Allengra’s Ultrasonic Sensor Technology: Precision Control for Smart Dosing

Kärcher is making the next generation of their floor cleaning machines with combined sensors in a compact control valve without moving parts more intelligent and more precise in dosing.

For an extended period of time, the unit price of ultrasonic flow meters was too high and the dimensions too large to be integrated into devices for everyday use.

In 2011, Allengra GmbH, with the help of a southern German chip manufacturer, was able to develop an ultrasonic sensor for large series in a compact design for several manufacturers of gas wall heating devices and finally deliver it in series.

However, in 2015 Kärcher, the manufacturer of cleaning devices and systems and the world market leader in its field, became aware of the volume flow sensor.

Kärcher is working on a new generation of floor cleaning machines that will be equipped with intelligent technology to be even more precise in handling and dosing. The development department combines flow measurement with control and integrates it into a compact control valve with flow measurement without moving parts, so that the measurement is not affected by impurities in the water.

In addition, Kärcher was looking for an actuator in which various sensors are installed that can measure the finest flow rates as well as minimal pressure differences.

Our team is exactly the right partner for the development of a small actuator tailored to cleaning machines, which is intended to regulate the dosage of the cleaning solution with great precision.

Allengra had already presented a design for a simple and compact sensor with a well-evaluated and tested actuator combined with a ceramic valve control system at the ISH 2017. A control valve in this compact form with flow and pressure measurement was a novelty on the market, until we launched our Smart Valve.

Pressure sensor measures liquid level accurate to the millibar

For a specific line of its scrubber driers, Kärcher needs an actuator with an ultrasonic flow meter that measures the inflow of cleaning agent with high precision, making it easy to control and adjust.

An additional pressure sensor indicates the level in the freshwater tank, which varies between 0 and 90 cm. The measurement should be made on a scale from 0 to 90 millibars – an demanding task which the pressure sensor solved exceptionally.

Kärcher wanted a clean and even more precise solution for dosing the cleaning solution than in the previous floor cleaning machines. To do this, the valve for dispensing the cleaning solution not only has to be 100% tight, but also close quickly.

Allengra's control valve achieves a shutter speed of 1.4 seconds.

Fast and Cost-Efficient Development

Since Kärcher devices are used all over the world, the robustness of all components is one of the most important criteria. More employees were successively involved in the project and the bar was set higher and higher.

Through intensive tests, Allengra and Kärcher were able to continue to refine the control valve. The ultrasonic control valve is now being tested in the field and the market launch will take place this year.

The project is a win for both Kärcher and Allengra as an agile think tank with a dynamic team, Allengra is an important partner for the fast and cost-effective development of a highly specialized product that, due to its size alone, could be easily integrated thanks to modern, space-saving sensors.

For Allengra, the Kärcher project team was a professional sparring partner with a great deal of development experience and an established global infrastructure; both opened up possibilities for the project to integrate the new controller into the next generation of scrubbing machines.

No Suspended Particles affect Long-Term Stability and Measurement Accuracy

The ultrasonic control valve can handle a medium temperature of 5-60 °C and a pressure between 0-1 bar. If a particular situation arises, the regulator can be adjusted to an operating pressure of 6 bar.

Communication takes place, for example, via UART and PWM pulse output. The power supply can be provided with a long-lasting lithium battery if required. By doing without mechanical moving parts in the sensors, no suspended particles, dirt or sand affect the long-term stability or the accuracy of the measurement.

Furthermore, WLAN or Bluetooth communication and a CAN bus are to be implemented in the Smart Valve in order to make the product fit for integration in Industry 4.0 and automotive environments.

Dead spaces are to be eliminated in the future in order to meet hygienic requirements, which also qualify the controller for the food industry.