Optical level gauge

Abstract

An optical level measuring device (1) is specified, comprising: a carrier plate (10) with an optical module (12) arranged thereon, surrounded by a housing body (2), wherein the inner wall of the housing body (2) has a flat contact surface (14) which serves as a stop surface for the carrier plate (10), with a spring element (20) which rests against the carrier plate (10), wherein the carrier plate (10) is resiliently mounted against the contact surface (14) via the spring element (20), with a front window (15) which is formed as part of the housing body (2), with an energy source (E) arranged within the housing body (2), wherein the optical module (12) is arranged behind an inner surface of the front window (15), wherein the optical module (12) is aligned on the inner wall of the housing body (2) by means of the carrier plate (10) and held at a distance from the front window (15).wherein the carrier plate (10) and the contact surface (14) are sealed in a moisture-resistant manner by means of an adhesive strip (24).

Description

[0001] The invention relates to an optical level measuring device according to claim 1.

[0002] Optical level measuring devices are known from the state of the art, which detect the level of a liquid or solid in a container by emitting and receiving light.

[0003] Optical level gauges for determining the amount of light transmitted through a container wall are known from US 2018 / 0 136 029 A1 and EP 0 952 432 A1. A disadvantage is that the measurement is attenuated by the container wall.

[0004] Mobile level measuring devices operate energy-efficiently, use a battery as a power source, communicate wirelessly via an interface and use this interface to configure the device and / or to remotely monitor the device as well as to transmit statuses.

[0005] Optical level gauges are typically attached to a container to measure the level inside the container. To avoid any interference with the container's interior wall, the measuring beam of the optical level gauge must generally be aligned with the container and the container wall. This is done either individually during installation, or the optical module of the level gauge, and thus the device's optical transmitter and receiver, is positioned at a defined angle to a mounting surface, allowing the device to be easily placed and attached to a container.

[0006] The correct alignment of the optics module to the container wall is crucial for the measurement result and influences the quality of the measurement.

[0007] Level measuring devices for mobile use are subject to particularly stringent requirements in terms of workmanship and / or robustness. To meet leak and / or contamination requirements, the housings of these mobile level measuring devices are often hermetically sealed. This means they are designed to prevent air and moisture exchange with the environment.

[0008] Mobile level measuring devices require a power source. Batteries are installed for this purpose. To increase the product lifespan, the batteries are replaceable. A battery compartment with a cover is usually provided for this purpose, which can be opened when necessary to replace the batteries. The battery compartment is usually sealed by the cover with a gasket. The disadvantage of this is that opening the battery compartment can allow moisture to penetrate the device. Closing the battery compartment traps the moisture in the device and prevents it from escaping. This in turn leads to condensation forming on the inside of the device. This type of condensation is particularly detrimental on surfaces that are used for optical purposes, e.g. on the front screen of an optical measuring device.Fogging or clouding of the optical surface has a negative effect on the measurement result, causes measurement errors and impairs the measuring accuracy of the device.

[0009] The object of the invention is to show a possibility of avoiding the formation of condensation on an optically used surface and the aforementioned disadvantages in an optical level measuring device.

[0010] The object is achieved by an optical level measuring device according to independent claim 1. Advantageous embodiments of the invention are specified in the subclaims.

[0011] According to the invention, an optical level measuring device with a self-contained housing body is specified, wherein the level measuring device has at least one carrier plate, for example a circuit board, on which an optical module is arranged inside the housing body. The housing body has a flat surface on an inner wall which serves as a support surface and / or stop surface for the carrier plate. A spring element rests against the carrier plate. The carrier plate is resiliently mounted against the support surface via the spring element. Furthermore, the level measuring device has a translucent front panel which is inserted into the housing and, as part of the housing body, forms the casing of the device. So that the optical level measuring device can be operated independently without a power connection, a battery is provided within the housing body as an energy source.The level gauge also features a wireless communication interface and an evaluation unit for operating the optics module.

[0012] According to the invention, the optical module is arranged behind an inner side of the front panel, so that light emitted by the optical module can be transmitted through the front panel and thus through the housing body to the surroundings and received. For this purpose, the optical module is aligned at a defined angle to the inner wall of the housing body by means of the carrier plate and is held at a distance from the front panel by this arrangement.

[0013] According to the invention, an adhesive strip is arranged between the carrier plate and the support surface. The adhesive strip has adhesive properties on its top and bottom sides, so that the carrier plate and the support surface are sealed with the respective side of the adhesive strip to prevent moisture penetration. The double-sided adhesive layer effectively prevents moisture penetration throughout the product's lifetime.

[0014] Advantageously, the carrier plate is permanently pressed against the support surface by means of a spring force using the spring element. This ensures that the carrier plate is pressed and held against the support surface throughout the device's entire service life. This is particularly advantageous in the case of vibration, impact, or shock loads, which frequently occur in mobile applications of a level gauge, as the spring element compensates for the loads acting on the carrier plate and thus on the optics module.

[0015] The spring element used to generate the spring force preferably has an S-shaped contour. This S-shape enhances the spring effect. The S-shape allows for a space-saving arrangement within the housing.

[0016] The spring element preferably has a bent end, with which the spring element is inserted into a counter-contour in a first assembly step and, in a second assembly step, is firmly connected to the housing body by means of a fastening element, e.g., a screw. This type of shaping simplifies the assembly of the spring, allowing it to be fully automated. In a first step, the spring is pre-inserted into the housing using a simple joining process. This ensures the spring is correctly positioned. In a further step, the spring is firmly fastened in the housing body to ensure its position is maintained even under load.

[0017] Preferably, the optical level measuring device has a locking mechanism with which the carrier plate and the spring element are detachably connected to one another, wherein the locking mechanism is designed to secure the position of the carrier plate against being pulled out and to ensure a spring-loaded range of motion between the carrier plate and the spring element.

[0018] The invention is explained in more detail below using exemplary embodiments with reference to the drawings.

[0019] In the following description of the preferred embodiments, like reference numerals designate like or comparable components.

[0020] They show schematically: Fig. 1 an optical level measuring device according to the invention in an isometric view from above; Fig. 2 the level measuring device according to Fig. 1 in a side view; Fig. 3 the level measuring device according to Fig. 1 or Fig. 2 in a sectional view; Fig. 4 a detailed view of the spring element according to Fig. 3.

[0021] Fig. Figure 1 shows the optical level measuring device 1 according to the invention in a closed housing body 2. The device is designed so that it can be mounted autonomously, i.e., without an external power supply, on a container wall in order to detect the container's fill level. Furthermore, the level measuring device 1 has a wireless communication interface with which the device can be set up and recorded data, measured values, and statuses can be transmitted to a higher-level unit.

[0022] Fig. 2 shows the optical level measuring device 1 according to Fig. 1 in a side view. The level gauge 1 has a cover on its underside that can be opened to change the battery. The underside is designed for mounting on a container wall. A device extension protrudes from the underside with a translucent front panel 15 embedded in the housing wall. Light from the optics module 12, which is located inside the housing body 2, can be emitted to and received from the environment through the front panel.

[0023] Fig. 3 shows the optical level measuring device 1 according to Fig. 1 and Fig. 2 in a sectional view. The housing body 2 is self-contained. Inside the housing body 2 there is a power source E, an evaluation unit AE with a wireless communication interface, and several carrier plates equipped with electronic components. An optics module 12 is mounted on the upper side of a carrier plate 10. According to the invention, the inner wall of the housing body 2 has a flat support surface 14, which serves as a stop surface for the carrier plate 10 with the optics module 12. This carrier plate 10 is resiliently mounted against the support surface 14 by a spring element 20, which rests against the carrier plate. The spring element 20 is bent at one end and inserted into a mating contour 30. In addition, the spring element 20 is secured in position with a fastening element 32. The spring element has an S-shaped contour, with which the spring force is generated.By means of the spring element, the carrier plate 10 is pressed against the support surface with spring force. The level measuring device 1 has a front panel 15, which is formed as part of the housing body 2, wherein the optics module 12 is arranged behind an inner side of the front panel 15, so that light from the optics module 12 can be sent through the front panel 15 through the housing body 2 to the environment and received again. The front panel 15 is spaced from the optics module 12. According to the invention, an adhesive strip 24 is arranged between the carrier plate 10 and the support surface 14, which has adhesive properties on its top and bottom sides, so that the carrier plate 10 and the support surface 14 are sealed with the respective side of the adhesive strip 24 in a moisture-resistant manner, and the space created between the carrier plate 10 and the support surface is hermetically sealed against the outside.This chamber contains the optics module 12, mounted on the carrier plate 10, which is hermetically sealed. Moisture that may accumulate inside the level gauge via the battery compartment when the batteries are immersed cannot enter the chamber. This effectively prevents fogging on the inside of the front panel 15 due to moisture penetration.

[0024] Fig. 4 shows the spring element 20 according to Fig.3 in a detailed view. The spring element 20 has an S-shape with which the spring force is generated. The spring element 20 has a contour at one end which can be introduced into a mating contour 30 in order to join and position the spring element 20 in the correct position. Optionally, locking lugs 36 can be provided at the other end of the spring element, which engage in corresponding receptacles on the carrier plate 10. With this locking mechanism, the carrier plate 10 and the spring element 20 are detachably connected to one another in order to secure the position of the carrier plate against lateral displacement and to ensure a spring-loaded range of motion between the carrier plate 10 and the spring element 20. List of reference symbols 1 level gauge 2 housing bodies 10 carrier plate 12 Optics module 14 Support surface 15 Windscreen 20 spring element 24 adhesive strips 30 Counter contour 32 Fastening element 36 locking lug E energy source AE evaluation unit

Claims

[1] Optical level measuring device (1) comprising an optical module (12) arranged on a carrier plate (10) which is surrounded by a self-contained housing body (2), wherein an inner wall of the housing body (2) has a flat support surface (14) which serves as a stop surface for the carrier plate (10), with a spring element (20) which rests on the carrier plate (10), wherein the carrier plate (10) is resiliently mounted against the support surface (14) via the spring element (20), with a front panel (15) formed as part of the housing body (2), with an energy source (E) arranged within the housing body (2), with a wireless communication interface and with an evaluation unit (AE) for operating the optical module (12), wherein the optical module (12) is arranged behind an inner side of the front panel (15), so that light from the optical module (12) is sent through the front panel (15) through the housing body (2) to the environment and is received, wherein the optical module (12) is aligned by means of the carrier plate (10) on the inner wall of the housing body (2) and held at a distance from the front panel (15), characterized by that an adhesive strip (24) with an upper side and a lower side is arranged between the carrier plate (10) and the support surface (14), both sides having adhesive properties, so that the carrier plate (10) and the support surface (14) are sealed with the respective side of the adhesive strip (24) in a moisture-inhibiting manner. [2] Optical level measuring device (1) according to claim 1, wherein the carrier plate (10) is pressed against the support surface (14) by means of the spring element (20) with a spring force. [3] Optical level measuring device (1) according to claim 2, wherein the spring element (20) has an S-shaped contour with which the spring force is generated. [4] Optical level measuring device (1) according to one or more of the preceding claims, wherein the spring element (20) has a bent end with which the spring element (20) can be introduced into a counter contour (30) in a first assembly step and with which the spring element (20) is firmly connected to the housing body (2) by means of a fastening element (32) in a second assembly step. [5] Optical level measuring device (1) according to one or more of the preceding claims, wherein the carrier plate (10) and the spring element (20) are detachably connected to one another by means of a latching mechanism, wherein the latching mechanism is designed to secure the position of the carrier plate (10) against being pulled out and to ensure a spring-loaded range of motion between the carrier plate (10) and the spring element (20).

Images