hyd accumulator

[Renze]

It is hard for me to see how a person could ever use an accumulator on a tractor loader to get both smoothing and speed increases. Rather, it will be the other way round...if it is used for smoothing, it will slow the loader down...since that accumulator has to get charged along with the cylinder end being pumped up.

I currently work at a small wheel loader builder in the netherlands. Hanomag (now Komatsu) was the first to show a study model with boom suspension based on an accumulator system, and our company, (way before my time) was the first to introduce it at their smallest 10t loader back in 1989 or so as standard equipment.
Right now it is allmost standard on every brand of wheel loader, volvo calls its BSS (boom suspension system) and Cat calls it ride control i think.
The system on our todays models with Parker hydraulics automatically switch it on above 7kmh. To do that, an automatic valve senses the pressure in the lift rams, then charges the accumulator to the same pressure, then opens the valve to make the lift cylinders communicate with the loader rams. If this wasnt done, the driver would encounter a sudden drop or rise of the boom whenever the valve would connect the suspension accumulator.

Also accumulators are used for steering damping, and for brake backup pressure. Its not really practical to use an accumulator for energy regeneration, because of its "accumulating" properties: in other words you can compress a spring when you go down in the elevator, but the very same compressed spring would not deliver the force to push you back up again (if it was strong enough to lift you, it would have never let you go down)

Next to that, a wheel loaders main task is scooping: power up, float down: when regenerating the energy of the downstroke it would slow down the operation too much: It must drop like dead weight to the ground in 1.5 second. (yes, it takes a better operator than me to get the max out of these loaders !)

in a commercial payloader, membrane accumulators just wont last: We use piston accumulators since 10 years or so.
From personal experiments i learned that it IS required to put the downstroke to float, even though i have long oil hoses on my frontloader that can be sucked vacuum to get some damping play, its not enough, the inward stroke of the loader cylinder must be freely connected to the tank. I will plumb one in when i have time, because my front axle suspension doesnt work with the loader on it, while i have it for loading bales (on rough land)

 

[charleyfarmall]

The Stoll loader on my New Holland has a factory accumulator on it - "Soft Drive". It is very nice when moving heavy objects over rough ground. It damps out the shock and smooths out the ride. The hard part of adding an accumulator as a shock damper is sizing it.

 

[Renze]

The hard part of adding an accumulator as a shock damper is sizing it.

AND giving it the correct nitrogen pre-charge...

 

[Redneck in training]

What was described in several previous threads should be called hydraulic capacitor. Hydraulic accumulator serves opposite purpose than smoothing ride.
We use hydraulic accumulator in hydraulic systems of steam turbines. There is a check valve between the accumulator, the pump and all the systems that will not require peak flow. Only systems (usually only control valves) are fed from the accumulator.

 

[DaveOmak]

From what I have found, capacitor is an electric term..... accumulator is a hydraulic term.... they provide the same function in their respective fields....

The electronic–hydraulic analogy (derisively referred to as the drain-pipe theory by Oliver Heaviside) is the most widely used analogy for "electron fluid" in a metal conductor. Since electric current is invisible and the processes at play in electronics are often difficult to demonstrate, the various electronic components are represented by hydraulic equivalents. Electricity (as well as heat) was originally understood to be a kind of fluid, and the names of certain electric quantities (such as current) are derived from hydraulic equivalents. As all analogies, it demands an intuitive and competent understanding of the baseline paradigms (electronics and hydraulics).

A hydraulic accumulator is a pressure storage reservoir in which a non-compressible hydraulic fluid is held under pressure by an external source. The external source can be a spring, a raised weight, or a compressed gas. An accumulator enables a hydraulic system to cope with extremes of demand using a less powerful pump, to respond more quickly to a temporary demand, and to smooth out pulsations. It is a type of energy storage device.
Compressed gas accumulators, also called hydro-pneumatic accumulators, are by far the most common type.

A capacitor (originally known as condenser) is a passive two-terminal electrical component used to store energy in an electric field.

 

[Soundguy]

if you look back to early computer design, I believe they called , what we now call registers, accumulators. they 'held' something...

 

[kubotakid USA]

Ive been kickin around the idea of building a mechinical/hydraulic accumulator. I think for my experiment it will be the most flexable. Ive never seen one, But have read about them. I thinking about using a 2" bore cylinder, And a 2" die spring. Meaning, the spring is used instead of gas.

I plan on using this to take the shock out of a hyd drive motor, So a small amount of give should be enough, Dunno but its sompthing Id like to try.

kubotakid USA

 

[Soundguy]

if you are talking about the problem with a motor deadheading to a stop when a valve is closed.. there is already 2 fixes for that.

a mechanical fix is to use an ORC so that when the motor stops, it's load can coast 'over' the motors locked shaft .. or.. more simply.. there are motor spool valves designed specifically for this application. I like to tonker so I like the ORC if I had one on hand to cut up and weld.. but if you are buying parts.. the motor control valve is an 'in the box' fix.. vs the 'out of the box' orc weld up cob job..


soundguy

 

[kubotakid USA]

if you are talking about the problem with a motor deadheading to a stop when a valve is closed.. there is already 2 fixes for that.

a mechanical fix is to use an ORC so that when the motor stops, it's load can coast 'over' the motors locked shaft .. or.. more simply.. there are motor spool valves designed specifically for this application. I like to tonker so I like the ORC if I had one on hand to cut up and weld.. but if you are buying parts.. the motor control valve is an 'in the box' fix.. vs the 'out of the box' orc weld up cob job..


soundguy

Soundguy,
This isnt your typical motor drive. Theres no way to change the valve. Iam working on a Case/Ingersoll 446 tractor. Unless your carefull they like to Buck when the drive is engaged. Some are worse than others.

kubotakid :united-states:

 

[Soundguy]

slightly different application than the straight hyd motor you aluded to earlier..

 

[kubotakid USA]

slightly different application than the straight hyd motor you aluded to earlier..

Sorry soundguy, I wasnt trying to elud u

 

[Baby Grand]

If you incorporate an accumulator in your design, make sure it has some kind of fail safe unloading device so the circuit doesn't stay energized when the pump isn't running. People have been maimed and killed by failure to observe this rule. A solenoid valve or a simple bleed down device can be sufficient.
-Jim

 

[kubotakid USA]

BG,
My thought/plan has been to put it between the TCV,.{travel control valve} and the foward imput of the drive motor.
So it would only effect the foward circut flow, And have nothing to do with reverse. My thought/understanding is that when, I put the TCV lever in nuteral there will be no pressure left in the system....Unless of course it was on a steep down hill grade, And the parking brake was not applied.
I have used combines, front end loaders, and skid steers with accumulators incorporated in the lift system and love the benifits,.. But I have never heard of one used in a drive motor application.
So I dont have much to go on.

Saftey is a priority,.and I welcome all other comments, and concerns.

kubotakid:united-states:

 

[Renze]

slightly different application than the straight hyd motor you aluded to earlier..

He wanted to use the, what you interpreted as a "straight hydraulic motor" as an accumulator. A piston accumulator, just with a spring behind it instead of nitrogen pressure.

 

[EE_Bota]

Do any of you ever see spring loaded hydraulic accumlators on real systems? I have not so far.

 

[Soundguy]

i've seen something similar used as a shock dampener