# regenerative shocker

sir,
i am working for baja atv in india
we'll be having an interview soon in 5
days and we have only one factor which could help ur to get through this interview. and that is innovation
we want to design self made regenerative shockers
that is instead of using the oil in the damper
we'll cut grooves in the piston of the dampers(pinion of rack and pinion type) and meshing it with rack on both sides of it such that when it moves up and down it also moves the 2 motors(rack) connected to it.
kindly help me to overcome the problems which this type of damper could face and also help me to clear the interview by making the judges satisfactorily understand the concept.
if ill b able to show even 1% probability that such thing could be made ill b selected .

## Replies

• Ramani Aswath
Shock absorbers with oil use the viscous drag of the oil to absorb the energy by converting it to heat. In your concept where does the energy developed by the two motors go. You may have to drive some generator and charge the battery in the vehicle or consume the energy using a heater element as the load. Sort of regenerative braking idea.
• sidh012
exactly thats what ill b doing.using the energy in a generator.but i need to show the judges its feasibility.
initially i thought of using 3-4 ,motors on either side of pinion with gradually increasing torque of the racks mean the pair of 1-1 motors with least torque and then 2-2 motors more and 3-3 the most thinking that this would give most damping.
but my professor said this would make more mechanical linkage and chances of breaking would increase
so i am now thinking of using only 1-1 rack..
• Ramani Aswath
In my opinion you should directly drive the generator from the rack and pinion. The grooves on the cylinder is the rack they can drive any number of pinions around the circumference. The number will depend upon the level of shock to be absorbed. There is no need of a motor. The voltage developed will depend on the roughness of the surface and speed and load in the vehicle. However, the reduction of the shock will need a variable load on the generator. A battery can take charging at various currents and is a good power absorber. So is a heater element.
Linear Induction generators are another option. As of now they are complex and expensive.
The following are some examples of Q and A. I am sure that if you spend half an hour quietly, you yourself can come up with more.

Q 1: Can you explain how your scheme works?
A: The shock energy is converted to electric power by the pinion driven by the rack on the piston. The pinion shaft drives the generator. The output of the generator charges a battery to absorb the shock. This is like regenerative braking used in cars. I can also use a heater element to consume the power. Both battery and heater can absorb varying loads and so are suitable for absorbing shock

Q 2. The rack moves both up and down how will you handle this?
A: The generator will be bidirectional. If necessary simple electronic circuits can make the output unidirectional.

Q 3: Hydraulic sock absorbers are easy to make and cheap. Do you think you can compete with them?
A: I have not worked out the economics. I feel that after tweaking the design, it should be a good alternative to conventional absorbers.
• sidh012
first of all thanx a ton for your so great support.the interview will b in your city only at dayanand college.
sir i have some questions

Q1should i use a pair of pinions on either side of the rack{0!0) or using 1pair of lower torque then another pair of heavy torque below{0!0} it. d {0 0}
or using 3 gradualy increasing torque pinion {0!0}
m {0 0}
a {0 0}
which arrangement as shown in the bracket would be best.???

Q2i went to the radio market nd found a generator of thumb size which generates 5w of electricity in one rotation.costing 400rs fair enough??

Q3if judges asked me there about any cacluctions done what would i say because this is just a begining nd i could make such damper but what kind of calculation involved it in.??

Q4 i am giving it the name as adaptive regenerative shocklers.{because i want to make the damping characteristics changeable manually but how could that be done i mean while moving in rough terrains an additional gear be mashed to the pinions that would make the pinions to move tightly. if this is possible?
• Ramani Aswath
1. In your concept the torque comes from the load on the generator. Higher the load greater the torque. It is best to have a load that is inherently variable like a battery or nichrome heater element so that if the input power increases the load automatically absorbs it. Having two diametrically opposite pinions will give better balance. All this means that you need only one pair of pinions and the load takes care of the torque. Since the linear movement in shock absorbers will be small, you may have to have a speed increasing gear train between the pinion and the generator shaft to increase the revolutions at the generator.

2. 5 W/Rev seems quite substantial for that size. At 60 RPM (quite small) it should generate 18 KWHr! Very unlikely. It is probably 5milliwatts/rev. Please check. Even at this the output @60RPM will be 18 WHr which is more likely for that size.Rs.400/single piece in a store means that in bulk the price will be below below Rs.40, which is acceptable.

3. You can say that it is currently in concept stage. Data on load, speed, road surface characteristics and details of the electrical damping (by battery or heater) will have to be configured into the design before even a prototype is attempted.

4. 'What is in a name' as Shakespeare said. If you design an adaptive load, there is no need of a manual control.

If you already have the generator, can you check the open circuit voltage at the output for different speeds? Later you can put a suitable rechargeable battery (a 6V two wheeler battery may work) as load and turn the shaft by hand at differing speeds and see if you can feel a difference in torque.

(I am currently on a visit to US and will be back in Bangalore only by the end of this month.)

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