I am doing a survey for a capstone engineering project. Our product is an attachment to brake pads on the Prius.

The product is able to increase the Prius by 6 mpg, and will cost around $600 to install. If the product takes about 5 years to pay it off, will you be willing to purchase the attachment?

I am also looking for comments, both pos and neg, about such a product.

 

The problem is insufficient information to justify this claim.

Bob Wilson

 

Well it's hard to comment because your post is short on details. However, I remember when disc brakes first came out a little trick we tried and used with springs to keep the pads off the rotors, until you applied the brakes (a little harder then normal), to get the most speed out of our cars, by the way of less brake drag on the rotors, on our drag and stock cars

 

I will need a LOT More Information about how this works to make an informed decision.

 

The product uses the heat generated from braking to supply additional power to the prius's storage in addition to the regenerative braking system. Our system generates energy passively, so the driver does not need to pull any switches or do anything outside of normal driving to make use.

The 6mpg saved is an estimate, since our product is still under proto-type phase. We are trying to collect data on whether Prius owners will be willing to pay for this addon if it takes about 5 years of gas fills to payoff the original cost and begin saving additional money.

 

Thank you but I'll pass. Hybrid electric, regenerative braking does not generate appreciable amounts of heat.

Bob Wilson

 

ATS09,

You need to do a LOT more research. The hydraulic brakes on Camry and Prius vehicles do not come into play until the car is going less than 10mph (unless you are in a panic stop). The is NO WAY that a stop from 10mph to 0mph will generate enough heat to produce anything unless you are running a paper route or delivering the mail.

 

We realize the actual use of the hydraulic brakes is during low speeds, but this is to account for high traffic areas in the US. In major cities, rush hour or dense traffic times will require drivers to stop nonstop. Also, there are drivers who do not anticipate braking much, causing a full stop from 20+ mph. The heat on the brake pads only need to reach around 200F (nonhybrids usually get to 400F on a normal drive) for our system to begin generating power. Note that our system is able to continue generating power once a temperature gradient is reached, and continue to create power even if the driver is no longer braking or moving.

 

I would recommend calculating the specific heat and energy required to change the speed of a typical Prius:

• brake pad - ~0.5 lbs, even at 200F, the amount of heat available for the four front pads and four rear shoes is closer to about 2-4 lbs
• vehicle weight - ~3,000 lbs, a fairly massive body that changing even 1 mph requires significant energy that is very much greater than 2 lbs at 200F

Do the math and I think you'll begin to understand our skepticism. Don't forget to include the thermodynamic efficiency that typically gets pretty low when the hot and cold points are closer together.

Bob Wilson

 

I am unsure at what you are getting at. All vehicles have a braking mechanism, most of which is at least two disc brakes. Even hybrids have disc brakes in additional to the regenerative braking system. When the pads are used, heat is created from the friction stopping the kinetic motion of the wheels, which gets to high temperatures. Our system is using that heat generated on the pad to create additional electric energy instead of letting it go to waste. The weigh of the pads are independent from how our system uses the heat.