Blade for a rainy day

Traditional windscreen wiper systems haven’t changed that much over the years. In wet conditions, rubber blades affixed to wiper arms transverse the windscreen in a reciprocating manner to clear it of rain or snow.

When it is dry or dusty, the windscreen can be washed by windscreen-wiper fluid pumped from a reservoir through nozzles on the car bonnet and onto the windscreen, after which it is then wiped away by the blades.

After analysing such windscreen washing systems in some detail, it became apparent to the engineers at French automobile-parts manufacturer Valeo that they had many limitations, some of which not only inconvenienced drivers, but also compromised their safety and that of their passengers.

Existing systems unevenly distribute fluid across the windscreen, have a cleaning ability that is dependent on the speed of the vehicle and waste a lot of the washing fluid, which is sprayed in an ad hoc manner across the screen. Most importantly, however, the spray from the systems can also obstruct a driver’s visibility, a problem that becomes very noticeable in urban night-driving conditions.

The vehicle’s mass can be reduced by 2kg, increasing its fuel economy and reducing CO2emissions

‘When drivers try to clean their windscreens, the washing fluid is projected onto the glass and until the wiper arm has moved across the glass, the vision of the driver can be obstructed for one second. This can be very dangerous, especially at night when you may have lights in front of you, and was one of the key issues with windscreen washing systems that we wanted to address,’ explained Samuel Papazian, marketing director of the Wiper Systems Division of Valeo.

So the engineers at Valeo set about developing a new system that would eliminate these problems. The result is the recently launched Valeo AquaBlade System, which, unlike traditional designs, distributes windscreen washer fluid along the wiper blade itself, rather than directly onto the screen through nozzles.

Because of its novel design, passengers in the vehicle are no longer sprayed with washer fluid through a sunroof or open windows, nor are motorists behind doused unexpectedly. It also improves driving safety because when it wipes the screen it does so without interrupting the visibility of the driver.

The AquaBlade, based on Valeo’s Flat Blade design, is composed of two parts. The upper holder has a spline and spoiler to which a water-distribution channel has been incorporated. A lower part holds the rubber blade, allowing it to be replaced without interfering with the fluid-distribution system.

In a complete system configuration, an electric pump sends the fluid from the vehicle’s reservoir up along and out of the tube embedded in the wiper arm onto a perforated edge that has been built into the blade. The delivery of the fluid is performed in a synchronised manner tied to the upward movement of the wiper arm.

‘The new system comes in two main variations, the first of which can be deployed in more traditional washer systems where a single continuously rotating electric motor is connected to mechanical linkages that provide the alternating movement of the washer arms. But it can also be deployed in more sophisticated incarnations where electronic motors may be directly attached to each arm of the wiper blades,’ Papazian said.

In order to synchronise the projection of the washer fluid onto the windshield with the arm movement, the designers had to ensure that the electronic control system in the vehicle can recognise where the arm is positioned at any given moment.

The position of the arm is tracked using data from magnetic position sensors inside the motors, which is then transmitted to a vehicle’s body-control unit adapted with new embedded software to control the timing of the delivery of the fluid.

“Until the wiper arm has moved across the glass, the vision of the driver can be obstructed”

Samuel Papazian, Valeo

The fluid is only sent to the forward edge of the blade and the pump is set to deliver liquid only when the wiper arm moves upwards. Because of this, fluid is wiped away as soon as it is deposited on the windshield, so the driver’s visibility is never impaired. No fluid is pumped when the blade moves downwards, because that would result in water being pumped onto the screen without it being immediately wiped away.
Aside from improving the safety of drivers, the new system also has benefits for the automotive OEM too.

‘Because water is only released from the system as the blade moves upwards and is precisely deposited at the right place on the screen, the amount of water required to be stored on the vehicle can be halved,’ Papazian added.

This means that the new system gives car designers the opportunity to reduce the size of the reservoir under the bonnet by a factor of two. Instead of having a four-litre tank, a two-litre tank can be used. Because of that, Papazian said, it is possible to reduce the mass of the vehicle by 2kg, increasing the fuel economy of the vehicle and reducing CO2 emissions by 0.2g/km, as well as saving material costs for the reservoir and the space it occupies under the bonnet.

There is another benefit too. The system also removes the need for the car designer to incorporate traditional nozzles onto the body of the vehicle, and eliminates the need for any calibration to be performed when the nozzles are installed. That is usually a compromising process because the exact location where the washing fluid hits the screen is highly dependent on the speed of the car.

At present, Papazian said that Valeo is in discussions with several OEMs that are interested in deploying the new washer system; not in the least because it is a technology that, once deployed, will make a significant difference to the driving experience of the car owner.

design essentials

The key facts to take away from this article

• The Valeo AquaBlade System distributes windscreen washer fluid along the wiper blade
• Fluid is wiped away as soon as it is deposited on the windshield, so it doesn’t obstruct the driver’s visibility
• It eliminates the problem of passengers being sprayed through an open window or sunroof