Hydraulic Power Assist ( regenerative braking system )

The hydraulic braking system using the concept of a four-wheel brake system was proposed in the year 1918 by Malcolm Loughead. The system capitalized on the use of fluids to make it possible to transfer a large force to the brake shoe when pressing the pedal with much less force. Most vehicles adopted this braking system in their cars. Since then many developments have been made to improve brakes, one of which is regenerative braking. A common regenerative braking method, called Generator Braking (GB) in this report, is used in electric cars and utilizes a motor that also acts as generator when the brakes are applied to conserve energy. Another regenerative braking system developed by The Ford Motor Company and the Eaton Corporation in the late 1920’s for a typical gasoline or diesel combustion engine that stores brake energy in the form of a compressed gas is called Hydraulic Power Assist Braking (HPA) (Baharom, Hussain, & Day, 2013).

HPA is used in gasoline and diesel combustion engines. HPA works by using the kinetic energy of the vehicle to power a reversible pump. This pump is triggered once the driver steps on the brake pedal and causes the hydraulic fluid, Nitrogen gas in the case for HPA, to be sent from low-pressure accumulator to a high-pressure accumulator inside the vehicle. This takes the kinetic energy of the car and stores it as pressure inside the accumulator which can be used again (Kumar, 2012).The vehicle is slowed down, until it finally stops and roughly 80 percent of the cars original kinetic energy is stored as pressure (Ohnishi, Saito, Oshima, & Higashihara, 2013) (Kumar 2012). The nitrogen gas stays under pressure until the accelerator is pressed by the driver, in which case, the pump reverses and releases the pressure and spins the drive shaft thus accelerating the car forward (Kumar 2012).

HPA performs best in city driving where there is a lot of traffic because of the constant starts and stops. HPA is better than the conventional braking systems because the excess kinetic energy is converted into a storable form of energy, namely pressure, that can be used to accelerate the car back up to speed. HPA has a long life span due to the reusable parts that do not take much wear and tear and is rather efficient (Kepner 2002). Conventionally excess kinetic energy is converted to heat by friction in the brakes, which is undesirable . Consequently, HPA has reduced the cost of driving because the cost of replacement of brake parts is minimized and the level of fuel consumption has been reduced since the pressurized nitrogen gas is doing most of the work to accelerate the car.

Generator Braking also conserves useful energy but is used on electric vehicles. These are vehicles that rely on an electric motors powered by a battery to propel the engine. Vehicles that utilize this technology do not have gasoline tanks but obtain energy by charging a battery from electrical sockets and recharging if the batteries have been depleted.

The electric motor technology has been in place for more a century and has had many advances including GB. Although it is difficult to exactly pinpoint the first inventor of an electric motor driven vehicle, innovators in America, Netherlands and Hungary can be attributed to the first innovation. For instance in USA, William Morrison invented the first vehicle that had a capacity of six passengers (Nykvist et al., 329-332). The electric motor car has had major impacts on the car industry. First, since they do not use fossil fuels, the cars do not directly pollute environment which is very important in the control of greenhouse gases emissions and global warming. This can be achieved if the cars use electricity produced from renewable energy resources, thus eliminating air pollution. Secondly, the electric motors technology has affected the consumer price in fueling or recharging their vehicles These vehicles have convenience of lasting anywhere between 100 and 200 miles on a single charge. Lastly, the electric motors produce an constant torque as opposed to that of combustion engines that increase depending on the revolution speed of the engine (Helmers et al., 1-15).

Although the technology of Generator Braking seems relatively new, it has been used for over one hundred years. The first real beneficial use was in the early 1900’s on trams (Raworth). Trams incorporated a regenerative braking system that used the engine to help slow down the tram on declining slopes (Raworth). A system very similar to the one used on trams in the early 1900’s is used in electric cars today.

The use of technology such as GB has even further improved the efficiency of the electric cars. GB improves the efficiency of the vehicle by reducing the amount of friction created between the brake pad and disk and converting it into electrical energy which can be used to recharge the battery of the car. The key to GB lies in the engine of the car. When electricity is applied to the engine, it accelerates the drive shaft and propels the car forward. However, when the car begins to stop, instead of the brake pad being pressed against the brake disk, the drive shaft rotates the opposite direction and the engines starts to produce electricity, effectively becoming a generator (Bosch). This means as the car stops, the battery powering the engine of the car is slowly recharged. This ultimately reduces the total amount of energy loss due to friction on the brake pad and uses it to power the engine of the car.

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