Mechanical amplification type battery cell pressure sensor

Abstract

The present disclosure provides a "mechanically amplified battery cell pressure sensor" that discloses a vehicle battery management system. The system can include a cell housing and a trip wire. The cell housing can include connecting walls that enclose an active area of a battery. At least one of the walls can define a weakened section. The trip wire can be stretched across the weakened section and configured to break in response to a pressure within the cell housing exceeding a predetermined threshold, thereby causing the weakened section to bulge toward the trip wire to interrupt current flow therein.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of batteries and battery modules. BACKGROUND

[0002] Hybrid vehicles typically include a high-voltage battery pack adapted to provide electrical power to various components of the vehicle including the motor, transmission, and electrical accessories. The battery pack can be composed of various chemistries such as lithium-ion, nickel-metal hydride, or nickel-cadmium. The battery pack can include a plurality of cells connected in series, parallel, or series / parallel configuration. Each cell can include a cathode, an anode, and an electrolyte, as well as external electrical connections to the anode and cathode. The electrolyte is a medium that allows ions to flow between the anode and the cathode. The anode and cathode are in electrical contact with a metal current collector that provides a means for delivering and receiving electrical current to external devices. It is the electrochemical reactions that occur within the cell that allow the battery pack to function as an energy source.

[0003] The performance of the battery pack can decrease over time due to irreversible chemical reactions at the anode or cathode during normal operation or during abuse conditions including, but not limited to, overcharging, internal shorting, external shorting, and over-discharging, among others. Gas build-up and subsequent pressure increase within the cell can occur in the breakdown of the electrolyte at the surface of the anode or cathode during conditions such as abuse. The increase in pressure can occur gradually due to the slow breakdown of the electrolyte over the life of the cell, or can occur rapidly in response to an increase in temperature within the cell. SUMMARY

[0004] According to one embodiment of the present disclosure, a vehicle battery management system is disclosed. The system can include a cell housing and a tripwire. The cell housing can include connecting walls that enclose a battery active area. At least one of the walls can define a weakened section. The tripwire can be stretched across the weakened section and configured to break in response to a pressure within the cell housing exceeding a predetermined threshold, thereby causing the weakened section to bulge toward the tripwire to interrupt current flow therein.

[0005] According to another embodiment of the present disclosure, a vehicle is provided. The vehicle can include a cell housing enclosing a battery active area, the cell housing including a weakened section defining a stiffness less than the cell housing. The vehicle can also include an electrically conductive gauge carried by the weakened section and configured to increase in resistance in response to an outward deflection of the weakened section caused by a build-up of pressure within the cell housing.

[0006] According to yet another embodiment of the present disclosure, a method of controlling a battery management system is provided. The method can include opening a set of contactors electrically connected to a battery cell in response to a strain gauge disposed along a weakened section of the battery cell having a resistance that exceeds a threshold value associated with a pressure within the battery cell. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a perspective view of a battery cell including an electromechanical pressure sensor and an integrated circuit.

[0008] Figures 2A-2C is a cross-sectional view of an electromechanical pressure sensor and battery cell in operation.

[0009] Figures 2D-2E is a cross-sectional view of a wire entanglement and battery cell in operation.

[0010] Figures 3A-3B is a detailed view of an electromechanical pressure sensor and integrated circuit.

[0011] Figure 4 is a schematic of a control circuit for an electromechanical sensor and integrated circuit.

[0012] Figure 5 is a flowchart illustrating the operation of a system or method for a battery management system. DETAILED DESCRIPTION

[0013] In accordance with the requirements of the present disclosure, detailed embodiments of the present invention are disclosed herein; however, it is understood that the disclosed embodiments are merely exemplary of the present invention, which can take many different forms. The drawings are not necessarily to scale; some features can be exaggerated or minimized for the purpose of clarity. The particular structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0014] Referring now to Figure 1 , a perspective view of a battery cell 100 according to one embodiment is provided. The illustrated battery cell 100 is a prismatic cell, but other configurations such as pouch can also be used. The cell 100 includes a cell housing 101 including connected planar walls 105 that enclose or envelope a battery active area. At least one planar wall 105 includes a pair of terminals 102a and 102b. The battery active area can contain anode, cathode, electrolyte, and separator layers in an organized (wound, z-folded, stacked, etc.) configuration connected to respective external electrode terminals 102a and 102b.

[0015] The cell housing 101 includes a weakened section 104. This section is designed to have lower stiffness relative to the surrounding cell wall 105 of the cell housing 101. In at least one embodiment, the weakened section can be recessed or indented and configured to deform outwardly as pressure within the cell increases. The weakened section can be implemented in various ways. For example, the thickness of the weakened section 104 can be less than the thickness of the surrounding wall 105. In other embodiments, the weakened section 104 can include a plurality of scores or indentations 107 Figure 3B ) to weaken the section 104.

[0016] In one embodiment, a tripwire 112 can be disposed or stretched across the weakened section 104. In another embodiment, an electromechanical gauge 106 can be disposed along a portion of the weakened section 104. The tripwire 112 and the electromechanical gauge 106 can be electrically connected to a battery pack sensing module (BPSM) 108, which can be disposed between a pair of terminals 102a and 102b. The electromechanical gauge 106 can be referred to as a strain gauge. In another embodiment, a Wheatstone bridge, which is a circuit that includes four resistors (one of which is a strain gauge), can be implemented, for example, within the BPSM 108.

[0017] As will be described in greater detail below, the gauge 106 has a resistance that increases as the cross-sectional area or thickness of the gauge decreases. As the weakened section 104 deflects in response to the build-up of pressure within the cell 100, the cross-sectional area or thickness of the gauge can decrease. The BPSM 108 can also measure the voltage or voltage change of the battery cell 100 and the temperature of the cell 100. In another embodiment, the BPSM 108 can have peer-to-peer (P2P) communication capabilities that enable the BPSM 108 to send the measured temperature and voltage of the battery cell 100 to the cloud or a network.

[0018] Referring now to Figures 2A-2C , a cross-sectional view taken along line 2-A is shown according to a first embodiment. The figure shows one example of a battery cell 100 and an electromechanical gauge 106 in operation. Figure 2A The cross-section in FIG. 1 shows that the top portion 105 of the cell 100 has an internal pressure that is less than a first threshold value. The top portion 105 has a thickness ti that is greater than the thickness t2 of the weakened section 104. The electromechanical gauge 106 has a thickness t3 that is greater than t2 but less than ti. The gauge 106 is disposed along the weakened section 104. Although the weakened section 104 is shown as having a greater thickness than the electromechanical gauge 106, in other embodiments, the gauge can be thicker than the weakened section 104, or the gauge 106 and the weakened section 104 can have the same thickness.

[0019] As pressure builds within the cell 100, the weakened section 104 begins to deflect or bend outward away from the active area of the battery as shown Figure 2B When the weakened section 104 bends, the thickness and cross-sectional area t4 of the electromechanical gauge 106 decreases. The thickness t4 and associated electrical resistance can be correlated to an intermediate amount of pressure that is less than the pressure associated with the thickness t3 of the electromechanical gauge 106. Figure 2C The deflection of the weakened section 104 and gauge 106 shown in Figure 2A and Figure 2B is greater than the amount shown in As the weakened section 104 deflects more, the cross-sectional area or thickness t5 of the electromechanical gauge 106 decreases and the resistance of the gauge 106 increases.

[0020] In response to the decreased cross-sectional area and thickness t4, the resistance of the gauge increases. The resistance can be measured by a Wheatstone bridge related to strain, which is a measure of deformation with reference to a known length. The change in resistance can be correlated to a known pressure within the cell. The resistance can be provided to the integrated circuit 108 or one or more controllers, as will be described in greater detail below, so that appropriate action can be taken.

[0021] Referring now to Figures 2D-2E , a cross-sectional view taken along line 2-2 is shown according to a second embodiment. Similar to the cross-sectional view shown in Figures 2A-2C , the battery cell 100 includes a planar wall 105 that includes a semi-rigid region 104. The semi-rigid region 104 is concave with respect to the top surface of the planar wall 105. An electrical wire 112 is disposed across the semi-rigid section 104. The wire conducts electrical power and can be electrically connected to one or more controllers. As pressure builds within the cell 100 and exceeds a threshold, the semi-rigid section bends or deflects toward the electrical wire 112. The wire then breaks, terminating the flow of current across the wire. The wire can be a continuous filament, or two or more filaments that are connected to one another and configured to break at the point of connection. Figures 2D-2E The configuration in the second embodiment shown can provide a cost-effective alternative to those of the first embodiment.

[0022] Referring now to Figure 3A and Figure 3B , detailed views of the semi-rigid section 104 and the electromechanical gauge 106 are shown. The electromechanical gauge 106 can be disposed along the semi-rigid section 104 and connected to the semi-rigid section by adhesive or other suitable fastening methods. The gauge 106 includes two end portions that are attached to the integrated circuit 108. With particular reference to Figure 3B , the semi-rigid section 104 includes a plurality of weakened slots or cuts 107. The slots 107 can facilitate bending and displacement of the semi-rigid section 104.

[0023] Referring now to Figure 4 A schematic diagram of a battery management system 110 is shown. The battery management system 110 includes a battery electronic control module (BECM) 120 in communication with the BPSM 108 and the electromechanical gauge 106. As described in greater detail below, the BECM can execute various algorithms or functions associated with physical characteristics associated with the cell 100. Additionally, the BECM is connected to various types of non-transitory or tangible computer program products or storage media, thereby implementing both temporary or non-persistent storage and persistent storage. In this illustrative embodiment, the non-persistent or temporary storage is implemented by random access memory (RAM) and the persistent storage is implemented by a non-transitory computer program product or medium such as a hard disk drive (HDD), flash drive, or flash memory. In general, persistent memory or storage devices can include all forms of memory or storage devices that maintain data when the computer or other device is powered off. Such memory or storage devices include, but are not limited to, HDDs, CDs, DVDs, magnetic tapes, solid state drives, portable USB drives, and any other suitable form of persistent memory.

[0024] The BECM 120 is also provided with a number of different inputs and outputs to facilitate user interaction with the processor and related devices. In this illustrative embodiment, the electromechanical gauge 106 and the BPSM 108 can provide various measurements of the cell 100 to the BECM. Although not explicitly shown, the vehicle components and ancillary components in communication with the BECM 120 can use a wired or wireless vehicle network, including but not limited to a CAN bus, to transmit signals representing data to and from the BECM 120 (or components thereof). In one embodiment, the electromechanical sensor 106 can provide a signal (resistance) indicative of pressure within the cell 100 to the BPSM 108. In another embodiment, the electromechanical sensor 106 can provide a signal directly to the BECM 120. In another embodiment, the electromechanical sensor 106 can provide a signal to both the BECM 120 and the BPSM 108.

[0025] The system outputs can include, but are not limited to, a visual display 116 and one or more contactors 122. The BECM 120 can enter a limited operation mode, reducing the amount of current drawn from the battery cell, or alert the user of the status of the cell by changing the visual display 116. Additionally, in some cases, the BECM 120 can send a signal to open one or more contactors to stop the flow of current from the battery cell 100 to one or more components. In certain conditions, pressure can build up within the battery cell 100. The pressure build-up within the cell can cause the weakened section 104 to deflect or bend, and reduce the cross-sectional area or thickness of the electromechanical gauge 106. While the electromechanical sensor 106 is shown as connected to the BECM 120, in other embodiments, the sensor 106 can transmit the measured resistance (and associated pressure) to the BPSM 108. In addition to the measured pressure, temperature and voltage can also be measured by the BPSM 108. The electromechanical gauge 106 and the BPSM 108 can provide these measurements to the BECM 120.

[0026] While only one cell 100 associated with a BPSM 108 and electromechanical sensor 106 is shown, more than one cell can be used that communicates with the sensor 106 and BPSM 108. As previously mentioned, the BPSM 108 can communicate through peer-to-peer communication such that one or more BPSM sensors 108 associated with additional battery cells 100 provide the measured resistance of the sensor 106, temperature and voltage of the cell 100 to the other BPSM sensors 108 and the BECM 120. The BECM can be provided with an operating system that includes an API for communicating with a modem application software. The modem application software can access the embedded module or firmware of the BLUETOOTH transceiver. BLUETOOTH is a subset of the IEEE 802 PAN (Personal Area Network) protocol. The IEEE 802 LAN (Local Area Network) protocol includes Wi-Fi and has considerable overlap with the IEEE 802 PAN protocol. Both are suitable for wireless communication within a vehicle. Other communication technologies can also be suitable for wired or wireless communication within a vehicle, such as free space optical communication (e.g., IrDA), non-standardized consumer infrared (IR) protocols, and the like.

[0027] Referring now to Figure 5 The flow diagram illustrates the operation of a system for operating a method 500 of a battery management system 110, in accordance with various embodiments. Although not explicitly stated or described, as will be appreciated by one of ordinary skill in the art, the various functions or processes shown can be performed in different orders, can be omitted, or can be repeatedly performed to achieve the various features and advantages described herein.

[0028] Controlling or operating the battery management system 110 can include powering the vehicle as shown by 502. Powering the vehicle can include drawing power from one or more batteries to provide power to the BECM or another component or both. Powering the vehicle can be accomplished through a "key-on" event when an occupant approaches or enters the vehicle while carrying a key fob or other suitable accessory. After the vehicle is powered on, the BECM can complete a self-check or diagnosis of the battery management system 110 as shown by 504. If an error is detected or determined during the self-check, the BECM determines whether one or more cells of the battery are not monitored or not in communication with the BECM as shown by 506. If all cells are monitored, the controller branches to operation 516, which will be described in greater detail below.

[0029] If one or more cells are not monitored, the BECM commands one or more contactors 122 to remain open as shown by 508. By keeping the contactors open, current flow from the battery through the contactors is prevented. In response to the determination at 506, a warning light or indicator 116 can be illuminated as shown by 510 to alert the user or operator of the problem. The error can be provided to a network via a direct wired connection or a wireless connection as shown by 512. The network can include the BECM 120 and one or more BPSMs 108. Finally, the system can be restarted or rebooted by shutting down and restarting as shown by 514.

[0030] If the self-check or diagnosis of the cells operates normally at 504, the self-check can be repeated after a predetermined amount of time as shown by 516. In contrast to the self-check at 504, this self-check can be performed while the vehicle is in motion or operation. If one or more cells are not monitored, the controller can enter a limited operation mode as shown by 524. The limited operation mode can reduce the amount of power used by the system 110. After the system is entered into the limited operation mode, a warning indicator can be illuminated as shown by 510, the results of the check can be provided to a network as shown by 512, and the system can be restarted as shown by 514.

[0031] If all cells are monitored at 518, the controller can measure the voltage and pressure of each cell as shown by 520. As described above, the voltage can be measured by the BPSM 108, and the pressure can be measured or determined through a resistance measurement provided from the electromechanical gauge 106. If the voltage is outside of a predetermined range or the pressure is above a threshold, the BECM can open the contactors 122 as shown by 522, thereby terminating the flow of electricity from the battery cells. Upon opening the contactors, a warning indicator can be illuminated as previously described, data can be provided to a network, and the system can be restarted.

[0032] While the foregoing describes exemplary embodiments, these embodiments are not intended to describe all possible forms of the application. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the application. Additionally, features of various implemented embodiments can be combined to form further embodiments of the application.

[0033] According to the present invention, there is provided a vehicle battery management system having a cell housing including a connecting wall enclosing a battery active area, at least one wall defining a weakened section; and a trip wire stretched across the weakened section and configured to break in response to pressure within the cell housing exceeding a predetermined threshold, thereby causing the weakened section to bulge towards the trip wire to interrupt current flow therein.

[0034] According to an embodiment, the weakened section is recessed below a surface of one of the walls.

[0035] According to an embodiment, the weakened section is thinner than the connecting wall.

[0036] According to an embodiment, the weakened section defines a plurality of scored regions.

[0037] According to an embodiment, the above invention is further characterized by: an integrated circuit carried by one of the connecting walls and electrically connected to the trip wire to measure a voltage associated with the battery active area.

[0038] According to an embodiment, the integrated circuit includes a reverse-biased diode configured to measure a temperature associated with the battery active area.

[0039] According to an embodiment, the above invention is further characterized by: a controller configured to open a set of contactors in response to the breaking of the trip wire.

[0040] According to the present invention, there is provided a vehicle having a cell housing enclosing a battery active area; and a conductor carried by the cell housing and configured to increase resistance in response to deflection caused by bulging of the cell housing due to accumulation of pressure therein.

[0041] According to an embodiment, the above invention is further characterized by: a controller configured to open a set of contactors in response to the resistance exceeding a threshold.

[0042] According to an embodiment, the above invention is further characterized by: a display configured to alert a user of the vehicle in response to the resistance exceeding a threshold.

[0043] According to embodiments, the above invention is further characterized by an integrated circuit configured to measure a voltage of the battery active area.

[0044] According to embodiments, the above invention is further characterized by the integrated circuit including a reverse-biased diode configured to measure a temperature of the battery active area.

[0045] According to embodiments, the controller is further configured to open the set of contactors in response to the temperature exceeding the threshold.

[0046] According to the invention, there is provided a method of controlling a battery management system, the method having: in response to a resistance of a strain gauge carried by a housing of a battery cell exceeding a threshold value as a result of a deflection of the strain gauge caused by a protrusion of the housing, commanding a set of contactors electrically connected to the cell to open.

[0047] According to embodiments, the above invention is further characterized by transmitting a plurality of signals from a plurality of battery cells to the controller prior to commanding the set of contactors to open, each battery cell including an integrated circuit and a strain gauge.

[0048] According to embodiments, the above invention is further characterized by commanding the controller to switch to a limited mode of operation to reduce power supplied from the plurality of battery cells in response to the controller not receiving a signal from at least one of the battery cells.

[0049] According to embodiments, the above invention is further characterized by displaying a warning in response to the resistance exceeding the threshold.

Claims

1. A vehicle battery management system, the vehicle battery management system comprising: a cell housing including a connecting wall that encloses a battery active area, at least one wall defining a weakened section; a strain gauge disposed along a portion of the weakened section and having an electrical resistance that increases as a cross-sectional area or thickness decreases; an integrated circuit carried by one of the connecting walls and electrically connected to the strain gauge to measure a voltage associated with the battery active area; and a controller configured to: receive a signal from each of a plurality of battery cells during vehicle travel, the signal generated by a respective integrated circuit based on a resistance measured by a strain gauge to indicate an internal pressure of a respective battery cell; determine whether the signal is received from each of the plurality of battery cells; in response to determining that the signal is received from each of the plurality of battery cells, determine whether the internal pressure of a respective battery cell exceeds a threshold based on the signal; in response to determining that the internal pressure exceeds a threshold, command an opening of a contactor electrically connected to the respective battery cell. the weakened section is recessed below a surface of one of the walls.

2. The vehicle battery management system of claim 1, wherein, the weakened section is thinner than the connecting wall.

3. The vehicle battery management system of claim 2, wherein, the weakened section defines a plurality of score regions.

4. The vehicle battery management system of claim 3, wherein, the controller is further configured to, in response to determining that the signal is not received from one or more of the plurality of battery cells, switch the plurality of battery cells to a limited operational mode to reduce an amount of power supplied from the plurality of battery cells.

5. The vehicle battery management system of claim 1, wherein, the integrated circuit includes a reverse-biased diode configured to measure a temperature associated with the battery active area.

6. The vehicle battery management system of claim 5, wherein, 7. A vehicle, the vehicle comprising: a cell housing enclosing a battery active area; a strain gauge carried by the cell housing and configured to increase an electrical resistance in response to a deflection caused by a bulge of the cell housing due to a build-up of pressure therein; and a controller configured to: receive a signal from each of a plurality of battery cells during vehicle travel, the signal indicating an internal pressure of a respective battery cell; determine whether the signal is received from each of the plurality of battery cells; in response to determining that the signal is received from each of the plurality of battery cells, determine whether the internal pressure of a respective battery cell exceeds a threshold based on the signal; in response to determining that the internal pressure exceeds a threshold, command an opening of a contactor electrically connected to the respective battery cell. the controller is further configured to, in response to determining that the signal is not received from one or more of the plurality of battery cells, switch the plurality of battery cells to a limited operational mode to reduce an amount of power supplied from the plurality of battery cells.

8. The vehicle of claim 7, wherein, 9. The vehicle of claim 7, further comprising: a display configured to alert a user of the vehicle in response to the internal pressure exceeding a threshold.

10. The vehicle of claim 7, further comprising: an integrated circuit configured to measure a voltage of the battery active area. ​ 11. The vehicle of claim 10, wherein, The integrated circuit includes a reverse-biased diode configured to measure a temperature of the battery active area.

12. The vehicle of claim 11, wherein, The controller is further configured to open a set of contactors in response to the temperature exceeding a threshold.

13. A method of controlling a battery management system, the method comprising: receiving a signal from each of a plurality of battery cells during travel of a vehicle, the signal indicative of an internal pressure of a respective battery cell determined based on a resistance of a strain gauge, the strain gauge carried by a housing of the battery cell and configured to increase resistance in response to a deflection caused by a bulge of the housing of the battery cell resulting from a build-up of pressure therein; determining whether the signal is received from each of the plurality of battery cells; in response to determining that the signal is received from each of the plurality of battery cells, determining whether the internal pressure of the respective battery cell exceeds a threshold based on the signal; in response to determining that the internal pressure exceeds a threshold, commanding an opening of a contactor electrically connected to the respective battery cell.

14. The method of claim 13, the method further comprising: in response to determining that the signal is not received from one or more of the plurality of battery cells, switching the plurality of battery cells to a limited operational mode to reduce an amount of power supplied from the plurality of battery cells.

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