A TMR sensor assembly for detecting a urea tank level

Abstract

A kind of TMR sensor assembly for detecting urea tank liquid level, including PCB substrate and TMR magnetic control IC arranged on PCB substrate, patch resistance, one end of PCB substrate is provided with blank and narrower connecting end, and connecting end is electrically connected with corresponding connector crimping terminal in connector plastic shell by multiple connecting wires.The utility model has the advantages of smaller size, smaller gear interval can be set, higher resolution compared with traditional dry reed sensor, its life is much longer than the switch life of dry reed, and reliability is greatly improved.

Description

Technical Field

[0001] This utility model relates to a sensor assembly, specifically a TMR sensor assembly for detecting the liquid level in a urea tank. Background Technology

[0002] With increasingly stringent vehicle emission regulations, reducing NO and PM emissions from diesel engines has become one of the biggest challenges in diesel engine applications. SCR (Sequencing Controlled Reduction) has been recognized as one of the effective technologies for reducing NO emissions from heavy-duty diesel engines. In today's SCR systems, urea aqueous solution is usually used as a reducing agent, and the urea level sensor in the urea tank has become an indispensable component of the diesel engine.

[0003] Currently, the industry primarily uses reed switch level switches as the main solution for level measurement. Reed switches are encapsulated in glass shells filled with inert gas. Due to the fragility of the glass shells, this solution is susceptible to damage during transportation and assembly. Furthermore, the relatively large size of reed switches makes it difficult to achieve short-interval level control requirements. In addition, the reed switch leads require shaping, trimming, positioning, and soldering, involving numerous processes that are difficult to automate and control in terms of quality. In recent years, HALL level sensors have emerged, using HALL elements instead of reed switches. While overcoming the fragility of the glass shells and the large design intervals of reed switches, they still have shortcomings in terms of power consumption, sampling error, and anti-interference capabilities. Utility Model Content

[0004] To address the aforementioned problems, the purpose of this invention is to provide a TMR sensor assembly for detecting the liquid level in a urea tank.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows: a TMR sensor assembly for detecting the liquid level of a urea tank, comprising a PCB substrate and a TMR magnetic control IC and a surface mount resistor disposed on the PCB substrate. One end of the PCB substrate is provided with a blank and narrow connection end, which is electrically connected to the corresponding connector crimp terminal inside the connector housing through multiple connecting wires.

[0006] Furthermore, a transparent PC sleeve is fitted over the outside of the PCB substrate, and rubber upper plugs and rubber lower plugs are respectively fixed to both ends of the transparent PC sleeve.

[0007] Furthermore, the number of surface mount resistors is equal to the number of gear positions, and together with the number of gear positions minus one TMR magnetic control IC arranged in the same direction, they form the PCBA liquid level circuit module circuit, with the surface mount resistors arranged in series.

[0008] Furthermore, all TMR magnetic control ICs are connected to the 5V power supply VDD and GND, and the output pins of each TMR magnetic control IC are distributed crosswise between the surface mount resistors.

[0009] Furthermore, the TMR magnetic control IC uses an SOT-23 package, and the surface mount resistor 3 uses a 0805 package.

[0010] With the above settings, this utility model patent uses the TMR parallel magnetic field principle combined with a magnetic float to measure the urea level in the urea tank. Compared with traditional reed switch sensors, it has the advantages of smaller size, smaller adjustable intervals, and higher resolution. Its lifespan is much longer than that of a reed switch, greatly improving reliability. Compared with the HALL level sensor that has emerged in recent years, the TMR magnetic control IC of the TMR sensor component has an extremely high resistance value, which enables the TMR sensor component to work in a full-time power supply mode. While maintaining low power consumption, it achieves true continuous detection of magnetic field signals and avoids the sampling errors caused by the traditional time-sharing power supply mode. Attached Figure Description

[0011] The present invention will now be further described with reference to the accompanying drawings.

[0012] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the PCB substrate structure of this utility model. Figure 3 This is a circuit schematic diagram of an embodiment of the present invention. Detailed Implementation

[0013] like Figure 1-2 As shown, a TMR sensor assembly for detecting the liquid level in a urea tank includes a PCB substrate 1 and a TMR magnetic control IC 2 and a surface mount resistor 3 disposed on the PCB substrate 1. One end of the PCB substrate 1 has a blank and narrow connection end 4, which is electrically connected to the corresponding connector crimp terminals 7 inside the connector housing 8 through multiple connecting wires 6 for connecting to an external control circuit. The TMR magnetic control IC 2 is an SOT-23 packaged IC, and the surface mount resistor 3 is a 0805 packaged surface mount resistor. In addition, a transparent PC sleeve 11 is fitted over the PCB substrate 1. Both ends of the transparent PC sleeve 11 are covered and fixed with upper rubber plugs 9 and lower rubber plugs 10, respectively, for overall protection and waterproof sealing of the PCBA liquid level circuit module, reducing the impact of product handling.

[0014] The number of surface mount resistors is equal to the number of gear positions. Together with the number of gear positions minus one TMR magnetic control IC, they form the PCBA liquid level circuit module circuit. The surface mount resistors are arranged in series. All TMR magnetic control ICs are connected to the 5V power supply VDD and GND. The output pins of each TMR magnetic control IC2 are distributed crosswise between the surface mount resistors.

[0015] The working principle of this invention is as follows: The TMR magnetic control IC2 and the surface mount resistor 3 are distributed sequentially on the PCB substrate 1 according to the design requirements, and are electrically connected through copper-plated wires on the PCB substrate 1. The TMR magnetic control IC is used to sense the external magnetic field. When the external magnetic field moves along the chip distribution direction, the corresponding TMR magnetic control IC generates an analog voltage signal. After circuit processing, the output logic judgment level is generated, that is, a low-level output is generated, which is equivalent to the output pin being connected to the GND pin.

[0016] The circuit schematic of the PCBA liquid level circuit module is as follows: Figure 3 As shown, the specific working principle is as follows: It consists of n (assuming the number of gear positions is n) surface-mount resistors and n-1 TMR magnetic control ICs arranged in the same direction. The surface-mount resistors are connected in series, and all TMR magnetic control ICs are connected to the 5V power supply VDD and GND. The output pins of each TMR magnetic control IC are distributed across the surface-mount resistors. If the module circuit is not affected by the magnetic effect, according to the working principle of the TMR magnetic control IC, all TMR magnetic control IC output pins will output a high level. Therefore, the resistance output between the LEVEL pin and the GND pin of the circuit feedback to the external control module is: If the i-th TMR magnetic control IC is affected by the magnetic effect, its output pin will output a low level, that is, the GND pin and OUT pin of the i-th TMR magnetic control IC will be connected. At this time, the resistance output between the LEVEL pin and GND pin fed back to the external control module is: According to the circuit schematic ( Figure 3 Each TMR magnetic control IC is associated with a different resistance value. Therefore, when affected by the magnetic effect of the float, the total resistance value fed back to the external control module by the sensor assembly will be different. In other words, by judging the value of the feedback resistor R, it can be determined which TMR magnetic control IC is affected by the magnetic effect generated by the float, and thus the position of the float can be known, and the liquid level in the measured container becomes obvious.

[0017] The core components of the TMR sensor assembly use SOT-23 packaged ICs and 0805 packaged surface mount resistors. Compared with traditional reed switch sensor assemblies, it has the advantages of smaller size, smaller adjustable range intervals, and higher resolution. Its lifespan is much longer than that of a reed switch, greatly improving reliability. The TMR magnetic control IC of the TMR sensor assembly has an extremely high resistance value, which enables the TMR sensor assembly to operate in a full-time power supply mode. While maintaining low power consumption, it achieves true continuous detection of magnetic field signals and avoids the sampling errors caused by the time-sharing power supply mode of traditional HALL magnetic switches.

[0018] The above description is merely an illustrative embodiment of this utility model and is not intended to limit the scope of this utility model. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of this utility model should fall within the protection scope of this utility model.

Claims

1. A TMR sensor assembly for detecting the liquid level in a urea tank, comprising a PCB substrate (1) and a TMR magnetic control IC (2) and a surface mount resistor (3) disposed on the PCB substrate (1), characterized in that: One end of the PCB substrate (1) is provided with a blank and narrow connection end (4), which is electrically connected to the corresponding connector crimp terminal (7) inside the connector housing (8) through multiple connecting wires (6).

2. The TMR sensor assembly for detecting the liquid level in a urea tank as described in claim 1, characterized in that: The PCB substrate (1) is covered with a transparent PC sleeve (11), and the two ends of the transparent PC sleeve (11) are respectively covered and fixed with an upper rubber block (9) and a lower rubber block (10).

3. The TMR sensor assembly for detecting the liquid level in a urea tank as described in claim 1, characterized in that: The number of chip resistors (3) is the number of gear positions, and together with the number of gear positions minus one TMR magnetic control IC arranged in the same direction, they form the PCBA liquid level circuit module circuit. The chip resistors (3) are arranged in series.

4. The TMR sensor assembly for detecting the liquid level in a urea tank as described in claim 3, characterized in that: All TMR magnetic control ICs (2) are connected to the 5V power supply VDD and GND. The output pins of each TMR magnetic control IC (2) are distributed crosswise between the surface mount resistors (3).

5. The TMR sensor assembly for detecting the liquid level in a urea tank as described in claim 1, characterized in that: The TMR magnetic control IC (2) is an SOT-23 packaged IC, and the surface mount resistor (3) is an 0805 packaged surface mount resistor.

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