GB2602001A

GB2602001A - Optical liquid detection sensor device

Info

Publication number: GB2602001A
Application number: GB2019513.7A
Authority: GB
Inventors: Wójcik Grzegorz
Original assignee: Lisa Draexlmaier GmbH
Current assignee: Lisa Draexlmaier GmbH
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2022-06-22
Also published as: GB202019513D0

Abstract

Various optical liquid detection sensor devices for detection of liquids inside a battery pack of an electric vehicle, as a result of leak or liquid intrusion, are disclosed, comprising: an optical block, placeable within a battery pack of an electric vehicle, wherein the optical block comprises at least one optical sensing surface, an optical input and an optical output; an optical transmitter configured to provide an optical signal at the optical input, wherein the optical block is configured to output a reflection of the optical signal at the optical output based on liquid inside the battery pack wetting at least part of the at least one optical sensing surface: and an optical receptor, configured to receive the reflection of the optical signal at the optical output for liquid detection. The optical block may be a trapezoidal prism. The sensor driver circuit may use pulse width modulation to drive the optical input. The sensor driver circuit may detect an amount of liquid intrusion based on a change in intensity of the reflected optical signal.

Description

Optical liquid detection sensor device

TECHNICAL FIELD

The disclosure relates to an optical liquid detection sensor (OLDS) device and a method for detection of liquids inside a housing, in particular inside a battery pack of an electric vehicle.

BACKGROUND

Many electric vehicles (EVs) use cooling systems for their battery pack systems. However, if an instance of water leakage were to occur in the battery pack, it would create dangerous conditions. On the other hand, battery packs tend to be hermetically sealed to prevent dust or any other liquid from getting inside. Therefore, some EV manufacturers equip the batteries with electrical liquid detection sensors, in particular resistive or capacitive electrical liquid detection sensors in order to detect any liquid leakage or intrusion. Such sensors are susceptible to environment conditions and ageing and have to be galvanically isolated. Due to electrolysis of liquid and sensor, it is not suggested to use such an electrical sensor for more than 1 hour in liquid. Furthermore, this sensor must be replaced after a warning is indicated to the user of the vehicle. These are serious disadvantages that decrease robustness of the sensor and potentially increase maintenance cost over the car's lifespan. Furthermore, electrical sensors are susceptible to electromagnetic interference (EMI). When there is a significant change of current drawn from the battery, e.g. during cars acceleration or deceleration, the electromagnetic field is generated and coupled with other components, also referred to as Electronic Control Units, ECU's. This results in an electrical noise to the information-carrying signals, e.g. of electrical sensors.

SUMMARY

It is an object of this disclosure to provide a liquid detection sensor for use in a housing, in particular for use in an electric vehicle, that is robust against environment conditions like electrolysis and electromagnetic interference.

In particular, it is an object of this disclosure to provide a robust and reliable liquid detection sensor for use in an EV's battery pack.

This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

A basic idea of this disclosure is to detect liquid presence, e.g. of water or oil, inside a housing, in particular inside a battery pack of an electric vehicle, by using light instead of electricity. Such optical liquid detection can be realized by applying the Snell's law, i.e. the law of refraction.

Snell's law is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, or air. Snell's law states that the ratio of the sines of the angles of incidence and refraction is equivalent to the ratio of phase velocities in the two media, or equivalent to the reciprocal of the ratio of the indices of refraction.

Two plastic optic fibre (PDF) cables guide light into a carefully designed optical block (e.g. of PMMA/polycarbon material). The optical block is designed in such way, that any presence of liquid will cause refraction of the light. If this happens, significantly less light will return to a photodetector and a liquid intrusion/leakage can be detected.

Such a solution provides the following advantages: The optical liquid detection according to this disclosure is more robust than existing solutions and has no risk of electrolysis, since there are no exposed areas or electrodes that may corrode over time. Furthermore, no electrostatic discharge, ESD, protection is needed due to the optical sensing. The sensor's driver (electronics: transmitter and receiver) can be placed in a low-voltage area, e.g. together with battery management system electronics. Sensing signals may be guided via polymer optic fibers. The sensor itself is not susceptible to electromagnetic interference. It offers cost reductions, as no expensive isolation is needed for electric signals. The optical liquid detection sensor can be produced either as a dedicated module for automotive batteries or as a part of battery management system.

In order to describe the invention in detail, the following terms, abbreviations and notations will be used: EV electric vehicle ECU electronic control unit EMI electromagnetic interference OLDS optical liquid detection sensor POE plastic optic fiber MCU motor control unit PCB printed circuit board PMMA Polymethyl methacrylate, also known as acrylic glass PC Polycarbonates An electric vehicle (EV) according to this disclosure is a vehicle that uses one or more electric motors or traction motors for propulsion. An electric vehicle may be powered through a collector system by electricity from off-vehicle sources, or may be self-contained with a battery, solar panels, fuel cells or an electric generator to convert fuel to electricity. EVs include, but are not limited to, road and rail vehicles, surface and underwater vessels, electric aircraft and electric spacecraft.

An electronic control unit (ECU) according to this disclosure is an embedded system in automotive electronics that controls one or more of the electrical systems or subsystems in a vehicle. Types of ECU include engine control module (ECM), powertrain control module (PCM), Transmission Control Module (TCM), Brake Control Module (BCM), Central Control Module (CCM), etc. Polymethyl methacrylate (PMMA), also known as acrylic, or acrylic glass, is a transparent thermoplastic often used in sheet form as a lightweight or shatter-resistant alternative to glass.

Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent.

In this disclosure, battery cells, battery modules and battery packs are described.

Battery cells are low voltage -each cell has a specific voltage range, e.g. for lithium ion chemistry the operating voltage range is 3.0V-4.2V.

Battery modules are made of many cells connected in series (to increase total voltage), and parallel (to increase total capacity). Battery modules are commonly designed to meet low voltage specification (e.g. according to IS06469), so they can be manufactured and handled without additional precautions.

Battery pack is made of many battery modules, connected in series and/or in parallel as well. Battery pack's area is high voltage. Battery packs consist not only of battery cells and modules, but electronics, switch-box, heat management systems as well.

According to a first aspect, the disclosure relates to an optical liquid detection sensor device for detection of liquids inside a housing, in particular inside a battery pack of an electric vehicle, the optical liquid detection sensor device, comprising: an optical block, placeable within a housing, in particular within a battery pack of an electric vehicle, wherein the optical block comprises at least one optical sensing surface, an optical input and an optical output; an optical transmitter configured to provide an optical signal at the optical input, wherein the optical block is configured to output a reflection of the optical signal at the optical output based on liquid inside the housing wetting at least part of the at least one optical sensing surface; and an optical receptor, configured to receive the reflection of the optical signal at the optical output for liquid detection.

Such an optical liquid detection sensor device has the advantage of detecting leakage without having the need of galvanic isolation, i.e. no dedicated electronics near high-voltage connections of battery modules is necessary. The optical liquid detection sensor device further offers increased robustness and cost reduction.

In an exemplary implementation of the optical liquid detection sensor device, the optical block is formed as a trapezoidal prism.

This provides the advantage that such a geometrical shape is well suited for applying Snell's law.

In an exemplary implementation of the optical liquid detection sensor device, the optical block is made of transparent thermoplastic, in particular Polymethylmethacrylate, PMMA, also known as acrylic glass, or optically transparent polycarbonate, PC.

This provides the advantage that the material is lightweight and shock proof and well suited for guiding light.

In an exemplary implementation of the optical liquid detection sensor device, the optical block is configured to reflect the optical signal based on total internal reflection in the optical block, wherein the total internal reflection is distorted by the liquid wetting at least part of the at least one optical sensing surface This provides the advantage that the distortion of the total internal reflection is a suitable measure for detecting liquids.

In an exemplary implementation of the optical liquid detection sensor device, the optical block comprises three optical sensing surfaces formed at contiguous edges of the optical block.

This provides the advantage that by using three optical sensing surfaces, improved detection of liquid can be realized. The optical liquid detection sensor device can be placed in the battery pack such that small drops of liquid can be detected.

In an exemplary implementation of the optical liquid detection sensor device, two noncontiguous optical sensing surfaces of the three optical sensing surfaces are formed at an angle of about 120 degrees to the third optical sensing surface.

This provides the advantage that the light ray path can be reflected at each of the three sensing surfaces, thereby enabling liquid detection at each of the three sensing surfaces. This provides a very precise liquid detection.

In an exemplary implementation of the optical liquid detection sensor device, the optical block comprises two optical sensing surfaces formed at non-contiguous edges of the optical block.

This provides the advantage that liquid detection can be advantageously performed at different places.

In an exemplary implementation of the optical liquid detection sensor device, each of the two optical sensing surfaces is formed at an angle of about 135 degrees to a third optical surface formed between the two optical sensing surfaces.

This provides the advantage that the light ray path can be reflected at each of the two noncontiguous optical sensing surfaces, thereby providing precise liquid detection.

In an exemplary implementation of the optical liquid detection sensor device, the optical block comprises a main optical sensing surface and a second optical surface opposite to the main optical sensing surface, and the optical signal is reflected at the main optical sensing surface and at the second optical surface.

This provides the advantage that the light ray path can have multiple reflections before being output at the optical output. These multiple reflections enable interference with liquid wetting different places of the optical block, thereby improving detection sensibility.

In an exemplary implementation of the optical liquid detection sensor device, the optical block is arranged at a bottom of the housing.

This provides the advantage that liquids flowing to the bottom of the housing, in particular the bottom of the battery pack, due to gravity can be efficiently detected.

In an exemplary implementation of the optical liquid detection sensor device, the optical liquid detection sensor device comprises: a sensor driver circuit, configured to detect a liquid intrusion based on a refraction of the optical signal at the at least part of the at least one optical surface wetted by the liquid.

This provides the advantage that such a sensor driver circuit can efficiently detect liquid and particularly an amount of the liquid wetting the optical block due to the relation of refracted light versus reflected light.

In an exemplary implementation of the optical liquid detection sensor device, the optical liquid detection sensor device comprises: a pair of plastic optical fibers configured to couple the sensor driver circuit to the optical input and the optical output of the optical block.

This provides the advantage that the plastic optical fibers enable decoupling of the optical stage of the sensor device, i.e. the optical block, from the electrical stage of the sensor device, i.e. the driver circuit. Hence, the decoupling avoids electromagnetic interference. Therefore, no costly electromagnetic shielding is necessary.

In an exemplary implementation of the optical liquid detection sensor device, the sensor driver circuit is configured to drive the optical input of the optical block based on a pulse width modulated electrical signal.

This provides the advantage that by using a pulse modulated electrical signal, differentiation between the three states: liquid detected, liquid not detected and sensor disconnected is possible.

In an exemplary implementation of the optical liquid detection sensor device, the sensor driver circuit is configured to detect an amount of liquid intrusion based on a change of a reflected optical signal's property, e.g. a change of light intensity causing a change of ADC (Analog to Digital Converter) sensor voltage.

This provides the advantage that a very precise liquid detection can be achieved, particularly a precise measurement of the amount of liquid in the battery pack.

According to a second aspect, the disclosure relates to a method for detection of liquids inside a housing, in particular inside a battery pack of an electric vehicle, the method comprising: placing an optical block within a housing, in particular within a battery pack of an electric vehicle, wherein the optical block comprises at least one optical sensing surface, an optical input and an optical output, wherein the optical block is configured to output a reflection of an optical signal at the optical output based on a liquid inside the housing wetting at least part of the at least one optical sensing surface; providing the optical signal at the optical input; and detecting a liquid inside the housing based on a reflection of the optical signal at the optical output.

Such a method for optical liquid detection has the advantage of detecting leakage without having the need of galvanic isolation, i.e. no dedicated electronics near high-voltage connections of battery modules is necessary. The optical liquid detection method further offers increased robustness and cost reduction.

According to a third aspect, the disclosure relates to a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the method according to the second aspect. Such a computer program product may include a non-transient readable storage medium storing program code thereon for use by a processor, the program code comprising instructions for performing the method as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Further examples will be described with respect to the following figures, in which: Fig. la shows a schematic diagram illustrating an optical liquid detection sensor device 100 according to a first example in the presence of liquid 101; Fig. lb shows a schematic diagram illustrating the optical liquid detection sensor device 100 in the absence of liquid; Fig. 2a shows a schematic diagram illustrating an optical liquid detection sensor device 200 according to a second example; Fig. 2b shows a 3D view of the optical liquid detection sensor device 200; Fig. 2c shows a further 3D view of the optical liquid detection sensor device 200; Fig. 3a shows a schematic diagram illustrating an optical liquid detection sensor device 300 according to a third example; Fig. 3b shows a 3D view of the optical liquid detection sensor device 300; Fig. 3c shows a further 3D view of the optical liquid detection sensor device 300; Fig. 4 shows a schematic diagram illustrating an optical liquid detection sensor device 400 according to a fourth example; Fig. 5 shows a schematic diagram illustrating an exemplary sensor driver circuit 500 for an optical liquid detection sensor device according to the disclosure; Fig. 6 shows a 3-dimensional view of an optical liquid detection sensor device 600 according to a fifth example; Fig. 7 shows another 3-dimensional view of the optical liquid detection sensor device 600 according to the fifth example; Fig. 8 shows another 3-dimensional view of the optical liquid detection sensor device 600 according to the fifth example; and Fig. 9 shows a schematic diagram of a method 900 for detection of liquids inside a battery pack of an electric vehicle according to the disclosure

DETAILED DESCRIPTION OF EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

Fig. la shows a schematic diagram illustrating an optical liquid detection sensor device 100 according to a first example in the presence of liquid 101 and Fig. lb shows the same optical liquid detection sensor device 100 in the absence of liquid.

The detection scheme of the optical liquid detection sensor device 100 can be described with respect to Figures la and lb as follows: Light 106 is transmitted into carefully designed optics 102, made e.g. of an acrylic glass/PMMA, at particular angles. The angles can be calculated according to Snell's law and may be for example about 45° or about 60°. In Figure lb and Figure 3a below, an angle of 45° is shown, while in Figure 2a below, an angle of 60° is shown. If there is a liquid drop 101 present on the surface 111 (referred hereinafter as optical sensing surface), then the light beam 106 refracts 108 and less light 107 is received by the receptor 109, e.g. a photodiode or a phototransistor. Light 106 may be guided from the driver 401 (located even few meters away as shown below in Fig. 4) via plastic optic fibres (POF) 402. The driver 401 may consist of electronics with MCU and other basic components such as LED, phototransistor, etc. The optical liquid detection sensor device 100 shown in Figures la and lb can be used for detection of liquids 101 inside a housing, in particular inside a battery pack of an electric vehicle.

The optical liquid detection sensor device 100 comprises: an optical block 102, an optical transmitter 105 and an optical receptor 109.

The optical transmitter 105 is configured to provide an optical signal 106 at the optical input 103 The optical block 102 is placeable within a battery pack of an electric vehicle. The optical block 102 comprises at least one optical sensing surface 111, an optical input 103 and an optical output 104.

The optical block 102 is configured to output a reflection 107 of the optical signal 106 at the optical output 104 based on liquid 101 inside the battery pack wetting at least part of the at least one optical sensing surface 111.

The optical receptor 109 is configured to receive the reflection 107 of the optical signal 106 at the optical output 104 for liquid detection The optical block 102 may be formed as a trapezoidal prism as shown in Figures la and lb. The optical block 102 can be made of transparent thermoplastic, e.g. made of Polymethylmethacrylate, PMMA, also known as acrylic glass. The optical block 102 may be formed as a single block of transparent thermoplastic, e.g. PMMA.

The optical block 102 may be configured to reflect the optical signal 106 based on total internal reflection in the optical block 102, wherein the total internal reflection is distorted by the liquid 101 wetting at least part of the at least one optical sensing surface 111.

The optical block 102 may comprise a main optical sensing surface 111 and a second optical surface 110 opposite to the main optical sensing surface 111. The optical signal 106 may be reflected at the main optical sensing surface 111 and at the second optical surface 110. For example, two reflections at the main optical sensing surface 111 and one reflection at the second optical surface 110 may occur as shown in Figures 1a and 1 b. Alternatively more or less reflections may occur at the main optical sensing surface 111 and at the second optical surface 110, e.g. only one reflection at main optical sensing surface 111 and one reflection at the second optical surface 110 or one reflection at main optical sensing surface 111 and two reflections at the second optical surface 110 or three reflections at main optical sensing surface 111 and two reflections at the second optical surface 110 or any other number of reflections.

The optical block 102 may, for example, be arranged at a bottom of the battery pack. At the bottom of the battery pack it is assumed that liquid may be present due to gravity.

The optical liquid detection sensor device 400 may further comprise a sensor driver circuit 401, 500, e.g. as shown in Figures 4 and 5, configured to detect a liquid 101 intrusion based on a refraction 108 of the optical signal 106 at the at least part of the at least one optical surface 111 wetted by the liquid 101.

The optical liquid detection sensor device 400 may further comprise a pair of plastic optical fibers 402, 603, as shown for example in Figures 4 and 6 to 8, configured to couple the sensor driver circuit 401, 500 to the optical input 103 and the optical output 104 of the optical block 102.

The sensor driver circuit 401, 500 may be configured to drive the optical input 103 of the optical block 102 based on a pulse width modulated electrical signal 540, e.g. as shown in Figure 5.

The sensor driver circuit 401, 500 may be configured to detect an amount of liquid 101 intrusion based on an amplitude reduction of the reflected optical signal 107 with respect to a reference signal indicating an absence of liquid 101 intrusion. Such a reference signal can be for example a reflected optical signal 107 at the optical output 104 of Figure lb, in which no liquid is present. This reference signal may be generated under test conditions ensuring that no liquid is present at the optical sensing surface 111.

Fig. 2a shows a schematic diagram illustrating an optical liquid detection sensor device 200 according to a second example. Fig. 2b shows a 3D view of the optical liquid detection sensor device 200 and Fig. 2c shows a further 3D view of the optical liquid detection sensor device 200.

The optical liquid detection sensor device 200 is similar constructed as the optical liquid detection sensor device 100 described above with respect to Figures la and lb The optical liquid detection sensor device 200 that can be used for detection of liquids 101 inside a battery pack of an electric vehicle, comprises an optical block 102, an optical transmitter 105 (not shown in Fig. 2a) and an optical receptor 109 (not shown in Fig. 2a). Figure 2a shows the optical block 102 and a housing 202 with POF connector openings 211, 212 for inserting the POF connectors for the pair of POF cables 402, as shown in Fig. 4. Figure 2a also shows the mounting holes 214, 215 for connecting a lower part 604 of the housing 202 with an upper part 605 of the housing 202 as shown in Figures 6 to 8. Figure 2a also shows dimensions of the housing 202 and the optical block 102 in millimeters.

As described above with respect to Figures la and lb, the optical transmitter 105 is configured to provide an optical signal 106 at the optical input 103. The optical receptor 109 is configured to receive the reflection 107 of the optical signal 106 at the optical output 104 for liquid detection. The optical block 102 is placeable within a battery pack of an electric vehicle. The optical block 102 comprises at least one optical sensing surface 111, 112, 113, an optical input 103 and an optical output 104. In this example of Figure 2a, the optical block 102 comprises the three optical sensing surfaces 111, 112, 113. The optical block 102 is configured to output a reflection 107 of the optical signal 106 at the optical output 104 based on liquid 101 inside the battery pack wetting at least part of the at least one optical sensing surface 111, 112, 113. A light ray path 201 corresponding to the path of the optical signal 106 is illustrated in Figure 2a. The optical signal 106 is first reflected at left-side optical sensing surface 113, then at upper optical sensing surface 111 and finally at right-side optical sensing surface 112 before being output at the optical output 104.

The optical block 102 comprises three optical sensing surfaces 111, 112, 113 formed at contiguous edges of the optical block 102. Two non-contiguous optical sensing surfaces 112, 113 of the three optical sensing surfaces 111, 112, 113 are formed at an angle of about 120 degrees to the third optical sensing surface 111. In Figure 2a an angle of 60° is depicted which is from the left-side optical sensing surface 113 to the horizontal, i.e. an angle of 120° results from the left-side optical sensing surface 113 to the upper optical sensing surface 111. Light comes in from the bottom side and falls at an angle of 30° at the left-side optical sensing surface 113, is reflected from this surface 113 and follows the light ray path 201 shown in Figure 2a.

Fig. 3a shows a schematic diagram illustrating an optical liquid detection sensor device 300 according to a third example. Fig. 3b shows a 3D view of the optical liquid detection sensor device 300 and Fig. 3c shows a further 3D view of the optical liquid detection sensor device 300.

The optical liquid detection sensor device 300 is similar constructed as the optical liquid detection sensor device 100 described above with respect to Figures la and lb and as the optical liquid detection sensor device 200 described above with respect to Fig. 2a.

The optical liquid detection sensor device 300 that can be used for detection of liquids 101 inside a battery pack of an electric vehicle, comprises an optical block 102, an optical transmitter 105 (not shown in Fig. 3a) and an optical receptor 109 (not shown in Fig. 3a). As described above with respect to Figure 2a, also Figure 3a shows the optical block 102 and a housing 202 with POE connector openings 211, 212 for inserting the POE connectors for the pair of POE cables 402, as shown in Fig. 4. Figure 3a also shows the mounting holes 214, 215 for connecting a lower part 604 of the housing 202 with an upper part 605 of the housing 202 as shown in Figures 6 to 8. Figure 2a also shows dimensions of the housing 202 and the optical block 102 in millimeters.

As described above with respect to Figures la and lb, the optical transmitter 105 is configured to provide an optical signal 106 at the optical input 103. The optical receptor 109 is configured to receive the reflection 107 of the optical signal 106 at the optical output 104 for liquid detection. The optical block 102 is placeable within a battery pack of an electric vehicle. The optical block 102 comprises at least one optical sensing surface 111, 112, 113, an optical input 103 and an optical output 104. In this example of Figure 3a, the optical block 102 comprises the two optical sensing surfaces 112, 113, while upper optical surface 111 is not used for sensing. The optical block 102 is configured to output a reflection 107 of the optical signal 106 at the optical output 104 based on liquid 101 inside the battery pack wetting at least part of the at least one optical sensing surface 112, 113. A light ray path 301 corresponding to the path of the optical signal 106 is illustrated in Figure 3a. The optical signal 106 is first reflected at left-side optical sensing surface 113 and then at right-side optical sensing surface 112 before being output at the optical output 104. Due to the specific geometry of the optical block 102, there is no significant reflection at the upper-side surface 111. There will be some reflections, because the light 106 coming out of the plastic opic fibre 402 is not a laser beam. So the light 106 will partially hit the upper optical surface 111. But if there is a liquid drop present, then the refraction will be way much smaller than for the example in Figure 2a.

The optical block 102 comprises two optical sensing surfaces 112, 113 formed at noncontiguous edges of the optical block 102. Each of the two optical sensing surfaces 112, 113 is formed at an angle of about 135 degrees to the third optical surface 111 that is formed between the two optical sensing surfaces 112, 113. In Figure 3a an angle of 45° is depicted which is from the left-side optical sensing surface 113 to the horizontal, i.e. an angle of 135° results from the left-side optical sensing surface 113 to the upper optical surface 111. Light comes in from the bottom side and falls at an angle of 45° at the left-side optical sensing surface 113, is reflected from this surface 113 and follows the light ray path 301 to the right-side optical sensing surface 112 as shown in Figure 3a.

Fig. 4 shows a schematic diagram illustrating an optical liquid detection sensor device 400 according to a fourth example.

The optical liquid detection sensor device 400 shown in Figures 4 can be used for detection of liquids 101 inside a battery pack of an electric vehicle. The optical liquid detection sensor device 400 is constructed similar to the sensor device 100 shown in Figure lb. It comprises: an optical block 102, an optical transmitter 105 (integrated in the driver circuit 401) and an optical receptor 109 (integrated in the driver circuit 401).

The optical transmitter 105 or the driver circuit 401, respectively, is configured to provide an optical signal 106 at the optical input 103. The optical signal 106, generated by the driver circuit 401, is guided by POF cables 402 before reaching the optical input 103.

The optical receptor 109 or the driver circuit 401, respectively, is configured to receive the reflection 107 of the optical signal 106 at the optical output 104 for liquid detection. The reflected optical signal 107 is guided by the POF cables 402 to the driver circuit 401.

As described above with respect to Figures la and lb, the optical block 102 is placeable within a battery pack of an electric vehicle. The optical block 102 comprises at least one optical sensing surface 111, an optical input 103 and an optical output 104. The optical block 102 is configured to output a reflection 107 of the optical signal 106 at the optical output 104 based on liquid 101 inside the battery pack wetting at least part of the at least one optical sensing surface 111. An example of the driver circuit 401 is shown in Figure 5.

In an example, the driver circuit 401 may be integrated with battery management system electronics of the vehicle as described in the following. In this example, main PCB (e.g. BCU, BMS) is equipped with plastic optic fiber transceiver and few basic components. The generated light is passed via two plastic optic fibers 402 (one for sending and one for receiving) to the optical block 102. The optical block 102 is sensitive to a change of medium as described above. Thanks to the plastic optic fibers 402, the sensor itself (including the optical block 102 and the POF connectors) can be placed a few meters away from the controller 401 The sensor driver circuit 401 may be configured to detect a liquid 101 intrusion based on a refraction 108 of the optical signal 106 at the at least part of the at least one optical surface 111 wetted by the liquid 101.

As described above, the optical liquid detection sensor device 400 comprises a pair of plastic optical fibers 402 configured to couple the sensor driver circuit 401 to the optical input 103 and the optical output 104 of the optical block 102.

The sensor driver circuit 401 may be configured to drive the optical input 103 of the optical block 102 based on a pulse width modulated electrical signal 540, e.g. as shown in Figure 5.

The sensor driver circuit 401 may be configured to detect an amount of liquid 101 intrusion based on an amplitude reduction of the reflected optical signal 107 with respect to a reference signal indicating an absence of liquid 101 intrusion.

In an example, electrical sensor's output signal may be LOW for "Liquid not detected" as well as "Sensor disconnected" state. From the perspective of functional safety, optical sensor is more robust. This is because it's LOW state clearly indicate an error: liquid detected or connection problem. If the carrier signal is modulated (e.g. with a PWM), then the difference between "Sensor disconnected" and "Liquid detected" can be observed as well, see Table 1 below.

Table 1: different states of liquid detection sensor Liquid sensor Electrical Optical Liquid not detected LOW HIGH Liquid detected HIGH LOW Sensor disconnected LOW LOW Fig. 5 shows a schematic diagram illustrating an exemplary sensor driver circuit 500 for an optical liquid detection sensor device according to the disclosure. The sensor's driver example schematic can be made as an individual ECU, for example.

The POF connector 510 is shown at the top right side of the figure. It includes a transmitter 511 and a receiver 513 The POF connector 510 may correspond to the POF connectors shown in Figures 2 and 3. The transmitter 511 may correspond to the optical transmitter 105 described above with respect to Figures la and lb. The receiver 513 may correspond to the optical receptor 109 described above with respect to Figures la and lb. The POF connector 510 may further correspond to the POE connector shown in Figures 6 to 8.

The transmitter 511 includes an LED 512 and the receiver 513 includes a photo transistor 514, or a photodiode. The emitter of transistor 514 is connected via resistor R2 515 to ground 516. The emitter of transistor 514 is further connected to port A2 of integrated circuit 517.

Port A2 of IC 517 is an ADC (analog-to-digital converting) sensing input. Port A2 of IC 517 is measuring voltage at phototransistors emitter. Port Al of integrated circuit 517 is connected to LED 512 of transmitter 511. Port Al of IC 517 is pulse-width modulated (PWM) output providing an electrical PWM signal to LED 512. The PWM may have for example a 50% duty cycle. Port Al of IC 517 may be connected as current source, e.g. for 0 to 30mA with 3mA step size and for 36 to 48 mA with 6mA step size.

Ports A3 and A4 are optional. Port AS of IC 517 is connected to ground 518. Port A6 of IC 517 is connected via resistor R1 to port C3 of connector 532. Port A7 of IC 517 is connected to port 02 of connector 532. Port AS of IC 517 is driven by supply voltage 520 and connected via diode D1 in blocking direction to supply voltage 530 and port Cl of connector 532. Port AS of IC 517 is connected via parallel connection of diode D3 523 and capacitor Cl 521 and capacitor C2 519 to ground 522. Port A6 of IC 517 is connected via diodes D2 to ground 528. Port C3 of connector 532 is connected via capacitor 03 to ground 528. Port 04 of connector 532 is connected to ground 531.

Figures 6, 7 and 8 show different 3-dimensional views of an optical liquid detection sensor device 600 according to a fifth example.

The optical liquid detection sensor device 600 that can be used for detection of liquids 101 inside a battery pack of an electric vehicle, comprises an optical block 102, an optical transmitter 105 (not shown in Fig. 6) and an optical receptor 109 (not shown in Fig. 6). Figures 6 to 8 show the optical block 102 and a housing 604 (lower part) with POE connector openings in which the POE connectors for the pair of POE cables 603 are inserted. The POE connectors are sealed with the housing 604 by sealings 601, 602. Mounting holes are shown for connecting the lower part 604 of the housing with an upper part 605 of the housing shown in Figure 8.

As described above, the optical transmitter 105 is configured to provide an optical signal 106 at the optical input 103. The optical receptor 109 is configured to receive the reflection 107 of the optical signal 106 at the optical output 104 for liquid detection. The optical block 102 inserted in the housing 604, 605 is placeable within a battery pack of an electric vehicle. The optical block 102 comprises at least one optical sensing surface as described above, an optical input 103 and an optical output 104. The optical block 102 is configured to output a reflection 107 of the optical signal 106 at the optical output 104 based on liquid 101 inside the battery pack wetting at least part of the at least one optical sensing surface, as described above.

The solution shown in Figures 6 to 8 may use off-the shelf components and custom parts for sensor housing 604, 605 and optical block 102. The optical block 102 can be a laser-cut or molded optical block. For example, a slightly modified off-the shelf transceiver may be used. A laser-cut (or molded) optical block 102 (PMMA) and housing (molded) may be used. For example, off-the shelf LWL insert and an off-the shelf plastic optic fiber may be used. The Sensor's driver (electronics) may be implemented as described above with respect to Fig. 5.

Fig. 9 shows a schematic diagram of a method 900 for detection of liquids inside a battery pack of an electric vehicle according to the disclosure.

The method 900 comprises the following steps: placing 901 an optical block 102 within a battery pack of an electric vehicle, e.g. an optical block 102 as described above with respect to Figures 1 to 8, wherein the optical block 102 comprises at least one optical sensing surface 111, 112, 113, an optical input 103 and an optical output 104, wherein the optical block 102 is configured to output a reflection 107 of an optical signal 106 at the optical output based on a liquid inside the battery pack wetting at least part of the at least one optical sensing surface.; providing 902 the optical signal 106 at the optical input 103; and detecting 903 a liquid 101 inside the battery pack based on a reflection 107 of the optical signal 106 at the optical output 104.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.

The following reference signs are used in this disclosure: optical liquid detection sensor device 101 liquid 102 optical block 103 optical input of the optical block 104 optical output of the optical block optical transmitter 106 optical signal 107 reflection of the optical signal 108 refraction of the optical signal 109 optical receptor second optical surface 111, 112, 113 optical sensing surfaces optical liquid detection sensor device 202 housing 211, 212 recess for optical connector (PDF) 214, 215 mounting holes 300 optical liquid detection sensor device 400 optical liquid detection sensor device 401 sensor driver circuit 402 plastic optical fiber pair (PDF) 500 sensor driver circuit 510 POE connector 511 transmitter 512 LED1 513 receiver 514 photo-transistor 515 resistor R2 516 ground, GND 517 integrated circuit 518 ground 519 capacitor C2 520 supply voltage, 12V 521 capacitor Cl 522 ground 523 diode D3 524 diode D1 525, 526 diodes D2 527 resistor R1 528 ground 529 capacitor C3 530 supply voltage, 12V 531 ground 532 connector 540 electrical PWM signal 541 ADC sensor signal 600 optical liquid detection sensor device 601,602 sealings 603 plastic optical fiber, POF; pair 604 housing, lower part 605 housing, upper part 900 method for liquid detection 901 first step: placing 902 second step: providing 903 third step: detecting

Claims

Claims: 1. An optical liquid detection sensor device (100, 200, 300, 600) for detection of liquids (101) inside a housing, the optical liquid detection sensor device (100, 200, 300) comprising: an optical block (102), placeable within a housing, wherein the optical block (102) comprises at least one optical sensing surface (111, 112, 113), an optical input (103) and an optical output (104); an optical transmitter (105) configured to provide an optical signal (106) at the optical input (103), wherein the optical block (102) is configured to output a reflection (107) of the optical signal (106) at the optical output (104) based on liquid (101) inside the housing wetting at least part of the at least one optical sensing surface (111, 112, 113); and an optical receptor (109), configured to receive the reflection (107) of the optical signal (106) at the optical output (104) for liquid detection.
The optical liquid detection sensor device (100, 200, 300, 600) according to claim 1, wherein the optical block (102) is formed as a trapezoidal prism.
3. The optical liquid detection sensor device (100, 200, 300, 600) according to claim 1 or wherein the optical block (102) is made of transparent thermoplastic, in particular Polymethylmethacrylate, PMMA, also known as acrylic glass, or optically transparent polycarbonate, PC.
4. The optical liquid detection sensor device (100, 200, 300, 600) according to one of the preceding claims, wherein the optical block (102) is configured to reflect the optical signal (106) based on total internal reflection in the optical block (102), wherein the total internal reflection is distorted by the liquid (101) wetting at least part of the at least one optical sensing surface (111, 112, 113).
5. The optical liquid detection sensor device (200) according to one of the preceding claims, wherein the optical block (102) comprises three optical sensing surfaces (111, 112, 113) formed at contiguous edges of the optical block (102).
6. The optical liquid detection sensor device (200) according to claim 5, wherein two non-contiguous optical sensing surfaces (112, 113) of the three optical sensing surfaces (111, 112, 113) are formed at an angle of about 120 degrees to the third optical sensing surface (111).
7. The optical liquid detection sensor device (300) according to one of claims 1 to 4, wherein the optical block (102) comprises two optical sensing surfaces (112, 113) formed at non-contiguous edges of the optical block (102).
8. The optical liquid detection sensor device (300) according to claim 7, wherein each of the two optical sensing surfaces (112, 113) is formed at an angle of about 135 degrees to a third optical surface (111) formed between the two optical sensing surfaces (112, 113).
9. The optical liquid detection sensor device (100) according to one of claims 1 to 4, wherein the optical block (102) comprises a main optical sensing surface (111) and a second optical surface (110) opposite to the main optical sensing surface (111), wherein the optical signal (106) is reflected at the main optical sensing surface (111) and at the second optical surface (110).
10. The optical liquid detection sensor device (100, 200, 300, 600) according to one of the preceding claims, wherein the optical block (102) is arranged at a bottom of the housing.
11. The optical liquid detection sensor device (400) according to one of the preceding claims, comprising: a sensor driver circuit (401, 500), configured to detect a liquid (101) intrusion based on a refraction (108) of the optical signal (106) at the at least part of the at least one optical surface (111, 112, 113) wetted by the liquid (101).
12. The optical liquid detection sensor device (400) according to claim 11, comprising: a pair of plastic optical fibers (402, 603) configured to couple the sensor driver circuit (401, 500) to the optical input (103) and the optical output (104) of the optical block (102).
13. The optical liquid detection sensor device (400) according to claim 11 or 12, wherein the sensor driver circuit (401, 500) is configured to drive the optical input (103) of the optical block (102) based on a pulse width modulated electrical signal (540).
14. The optical liquid detection sensor device (400) according to one of claims 11 to 13, wherein the sensor driver circuit (401, 500) is configured to detect an amount of liquid (101) intrusion based on a change of a reflected optical signal's (107) property, in particular a change of light intensity causing a change of ADC sensor voltage (541).
15. A method (900) for detection of liquids inside a housing, the method comprising: placing (901) an optical block (102) within a housing, wherein the optical block (102) comprises at least one optical sensing surface (111, 112, 113), an optical input (103) and an optical output (104), wherein the optical block (102) is configured to output a reflection (107) of an optical signal (106) at the optical output based on a liquid inside the housing wetting at least part of the at least one optical sensing surface; providing (902) the optical signal (106) at the optical input (103); and detecting (903) a liquid (101) inside the housing based on a reflection (107) of the optical signal (106) at the optical output (104).
16. The method (900) according to claim 15, wherein the optical block (102) is formed as a trapezoidal prism and is made of transparent thermoplastic, in particular Polymethylmethacrylate, PMMA, also known as acrylic glass, or optically transparent polycarbonate, PC.