Device for monitoring pressure in battery housing, battery management equipment having the device, and battery system

Abstract

Disclosed is a device (AO) for monitoring the pressure in a battery housing (BG) of a battery system (BS), comprising: a first current supply path (SP1); a pressure measuring unit (DM) for measuring the pressure in the battery housing (BG), the pressure measuring unit being electrically connected to the first current supply path (SP1) for current supply; a pressure-sensitive mechanical switch unit (SB), the switch unit being arranged in the battery housing (BG) and being electrically connected in series with the pressure measuring unit (DM) on the first current supply path (SP1) via two electrical connection terminals (A1, A2); wherein the switch unit (SB) is configured to switch to an electrically conductive switch state when the pressure in the battery housing (BG) exceeds a predetermined pressure threshold, thereby establishing a current supply to the pressure measuring unit (DM) via the first current supply path (SP1), and to switch to an electrically blocked switch state when the pressure in the battery housing (BG) is lower than the pressure threshold, thereby interrupting the current supply to the pressure measuring unit (DM) via the first current supply path (SP1).

Description

Technical Field

[0001] The present invention relates to a device for monitoring the pressure in a battery housing of a battery system, in particular a traction battery system of an electric vehicle, and a battery management system for operating a battery system, in particular a traction battery system of an electric vehicle, comprising the aforementioned device. Furthermore, the present invention relates to a battery system, in particular a traction battery system of an electric vehicle, comprising the battery management system or the aforementioned device. Background Art

[0002] Lithium-ion battery cells or other battery cells with similar properties are used, in particular, in traction battery systems of electrically driven vehicles to drive the vehicle. Due to their properties, in particular the cell chemistry, these battery cells are susceptible to external influences, such as strong heat dissipation. In critical situations, such as overheating, so-called thermal runaway can occur in the battery cells. In the event of thermal runaway, the individual components of the battery cells react with each other in an uncontrolled manner, resulting in strong heat dissipation and the formation of large amounts of gas, which can lead to fire or explosion of the battery system. To avoid this, thermal runaway in the battery cells must be detected early. Summary of the Invention

[0003] The object of the present application is therefore to provide a method for determining states in a battery system, by means of which critical states, in particular thermal runaway, can be reliably detected in the battery system or in the battery cells of the battery system.

[0004] This object is achieved by the present invention.

[0005] According to a first aspect of the invention, an (electrical or electromechanical) device is provided for monitoring the pressure in a battery housing of a battery system, in particular a traction battery system of an electrically driven vehicle, wherein the battery system has, in addition to the battery housing, a number of battery cells arranged in the battery housing.

[0006] The device has a first current supply path and a pressure measuring cell for measuring the pressure in the battery housing, wherein the pressure measuring cell is electrically connected to the first current supply path for current supply (via the battery system or its cells).

[0007] The device further comprises a pressure-sensitive mechanical switching unit, in particular a pressure-sensitive electromechanical switching unit, which is arranged in the battery housing and is electrically connected in series with the pressure measuring cell via two electrical connections on the first current supply path.

[0008] The switching unit is configured to switch to an electrically conductive switching state when the pressure in the battery housing exceeds a predetermined pressure threshold, thereby establishing a current supply to the pressure measuring unit via the first current supply path (through the battery system or its battery cells), and to switch to an electrically cutoff switching state when the pressure in the battery housing is lower than the pressure threshold, thereby interrupting the current supply to the pressure measuring unit via the first current supply path.

[0009] The present invention utilizes the gas formation inside the battery housing of a battery system, which gas formation usually occurs in the battery cells due to critical states, in particular thermal runaway, in order to be able to identify critical states or thermal runaway in the battery cells or battery systems early. In this case, the (air or gas) pressure or pressure change inside the battery housing is used to monitor the critical state, and the pressure / pressure change is directly related to the gas formation. Therefore, in order to monitor the critical state, the (air or gas) pressure inside the battery housing is continuously detected, and a critical state in the battery cell or battery system is diagnosed when the detected pressure deviates from a predetermined pressure threshold range or when the detected pressure exceeds a predetermined pressure threshold. In this case, the pressure is monitored by means of the pressure measuring unit, which is supplied with current from the battery system via the first current supply path.

[0010] The pressure-sensitive mechanical switching unit is capable of changing its switching state independently of the pressure measuring unit and, in particular, solely under the influence of the pressure prevailing inside the battery housing. The switching unit, for example, as a pressure-sensitive mechanical switch, may include a strain gauge, for example, and may be designed to change its size, shape, or other similar physical (mechanical) properties when the (air or gas) pressure acting on the strain gauge changes, thereby switching autonomously between an electrically conductive switching state and an electrically blocked switching state independently of the pressure measuring unit. The switching unit is designed to switch to the electrically conductive switching state at a pressure above a predetermined pressure threshold and to the electrically blocked switching state at a pressure below the pressure threshold.

[0011] Here, the pressure threshold is a predeterminable pressure value, above which the pressure inside the battery housing indicates the presence or imminent occurrence of a critical state in the battery cell or battery system, in particular the presence or imminent occurrence of thermal runaway. The pressure threshold is selected such that a (possibly imminent) critical state, in particular a (possibly imminent) thermal runaway, and the resulting pressure increase inside the battery housing can be detected early / in time.

[0012] In the electrically conductive switching state, the switching cell, which is electrically connected in series with the pressure measuring cell in the current supply path, establishes a current supply for the pressure measuring cell. This current supply allows the pressure measuring cell to measure the pressure inside the battery housing with the required high accuracy and forward the pressure measurement value to a downstream battery management system for more accurate analysis. The battery management system compares the pressure measurement value, for example, with a critical pressure threshold value and, based on the comparison result, makes a more accurate statement about the critical state and, if necessary, initiates further necessary steps, such as outputting a warning signal.

[0013] In this case, the current is usually supplied by the battery cells of the battery system, to which the device is also electrically connected (directly or indirectly).

[0014] As a pressure-sensitive mechanical switching unit, the switching unit itself does not consume current and does not load the battery system, in particular during the idle phase (sleep mode) of the battery system, thus protecting the battery system and thus also protecting the battery system from deep discharge.

[0015] Since the switching unit interrupts the current supply to the pressure measuring cell (from the battery system) during a time period in which the pressure inside the battery housing is below a predetermined pressure threshold and therefore there is no risk of a critical state in the battery system, the switching unit avoids (unnecessary) current consumption by the pressure measuring cell and additionally protects the battery system.

[0016] Once the pressure inside the battery housing exceeds a predetermined pressure threshold, the switching unit establishes a current supply to the pressure measuring unit via the first current supply path by changing its size, shape or other similar physical (mechanical) properties, so that from now on, the pressure measuring unit can measure the pressure inside the battery housing more accurately, and the above-mentioned battery management device can use these more accurate measurement values ​​to accurately and reliably make statements about critical conditions, and can initiate further necessary steps, such as outputting warning signals, etc.

[0017] In summary, in particular during the deactivation phase of the battery system, the pressure measuring unit is only activated in an event-controlled manner, wherein the activation is controlled by the pressure-sensitive mechanical switching unit, which is connected upstream of the pressure measuring unit and operates autonomously independently of the pressure measuring unit or other control units and only responds to pressure changes, in particular pressure increases, inside the battery housing without consuming any current itself.

[0018] This provides a possibility for determining states in a battery system, by means of which critical states in the battery system or in the battery cells of the battery system, in particular thermal runaway, can be reliably detected.

[0019] For example, the device is further designed to be operable in a sleep mode, in which the device interrupts the current supply to the pressure measuring cell, so that the pressure measuring cell does not obtain energy to perform its functions, including measuring the pressure in the battery housing. In this sleep mode, the pressure measuring cell does not measure pressure. Here, the switching unit is further configured to switch to an electrically conductive switching state in the sleep mode of the device and when the pressure in the battery housing exceeds a predetermined pressure threshold, thereby establishing a current supply to the pressure measuring cell via the first current supply path (through the battery system or its battery cells), and to switch to an electrically blocked switching state in the sleep mode of the device and when the pressure in the battery housing falls below the pressure threshold, thereby interrupting the current supply to the pressure measuring cell via the first current supply path.

[0020] For example, the pressure threshold is lower than a critical pressure threshold, which is a pressure value above which a critical or fault condition, such as thermal runaway, exists in the battery system or battery cell, or at least indicates the presence of a critical or fault condition in the battery system or battery cell.

[0021] For example, the pressure measuring cell comprises a pressure sensor with a pressure-sensitive microelectromechanical system (MEMS) element, wherein the MEMS element is configured as part of the switching unit. The MEMS element is configured to electrically short-circuit two terminals of the switching unit when the pressure in the battery housing exceeds a pressure threshold, thereby establishing a current supply to the pressure measuring cell via a first current supply path, and to electrically disconnect the two terminals from each other when the pressure in the battery housing falls below the pressure threshold, thereby interrupting the current supply to the pressure measuring cell via the first current supply path.

[0022] For example, the device has a pressure-balancing valve for balancing the air pressure in the battery housing, which in turn has a diaphragm that can be reversibly moved or reversibly / elastically deformed under pressure. In this case, the diaphragm is constructed as part of the switching unit and is configured so that when the pressure in the battery housing exceeds a pressure threshold due to a movement caused by the (increased) pressure effect or a deformation caused by the (increased) pressure effect, the two connection ends of the switching unit are electrically short-circuited to each other, thereby establishing a current supply to the pressure measuring cell via a first current supply path, and when the pressure in the battery housing falls below the pressure threshold due to the reversible movement or reversible deformation, the two connection ends are electrically disconnected from each other, thereby interrupting the current supply to the pressure measuring cell via the first current supply path. The diaphragm is provided with an electrically conductive material.

[0023] The pressure-sensitive diaphragm of the pressure-balancing valve monitors pressure, primarily for balancing air pressure. If an overpressure (equal to or greater than the pressure threshold) is applied to the diaphragm within the battery housing, the diaphragm deforms (stretches) or moves. This deformation or movement causes the diaphragm, with its conductive material, to contact the two connection terminals of the switch unit, thereby electrically connecting the two connection terminals.

[0024] For example, the device further comprises an air or gas flow channel, which is fluidically connected to the aforementioned pressure equalization valve and is configured to discharge air or gas from the interior of the battery housing into the environment of the battery housing (particularly in the event of an overpressure in the battery housing). Furthermore, the device comprises, for example, an air mass flow sensor, which is arranged in the air flow channel and is connected on the signal output side to a measurement signal input of (one or the aforementioned) measurement value evaluation circuit of the pressure measuring unit and is configured to measure the mass flow of gas / air flowing out of the battery housing via the air flow channel (particularly when the pressure in the battery housing exceeds the pressure threshold) and forward the measured value to the measurement value evaluation circuit. The measurement value evaluation circuit is, for example, further configured to determine the pressure in the battery housing (particularly) based on the measured value transmitted by the air mass flow sensor.

[0025] For example, the device further comprises a second current supply path designed in parallel with the first current supply path. Furthermore, the device further comprises a controllable switch electrically connected to the second current supply path. The pressure measuring cell is also electrically connected in series with the switch on the second current supply path for current supply. The switch is designed to be switchable between a closed, conductive switch state, in which the switch establishes a current supply to the pressure measuring cell via the second current supply path (through the battery system or its battery cells), and an open, blocked switch state, in which the switch interrupts the current supply to the pressure measuring cell via the second current supply path.

[0026] In particular, the switch is configured to be controllable by the aforementioned battery management device. Here, the battery management device is configured to interrupt the current supply to the pressure measuring cell via the second current supply path by opening the switch in the aforementioned sleep mode. Furthermore, the device is configured to operate in an active operating mode, wherein in this active operating mode, the battery management device establishes a current supply to the pressure measuring cell via the second current path (through the battery system or its cells) by closing the switch, so that the pressure measuring cell receives current (from the battery system or its cells) via the second current path to perform its functions, including measuring the pressure within the battery housing. In this operating mode, the pressure measuring cell measures the pressure within the battery housing.

[0027] According to a second aspect of the present invention, a battery management device is provided for operating a battery system, in particular a traction battery system of an electrically driven vehicle, the battery system having a battery housing and a number of battery cells arranged in the battery housing.

[0028] The battery management device comprises the previously described apparatus and the previously mentioned battery management device for operating a battery system. The pressure measuring cell of the apparatus is connected to the battery management device (or to a signal input of the battery management device) via signal technology at the signal output side and is further configured to forward measured values ​​of the pressure in the battery housing to the battery management device. The battery management device is further configured to detect (imminent) critical states, in particular (imminent) thermal runaway, in the battery system or the battery cells based on the transmitted measured values.

[0029] For example, the battery management device is also connected to the control signal connection end of the switch in signal technology via the control signal output end, and is configured to open the switch in the sleep mode of the device, thereby interrupting the current supply to the pressure measuring cell via the second current supply path, and to close the switch in the active operating mode, thereby establishing the current supply to the pressure measuring cell via the second current supply path.

[0030] For example, the battery management system is electrically connected in series with the switch unit and the pressure measuring cell on the first current supply path. The switch unit is further configured to establish a current supply to the battery management system (excluding the pressure measuring cell) via the first current supply path in the electrically conductive switching state, and to interrupt the current supply to the battery management system via the first current supply path in the electrically blocked switching state. In this case, the switch unit can autonomously control the current supply to the pressure measuring cell and the entire battery management system via the first current supply path, without consuming its own current, solely in response to pressure changes, particularly pressure increases, inside the battery housing.

[0031] According to a third aspect of the present invention, a battery system is provided, in particular a traction battery system for an electrically driven vehicle.

[0032] The battery system comprises a battery housing and a number of battery cells arranged in the battery housing. The battery system further comprises a battery management device as described above for operating the battery system, wherein the battery management device is also configured to monitor the pressure in the battery housing of the battery system using the device described above and, based on this, to detect critical states, in particular thermal runaway, in the battery system or the battery cells.

[0033] As long as the advantageous design of the above-mentioned device can be applied to the above-mentioned battery management device or the above-mentioned battery system, it is also regarded as an advantageous design of the above-mentioned battery management device or the above-mentioned battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The exemplary embodiments of the present invention are explained in more detail below with reference to the accompanying drawings.

[0035] Figure 1 A first schematic diagram shows a battery system (or a portion thereof) having a portion of a battery management device according to an exemplary embodiment of the present invention;

[0036] Figure 2 A second schematic diagram shows another exemplary embodiment of the present invention. Figure 1 Part of a battery management device; Figure 3The third schematic diagram shows another exemplary embodiment of the present invention. Figure 1 part of the battery management identification; and

[0037] Figure 4 A fourth schematic diagram shows a battery system (or a portion thereof) having a portion of a battery management device according to another exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0038] Figure 1 A schematic diagram shows a battery system BS (or a part thereof) having a battery management identifier BV (or a part thereof) according to a first exemplary embodiment of the present invention.

[0039] In this embodiment, battery system BS is configured as a traction battery system for an electric vehicle. Battery system BS includes a battery housing BG and a plurality of battery cells BZ. Battery cells BZ are arranged in battery housing BG and protected from mechanical and other external influences by battery housing BG. Lithium-ion battery cells, for example, in the form of pouch-type cells, are installed as battery cells BZ.

[0040] The battery housing BG has an opening OF on the housing wall (with Figure 2 and Figure 3 In comparison, air or gas can flow between the inside of the battery housing BG and the environment of the battery housing BG through the opening OF. The air pressure or gas pressure inside the battery housing BG is balanced with the air pressure in the environment of the battery housing BG through the opening OF.

[0041] The battery management unit BV is also located in the battery housing BG and is used to determine or monitor the state of the battery system BS and to operate the battery system BS according to the determined state and based on the requirements of the higher-level central control unit of the vehicle. The battery management unit BV operates the battery system BS or its battery cells BZ in such a way that the battery cells BZ operate as sensitively as possible, in particular, they are protected from overcharging or deep discharge. To this end, the battery management unit BV includes a battery management device BA, which in particular includes a controllable switch or a controllable / regulatable DC voltage converter, each of which is connected upstream of one of the battery cells BZ and assigned to the respective battery cell BZ. The battery management device BA is configured to control or regulate the associated switch or DC voltage converter of the respective battery cell BZ based on the determined state of the respective battery cell BZ and the requirements of the battery management unit BV, so that the battery cell BZ operates sensitively and is protected from failure.

[0042] Despite the protective battery housing BG, the battery cells BZ are still subject to numerous external influences, such as high ambient temperatures or severe temperature fluctuations or strong mechanical vibrations, which, in particular due to use in vehicles, can impair the functionality of the battery cells BZ and can even lead to premature failure of the battery cells BZ.

[0043] Furthermore, like virtually all technical components, the battery cells BZ are subject to unavoidable aging processes which, in addition to the aforementioned effects, can also impair the functionality of the battery cells BZ and can lead to premature failure of the battery cells BZ.

[0044] Furthermore, battery cells BZ themselves present various potential hazards due to their properties and material composition. One potential hazard emanating from battery cells BZ, such as lithium-ion cells, is so-called thermal runaway. Due to their chemical composition, battery cells BZ can overheat uncontrollably under certain circumstances, such as mechanical damage or an electrical short circuit. This can lead to fire or explosion of the entire battery system BS.

[0045] In order to monitor the functionality of the battery cells BZ and thereby the functionality of the battery system BS and to identify impending failures and hazards of the battery cells BZ as early as possible, such as (imminent) thermal runaway caused by the battery cells BZ, and to be able to initiate appropriate measures, the battery management device BV has a device AO for monitoring the (air or gas) pressure in the battery housing BG of the battery system BS.

[0046] Device AO includes a pressure-sensitive mechanical switch unit SE and a pressure measuring unit DM for measuring the pressure within the battery housing BG. Device AO also includes a first current supply path SP1 that electrically connects the pressure measuring unit DM to a selected set of battery cells BZ electrically connected in series, thereby supplying current to the pressure measuring unit DM. These selected battery cells BZ provide the nominal voltage required to operate the pressure measuring unit DM, for example, 5 volts or 12 volts. In this first current supply path SP1, the pressure measuring unit DM and the switch unit SE are electrically connected in series. The pressure measuring unit DM and the switch unit SE are also located within the battery housing BG.

[0047] The switching unit SE furthermore has two electrical terminals A1 , A2 and is electrically connected in series with the pressure measuring unit DM via these two terminals A1 , A2 on a first current supply path SP1 .

[0048] The pressure measuring unit DM has a pressure sensor DS with a pressure-sensitive microelectromechanical element DE, wherein the microelectromechanical element DE is designed as part of a switching unit SE. The pressure measuring unit DM also has a measured value evaluation circuit MS, which is connected on the signal input side to a signal output of the pressure sensor DS and on the signal output side to a signal input of the battery management unit BA.

[0049] The device AO also has a second current supply path SP2, which is arranged parallel to the first current supply path SP1 and thus electrically connects the pressure measuring cell DM to the aforementioned battery cell group. The device AO also has a controllable switch ST, for example in the form of a semiconductor switch, which is electrically connected in series with the pressure measuring cell DM in the second current supply path SP2. The switch ST is designed to be switchable between a closed, conductive switching state, in which the switch ST establishes the current supply to the pressure measuring cell DM via the second current supply path SP2, and an open, blocked switching state, in which the switch ST interrupts the current supply to the pressure measuring cell DM via the second current supply path SP2. Therefore, if necessary, the pressure measuring cell DM can also be supplied with current via the second current supply path SP2 instead of the first current supply path SP1. The switch ST is controlled by the battery management unit BA, which is connected to the control terminal of the switch ST via a control signal connection.

[0050] Based on Figure 1 Having described in detail the structure of the battery management device BV, in particular the device AO for monitoring the pressure, its mode of operation will now be described in more detail:

[0051] The battery system BS and therefore also the battery management device BV together with the arrangement AO are designed to be operable in an active operating mode and a sleep mode.

[0052] In active operating mode, the battery system BS provides a "high" current, for example, to drive the vehicle or to perform vehicle functions related to, for example, vehicle comfort (such as operating the vehicle's auxiliary heater or navigation system), or is connected to a charging station for charging or charged by using the vehicle's brake energy recovery.

[0053] In this operating mode of the battery system BS, the battery management unit BV is also in this operating mode and controls the battery system BS and regulates the current flowing to and from the individual battery cells BZ of the battery system BS. Furthermore, the battery management unit BV or the battery management system BA controls the device AO or its pressure measuring unit DM so that the pressure measuring unit continuously measures the air / gas pressure inside the battery housing BG at regular short time intervals, for example, a few to tens of milliseconds, and forwards the measured values ​​(particularly unprocessed) directly to the battery management unit BA. The battery management unit BA evaluates the transmitted measured values ​​in a manner known to those skilled in the art (e.g., by comparing them with predetermined critical pressure thresholds) and, based on these values, analyzes the state of the battery system BS. Furthermore, based on the analysis results, the battery management unit BA identifies, in particular, whether a critical state exists, such as overpressure inside the battery housing BG due to thermal runaway. If a critical state is detected, the battery management unit BA outputs a warning signal to the battery management unit BV, thereby prompting the battery management unit BV to shut down the entire battery system BS and / or initiate further appropriate measures.

[0054] In this operating mode, the battery management device BA closes the switch ST, thereby establishing a current supply to the pressure measuring unit DM via the second current supply path SP2. The pressure measuring unit DM draws current from the battery cell group via the second current supply path SP2 for its function and thus loads the battery cell group.

[0055] As long as the air pressure / gas pressure inside the battery housing BG is below a predefined pressure threshold value (which is below the aforementioned critical pressure threshold value), the switching unit SE remains in the electrically blocked switching state.

[0056] If the air pressure inside the battery housing BG exceeds the aforementioned critical pressure threshold, for example due to thermal runaway in one or other of the battery cells BZ, the battery management device BA recognizes the presence of thermal runaway by comparing the pressure measurement value measured and transmitted by the pressure measuring unit DM with the critical pressure threshold and outputs a warning signal.

[0057] In the sleep mode, the vehicle is parked. In the sleep mode, no current or "significant" current is drawn from the battery system BS, nor is current supplied to the battery system BS. In this sleep mode A, only safety-related vehicle functions, such as anti-theft functions, are performed.

[0058] In the battery management device BV, most functions, particularly those not relevant to safety, are deactivated. Accordingly, the pressure measuring unit DM is placed in a sleep mode, in which it no longer measures air / gas pressure. To this end, the battery management arrangement BA closes the switch ST and thus interrupts the current supply to the pressure measuring unit DM via the second current supply path SP2. The battery management arrangement BA preferably remains in this operating mode, in which it continues to perform safety-related functions.

[0059] In this sleep mode, the state or pressure monitoring in the battery system BS is performed (only) in a currentless and autonomous manner by the switching unit SE and its pressure-sensitive microelectromechanical element DE. The pressure-sensitive element DE is designed to move, deform, or otherwise change its electromechanical properties when air / gas pressure acts. If the air / gas pressure inside the battery housing BS exceeds a predetermined pressure threshold, the element DE moves, deforms, or changes its electromechanical properties, causing the element DE to electrically short-circuit the two terminals A1, A2 of the switching unit SE. As a result, a current supply is established via the battery cell group to the pressure measuring unit DM via the first current supply path SP1. This current supply enables the pressure measuring unit DM to more accurately measure the air / gas pressure inside the battery housing BG and forwards the measured value to the battery management unit BA. If the battery management unit BA receives the measured value from the pressure measuring unit DM, it checks whether a critical state, such as thermal runaway, is actually present in the battery system BS, for example, by comparing it with a predetermined critical pressure threshold.

[0060] As long as the air pressure / gas pressure inside battery housing BG is below the aforementioned pressure threshold of pressure-sensitive element DE, pressure-sensitive element DE maintains its shape, position, or electromechanical properties such that the two terminals A1 and A2 of switch unit SE are not electrically short-circuited. Accordingly, first current supply path SP1 remains disconnected, and pressure measuring unit DM does not receive current via first current supply path SP1.

[0061] In an alternative embodiment (not shown), the battery management device BA is electrically connected in series with the switching unit SE and the pressure measuring unit DM on the first current supply path SP1. In this case, the switching unit SE is configured to establish a current supply to the battery management device BA via the first current supply path SP1 in the electrically conductive switching state and to interrupt the current supply to the battery management device BA via the first current supply path SP1 in the electrically blocked switching state. Accordingly, the battery management device BA is also placed in the sleep mode during the sleep mode of the battery system BS and only activates into the operating mode when the switching unit SE or its pressure-sensitive element DE detects an overpressure or an air / gas pressure exceeding a pressure threshold inside the battery housing BG, or when a current supply via the first current supply path SP1 is established.

[0062] Figure 2 A second schematic diagram shows another exemplary embodiment of the present invention. Figure 1 Part of Battery Management Equipment BV.

[0063] In this embodiment, the device AO of the battery management apparatus BV has a pressure-compensating valve DV, which is arranged at the above-mentioned opening OF of the battery housing BG and is configured to discharge gas from the battery housing into the environment of the battery housing when the interior of the battery housing BG is under overpressure. The pressure-compensating valve DV has a diaphragm MB, which is designed to reversibly move or reversibly / elastically deform under the action of pressure. Due to the movement or deformation, the diaphragm MB opens the pressure-compensating valve DV, whereby gas is discharged from the battery housing into the environment of the battery housing. Here, the diaphragm MB is constructed as part of the switching unit SE and is elastically retained on the housing wall in the area of ​​the above-mentioned opening OF via two or more spring arms FA. Here, the spring arms FA hold the diaphragm MB in a closed position, in which the diaphragm MB closes the opening OF and thereby interrupts the air flow / gas flow between the interior of the battery housing BG and the environment of the battery housing BG (as in Figure 2 In the event of an overpressure inside the battery housing BG, the diaphragm MB is pressed into the open position by the pressure of the overpressure inside the battery housing BG (which pressure is greater than the spring force of the spring arm FA), in which the diaphragm MB opens the opening OF and thus allows air / gas from the interior of the battery housing BG to flow into the environment of the battery housing BG (and the surrounding air). Figure 2 (as indicated by the arrow in section B).

[0064] The diaphragm MB further comprises a thin copper sheet KB which, when the diaphragm MB is in the open position (when the pressure inside the battery housing BG exceeds a pressure threshold), brings the two terminals A1, A2 of the switching power supply SE into contact and thereby electrically short-circuits the two terminals A1, A2 to one another, thereby establishing a current supply to the pressure measuring cell DM via the first current supply path SP1 (and in Figure 2 In the closed position of the diaphragm MB (when the pressure inside the battery housing BG is below the pressure threshold), the spring element FA of the diaphragm MB pulls the copper sheet KB away from the two terminals A1, A2, so that the electrical connection via the two terminals A1, A2 is interrupted and thus also the current supply to the pressure measuring cell DM via the first current supply path SP1 is interrupted (and in Figure 2 ).

[0065] Figure 3 The second schematic diagram shows Figure 2 An extension of the device AO shown in .

[0066] In addition to the pressure balancing valve DV, Figure 3 The device AO in the embodiment further comprises an air flow channel LK for discharging gas from the battery housing BG into the environment of the battery housing BG, which air flow channel is connected to the pressure equalization valve DV in terms of flow technology. The device AO further comprises an air volume sensor LS arranged in the air flow channel LK. Here, the air volume sensor LS is connected to the measurement signal input of the measured value evaluation circuit MS of the pressure measuring unit DM in terms of signal technology on the signal output side and is configured to measure the mass flow of gas flowing out of the battery housing BG via the air flow channel LK (and the mass flow of gas flowing out of the battery housing BG via the air flow channel LK). Figure 3 The measured values ​​are indicated by the arrows in the section B of FIG. 1 and forwarded to the measured value evaluation circuit MS. In this case, the measured value evaluation circuit MS is also configured to determine the exact air pressure / gas pressure inside the battery housing BG based on the measured mass flow measurement values ​​delivered by the air mass sensor LS and the pressure measurement values ​​delivered by the pressure measuring unit DM.

[0067] Figure 4 A fourth schematic diagram shows a battery system BS (or a portion thereof) having a portion of a battery management device BV according to another exemplary embodiment of the present invention.

[0068] Figure 4 The battery management device BV shown is Figure 1The battery management device BV shown differs in that the pressure-sensitive microelectromechanical element DE of the switching unit SE is designed so that, when the pressure inside the battery housing BG exceeds a pressure threshold, the switching unit SE directly wakes up the battery management device BA from sleep mode to active operating mode. The battery management device BA was previously also switched to sleep mode during the sleep mode of the battery system BS. Upon waking up to active mode, the battery management device BA controls the switching unit SE so that it electrically connects the two terminals A1, A2 to one another and thus establishes a current supply to the pressure measuring unit DM via the first current supply path SP1.

Claims

1. An apparatus (AO) for monitoring the pressure inside a battery housing (BG) of a battery system (BS), comprising: - a first current supply path (SP1); a pressure measuring unit (DM) for measuring the pressure inside the battery housing (BG), the pressure measuring unit being electrically connected to the first current supply path (SP1) for current supply; a pressure-sensitive mechanical switching unit (SE), which is arranged in the battery housing (BG) and is electrically connected in series with the pressure measuring unit (DM) via two electrical connections (A1, A2) on the first current supply path (SP1); - wherein the switch unit (SE) is configured to switch to an electrically conductive switch state when the pressure in the battery housing (BG) exceeds a predetermined pressure threshold, thereby establishing a current supply to the pressure measuring unit (DM) via the first current supply path (SP1), and to switch to an electrically blocked switch state when the pressure in the battery housing (BG) falls below the pressure threshold, thereby interrupting the current supply to the pressure measuring unit (DM) via the first current supply path (SP1), Wherein the device (AO) further comprises: - a second current supply path (SP2) designed in parallel with the first current supply path (SP1); - a controllable switch (ST) electrically connected in said second current supply path (SP2); - wherein the pressure measuring unit (DM) is electrically connected in series with the switch (ST) on the second current supply path (SP2) for current supply; - wherein the switch (ST) is designed to be switchable between a closed, conductive switch state, in which the switch establishes a current supply to the pressure measuring unit (DM) via the second current supply path (SP2), and an open, cut-off switch state, in which the switch interrupts the current supply to the pressure measuring unit (DM) via the second current supply path (SP2).

2. The device (AO) according to claim 1, - wherein the device (AO) is designed to be operable in a sleep mode in which the device (AO) interrupts the current supply to the pressure measuring unit (DM) and the pressure measuring unit (DM) does not measure the pressure; - wherein the switching unit (SE) is further configured to switch to the electrically conductive switching state in a sleep mode of the device (AO) and when the pressure in the battery housing (BG) exceeds the predetermined pressure threshold value, and Switching to the electrical cut-off switch state in a sleep mode of the device (AO) and when the pressure inside the battery housing (BG) is below the pressure threshold.

3. The device (AO) according to any one of claims 1 to 2, wherein: The pressure threshold is below a critical pressure threshold, wherein a critical state exists in the battery system (BS) when the pressure in the battery housing (BG) exceeds the critical pressure threshold.

4. The device (AO) according to any one of claims 1 to 2, wherein: The pressure measuring unit (DM) has a pressure sensor (DS) with a pressure-sensitive microelectromechanical element (DE), wherein the microelectromechanical element (DE) is constructed as a part of the switching unit (SE) and is configured to electrically short-circuit two connection terminals (A1, A2) when the pressure in the battery housing (BG) exceeds the pressure threshold, and to electrically separate the two connection terminals (A1, A2) from each other when the pressure in the battery housing (BG) is below the pressure threshold.

5. The device (AO) according to any one of claims 1 to 2, further comprising: - a pressure equalizing valve (DV) for venting gases from the battery housing (BG); - the pressure-balancing valve (DV) has a diaphragm (MB) which can be reversibly moved or deformed under the action of pressure; -The diaphragm (MB) is constructed as a part of the switch unit (SE) and is configured to electrically short-circuit the two connection terminals (A1, A2) of the switch unit (SE) when the pressure in the battery housing (BG) exceeds the pressure threshold due to movement caused by the pressure effect or deformation caused by the pressure effect, and to electrically separate the two connection terminals (A1, A2) from each other when the pressure in the battery housing (BG) is lower than the pressure threshold.

6. The device (AO) according to claim 5, further comprising: - an air flow channel (LK) for discharging gases from the battery housing (BG) into the environment of the battery housing (BG), which air flow channel is fluidically connected to the pressure equalization valve (DV); an air mass sensor (LS) which is arranged in the air flow channel (LK), is connected on the signal output side to a measurement signal input of a measured value evaluation circuit (MS) of the pressure measuring unit (DM) and is configured to measure the mass flow of the gas flowing out of the battery housing (BG) via the air flow channel (LK) and to forward the measured value to the measured value evaluation circuit (MS); - wherein the measured value evaluation circuit (MS) is further configured to determine the pressure inside the battery housing (BG) based on the measured value delivered by the air mass sensor (LS).

7. A battery management device (BV) for operating a battery system (BS), the battery system having a battery housing (BG) and a number of battery cells (BZ) arranged in the battery housing (BG), the battery management device comprising: - an apparatus (AO) according to any one of claims 1 to 6; - a battery management device (BA) for operating the battery system (BS); - wherein the pressure measuring unit (DM) is connected to the battery management unit (BA) in terms of signal technology on the signal output side and is also configured to forward the measured value of the pressure in the battery housing (BG) to the battery management unit (BA); - wherein the battery management device (BA) is further configured to detect a critical state in the battery system (BS) based on the transmitted measured values.

8. The battery management device (BV) according to claim 7, wherein: The battery management device (BA) is also connected to the control signal connection terminal of the switch (ST) in a signaling manner via the control signal output terminal and is configured to disconnect the switch (ST) in a sleep mode, thereby interrupting the current supply to the pressure measuring unit (DM) via the second current supply path (SP2).

9. The battery management device (BV) according to claim 7, - wherein the battery management device (BA) is electrically connected in series with the switching unit (SE) and the pressure measuring unit (DM) on the first current supply path (SP1); - wherein the switch unit (SE) is further configured to establish a current supply to the battery management device (BA) via the first current supply path (SP1) in an electrically conductive switch state, and to interrupt the current supply to the battery management device (BA) via the first current supply path (SP1) in an electrically cut-off switch state.

10. A battery system (BS) comprising: - a battery housing (BG) and a number of battery cells (BZ) arranged in the battery housing (BG); - A battery management device (BV) according to any one of claims 7 to 9; - wherein the battery management device (BA) is also configured to monitor the pressure in the battery housing (BG) of the battery system (BS) by means of the device (AO).

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