CN112240797A

CN112240797A - Measuring device for monitoring a vehicle battery

Info

Publication number: CN112240797A
Application number: CN202010701560.5A
Authority: CN
Inventors: C.维克
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2019-07-18
Filing date: 2020-07-20
Publication date: 2021-01-19
Also published as: KR102422390B1; KR20210010418A; DE102019210592B3

Abstract

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

Description

Measuring device for monitoring a vehicle battery

Technical Field

The invention relates to a measuring device for monitoring a vehicle battery with regard to a liquid level, in particular with regard to a water level in a battery housing. The invention also relates to a vehicle battery having such a measuring device.

Background

An electric or motor-driven or electrically drivable or motor-driven motor vehicle, for example an electric vehicle or a hybrid vehicle, usually comprises an electric motor with which one or both axles can be driven. For supplying electrical energy, the electric motor is usually connected to a (high-voltage) battery inside the vehicle as an electrical energy storage.

Here and in the following, an electrochemical cell is understood to mean, in particular, a so-called secondary cell of a motor vehicle

For such (secondary) vehicle batteries, the consumed chemical energy can be recovered by means of a charging process. Such a vehicle battery is embodied, for example, as an electrochemical battery, in particular as a lithium-ion battery. 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.

The battery cells or battery modules are usually accommodated in a battery housing of a vehicle battery. In order to monitor and protect and to control and/or regulate the connected battery cells/battery modules, battery electronics in the form of a controller is usually provided as a control device or Battery Management System (BMS).

In addition to controlling or monitoring the operating functions of the vehicle battery, such as state of charge detection, deep discharge protection or overcharge protection, the battery electronics are coupled, for example, to a water level sensor inside the battery housing in order to detect an undesired penetration of moisture or humidity into the battery housing. Such water level sensors are costly and must be installed deep in the battery housing for functional reasons. For coupling to the battery electronics, such a water level sensor has, in particular, electrical connections suitable for a motor vehicle.

DE 69527386T 2 describes a measuring device for detecting a liquid level, in which light is guided via optical fibers to a prism arrangement which can be exposed to the liquid, so that a change in the reflection of the light occurs in the prism arrangement as a function of the liquid level.

Disclosure of Invention

The object of the present invention is therefore to provide a particularly suitable measuring device for detecting a liquid level in a vehicle battery. In particular, a measuring device is to be provided which is as inexpensive as possible and which is suitable for motor vehicles. The object of the invention is also to provide a particularly suitable vehicle battery having such a measuring device.

The object is achieved by a measuring device according to the invention and a vehicle battery according to the invention. Advantageous embodiments and further embodiments are also subject of the present invention. The advantages and embodiments mentioned in the context of the measuring device can also be transferred to the vehicle battery and vice versa.

The measuring device according to the invention is suitable and provided for monitoring a vehicle battery with regard to the liquid level. Here and in the following, the liquid level or the liquid level is to be understood in particular as the height of the liquid level, i.e. the liquid surface, relative to the defined marking, in particular relative to the bottom of the battery housing of the vehicle battery. In particular, the liquid to be monitored is water, which means that the measuring device is designed in particular as a water sensor or water level sensor of a vehicle battery.

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 having a feed unit for feeding the optical measuring signal into the first optical waveguide and having a receiving unit for receiving the response signal in the second optical waveguide and forwarding it to the evaluation unit.

A deflection element is or can be arranged on the cell-side end face of the optical waveguide pair. The deflection element is arranged and designed to transmit the measuring signal of the first optical waveguide as a response signal at least partially to the second optical waveguide, i.e. to be deflected or coupled. The deflection element is arranged in a deflection element housing through which a liquid in the vehicle battery can pass.

The deflection element is designed such that, when the liquid level in the vehicle battery changes, a change in the transmission between the optical waveguides of the optical waveguide pair results. This means that a change in the transmission or transmission of the measurement signal as a response signal results when the liquid level changes. In other words, for example, a larger or smaller portion of the measurement signal is guided as a response signal to the second optical waveguide. A particularly suitable measuring device is thereby realized.

A transmission change between the optical waveguides is understood here to mean, in particular, a change in the propagation of a signal 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 clock light beam or as light pulses.

In this context, a change in the liquid level or a change in the liquid level is to be understood as meaning, 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 rising of the liquid level, the liquid level in the vehicle battery can be detected and monitored in a simple manner by means of the 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 level of the monitored vehicle battery. The monitoring of the vehicle battery with respect to penetrating liquids or water is thereby achieved in a simple and cost-effective manner.

The deflection element has a substantially known degree of transmission, i.e. a measure of the transmission of the measurement signal as a proportion of the response signal to the second optical waveguide, when the liquid level in the deflection element housing is low or non-existent. The change in the liquid level influences the degree of transmission, so that a change in the transmission between the optical waveguides is caused by the deflection element. The signal propagation is thereby influenced, so that by evaluating the signal propagation, i.e. by evaluating the response signal, a transmission change and thus a liquid level change can be inferred.

The evaluation unit is designed and arranged such that, depending on the signal propagation of the measurement signal detected by the receiving unit, a transmission change and thus a liquid level change are inferred from the response signal and the liquid level change is determined. In particular, the line attenuation due to the conductor material of the optical waveguide and/or of the deflection element is also taken into account in the signal evaluation. The conjunction "and/or" is understood here and in the following to mean that the features connected by means of the conjunction can be designed both together and as an alternative to one another.

For example, the optical waveguide is embodied as an optical fiber or a 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). The feed unit and the receiving unit are preferably designed as a common transceiver unit, i.e. a transceiver.

The evaluation unit is for example also part of the transceiver, so that the evaluation takes place directly at the receiving location. Alternatively, the evaluation unit is implemented externally, i.e. separately from the measuring device. For example, especially for the use of the measuring device in a motor vehicle, it is provided 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. A particularly cost-effective and resource-efficient evaluation can thereby be achieved.

The level of the liquid in the vehicle battery can be reliably and operationally detected by this monitoring. In particular, the vehicle battery can be monitored such that the liquid does not exceed a maximum permissible liquid level in the vehicle battery or in the battery housing. The evaluation unit is suitable and provided for example for displaying or communicating the current liquid level to a user and, if necessary, for generating a warning signal if the liquid level reaches or exceeds an undesired height in the vehicle battery or in the deflector element housing.

In a preferred embodiment, the Optical module is implemented as a Fiber optic transmitter-receiver (FOT) with a combined feed unit and receiving unit. The FOT is implemented here using bus System technology, in particular Media Oriented System Transport bus System technology (MOST bus). In other words, the optical module is adapted and arranged for MOST compatible sending, transmitting and receiving of optical signals. This means that the optical module is implemented in particular as a MOST FOT structure group.

MOST bus is a serial bus system that is suitable and arranged for transmitting data signals via optical waveguides. MOST technology is commonly used in multimedia applications in automotive vehicles to enable optical communication via optical waveguide pairs, particularly low cost and suitable for automotive or automotive-compliant, by using MOST FOT structural groups to determine liquid levels within a vehicle battery.

The fiber optic transmitter-receiver uses fiber optic technology to transmit and receive measurement signals and response signals. The transmitter/receiver has electronic (conversion) components for processing and encoding or decoding the data into optical pulses (and vice versa) and then transmits these data, in particular as electrical signals, to a coupled evaluation unit. The optical measurement signals and the response signals of the measuring device are generated in particular as a function of the type of MOST bus signal.

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 module-side end face of the optical waveguide pair is provided with a plug connector which is or can be plug-connected to a corresponding socket of the optical module. The plug connection or the plug connector or socket is preferably implemented according to MOST technology. This allows the optical waveguide pair to be reliably coupled to the optical module in a operationally safe and suitable manner for a motor vehicle.

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. The optical waveguide pair suitably has a MOST-compatible plug connector which can be inserted into a corresponding socket of the deflection element housing. This also enables a simple, reliable and cost-effective coupling to the deflection element housing accommodating the deflection element.

In a conceivable design, the deflection element is an optical prism which is fixedly coupled to the cell-side end face of the optical waveguide pair. The prism is connected to the first optical waveguide in such a way that the optical measurement signal is coupled into the prism and is deflected there in the direction of the second optical waveguide, in particular by total internal reflection (TIR total internal reflection) on the prism surface. The second optical waveguide is suitably connected to the prism so that the reflected and deflected optical signal can be coupled as a response signal to the second optical waveguide as free of losses as possible. The cross section of the prism is in particular triangular, preferably right-angled triangular, wherein the optical waveguide pair is arranged on the hypotenuse side such that two total reflections occur on the right-angled sides of the prism (adjacent, opposite sides).

As the liquid level rises, the prism comes into contact with the liquid. The refractive index at the interface or transition surface of the prism is thereby changed, in particular the refractive index in the prism environment is thus increased to a value greater than the refractive index of the prism material, whereby no total reflection occurs at the prism flanks. The measurement signal is thus no longer reflected as a response signal into the second optical waveguide, thereby reducing the degree of transmission. This means that the amplitude or intensity of the response signal is reduced, thereby enabling a simple detection of the liquid level.

In a conceivable embodiment, if no liquid or water is present in the vehicle battery or in the deflection element housing, the optical signal, i.e. the measurement signal, from the MOST FOT structure group is deflected as a response signal back to the MOST FOT structure group by means of the prism. Conversely, if there is liquid or water in the vehicle battery or deflection element housing, the measurement signal from the MOST FOT structure set is not deflected back due to the change in refractive index at the prism-liquid interface. And thus does not receive a response signal from the MOST FOT structure group.

In an alternative embodiment, the deflecting element is embodied as a mechanical float. The deflecting element is therefore designed as an object with (static) buoyancy in the liquid, wherein the buoyancy is preferably sufficiently large that the deflecting element is not completely immersed in the liquid, i.e. stands at least partially at or above the liquid level. Thus, when the liquid level increases, the deflecting element or float rises and is thereby guided to the battery-side end face of the optical waveguide. In a preferred embodiment, a third optical waveguide is integrated in the deflection element, which third optical waveguide guides the measurement signal of the first optical waveguide in the respective liquid level, at which the deflection element is substantially in contact with the battery-side end face of the optical waveguide pair, and feeds it as a response signal to the second optical waveguide. This means that the light transmission or deflection is mechanically controlled by the variable liquid level.

If no or only a low liquid level is present in the vehicle battery or in the deflecting element housing, the deflecting element is located substantially on the floor and is therefore arranged spaced apart from the optical waveguide pair. Thus, if no liquid or water is present in the vehicle battery or deflection element housing, the measurement signal from the MOST FOT structure set is not deflected. Conversely, if liquid or water is present in the vehicle battery or the deflecting element housing, the deflecting element rises by the rise of the liquid level and is guided to the optical waveguide. Thereby, the measurement signal from the MOST FOT structure group is deflected back via the third optical waveguide of the deflection element. Thereby receiving a response signal from the MOST FOT structure group.

In a preferred application, the measurement device is part of a vehicle battery to be monitored. The vehicle battery is preferably an energy store in a vehicle of a motor vehicle, in particular an electrically driven or drivable motor vehicle, for example an electric vehicle or a hybrid vehicle. The vehicle battery has a battery housing and a battery electronics in the form of a controller or a battery manager.

In a preferred embodiment, the controller or the battery electronics is formed at least in the core by a microcontroller with a processor and a data memory, in which the functionality for operating the associated vehicle battery is implemented programmatically in the form of operating software (firmware), so that the method is automatically implemented when the operating software is implemented in the microcontroller (optionally interactively with the user of the device). In the alternative, the controller can also be formed by a non-programmable electronic component, such as an application-specific integrated circuit (ASIC), in which the function for operating the vehicle battery is implemented using a circuit-technology arrangement.

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 module of the measuring device is arranged. In other words, the optical module or MOST FOT structure group is disposed on a circuit board or printed circuit board of the battery management electronics of the vehicle battery. This results in a particularly suitable arrangement of the optical module, which is arranged in particular here outside the battery housing and is therefore arranged spatially separated or separated from the possible liquid level.

In a suitable embodiment, the deflecting element housing is arranged on the bottom of the battery housing. The liquid which enters or flows into the battery housing in an undesired manner collects on the bottom, i.e. on the housing region facing the ground, as a result of gravity, so that the arrangement of the deflector element housing makes it possible to detect the liquid level particularly reliably and quickly.

Drawings

Embodiments of the present invention are explained in more detail below with reference to the drawings. In the accompanying drawings, in a schematic and simplified illustration:

figure 1 shows a vehicle battery with a battery housing and battery electronics and a measuring device for monitoring the vehicle battery with regard to the liquid level,

figure 2 shows a first embodiment of the measuring device in the case of a battery housing which is not filled with a liquid,

figure 3 shows the measuring device according to figure 2 in the case of a liquid level inside the battery housing,

fig. 4 shows a second embodiment of the measuring device without a liquid-filled battery housing, and

figure 5 shows the measuring device according to figure 4 in the case of a liquid level inside the battery housing,

throughout the drawings, parts and dimensions corresponding to each other have the same reference numerals.

Detailed Description

Fig. 1 shows a schematic and simplified illustration of a vehicle battery 2 of a motor vehicle, which has a battery housing 4, in which, for example, four battery modules 6 are accommodated. For controlling and/or regulating the battery operation, the vehicle battery 2 has a controller or battery electronics 8 as a battery manager. The battery electronics 8 are arranged outside the battery housing 4, for example.

The vehicle battery 2 has a measuring device 10 for monitoring the vehicle battery 2 or the battery housing 4 with respect to a level 12 (see fig. 3, 5) of a liquid 14. The liquid 14 is in particular water, which means that the measuring device 10 is in particular designed as a water or water level sensor of the vehicle battery 2 or of the battery housing 4.

A first embodiment of the measuring device 10 is explained in more detail below with reference to fig. 2 and 3.

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 implemented as a fiber optic transceiver in the form of a MOST FOT fabric group and has a feed unit 18, the feed unit 18 being combined with a receiver unit 20. The feed unit 18 is embodied, for example, as a light-emitting laser diode semiconductor element (laser diode), wherein, for example, the receiver unit 20 is embodied as a light-sensitive photodiode semiconductor element (photodiode).

During operation of the measuring device 10, an optical measuring signal 22 is generated by means of the feed unit 18 and fed into the optical waveguide 24 of the 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 the optical waveguide pair 26 is guided in the battery housing 4. The measurement signal 22 is, for example, a light beam or a light pulse train, which is guided from the optical module 16 via an optical waveguide 24, which is embodied, for example, as an optical fiber or a fiber bundle, to a deflecting element housing 28 through which the liquid can pass. The measurement signal 22 escapes at an end face 30 of the optical waveguide pair 26 or of the battery side of the optical waveguide 24 and is coupled into a prism arranged at said end face as a deflection element 32.

The cross-section of the prism or deflection element 32 has the shape of a right triangle, with the hypotenuse abutting 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 within 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 shown by an arrow in the figure.

The liquid-permeable or water-permeable deflecting element housing 28 is arranged on the (housing) bottom 38 of the battery housing 4.

The optical waveguide pair 26 has

plug connectors

40, 42 at its ends, respectively. The optical waveguide pair 26 is connected on the one hand to the optical module 16 by means of a plug connector 40 and on the other hand to the deflection element housing 28 by means of a plug connector 42, which is a MOST plug connection.

In operation, if there is no liquid or water 14 in the vehicle battery 2 or in the deflection element housing 28 (fig. 2), the measurement signal 22 from the MOST FOT structural group or module 16 is deflected as a response signal 34 by means of the prism 32 back to the receiving unit 20 of the module 16.

If the liquid 14 enters the cell housing 4, the liquid level 12 increases from the bottom 38. Thereby, the liquid 14 also enters the deflecting element housing 28 through which the liquid can pass. With liquid level 12 sufficiently elevated, prism 32 is in contact with liquid 14. Thus, the measurement signal 22 is not totally reflected or deflected back into the optical waveguide 36 due to the change in refractive index at the prism-liquid interface. Thus, the receiving unit 20 does not receive the response signal 34.

The module 16 forwards the received response signal 34 to the evaluation unit of the battery electronics 8. The evaluation unit of the battery electronics 8 is suitable and designed for determining the liquid level 12 in the deflection element housing 28 and thus in the battery housing 4 as a function of the amplitude of the response signal 34.

Fig. 4 and 5 show a second embodiment of the measuring device 10. In this embodiment, a deflection element 44 designed as a mechanical float is arranged in the deflection element housing 28. This deflecting 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 that the float 44 is not completely immersed in the liquid 14, i.e. stands at least partially above the liquid level 12 (fig. 5). Thus, as 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.

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

If there is no liquid level 12 or only a very low liquid level 12 in the vehicle battery 2 or in the deflector housing 28, the float 44 is located substantially on the bottom and is therefore arranged spaced apart from the optical waveguide pair 26 (fig. 4). Thus, if a sufficiently high liquid level 12 is not present in the vehicle battery 2 or the deflection element housing 28, the measurement signal 22 from the module 16 is not deflected into the optical waveguide 36. Conversely, if a sufficiently high liquid level 12 is present in the vehicle battery 2 or the deflecting element housing 28, the float 44 is lifted by the liquid 14 and guided to the light guides 24, 36. The measurement signal 22 from the module 16 is thereby deflected via the optical waveguide 46 to the optical waveguide 36. The module 16 thus receives the response signal 34 and forwards it to the evaluation unit of the battery electronics 8.

The claimed invention is not limited to the embodiments described before. Rather, those skilled in the art can derive other variations of the invention within the scope of the disclosure of the invention without departing from the claimed invention. In particular, all individual features described in connection with 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.

List of reference numerals

2 vehicle battery

4 Battery case

6 Battery module

8-cell electronic device

10 measuring device

12 liquid level

14 liquid

16 module

18 feeding unit

20 receiving unit

22 measuring signal

24 optical waveguide

26 optical waveguide pair

28 deflecting element housing

30 end face

32 deflecting element/prism

34 response signal

36 optical waveguide

38 bottom

40, 42 plug-in connector

44 deflecting element/float

46 optical waveguide

Claims

1. A measuring device (10) for monitoring a vehicle battery (2) with respect to a liquid level (12), having:

-an optical waveguide pair (26) with a first and a second optical waveguide (24, 36), which optical waveguide pair is guided to the vehicle battery (2),

and an optical module (16) having a feeding unit (18) for feeding an optical measurement signal (22) into the first optical waveguide (24) and having a receiving unit (20) for receiving a response signal (34) in the second optical waveguide (36) and forwarding the response signal (34) to the evaluation unit,

and a deflection element (32, 44) which is arranged or can be arranged on a battery-side end face (30) of the optical waveguide pair (26) and with which a measurement signal (22) of the first optical waveguide (24) can be transmitted at least partially as a response signal (34) to the second optical waveguide (36),

-wherein the deflection element (32, 44) is arranged in a deflection element housing (28) through which liquid within the vehicle battery (2) can pass, and

-wherein a change in transmission of the deflection element (32, 44) between the optical waveguides (24, 36) of the optical waveguide pair (26) is caused upon a change in the liquid level (12).

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 receiving unit (20) with a fiber-optic transmitter-receiver.

3. The measurement device (10) according to claim 1 or 2, wherein the optical waveguide pair (26) is coupled to the optical module (16) with a first plug connection (40).

4. The measuring device (10) according to 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) with a second plug connection (42).

5. The measuring device (10) according to one of claims 1 to 4, characterized in that the deflection element (32) is an optical prism which is fixedly coupled to a cell-side end face (30) of the optical waveguide pair (26).

6. The measuring device (10) according to one of claims 1 to 5, characterized in that the deflection element (44) is a float which is guided to the battery-side end face (30) of the optical waveguide pair (26) when the liquid level (12) increases.

7. Measuring device (10) according to claim 6, characterized in that a third optical waveguide (46) is integrated in the deflection element (44), which third optical waveguide guides the measuring signal (22) of the first optical waveguide (24) in the liquid level (12) and feeds it as a response signal (34) to the second optical waveguide (36).

8. A vehicle battery (2) of a motor vehicle, having a battery housing (4) and battery electronics (8) and a measuring device (10) according to one of claims 1 to 7.

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

10. Vehicle battery (2) according to claim 8 or 9, characterized in that the deflecting element housing (28) is arranged on the bottom (38) of the battery housing (4).