Measuring device for monitoring vehicle batteries

Abstract

The invention relates to a measuring device for monitoring a vehicle battery with respect to the filling level, the measuring device comprising an optical waveguide pair with a first and a second optical waveguide, the optical waveguide pair being guided to the vehicle battery, an optical module having a feed unit for feeding an optical measurement signal into the first optical waveguide, and a receiving unit for receiving a response signal in the second optical waveguide and forwarding the response signal to an evaluation unit, and a deflection element, which is arranged or can be arranged on an end face of the optical waveguide pair on the battery side and by means of which the measurement signal of the first optical waveguide can be at least partially transmitted as a response signal to the second optical waveguide, wherein the deflection element is arranged in a deflection element housing through which the liquid in the vehicle battery can pass, and wherein a change in the filling level causes a change in the transmission of the deflection element between the optical waveguides of the optical waveguide pair.

Description

Technical Field

[0001] The invention relates to a measuring device for monitoring a vehicle battery with respect to a fill level, in particular a water level in a battery housing. The invention also relates to a vehicle battery having such a measuring device. Background Art

[0002] Electrically driven or motor-driven or electrically drivable or motor-drivable motor vehicles, such as electric vehicles or hybrid vehicles, usually include an electric motor, with which one or two axles can be driven. To supply electrical energy, the electric motor is usually connected to a (high-voltage) battery inside the vehicle as an electrical energy storage device.

[0003] Here and hereinafter, an electrochemical battery is understood to be in particular a so-called secondary battery of a motor vehicle. For such (secondary) vehicle batteries, the consumed chemical energy can be restored by means of a charging process. For example, such vehicle batteries are designed as electrochemical accumulators, in particular lithium-ion accumulators. In order to generate or provide a sufficiently high operating voltage, such vehicle batteries usually have at least one battery module in which a plurality of individual battery cells are connected in a modular manner.

[0004] In this case, battery cells or battery modules are usually accommodated in a battery housing of a vehicle battery. For monitoring and protection as well as control and / or regulation of the connected battery cells / battery modules, battery electronics in the form of a controller are usually provided as a control device or battery management system (BMS).

[0005] In addition to controlling or monitoring operating functions of the vehicle battery, such as charge state detection, deep discharge protection or overcharge protection, the battery electronics are also coupled to a water level sensor inside the battery housing, for example, in order to detect unwanted penetration of water or moisture into the battery housing. Such water level sensors are complex and must be installed deep in the battery housing for functional reasons. In order to couple to the battery electronics, such water level sensors have electrical connections that are suitable for the vehicle.

[0006] DE 695 27 386 T2 describes a measuring device for detecting a liquid level, in which light is guided via optical fibers to a prismatic device which can be exposed to a liquid, so that a change in the light reflection occurs in the prismatic device as a function of the liquid level. Summary of the invention

[0007] Therefore, the technical problem to be solved by the present invention is to provide a particularly suitable measuring device for detecting the liquid level in a vehicle battery. In particular, a measuring device that is as low-cost as possible and suitable for a vehicle is to be provided. In addition, the technical problem to be solved by the present invention is to provide a particularly suitable vehicle battery having such a measuring device.

[0008] The technical problem is solved by the measuring device according to the invention and the vehicle battery according to the invention. Advantageous designs and extensions are also the content of the invention. The advantages and designs mentioned in the measuring device can also be transferred to the vehicle battery by analogy, and vice versa.

[0009] The measuring device according to the invention is suitable and is designed for monitoring a vehicle battery with respect to the liquid level. Here and hereinafter, a liquid level or liquid surface is understood in particular to mean the height of the liquid level, i.e. the liquid surface, relative to a defined mark, in particular relative to the bottom of a battery housing of a vehicle battery. In particular, the monitored liquid is water, which means that the measuring device is designed in particular as a water sensor or water level sensor for a vehicle battery.

[0010] The measuring device has an optical waveguide pair with a first and a second optical waveguide, which is guided into or inside the vehicle battery. The measuring device also has an optical module with a feed unit for feeding an optical measurement signal into the first optical waveguide and a receiving unit for receiving a response signal in the second optical waveguide and forwarding the response signal to an evaluation unit.

[0011] A deflection element is or can be arranged on the battery-side end face of the optical waveguide pair. The deflection element is provided and designed to at least partially transmit, i.e. deflect or couple, the measurement signal of the first optical waveguide as a response signal to the second optical waveguide. The deflection element is arranged in a deflection element housing in the vehicle battery that is permeable to liquid.

[0012] The deflection element is designed in such a way that a change in the liquid level in the vehicle battery results in a change in the transmission between the optical waveguides of the optical waveguide pair. This means that a change in the liquid level results in a change in the transmission or transfer of the measurement signal as a response signal. In other words, for example, a larger or smaller portion of the measurement signal is directed to the second optical waveguide as a response signal. This results in a particularly suitable measuring device.

[0013] In this context, a change in the transmission between the optical waveguides is understood to be a change in the signal propagation from the first optical waveguide via the deflection element to the second optical waveguide. The measurement signal and the response signal are optical light signals, for example in the form of a continuous light beam or a pulsed light beam or a clocked light beam or as light pulses.

[0014] In this context, a change in the liquid level or a change in the liquid level is understood to be, in particular, an increase in the liquid level in the vehicle battery or in the housing of the deflection element, wherein the deflection element is at least partially in contact with the rising liquid level or with the liquid, thereby influencing the signal propagation of the measurement signal via the deflection element. By influencing the signal propagation during the rise of the liquid level, the liquid level in the vehicle battery can be detected and monitored in a simple manner with the aid of an evaluation unit. In other words, the optical waveguide pair with the deflection element acts as a measuring or sensor element for detecting the liquid level or liquid surface of the monitored vehicle battery. Monitoring of the vehicle battery with respect to penetrating liquid or water is thus achieved in a simple and cost-effective manner.

[0015] When the liquid level in the deflection element housing is low or absent, the deflection element has a substantially known transmission, i.e. a measure of the transmission of the measurement signal as a proportion of the response signal to the second optical waveguide. A change in the liquid level influences the transmission and thus leads to a change in the transmission between the optical waveguides by means of the deflection element. This influences the signal propagation, so that by evaluating the signal propagation, i.e. by evaluating the response signal, it is possible to infer a change in the transmission and thus a change in the liquid level.

[0016] The evaluation unit is designed and arranged in such a way that, based on the signal propagation of the measurement signal detected by the receiving unit, a transmission change and, from this, a level change are inferred from the response signal and the level change is determined. In particular, line attenuation due to the conductor material of the optical waveguide and / or the deflection element is also taken into account in the signal evaluation. Here and hereinafter, the conjunction "and / or" is understood to mean that the features connected by means of this conjunction can be designed both together and as alternatives to one another.

[0017] For example, the optical waveguide is implemented as an optical fiber or an optical fiber bundle. The feed unit is, for example, a light source, in particular a laser diode semiconductor (laser diode), wherein the receiving unit is in particular designed as a photodiode semiconductor (photodiode). Preferably, the feed unit and the receiving unit are designed as a common transceiver unit, i.e. a transceiver.

[0018] For example, the evaluation unit is also part of the transceiver, so that the evaluation takes place directly at the receiving location. Alternatively, the evaluation unit is implemented externally, that is, separately from the measuring device. In particular for the use of the measuring device in a motor vehicle, it is provided, for example, that the response signal received by the receiving unit is forwarded to an evaluation unit which is, for example, part of a battery manager and / or a higher-level (motor vehicle) control device. This makes it possible to achieve a particularly cost-effective and resource-efficient evaluation.

[0019] By means of this monitoring, the fill level of the liquid in the vehicle battery can be detected reliably and in an operationally safe manner. In particular, the vehicle battery can be monitored so that the liquid does not exceed a permissible maximum fill level in the vehicle battery or in the battery housing. In this case, the evaluation unit is suitable and provided, for example, for displaying or communicating the current fill level to a user and, if necessary, generating a warning signal if the fill level reaches or exceeds an undesirable height in the vehicle battery or in the deflection element housing.

[0020] In a preferred embodiment, the optical module is implemented as a fiber optic transceiver (FOT) with a combined feeding unit and receiving unit. Here, FOT is implemented using bus system technology, in particular using media-oriented system transmission-bus system technology (MOST bus). In other words, the optical module is suitable for and is configured to send, transmit and receive optical signals in a MOST-compatible manner. This means that the optical module is implemented in particular as a MOST FOT structural group.

[0021] The MOST bus is a serial bus system suitable and designed for transmitting data signals via optical waveguides. MOST technology is often used in multimedia applications in motor vehicles, so that particularly low-cost and automotive-friendly or automotive-compliant optical communication via optical waveguide pairs is achieved by using the MOST FOT structure group in order to determine the fill level in the vehicle battery.

[0022] Fiber-optic transmitter-receivers use fiber-optic technology to send and receive measurement signals and response signals. In this case, the transmitter-receiver has electronic (conversion) components for processing and encoding or decoding data into light pulses (or vice versa), and then transmits these data, in particular as electrical signals, to a coupled evaluation unit. The optical measurement signals and response signals of the measuring device are generated, in particular, according to the type of MOST bus signal.

[0023] In an advantageous embodiment, the optical waveguide pair is coupled to the optical module by means of a first plug connection. This means that the optical waveguide pair is provided with a plug connector on the module-side end face, which plug connector is or can be plug-connected to a corresponding socket of the optical module. The plug connection or the plug connector or the socket is preferably implemented according to MOST technology. This enables a reliable, operationally safe and automotive-friendly coupling of the optical waveguide pair to the optical module.

[0024] In a suitable embodiment, the battery-side end face of the optical waveguide pair is coupled to the deflection element housing by means of a second plug connection. In this case, the optical waveguide pair expediently has a MOST-compatible plug connector, which can be plugged into a corresponding socket of the deflection element housing. This also enables a simple, reliable and cost-effective coupling to the deflection element housing that accommodates the deflection element.

[0025] In a conceivable design, the deflection element is an optical prism fixedly coupled to the battery-side end face of the optical waveguide pair. The prism is connected to the first optical waveguide so that the optical measurement signal is coupled into the prism and there, in particular by means of total internal reflection (TIR) ​​on the prism surface, it is deflected in the direction of the second optical waveguide. The second optical waveguide is appropriately connected to the prism so that the reflected and deflected optical signal can be coupled to the second optical waveguide as a response signal with as little loss as possible. The cross section of the prism is in particular triangular, preferably a right-angled triangle, wherein the optical waveguide pair is arranged on the hypotenuse side so that two total reflections occur on the right-angled sides of the prism (adjacent right-angled sides, opposite right-angled sides).

[0026] As the liquid level rises, the prism comes into contact with the liquid. This changes the refractive index at the interface or transition surface of the prism, and in particular, the refractive index in the prism environment is increased to a value greater than the refractive index of the prism material, so that no total reflection occurs at the prism side. As a result, the measurement signal is no longer reflected as a response signal into the second optical waveguide, thereby reducing the transmission degree. This means that the amplitude or intensity of the response signal is reduced, thereby achieving a simple detection of the liquid level.

[0027] In a conceivable embodiment, if there is no liquid or water in the vehicle battery or the deflection element housing, the light signal, i.e. the measurement signal, from the MOST FOT structure group is deflected back to the MOST FOT structure group as a response signal by means of a prism. Conversely, if there is liquid or water in the vehicle battery or the deflection element housing, the measurement signal from the MOST FOT structure group will not be deflected back due to the change in the refractive index at the prism-liquid interface. As a result, no response signal from the MOSTFOT structure group is received.

[0028] In an alternative embodiment, the deflection element is implemented as a mechanical float. Therefore, the deflection element is designed as an object with (static) buoyancy in the liquid, wherein the buoyancy is preferably large enough so that the deflection element is not completely immersed in the liquid, i.e., at least partially stands above the liquid level or liquid surface. Thus, when the liquid level increases, the deflection element or float rises and is thereby guided to the end face of the optical waveguide on the battery side. Here, in a preferred extension, a third optical waveguide is integrated in the deflection element, which guides the measurement signal of the first optical waveguide in the corresponding liquid level at which the deflection element is substantially in contact with the end face of the optical waveguide pair on the battery side, and feeds it as a response signal to the second optical waveguide. This means that the light conduction or deflection is mechanically controlled by a variable liquid level.

[0029] If there is no liquid level or only a low liquid level in the vehicle battery or the deflection element housing, the deflection element is essentially located on the bottom and is therefore arranged spaced apart from the optical waveguide pair. As a result, if there is no liquid or water in the vehicle battery or the deflection element housing, the measurement signal from the MOST FOT structural group is not deflected. On the contrary, if there is liquid or water in the vehicle battery or the deflection element housing, the deflection element rises due to the increase in the liquid level and is guided to the optical waveguide. As a result, the measurement signal from the MOST FOT structural group is deflected back via the third optical waveguide of the deflection element. As a result, a response signal from the MOST FOT structural group is received.

[0030] In a preferred application, the measuring device is part of a vehicle battery to be monitored. The vehicle battery is preferably a vehicle-internal energy storage device of a motor vehicle, in particular an electrically driven or electrically drivable motor vehicle, such as an electric vehicle or a hybrid vehicle. In this case, the vehicle battery has a battery housing and battery electronics in the form of a controller or battery manager.

[0031] In a preferred embodiment, the control unit or the battery electronics is formed at least in its core by a microcontroller having a processor and a data memory, in which the functions for operating the associated vehicle battery are implemented programmatically in the form of operating software (firmware), so that the method is automatically implemented when the operating software is executed in the microcontroller (if necessary interactively with a user of the device). In an alternative, the control unit can also be formed by a non-programmable electronic component, such as an application-specific integrated circuit (ASIC), in which the functions for operating the vehicle battery are implemented by means of circuit technology.

[0032] An additional or further aspect of the invention provides that the battery electronics or (battery) controller has a circuit board on which the optical module or the MOST FOT assembly of the measuring device is arranged. In other words, the optical module or the MOST FOT assembly is arranged on a circuit board or printed circuit board of the battery management electronics of the vehicle battery. This makes it possible to arrange the optical module particularly well, in particular, the optical module is arranged outside the battery housing and is therefore spatially spaced or separated from any fill level.

[0033] In a suitable embodiment, the deflection element housing is arranged on the bottom of the battery housing. Liquids that enter or flow into the battery housing in an undesirable manner collect on the bottom due to gravity, i.e. on the housing area facing the ground, so that the arrangement of the deflection element housing allows particularly reliable and rapid detection of the liquid level. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. In the accompanying drawings, schematic and simplified diagrams are provided:

[0035] Figure 1 A vehicle battery having a battery housing and battery electronics and a measuring device for monitoring the vehicle battery with respect to the filling level is shown.

[0036] Figure 2 A first embodiment of the measuring device is shown without a battery housing filled with liquid.

[0037] Figure 3 The following table shows the situation in which there is a liquid level inside the battery housing. Figure 2 The measuring device,

[0038] Figure 4 A second embodiment of the measuring device is shown without a battery housing filled with liquid, and

[0039] Figure 5 The following table shows the situation in which there is a liquid level inside the battery housing. Figure 4 The measuring device,

[0040] In all the figures, parts and dimensions which correspond to one another are always provided with the same reference symbols. DETAILED DESCRIPTION

[0041] Figure 1A vehicle battery 2 of a motor vehicle is shown in a schematic and simplified illustration, which has a battery housing 4 in which, for example, four battery modules 6 are accommodated. For the control and / or regulation of battery operation, the vehicle battery 2 has a control unit or battery electronics 8 as a battery manager. The battery electronics 8 is arranged, for example, outside the battery housing 4.

[0042] The vehicle battery 2 has a measuring device 10 for measuring a fill level 12 of a liquid 14 (see Figure 3 , Figure 5 ) aspect monitors the vehicle battery 2 or the battery housing 4. Here, the liquid 14 is especially water, which means that the measuring device 10 is especially designed as a water sensor or water level sensor of the vehicle battery 2 or the battery housing 4.

[0043] Refer to the following Figure 2 and Figure 3 A first embodiment of the measuring device 10 will be explained in more detail.

[0044] The measuring device 10 has an optical module 16, which is arranged on a circuit board of the battery electronics 8. The module 16 is designed as a fiber-optic transceiver in the form of a MOST FOT assembly and has a feed unit 18, which is combined with a receiver unit 20. The feed unit 18 is designed, for example, as a light-emitting laser diode semiconductor element (laser diode), wherein the receiver unit 20 is designed, for example, as a light-sensitive photodiode semiconductor element (photodiode).

[0045] During operation of the measuring device 10, an optical measurement signal 22 is generated by means of the feed unit 18 and fed into an optical waveguide 24 of an optical waveguide pair 26. The optical waveguide pair 26 is introduced from the battery electronics 8 or from the module 16 into the battery housing 4 or is guided in the battery housing 4. The measurement signal 22 is, for example, a light beam or a sequence of light pulses, which is guided from the optical module 16 via the optical waveguide 24, which is designed, for example, as an optical fiber or a fiber bundle, to a liquid-permeable deflection element housing 28. The measurement signal 22 escapes at the battery-side end face 30 of the optical waveguide pair 26 or optical waveguide 24 and is coupled into a prism arranged at the end face as a deflection element 32.

[0046] The cross section of the prism or deflection element 32 has the shape of a right triangle, wherein the hypotenuse abuts against the end face 30. The measurement signal 22 entering the deflection element 32 from the end face 30 is reflected back to the end face 30 via two total reflections in the deflection element 32 and there enters the (second) optical waveguide 36 of the optical waveguide pair 26 as a response signal 34. The course of the measurement signal 22 is schematically indicated in the figure by arrows.

[0047] The liquid-permeable or water-permeable deflection element housing 28 is arranged on a (housing) bottom 38 of the battery housing 4 .

[0048] The optical waveguide pair 26 has at its ends a plug connector 40, 42. The optical waveguide pair 26 is connected to the optical module 16 by means of the plug connector 40 and to the deflection element housing 28 by means of the plug connector 42, which is designed as a MOST plug connection.

[0049] In operation, if there is no liquid or water 14 ( Figure 2 ), the measurement signal 22 from the MOST FOT structure group or module 16 is then deflected back to the receiving unit 20 of the module 16 as a response signal 34 by means of a prism 32.

[0050] If liquid 14 enters the battery housing 4, the liquid level 12 increases starting from the bottom 38. As a result, the liquid 14 also enters the liquid-permeable deflection element housing 28. In the case of a sufficient increase in the liquid level 12, the prism 32 is in contact with the liquid 14. As a result, the measurement signal 22 is not totally reflected or deflected back to the optical waveguide 36 due to the change in the refractive index at the prism-liquid interface. As a result, the receiving unit 20 does not receive the response signal 34.

[0051] The module 16 forwards the received response signal 34 to the evaluation unit of the battery electronics 8 , which is suitable and designed to determine the liquid level 12 in the deflection element housing 28 and thus in the battery housing 4 based on the amplitude of the response signal 34 .

[0052] Figure 4 and Figure 5 A second embodiment of the measuring device 10 is shown. In this embodiment, a deflection element 44 designed as a mechanical float is arranged in the deflection element housing 28. The deflection element or float 44 is designed as an object with (static) buoyancy in the liquid 14, wherein the buoyancy is designed to be sufficiently large so that the float 44 is not completely immersed in the liquid 14, i.e. stands at least partially above the liquid level 12 ( Figure 5 ). As a result, when the liquid level 12 increases, the float 44 rises from the bottom 38 and is thereby guided to the end face 30 of the optical waveguide pair 26 .

[0053] The float 44 has an integrated optical waveguide 46 for Figure 5 The fill level 12 is shown at which the float 44 is in contact with the end face 30 of the optical waveguide pair 26 , which guides the measurement signal 22 of the optical waveguide 24 and feeds it as a response signal 34 to the optical waveguide 36 .

[0054] If there is no fill level 12 or only a very low fill level 12 in the vehicle battery 2 or in the deflection element housing 28, the float 44 lies essentially on the bottom and is therefore arranged at a distance from the optical waveguide pair 26 ( Figure 4 ). Thus, if there is no sufficiently high liquid level 12 in the vehicle battery 2 or in the deflection element housing 28, the measurement signal 22 from the module 16 is not deflected into the optical waveguide 36. Conversely, if there is a sufficiently high liquid level 12 in the vehicle battery 2 or in the deflection element housing 28, the float 44 is raised by the liquid 14 and is guided to the optical waveguide 24, 36. Thus, the measurement signal 22 from the module 16 is deflected via the optical waveguide 46 to the optical waveguide 36. Thus, the module 16 receives the response signal 34 and forwards it to the evaluation unit of the battery electronics 8.

[0055] The claimed invention is not limited to the previously described embodiments. Rather, a person skilled in the art may derive other variants of the invention within the scope of the disclosure of the invention without departing from the content of the claimed invention. In particular, all individual features described in conjunction with the different embodiments may also be combined in other ways within the scope of the disclosure of the invention without departing from the content of the claimed invention.

[0056] Reference numerals list

[0057] 2 Vehicle battery

[0058] 4 Battery housing

[0059] 6 Battery Module

[0060] 8 Battery Electronic Devices

[0061] 10. Measuring device

[0062] 12 Liquid Level

[0063] 14 Liquid

[0064] 16 Modules

[0065] 18 Feeding unit

[0066] 20 Receiving Unit

[0067] 22 Measurement signal

[0068] 24 Optical waveguide

[0069] 26 Optical waveguide pairs

[0070] 28 Deflection element housing

[0071] 30 End face

[0072] 32 Deflection element / prism

[0073] 34 Response signal

[0074] 36 Optical waveguide

[0075] 38 bottom

[0076] 40, 42 plug connector

[0077] 44 Deflection element / float

[0078] 46 Optical waveguide

Claims

1. A measuring device (10) for monitoring a vehicle battery (2) with respect to a filling level (12), the measuring device comprising: an optical waveguide pair (26) with a first and a second optical waveguide (24, 36), which is directed to the vehicle battery (2), and an optical module (16) having a feed unit (18) for feeding an optical measurement signal (22) into a first optical waveguide (24) and having a receiving unit (20) for receiving a response signal (34) in a second optical waveguide (36) and forwarding the response signal (34) to an evaluation unit, and a deflection element (32, 44) which is arranged or can be arranged on the battery-side end face (30) of the optical waveguide pair (26), by means of which a measurement signal (22) of the first optical waveguide (24) can be at least partially transmitted as a response signal (34) to the second optical waveguide (36), - wherein the deflection element (32, 44) is arranged in a liquid-permeable deflection element housing (28) within the vehicle battery (2), and - wherein a change in the liquid level (12) results in a change in the transmission of the deflection element (32, 44) between the optical waveguides (24, 36) of the optical waveguide pair (26), in, The deflection element (44) is a float, a third optical waveguide (46) is integrated into the deflection element (44), and When the deflection element (44) contacts the battery-side end face (30) of the optical waveguide pair (26) as the liquid level (12) increases, the third optical waveguide guides the measurement signal (22) of the first optical waveguide (24) and feeds it as a response signal (34) to the second optical waveguide (36).

2. The measuring device (10) according to claim 1, characterized in that The optical module (16) is implemented as a combined feed unit (18) and receiver unit (20) using a fiber optic transmitter-receiver.

3. The measuring device (10) according to claim 1, characterized in that The optical waveguide pair (26) is coupled to the optical module (16) using a first plug connection (40).

4. The measuring device (10) according to any one of claims 1 to 3, characterized in that The battery-side end face (30) of the optical waveguide pair (26) is coupled to the deflection element housing (28) by means of a second plug connection (42).

5. A vehicle battery (2) for a motor vehicle having a battery housing (4) and battery electronics (8) and a measuring device (10) according to any one of claims 1 to 4.

6. The vehicle battery (2) according to claim 5, characterized in that The battery electronics system (8) has a printed circuit board on which an optical module (16) of the measuring device (10) is arranged.

7. The vehicle battery (2) according to claim 5 or 6, characterized in that: The deflection element housing (28) is arranged on a bottom (38) of the battery housing (4).

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