HOUSING FOR VEHICLE SENSOR WITH ANTI-FOG FUNCTION

Abstract

Vehicle vision sensor system comprehensive: at least one vision sensor (20, 22, 24) with a housing (200) defining a cavity (212) and a sensor element arranged inside the cavity (212), a voltage-controlled heating element wound around the housing (200), a local temperature and humidity sensor (30) arranged near the housing (200) and configured to detect temperature and relative humidity in the cavity (212); and a control unit (40) connected to the local temperature and humidity sensor (30) and an outside air temperature sensor (32), wherein the control unit (40) includes a memory in which commands are stored that cause the control unit (40) to determine a dew point in the cavity (212), to compare the temperature of the cavity (212) with the dew point and to apply a voltage to the voltage-controlled heating element when the temperature of the cavity (212) is below the dew point.

Description

INTRODUCTION

[0001] The present disclosure relates to housings for vehicle sensors and in particular a housing with an anti-fog function.

[0002] Vehicle vision and object recognition systems use a network of sensors distributed around the vehicle to detect objects and features outside the vehicle, as well as the positions of these objects and features relative to the vehicle. The data is processed by a control unit and made available to other systems within the vehicle, enabling them to react appropriately to the objects.

[0003] These sensors are typically housed in a casing to protect them from environmental factors such as gravel, road grime, etc. If the temperature and humidity inside the sensor casing fall below the dew point, condensation and fogging can form inside the casing and surround the sensor. This condensation and fogging can, in turn, impair the accuracy and / or reliability of the sensor output.

[0004] Therefore, it is desirable to provide sensor housings that are able to reduce or eliminate fogging and condensation within a sensor housing.

[0005] DE 11 2019 001 176 T5 discloses a system for utilizing electromagnetic waves, in which a device for transmitting and receiving electromagnetic waves is used on a through-passage. The through-passage has an inner component facing the device and an outer component facing away from the device, with a thermal insulation section provided between the two components. The thermal insulation section prevents condensation on the section of the inner component through which the electromagnetic wave passes. Further prior art is known from DE 10 2021 120 096 A1, DE 11 2020 006 734 T5 and DE 10 2020 000 291 A1. BRIEF SUMMARY OF THE INVENTION

[0006] The object of the invention is to provide an improved vehicle vision sensor system.

[0007] To solve the problem, a system with the features of claim 1 is provided. Advantageous embodiments of the invention can be found in the dependent claims, the description, and the drawings.

[0008] According to the invention, the vehicle vision sensor system comprises at least one vision sensor with a housing that defines a cavity and a sensor element arranged within the cavity. A voltage-controlled heating element is wound around the housing. A local temperature and humidity sensor is located near the housing and is configured to detect the temperature and relative humidity within the cavity. A control unit is connected to the local temperature and humidity sensor and an ambient air temperature sensor. The control unit includes a memory in which commands are stored that cause the control unit to determine a dew point in the cavity, compare the temperature of the cavity with the dew point, and apply a voltage to the voltage-controlled heating element if the temperature of the cavity is below the dew point.

[0009] In addition to one or more of the features described here, at least one vision sensor is a LiDAR sensor, a RADAR sensor or a camera.

[0010] In addition to one or more of the features described here, the voltage-controlled heating element is a resistance heating element that is wound around the housing.

[0011] In addition to one or more of the features described here, the voltage-controlled heating element is not in direct contact with the sensor element.

[0012] In addition to one or more of the features described herein, comparing the temperature of the cavity with the dew point and applying the voltage to the voltage-controlled heating element when the temperature of the cavity is below the dew point also includes determining a difference between a dew point of the cavity and a temperature of the cavity, and determining an amount of voltage based on the difference.

[0013] In addition to one or more of the characteristics described here, the voltage level is determined using a lookup table stored in the control unit.

[0014] In addition to one or more of the features described here, the vehicle vision system also includes at least one display that is connected to the control unit and is designed to display the condensation reduction system status of the at least one vision sensor.

[0015] In addition to one or more of the features described herein, the vehicle vision sensor system comprises a plurality of vision sensors, each of the plurality of vision sensors comprising a corresponding sensor element arranged in the cavity, a corresponding voltage-controlled heating element wound around the corresponding housing, and a corresponding local temperature and humidity sensor arranged near the housing and configured to detect temperature and relative humidity within the cavity.

[0016] In addition to one or more of the features described here, the control unit is designed to control each vision sensor.

[0017] The aforementioned features and advantages, as well as other features and advantages of the disclosure, will become apparent from the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further features, advantages, and details are listed only as examples in the following detailed description, which refers to the drawings. These show: Fig. 1. A schematic representation of a vehicle; Fig. 2 a schematic representation of a sensor housing; Fig. 3 an exemplary control scheme for a single sensor; Fig. 4. A diagram illustrating the dew point at different humidity levels and different outside temperatures; and Fig. 5 an automatic method for operating a resistance heater. DETAILED DESCRIPTION

[0019] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or its use. It should be noted that in the drawings, corresponding reference numerals denote identical or corresponding parts and features.

[0020] According to one embodiment, methods, devices, and systems for implementing a condensation elimination function in a sensor housing are provided. The general arrangement includes a resistance heating element arranged around the sensor housing and a local temperature and humidity sensor located immediately adjacent to or on top of the sensor housing. The local temperature and humidity sensor detects the relative humidity inside the sensor housing. The term "immediately adjacent" here refers to a sensor positioned so close to the housing that the sensor output and the temperature and humidity of the housing coincide within the sensor's error margin. In one example, this could mean within two centimeters (cm) of the housing.

[0021] A control unit in the vehicle monitors the relative humidity at the housing using a local temperature and humidity sensor. Based on the measured relative humidity, a known ambient air temperature, and a dew point lookup table, the control unit applies a voltage to the resistance heating element, raising the housing temperature above the dew point and preventing condensation from forming inside. By using a local temperature and humidity sensor, the precise local relative humidity of the corresponding vision sensor can be determined and utilized, ensuring that the housing is adequately heated and condensation is prevented without overheating.

[0022] The embodiments described here offer numerous advantages and technical benefits. These include reduced condensation in the vehicle vision system sensors and localized control, which allows each sensor to receive a different intensity of resistance heating.

[0023] The embodiments are not limited to use in a specific vehicle, but can be applied in various contexts. For example, local monitoring and heating can be applied with similar sensor configurations and is not limited to sensors of the vehicle's vision system. In alternative examples, local monitoring and heating can also be used in other vehicle types such as unmanned vehicles, industrial vehicles, commercial vehicles, etc.

[0024] As in Fig.As shown in Figure 1, a vehicle 10 comprises a body 12 and a passenger compartment 14. Several sensors of the vehicle vision system are arranged around the vehicle 10, including a camera 20, a LiDAR sensor 22, and a radar sensor 24. Immediately adjacent to or on each of the sensors 20, 22, 24 is a corresponding local humidity and temperature sensor 30, configured to detect the relative humidity within a housing of the sensor 20, 22, 24. A practical vehicle 10 can include more sensors 20, 22, 24 of each type, with the sensors 20, 22, 24 being distributed around the vehicle body 12 as needed to implement the vision systems for the vehicle 10. The anti-condensation structures and methods described here can be applied equally to one or all of these sensors 20, 22, 24, depending on their susceptibility to condensation.

[0025] Furthermore, an outside air temperature sensor 32 is attached to the vehicle 10. The outside air temperature sensor 32 detects the general ambient conditions of the vehicle 10 and is therefore positioned at an ideal location on the vehicle 10. The specific position of the outside air temperature sensor 32 depends on the structure of the vehicle 10 and can be determined according to standard practice in this field, depending on the specific structure of the vehicle 10.

[0026] Each of the vehicle vision system sensors 20, 22, 24, the corresponding local humidity and temperature sensors 30, and the outside temperature sensor 32 are connected to a control unit 40. In one example, the control unit 40 is a special control unit for preventing condensation. In alternative examples, the control unit 40 could be a general control unit with subprograms for a condensation prevention procedure, several distributed control units that communicate with each other and are configured to cooperate, or a similar control configuration.

[0027] With further reference to Fig. 1 shows Fig.Figure 2 shows an exemplary sensor housing 200 that includes one of the sensors 20, 22, 24. A housing body 210 defines an open cavity 212 in which the sensor 20, 22, 24 is located. One or more coils of a resistance heater 214 are wound around the housing body 210. Because the resistance heater coils 214 are wound around the housing 200, the resistance heater 214 can heat the open cavity 212 without directly contacting the sensor 20, 22, 24. The local humidity and temperature sensor 30 is attached directly to the housing body 210 and is configured to detect the relative humidity in the cavity 212.

[0028] The measured values ​​from sensors 20, 22, 24 and the local humidity and temperature sensor 30 are forwarded to the control unit 40 ( Fig.1) Furthermore, the resistance heater 214 is connected to a control unit output or another power source controlled by the control unit 40, so that the control unit 40 regulates the voltage applied to the resistance heater 40. When a voltage is applied to the resistance heater 214, the resistance heater 214 generates heat, the amount of heat generated being proportional to the voltage applied to the resistance heater 214 according to a known ratio.

[0029] The dew point in a volume of space, e.g., cavity 212, is the temperature below which the air in the volume is saturated with water. This temperature depends on the relative humidity of the volume and the temperature of the air surrounding volume 212 (outside air temperature). While other factors remain constant, as the temperature of volume 212 increases, the relative humidity decreases, and the dew point rises. This principle operates according to known equations. Using this knowledge and the data from the outside air temperature sensor 32 and the local temperature and humidity sensor 30, the control unit 40 can determine how much heat must be generated by the resistance heater 214 to raise the temperature of the housing 200 above the dew point and thus prevent the formation of fog or condensation inside the housing 200.

[0030] With further reference to Fig. 1 and Fig. 2 shows Fig. 3 a control scheme 300 for the operation of the in Fig. 1 and Fig. 2 described anti-fog systems, and Fig. Figure 4 illustrates a dew point lookup table 400 stored in the control unit 40. The control unit 40 receives the outside air temperature from the outside air temperature sensor 32 and the relative humidity in the housing 200 of the vision sensor 20, 22, 24 from the local humidity and temperature sensor 30.

[0031] Using this information, the control unit 40 queries the dew point lookup table 400 to determine the exact dew point of the volume 212. The dew point lookup table 400 contains several reference curves 402, 404, 406, 408, 410, each corresponding to a different relative humidity. In the example shown, the dew point lookup table contains a curve at 60% relative humidity (curve 402), at 70% relative humidity (curve 404), at 80% relative humidity (curve 406), at 90% relative humidity (curve 408), and at 100% relative humidity (curve 410). In a practical example, further curves are included in reference table 400, but these have been omitted from the figure for better illustration.

[0032] For example, if the outside air temperature T determined by the outside air temperature sensor 32 is and the relative humidity of the sensor 20, 22, 24 is 80% (curve 406), the dew point Dt can be determined by finding the intersection of curve 406 and the outside air temperature T at a point 412. Point 412 corresponds to a dew point Dt.

[0033] After determining the dew point Dt, the control unit 40 calculates the temperature increase required to raise the temperature of the volume 212 to just above the dew point Dt and applies a corresponding voltage to the resistance heater 214 to generate the required heat. In some training examples, the vehicle 10 may include a display 302 or an option to include a menu in an existing display 302, which shows the driver the dew point and heating processes determined by the control unit 40.

[0034] With further reference to Fig.1-4 shows Fig. 5 an automatic procedure 500 for operating the resistance heater 214. First, the dew point (Dt) is determined by consulting Table 400 in step 510. After determining the dew point Dt, the control unit 40 determines the internal temperature of the housing 210 using the local temperature and humidity sensor 30 and compares the internal temperature with the determined dew point Dt in a check 520 to see if the sensor temperature is below Dt. If the determined temperature is not below the dew point Dt, no heating is required, and no voltage is applied to the resistance heater 214 in step 530 (no heating required).

[0035] If the sensor temperature is below the dew point, the control unit 40 determines a difference between the measured temperature and the dew point Dt in a differential calculation step 540. This difference is used to query Table 1: Difference in degrees C Voltage (V) Less than 2°C 5V Greater than or equal to 2°C and less than 5°C 7,5V Greater than or equal to 5°C and less than 10°C 10V

[0036] The voltage value corresponding to the difference specified in Table 1 is then applied to the resistance heater 214 in step 550 (application of a corresponding voltage). The values ​​given in Table 1 apply to one embodiment. It is understood that alternative embodiments may use different values ​​for each entry and / or have additional entries, depending on the degree of control that can be exercised with regard to the voltage applied to the resistance heater 214.

[0037] This process 500 is repeated in real time so that the temperature of sensor 20, 22, 24 can be actively controlled and it is ensured that the temperature of sensor 20, 22, 24 is kept above the dew point Dt throughout the entire operation of the vehicle 10.

[0038] By incorporating the local relative humidity sensor 30 and determining the dew point based on the local relative humidity of the sensor 20, 22, 24, the anti-fog system prevents fogging, condensation and moisture within the volume 212 of the sensor housing 200, thereby preventing a deterioration of the sensor outputs, which improves the function of these sensors and eliminates the need for manual control of sensor-based anti-fog systems.

[0039] Although the use of a resistance heater 214 is described here, the systems and procedures can be modified so that they can be operated with any other type of heater controlled by a fixed voltage. The procedure is therefore not limited to resistance heaters 214.

[0040] In some alternative examples, vehicle 10 may include a manual control interface that allows the driver of vehicle 10 to manually activate or deactivate the anti-fog systems.

[0041] The terms "a" and "an" do not represent a quantity limitation, but rather indicate that at least one of the mentioned items is present. Unless the context clearly indicates otherwise, the term "or" means "and / or." When the description refers to "an aspect," this means that a specific element described in connection with the aspect (e.g., a characteristic, a structure, a step, or a property) is contained in at least one of the aspects described here and may, but does not necessarily, also occur in other aspects. Furthermore, it should be noted that the described elements can be combined in any suitable way across the various aspects.

[0042] When an element such as a layer, film, area, or substrate is described as being "on" another element, it may be located directly on top of the other element, or there may be intermediate elements. Conversely, when an element is described as being "directly on" another element, there are no intermediate elements.

[0043] Unless otherwise stated herein, all testing standards are the latest standard in force on the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the testing standard appears.

[0044] Unless otherwise specified, all technical and scientific terms used herein have the meanings that a person skilled in the field to which this disclosure relates would normally associate with such terms.

[0045] Although the above disclosure has been described with reference to exemplary embodiments, the person skilled in the art knows that various modifications can be made and equivalent elements substituted without altering its scope. Furthermore, many modifications can be made to adapt a particular situation or material to the teachings of the disclosure without deviating from its essential scope. Therefore, the present disclosure is not intended to be limited to the specific embodiments disclosed, but rather to encompass all embodiments that fall within its scope. legend

[0046] In the drawing figures, N stands for no and Y for yes.

Claims

[1] Vehicle vision sensor system comprising: at least one vision sensor (20, 22, 24) with a housing (200) defining a cavity (212) and a sensor element arranged inside the cavity (212), a voltage-controlled heating element wound around the housing (200), a local temperature and humidity sensor (30) arranged near the housing (200) and configured to detect temperature and relative humidity in the cavity (212); and a control unit (40) connected to the local temperature and humidity sensor (30) and an outside air temperature sensor (32), wherein the control unit (40) includes a memory in which commands are stored that cause the control unit (40) to determine a dew point in the cavity (212), to compare the temperature of the cavity (212) with the dew point and to apply a voltage to the voltage-controlled heating element when the temperature of the cavity (212) is below the dew point. [2] Vehicle vision sensor system according to claim 1, wherein the at least one vision sensor (20, 22, 24) is a LiDAR sensor, a RADAR sensor or a camera. [3] Vehicle vision sensor system according to claim 1, wherein the voltage-controlled heating element is a resistance heating element wound around the housing (200). [4] Vehicle vision sensor system according to claim 1, wherein the voltage-controlled heating element is not in direct contact with the sensor element. [5] Vehicle vision sensor system according to claim 1, wherein comparing the temperature of the cavity (212) with the dew point and applying the voltage to the voltage-controlled heating element when the temperature of the cavity (212) is below the dew point also includes determining a difference between a dew point of the cavity (212) and a temperature of the cavity (212) and determining an amount of voltage based on the difference. [6] Vehicle vision sensor system according to claim 5, wherein the voltage level is determined using a lookup table (400) stored in the control unit (40). [7] Vehicle vision sensor system according to claim 1, further comprising at least one display (302) which is connected to the control unit (40) and is configured to display the condensation reduction system status of the at least one vision sensor (20, 22, 24). [8] Vehicle vision sensor system according to claim 1, wherein the vehicle vision sensor system comprises a plurality of vision sensors (20, 22, 24), each of the plurality of vision sensors (20, 22, 24) comprising a corresponding sensor element arranged in the cavity (212), a corresponding voltage-controlled heating element wound around the corresponding housing (200), and a corresponding local temperature and humidity sensor (30) arranged near the housing (200) and configured to detect temperature and relative humidity within the cavity (212). [9] Vehicle vision sensor system according to claim 8, wherein the control unit (40) is configured to control each vision sensor (20, 22, 24) independently.

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