-connection paths 136 and 138. The active valve arrangement 164 is controlled by a system controller 170 to switch between an open state and an isolated state. In the isolated state, the active valve arrangement 150 isolates the first and second paths 115 and 125 regardless of a pressure difference between the subsystems 110 and 120. In the open state, however, the active valve arrangement 150 allows the passive valve arrangement 130 to operate as described above.

[0021] In certain embodiments, the control unit 170 is configured to receive inputs from one or more sensors 172 located on the thermal subsystems 110, 120. In some examples, the sensors 172 are located on the pump 114, 124 to determine whether the pump 114, 124 is functioning. In other examples, the sensors 172 are located on a respective accumulator located along the local path 115, 125 to check the coolant volume stored during normal operation. Other sensor types are possible. The control unit 170 analyzes the input signals to determine whether one of the subsystems 110, 120 is leaking or otherwise losing coolant. The control unit 170 issues shutdown commands if a leak is detected.

[0022] In certain embodiments, the active valve arrangement 150 comprises a first shut-off valve 166 arranged along the first cross-connection path 136, and a second shut-off valve 168 arranged along the second cross-connection path 138. During normal operation, the shut-off valves 166, 168 remain open regardless of the relative pressure of the subsystems 110, 120. For example, Figure 1 shows Fig. 6. The thermal management system 100 is configured in the first assistance state, while the shut-off valves 166, 168 remain open. However, upon receiving shutdown commands from the system controller 170, the shut-off valves 166, 168 close, thereby isolating the local paths 115, 125 between the thermal subsystems 110, 120.

[0023] In certain examples, shutdown commands are issued by the controller in the event of a leak L (see e.g. Fig. 7) Linking subsystems 110 and 120 while one subsystem 110 or 120 is leaking could lead to a leak in all linked subsystems. The active valve arrangement 164 protects against such an event by isolating subsystems 110 and 120 from each other in the event of a leak, even if one of the thermal subsystems 110 or 120 would otherwise fail. For example, Fig. 7. The shut-off valves 166 and 168 were in the closed state, while the thermal management system 100 was configured in the first assist state. In such a configuration, the first piece of equipment 112 is not thermally controlled by either the first subsystem 110 or the second subsystem 120. However, the leak L in the first subsystem 110 does not affect the function of the second subsystem 120, so the second piece of equipment 122 continues to be thermally controlled.

[0024] Aspects of revelation are described in the following example aspects: Aspect 1. A thermal management system, comprehensive: a first thermal subsystem configured to deliver coolant to a first piece of equipment, the first thermal subsystem comprising a first pump, a first heat exchanger and first lines forming a first path from the first pump to the first heat exchanger and to the first piece of equipment; a second thermal subsystem configured to deliver coolant to a second piece of equipment, wherein the second thermal subsystem comprises a second pump, a second heat exchanger and second lines forming a second path from the second pump to the second heat exchanger and to the second piece of equipment; a first cross-connection path that connects the first path at a first point upstream of the first pump with the second path at a second point upstream of the second pump; a second cross-connection path that connects the first path at a third point downstream of the first pump with the second path at a fourth point downstream of the second pump; a passive valve arrangement arranged along the first and second cross-connection paths, wherein the passive valve arrangement isolates the first and second paths during normal operation and allows flow from one of the first and second paths with higher pressure to one of the first and second paths with lower pressure during a component failure. Aspect 2. The thermal management system according to Aspect 1, wherein the passive valve arrangement comprises a first valve arrangement located along the first cross-connection path and a second valve arrangement located along the second cross-connection path. Aspect 3. The thermal management system according to aspect 2, wherein the first valve arrangement comprises a first check valve and a second check valve arranged in parallel. Aspect 4. The thermal management system according to one of aspects 1 to 3, further comprising: a control panel and an active valve arrangement arranged along the first and second cross-connection paths, wherein the active valve arrangement is configured to switch between an open state and an isolated state in response to instructions from the system control, wherein in the isolated state the active valve arrangement isolates the first and second paths. Aspect 5. The thermal management system according to one of aspects 1 to 4, wherein each of the first and second thermal subsystems includes an internal check valve located downstream of the pump and upstream of the second cross-connection path. Aspect 6. The thermal management system according to one of aspects 1 to 5, wherein the second equipment is essentially identical to the first equipment. Aspect 7. The thermal management system according to one of aspects 1 to 6, wherein the second equipment is located in a different location than the first equipment. Aspect 8. The thermal management system according to one of aspects 1 to 7, where the first piece of equipment is part of an aircraft propulsion system. Aspect 9. A comprehensive thermal management system: a first thermal subsystem with a first pump configured to deliver a first coolant along a first path to a first piece of equipment; a second thermal subsystem with a second pump configured to deliver a second coolant along a second path to a second piece of equipment; wherein the thermal management system is configured to automatically switch between a normal operating state, a first assistance state and a second assistance state, wherein the first and second paths are isolated from each other when the thermal management system is configured in the normal operating state, the first pump supplies the first coolant to both the first equipment and the second equipment when the thermal management system is configured in the first assistance state, and the second pump supplies the second coolant to both the first equipment and the second equipment when the thermal management system is configured in the second assistance state. Aspect 10. The thermal management system according to aspect 9, wherein the second equipment is essentially identical to the first equipment. Aspect 11. The thermal management system according to one of aspects 9 and 10, wherein the second piece of equipment is located in a different location than the first piece of equipment. Aspect 12. The thermal management system according to one of aspects 9 to 11, further comprising: a control panel and an active valve arrangement, wherein the active valve arrangement is configured to switch between an open state and an isolated state in response to instructions from the system control, wherein in the isolated state the active valve arrangement isolates the first and the second path. Aspect 13. The thermal management system according to one of aspects 9 to 12, furthermore including: a first cross-connection path that connects the first path at a first point upstream of the first pump with the second path at a second point upstream of the second pump; and a second cross-connection path that connects the first path at a third point downstream of the first pump with the second path at a fourth point downstream of the second pump. Aspect 14. The thermal management system according to aspect 13, furthermore comprehensive a first valve arrangement arranged along the first cross-connection path, wherein the first valve arrangement is configured to allow fluid to flow from one of the first and second paths at higher pressure to one of the first and second paths at lower pressure; and a second valve arrangement located along the second cross-connection path, wherein the second valve arrangement is configured to allow fluid to flow from one of the first and second paths at higher pressure to one of the first and second paths at lower pressure. Aspect 15. The thermal management system according to aspect 14, wherein the first valve arrangement comprises a first check valve and a second check valve arranged in parallel. Aspect 16. The thermal management system according to one of aspects 9 to 15, wherein the first piece of equipment is part of an aircraft propulsion system.

[0025] Having described the preferred aspects and embodiments of the present disclosure, a person skilled in the art can easily arrive at modifications and equivalents of the disclosed concepts. However, it is intended that such modifications and equivalents are included within the scope of the claims set forth herein.

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