NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Toshihiro Uchiyama) has developed the world's first hydraulic load detection device. The device can prevent overloading in vans, light trucks, and other vehicles. NSK first showed the device at Automotive Engineering Expo 2017. Check the video below for a closer look.

The video covers the features of the load detection device. We built a full demo car to demonstrate its potential to prevent overloading, and even improve driving safety and fuel economy.

Development Background

Vehicle overloading is a long-standing problem in many countries. Overloaded commercial vehicles, including light trucks and vans, are a costly social issue that is gaining attention. An overloaded vehicle has a longer braking distance, and is more difficult to steer. Overloading is a major contributor to serious accidents and road infrastructure damage (undulations, cracking, sinking), causing significant deterioration of road safety and comfort.

Governments are currently moving to strengthen regulations to prevent overloading. German highways, for example, have load sensors in the road at over 700 inspection sites. Drivers not only lose their license for violating load limits more than 3 times in a year, punitive measures make it harder to work as a professional driver after regaining their license. In Japan, highway toll booths have been installing electric scales, and large truck manufacturers are introducing on-board automatic load measurement systems. In light of the increasing need for overloading prevention in both developed and developing countries, NSK took up the challenge to create a compact on-board load detection device.

Features

NSK's load detection device is easy to install to the suspension of most vehicles, enabling precise weight measurement on the go. (Fig. 1)

The hydraulic device has a flexible diaphragm* that deforms under load, thereby increasing pressure in the fluid chamber. Load is calculated based on the increase in pressure. The hydraulic fluid is essentially non-compressible (high bulk modulus), which enables a design that operates with minimal diaphragm flex.

The device features a double layer seal to prevent fluid leakage. In the highly unlikely event that the hydraulic fluid leaks, the suspension spring will only extend a tiny amount to close a gap above the piston, resulting in no adverse effects on the suspension system.

The load detection device also features a thin, compact design to avoid significantly shortening suspension stroke. (Fig. 2)

* A thin material layer that flexes under pressure.

Demo Car

NSK developed a demo car equipped with the new load detection device. The device is attached to the suspension of the front and rear wheels, and is capable of measuring cargo load with an accuracy of ±5%. The device can also wirelessly transmit the cargo load (weight) to a mobile phone or on-board system, enabling the vehicle center of gravity to be calculated and utilized.

Ongoing Development

In addition to detecting overloading, NSK is further working to apply the data from the load detection device to develop environmentally friendly vehicle control systems, and enable safer, more comfortable driving experiences.

This includes safer braking by controlling front and rear brakes independently to account for load conditions, and improved fuel economy by controlling the transmission to account for load conditions. We are also considering several methods to use the technology to improve steering feel consistency and comfort. (Fig. 4)