Windshield Wiper Blades

One of the most important parts of the windshield wipers is its blades. The most common wiper blade available is the conventional blade, which consists of a metal frame that supports the rubber cleaning edge that rests against the windshield. The rubber strip is responsible for removing debris, dust, and water from the windshield. To maintain visibility in heavy rains or snow, it is therefore important for the rubber edge to retain smooth, even contact with the windshield.

Conventional Wiper blades

The role of the metal frame is to support the rubber edge and to evenly distribute the pressure as seen in Fig 1.a. The metal frame uses a linked tree mechanism to divide the pressure evenly. The pressure from the spring of the main arm is divided into subbranches that further divide the pressure to several pressure points on the rubber edge as shown in Fig 1.b. This helps to evenly divide the pressure and provide a clean wipe.

Fig 1.a - Components of a Conventional Wiper Blade
Fig 1.a - Components of a Conventional Wiper Blade
Fig 1.b- Pressure distribution in Conventional Wiper Blades
Fig 1.b- Pressure distribution in Conventional Wiper Blades

A disadvantage of this type of wiper blade is that the number of pressure points is limited, causing small gaps between the pressure points where the pressure is low. This can cause uneven wiping. In addition, conventional wipers are flat in comparison to the windshield which has a curved shape. As a result, they do not come in contact with every inch of the surface of the windshield. Also, due to the extra weight of the metal frame, conventional wipers are less aerodynamic. When driving at high speeds, high winds can produce a drag on the wiper blades that leads to “wind lift,” a condition in which the blade is lifted and separated from the windshield as shown in fig2. As the wiper blades lose contact with the windshield, drivers lose sight of the road. These problems can be solved using a beam style wiper blade.

Fig 2. Upward Lift force reducing pressure on windshield
Fig 2. Upward Lift force reducing pressure on windshield

Beam Style Wiper blades

The beam style wiper blades consist of a rubber blade attached to a tensioned metal strip Fig 3.a. This long single piece springs across the entire length of the blade which allows the wipers to have an infinite number of pressure points as shown in fig 3b. Beam blades are designed to match the curvature of modern-day windshields, ultimately leading to better coverage between the wiper and the windshield. With their aerodynamic design and infinite surface contact, beam blades use the wind to their advantage, creating a force that actually increases pressure on the blade and pushes it more tightly against the windshield as shown in fig3c. In other words, the stronger the force of wind hitting the beam blade, the better it will work.

Fig 3a- Components of a Beam Style Wiper Blade
Fig 3a- Components of a Beam Style Wiper Blade
Fig 3b - Pressure distribution in Beam Style Wiper Blades
Fig 3b - Pressure distribution in Beam Style Wiper Blades
Fig 3c - Downward lift force used to generate extra pressure on windshield
Fig 3c - Downward lift force used to generate extra pressure on windshield

Hybrid Wiper Blades

One more type of commonly used blade is the hybrid wiper blade. As their name suggests, they combine the aerodynamic shape of a flat blade with the solid construction of a conventional wiper. An articulated plastic frame forms the aerodynamic ‘skin’ of the wiper blade. This allows for a smoother airflow, which in turn creates an even down force along the entire length of the blade. Below the plastic frame lies the steel substructure which provides a sturdy support for the rubber wiper. This ingenious design allows the whole wiper to flex to the shape of the windshield producing a smooth, efficient, and quiet wiping action.

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