BACKGROUND OF THE INVENTION

The present invention concerns an air dryer cartridge and device comprising an air dryer cartridge, as well as a use of the air dryer cartridge and/or of the device, in particular in a battery housing of a vehicle, and further concerns a method for determining a moisture content.

In battery construction, in particular for use in vehicles, air dryer cartridges are currently utilized which dehumidify air in the housing interior. The battery takes up this air from the environment due to heating processes in operation of the battery. The air moisture condenses at battery parts upon cooling, which however is prevented by the dehumidification action of the air dryer cartridge.

Typically, the air dryer cartridge can be exchanged during servicing of the vehicle, e.g., in regular inspections. However, it may happen that the saturation of the drying agent in the air dryer cartridge is reached already prior to a scheduled service.

DE 10 2015 204 678 A1 discloses such an air dehumidification system. The air moisture of the drying agent is determined in this context by a weight sensor, i.e., gravimetrically.

DE 10 2014 015 188 A1 discloses a monitoring system of an air dryer cartridge on the basis of a capacitor with two measuring electrodes.

Moreover, DE 10 2008 034 698 A1 discloses an air dryer cartridge for a vehicle battery of a motor vehicle which comprises a hollow-cylindrical housing that comprises an air-permeable casing surface. In the housing, a bulk drying agent is provided which is mixed with a moisture-dependent color change agent so that, by means of a viewing glass at the housing, the color of the color change agent can be viewed in order to evaluate a moisture content. Disadvantageously, such an air dryer cartridge is not suitable for integration into an automated measured value detection system.

Finally, DE 10 2014 211 959 A1 discloses a drying system for a battery that comprises an air conveying device for providing an air flow into the battery housing, a filter, and a drying agent chamber. Moreover, a color indicator or moisture sensor for monitoring the moisture content of the drying agent is provided. The drying system is located outside of the battery housing so that the air can be supplied through a hose conduit to the battery housing.

Based on this prior art, it is the object of the present invention to enable a better possibility of monitoring the moisture content in an air dryer cartridge.

SUMMARY OF THE INVENTION

The present invention solves this object by an air dryer cartridge that comprises a component of an optical measuring system, namely a sensor unit, with which the moisture content of the drying agent can be determined, wherein the cartridge housing, at least in sections thereof, comprises a light-permeable casing surface section for passing through an optical signal emitted from a component of the optical measuring system.

The object is further solved by a device for determining a moisture level of an air dryer cartridge for installation at or in a housing, in particular an electronics housing, comprising:an air dryer cartridge for reducing the air moisture of air that can be supplied to a housing, wherein the air dryer cartridge comprises a cartridge housing through which air can be guided, and wherein a drying agent is arranged within the cartridge housing, andat least one component, fast with the housing, of an optical measuring system for determining the moisture content of the drying agent, wherein the optical measuring system is provided for emitting an optical signal which defines a beam path, and wherein the air dryer cartridge is arranged such relative to the optical measuring system that the air dryer cartridge is arranged in the beam path of the optical measuring system,

wherein the cartridge housing, at least in sections thereof, comprises a light-permeable wall section for passing through an optical signal emitted from the optical measuring system.

An air dryer cartridge according to the invention for reducing the air moisture of air that can be supplied to an electronics housing comprises a cartridge housing. Air can be guided through the cartridge housing. Within the cartridge housing, a drying agent is arranged.

The drying agent can be embodied preferably as a solid drying agent. Further preferred, this solid drying agent can be in the form of bulk material comprising a plurality of drying agent grains in the cartridge housing. The terms drying agent grain, drying agent granule and/or drying agent bead are to be understood as synonyms.

An inorganic drying agent or a polymer, in particular a silica gel, can be used particularly preferred as drying agent. Advantageously, the drying agent can comprise in addition a color indicator with one or a plurality of color change points at different moisture contents.

Preferably, the cartridge housing can be embodied in a tubular shape and can comprise a casing surface, also referred to as tubular casing surface.

According to the invention, the air dryer cartridge comprises at least one component of an optical measuring system with which the moisture content of the drying agent can be determined. The optical measuring system in this variant of the invention is thus at least partially a component of the air dryer cartridge.

An optical measuring system can comprise inter alia a sensor unit, also referred to as measuring feeder, and an evaluating and/or display unit, also referred to as transducer or transmitter.

In a preferred embodiment of the invention, a sensor unit of the optical measuring system can be arranged in or at a casing surface of the cartridge housing.

The sensor unit of the optical measuring system in a further, also preferred embodiment variant can also be present at or in a grain of the drying agent. In an embodiment that is not in accordance with the invention, the sensor which is embedded in the drying agent grain can also be based on a non-optical principle, for example, inductive, capacitive, or conductivity-based.

In the aforementioned variants, only the sensor unit as component of the measuring system is a part of the air dryer cartridge. However, it is also possible that the entire measuring system is part of the air dryer cartridge.

An infrared measuring system, a UV-Vis measuring system, a color sensor and/or a turbidity sensor can be utilized particularly preferred as optical measuring system. A sensor is to be understood according to the invention as a measuring element or sensing element which converts an optical signal into a processible electrical signal. Chemical color indicators which generate a color change due to a change in moisture are no sensors in the meaning of the present application because they do not provide an electrical signal that can be tapped for processing. According to the invention, it would however be possible to process such a chemical color change (indicator reaction) with an opto-electronic measuring device that appears suitable, for example, a photocell, a color sensor, and the like.

A device according to the invention for determining a moisture content of an air dryer cartridge is provided for installation at or in a housing, in particular in an electronics housing. The device comprises an air dryer cartridge and an optical measuring system fast with the housing.

Fast with the housing means in this context that the optical measuring system or at least its sensor unit is fixed or arranged at or in the housing in which the air dryer cartridge is installed. In this context, the air dryer cartridge is preferably arranged separate from the optical measuring system, in particular from its individual components, in the housing.

The air dryer cartridge in this context is configured for reducing the air moisture of air, in particular for reducing the air moisture of air that can be supplied to an electronics housing, wherein the air dryer cartridge comprises a cartridge housing through which air can be guided and wherein a drying agent is arranged within the cartridge housing.

The optical measuring system fast with the housing serves for determining the moisture contents of the drying agent.

The optical measuring system is provided for emitting an optical signal which defines a beam path wherein the air dryer cartridge is arranged in such a way relative to the optical measuring system that the air dryer cartridge is arranged in the beam path of the optical measuring system.

In the device according to the invention, an infrared measuring system, a UV-Vis measuring system, a color sensor and/or a turbidity sensor can also be utilized particularly preferred as optical measuring system.

In this context, the infrared measuring system and/or the UV-Vis measuring system defines preferably a beam path which penetrates the medium. In contrast thereto, the beam path in case of a turbidity and/or color sensor is changed, e.g., the optical signal is reflected, diffracted and/or scattered. Accordingly, the beam path can thus have a straight course only in sections thereof, e.g., up to the point of impinging on the drying agent.

The constructive configuration of the air dryer cartridge according to the invention, aside from the arrangement of the optical measuring system, can be embodied in analogy to the air dryer cartridge of the device according to the invention.

By the combination of at least one component of the optical measuring system and of the drying agent in the air dryer cartridge according to the invention and/or in a device with the component of the optical measuring system and with the air dryer cartridge, the state of the drying agent can be monitored with regard to its moisture level, for example, in order to indicate that an exchange of the air dryer cartridge is necessary.

Advantageous embodiments of the invention are subject matter of the dependent claims.

The component of the measuring system, in particular the sensor unit, can be arranged at the cartridge housing, preferably at a casing surface section, in particular at a casing surface section of an inner wall side of the cartridge housing.

Alternatively or additionally, the component of the measuring system can be arranged at or in the drying agent, preferably at or in an individual drying agent grain of the drying agent.

In the following, some advantageous embodiments will be explained in more detail which can be used in the air dryer cartridge according to the invention but also in the device according to the invention.

The cartridge housing comprises, at least in sections thereof, a light-permeable wall section for passage of an optical signal which is emitted from a component of the optical measuring system. The light-permeable wall section can preferably be embodied also as an air-permeable wall section. The optical signal is emitted, for example, by a sending module of the optical measuring system.

In the context of the present invention, the term optical signal encompasses an emitted signal which is emitted by a sending module of an optical measuring system as well as the received signal which is detected by a receiving module after having passed through the drying agent, after having been reflected at the drying agent, after having been scattered by the drying agent, and the like.

The sensor unit of the optical measuring system however must not comprise mandatorily a sending module and a receiving module. For example, it is possible that the sensor unit is a sending module or receiving module which can be operated in a sending mode or a receiving mode.

The optical measuring system can comprise at least one color sensor, preferably a color sensor with a light source, for determining the spectral range of the drying agent as a function of the moisture content. As a light source or sending module for illuminating the drying agent, preferably one or a plurality of broadband light sources can be employed in the color sensor. It can be in the form of one or a plurality of LEDs. Preferably one or a plurality of photo diodes, particularly preferred with integrated color filters, can be employed as a detector or receiving module for the color sensor. The color filters can operate based on interference. The photo currents which are received by the detector can be converted into voltages, filtered as needed, and amplified as needed. For this purpose, a transimpedance amplifier can be utilized. By means of a computing unit of an evaluation unit of the color sensor, a digitalized value can be transferred into color coordinates and transformed into Lab color spaces. Finally, by means of the computing unit, a comparison of the actual color coordinates with tolerance values stored in a table and/or further comparative color coordinates can be carried out. Finally, the so-called color detection is realized.

Alternatively or additionally, the optical measuring system can comprise at least one sensor unit with a sending module for emitting an optical signal in the form of an emitted signal, in particular an infrared signal, to the drying agent and with a receiving module for receiving the optical signal as a received signal correlated with the emitted signal after its passage through the drying agent. The operating manner of this optical measuring system can be realized in analogy to an infrared spectrometer. This variant of the optical measuring system is advantageous because the individual sensor components are easily available and the measuring method is well established.

The cartridge housing can advantageously be of a tubular configuration and have a longitudinal axis A wherein the cartridge housing comprises an air-permeable casing surface section through which air, in particular in radial direction relative to the longitudinal axis A, can flow to the drying agent. In this way, an optimal air feed to the drying agent is achieved.

The cartridge housing can advantageously also be embodied as a flexible housing, preferably a screen fabric, particularly preferred embodied of metal material and/or polymer material, or the cartridge housing can comprise such a material at least in sections thereof.

Signal export out of the cartridge housing of a measured signal, in particular of a current-equivalent and/or voltage-equivalent measured signal, can be realized by one or a plurality of energy and/or data line(s), in particular at a terminal end face. Other locations of exporting the aforementioned data/energy flows are possible, for example, at a casing surface.

The sensor unit may comprise in addition a signal processing unit wherein a measured signal which can be tapped or detected at the sensor unit is a voltage-equivalent and/or current-equivalent measured signal which can be determined from the optical signal, in particular from the emitted and/or the received signal, by the signal processing unit. In this way, the measured signal can also be forwarded to an evaluation or display unit.

For easy export of the measured signal out of the cartridge housing, the sensor unit can comprise a communication interface for detachable contacting with a display and/or evaluation unit or for wireless communication with the display and/or evaluation unit, wherein the measured signal can be exported out of the cartridge housing through the communication interface. The communication interface can be connected detectably to a communication interface at the housing, e.g., the electronics housing, e.g. in the form of a plug connection. However, it is also possible to realize contacting of the communication interfaces without their mechanical connection, e.g., by contacting contact elements on a circuit board, but also a wireless or contactless communication between the aforementioned communication interfaces, e.g., by means of a radio communication, is possible.

Moreover, the air dryer cartridge, in particular the air dryer cartridge according to the invention, may comprise an energy supply unit for energy supply of the sensor unit.

The air dryer cartridge of the device according to the invention is advantageously exchangeably arranged in the device in this context.

In contrast thereto, the optical measuring system, preferably the sensor unit, can be fixedly arranged in the device and in particular also in the housing in which the device is arranged.

The use of the air dryer cartridge according to the invention and/or of the device according to the invention for air dehumidification of the air contained in a battery housing, in particular of a lithium ion battery, of a vehicle is moreover also in accordance with the invention.

A method according to the invention for determining the moisture content of the drying agent of an air dryer cartridge according to the invention or of an air dryer cartridge of a device according to the invention comprises the following steps:a. emitting an optical signal, in particular as emitted signal, by a sending module onto or through the drying agent;b. receiving the optical signal, in particular as a received signal, by a receiving module with determination of a measured value;c. determining the moisture content of the drying agent by comparison of the measured value with a data set comprising measured value-specific values for different moisture contents of the drying agent and/or by use of a calculation rule concerning the moisture content of the drying agent as a function of the measured value.

Preferably, a comparison of the measured emitted signal with the received signal can be realized in step b.

The determination of the moisture content can be realized in various ways. A variant is the comparison based on existing data. A further variant is the application of a calculation rule by means of the measured value for determining the moisture content.

The measured value-specific values can advantageously encompass extinction values, transmission values and/or wavelengths of the visible spectral range for different moisture levels of the drying agent.

The method according to the invention can advantageously be performed in intervals or discontinuously. For example, a measurement of the moisture content can be performed e.g. only upon starting and shutting down the vehicle.

