HK1120858B - Sensor unit for fluids - Google Patents

Description

Sensor unit for fluids

Technical Field

【0001】 The invention relates to measuring the mass or volume flow and/or the thermal load and/or the pollutant level of a fluid under standard conditions.

Background

【0002】 Hot film anemometers for measuring mass flow are known. In this type of sensor, the airflow is directed through a heated region of the sensor. The heated region is cooled down by the flowing gas. The cooling value is the initial basis for determining the mass flow.

【0003】 Particles or condensates are also often transported by the gas and lead to deposits on the heated areas, which disadvantageously produce a shift in the measured values during operation.

Disclosure of Invention

【0004】 It is an object of the present invention to provide a sensor for measuring mass flow, in which particles or condensates in the fluid do not lead to a shift in the measured value.

【0005】 The considerations leading to the development of the present invention are based on the following facts: i.e. areas in the sensor where no fluid and residual particles flow, in principle no deposits can form.

【0006】 The invention is based on the principle of ram probe measurement, in which a reproducible pressure difference is generated as a function of the velocity and density of the fluid.

【0007】 In order to be able to determine the mass flow, volume flow or enthalpy flow of a fluid under standard conditions, the static pressure, pressure difference and temperature need to be known.

【0008】 According to the invention, the variables are detected by individual sensors located in an integrated unit, and the values detected by the individual sensors are subsequently processed in a computing unit which is likewise integrated.

【0009】 The sensor unit outputs a value to a downstream control unit, which value has taken into account other parameters and/or physical constants. This means that part of the calculations is advantageously performed in the sensor unit and the control unit is disengaged.

【0010】 One development of the invention provides the integration of another sensor, which is capable of analyzing the composition of a fluid. This allows the detection of the level of harmful substances in, for example, the engine exhaust.

【0011】 For example, optimal control of an internal combustion engine requires the above measured variables. The present invention advantageously overcomes the drawbacks of the prior art, since the drift of the measured values (drift) has a particularly adverse effect on the situation of the application.

【0012】 The advantage of integrating all sensors and calculation units is that a compact sensor unit with long-term stability of the measured values is obtained, which can be used in many places and for many applications.

Drawings

【0013】 Figure 1 shows the sensor unit in a perspective illustration,

【0014】 FIG. 2 shows a view of the sensor unit from below, an

【0015】 Fig. 3 shows a further embodiment of the sensor unit.

Detailed Description

【0016】 The sensor unit 1 has a measuring probe 2 which is in contact with the fluid, and the sensor unit 1 also has a tank portion 3 which is located outside the fluid.

【0017】 A separate sensor (not shown here) and a calculation unit are located in the box part 3.

【0018】 The sensor unit 1 is provided to be directly attached to a fluid-conducting line (fluid-conducting line). The measuring probe 2 can project into the liquid flow through a hole in the fluid line. The underside of the base portion 3 is provided with a seal 5 which seals the aperture.

【0019】 The measuring probe 2 is at least partially in the form of a punch probe 4. The fluid has a flow direction according to arrow S. In a known manner, a ram area 6 causes a flow-dependent pressure difference at both measuring openings.

【0020】 Fig. 2 is a view of the sensor 1 from below. This view shows the two measuring holes 7a and 7b of the punch probe 7.

【0021】 A further measuring orifice 8 for detecting the static pressure is located at the lower end of the punching zone 6. The measuring orifice 8 is arranged to let the fluid flow through it in a laminar (laminar) flow.

【0022】 A temperature sensor 9 is also located in the measuring probe 2. The temperature sensor arrangement is arranged in the measuring probe 2 close to the surface, which makes it possible to quickly detect temperature changes in the fluid. In the example shown, the temperature sensor 9 is located at the stamping surface. The stamping surface is constructed of a relatively small material and is therefore able to track temperature changes in the fluid in near real time.

【0023】 The temperature sensor 9 is preferably arranged at a location where the fluid flows in a laminar manner. This prevents particles carried in the fluid from forming a barrier on the outside of the measurement probe 2, which could distort the temperature measurement.

【0024】 The three measured variables of static pressure, dynamic pressure differential, and temperature may be used to determine the mass flow rate of the fluid.

【0025】 Advantageously, the housing of the sensor unit should be provided with a surface having so-called nanostructures in all or at least a partial area of the measuring probe 2.

【0026】 The consequence of such nanostructures is that particles transported in the fluid cannot be permanently deposited on the surface of the measurement probe.

【0027】 Fig. 3 shows an embodiment of the measuring probe which is particularly simple in terms of its production complexity.

【0028】 Here, a plurality of slots 10 are provided in the measurement probe. Only one slot can be seen in the selected example. These slots are in each case located in the outer walls of two ducts which lead to a pressure difference sensor in the housing part. The connecting wall between the two ducts is unchanged and is used as a stamping surface.

【0029】 The length of the slots gives some mean function if the flow rate of the fluid is different at different positions of the slots.

【0030】 Integration of additional gas analysis sensors (not shown here) may be used to also determine the level of harmful substances or condensates in the fluid. The gas analysis sensor in principle requires contact with a flowing fluid.

【0031】 Even if the gas analysis sensor experiences a shift in measurement, other sensors in the design of the present invention may be used to advantage to ensure that not all sensors are shifted. This combination is also novel in any case.

【0032】 This one calculation unit and sensors for dynamic pressure differences and sensors for static pressure are accommodated in a protected manner in the housing part 3.

【0033】 A temperature sensor 9 and/or a gas analysis sensor are also connected to the calculation unit. The calculation unit outputs a measured value obtained from the individual values of the different sensors.

【0034】 The calculation unit has a flexible design and can be adapted to different requirements from the subsequent control unit.

【0035】 The invention is industrially applicable in many fields where long term stability of the measured values is important.

Claims (4)

1. A sensor unit for a fluid, comprising a measuring probe in contact with the fluid and comprising a housing part in which a sensor is arranged, characterized in that:

a plurality of delivery pipes (7a, 7b) for detecting a dynamic pressure difference and one delivery pipe (8) for detecting a static pressure are provided in the measuring probe, and these delivery pipes (7a, 7b, 8) are connected to a dynamic pressure difference sensor and a static pressure sensor in the case portion (3) of the sensor unit (1), respectively;

a temperature sensor (9) is additionally provided in the measuring probe (2);

a gas analysis sensor is additionally provided in the measuring probe (2); and

a computing unit is integrated into the housing portion.

2. The sensor unit of claim 1, wherein: a plurality of slots (10a, 10b) are formed in the outer walls of the two ducts (7a, 7b), the two ducts (7a, 7b) leading to the dynamic pressure difference sensor in the housing part, and the wall (11) remaining between the ducts (7a, 7b) is used as a stamping surface.

3. Sensor unit according to one of claims 1 and 2, characterized in that: the sensor unit (1) has, in whole or in part, a surface with a nanostructure.

4. The sensor unit of claim 3, wherein: the measuring probe (2) has a surface with a nanostructure.