Lotus Renault GP: Fluid Inerter | ScarbsF1.com

23 Sep 2014 | Author: | Comments Off on Lotus Renault GP: Fluid Inerter | ScarbsF1.com

Lotus Renault GP: Fluid

Lotus Renault GP (LRGP) been on one of the teams most with their suspension the past decade. As RenaultF1 introduced the Tuned Mass (TMD) back in 2006 and since raced conventional Inerters are a special component in the to counteract spring effect of the using a spinning mass on a rod to control these loads.

have also been one of the racing hydraulically interlinked and have looked at other to legally alter the suspensions It seems this work has to the discovery of a new form of Inerter, using fluid for the Inerter This new development has been by the team a “Fluid Inerter”.

A section of the patented Fluid

The intellectual property rights to development have been by Patent, allowing the details to be accessible in the pubic domain source for the picture at the top of this My attention was drawn to this by Italian Mechanical Engineer De Vita, a specialist in Torsional and Dual Mass Flywheels


Becoming ever complex the suspension in an F1 car has a number of to counter loads fed into the in order to maintain the ideal at the tyre contact patch. We the role of springs and dampers, but remain other spring within the suspension system, not from the high profile Their spring effect undamped and hence is largely out of the of the teams in setting up the car.

able to counteract these forces in a suspension will the tyre to main better with the ground for more grip. In 2003 Cambridge Dr Malcolm Smith proposed a method of controlling these via the Inerter. McLaren took up idea and tested the idea in then went on to race an in 2005.

In size and construction the Inerter like any other damper. placed in the same position as a Damper it was well hidden and to most people. Until the saga in 2007, when the was referenced as both the “J-Damper” and “a with a Spinning Mass”.

It until May 2008 that I was to understand and expose the details of the concept, publishing its details in (subscribers only http://www.autosport.com/journal/article.php/id/1554 ). this article is cited in the documentation!

A Mechanical Interter

An can be configured in two ways: a linear and a format. In both guises the uses a toothed drive to a mass. Likened to the same as a bicycle bell, the load fed the bells lever is dissipated by the element.

In F1 teams use a cylindrical screwed onto a threaded rod a damper body. One end of the rod is affixed to one of the suspension and the damper body to the side of the suspension. Reacting to the of the suspension, the Inerter absorbs the that would otherwise not be by the velocity sensitive conventional

The Renault 2006 Front Mass Damper (TMD) Copyight: Craig Scarborough

The predates Renaults TMD, aimed to achieve the same With the TMD a weight is suspended on to offset the same forces fed into the chassis as the Inerter. first raced the TMD in 2005, its by Giorgio Piola around of that year; both a development race and an enquiry by the

It was subsequently banned on what to be false grounds. The FIA citing a aerodynamic effect as the reason for its

Unaware of its effect on the contact I initially saw the device as a means to the front wing pitching when braking. The inertia of the mass keeping the nose pitching downwards during the braking phase. This I would prevent the car from pitch sensitive.

Despite a court room case, “aero” function was upheld as the for the ban of the device.

Ironically the McLaren was the Inerter at the time, and despite it used for the same function was not and remains legal and in universal use to day.

LRGP#8217;s Fluid Concept

Reading the detail of the patent, it’s clear was at least partly a surprise The Patent states the discovery was on lab testing of another hydraulic device”, when it was found the effect of the fluid within the “has a very significant effect”.

I would suspect discovery was made during the of the linked suspension system. fluid lines are used to the suspension in a similar manner to the system I detailed earlier year (http://scarbsf1.wordpress.com/2011/10/17/mercedes-innovative-linked-rear-suspension/ ). Perhaps the fluid lines to link and rear suspension provided the rather than the very left to right linking I understand Renault have had linked suspension on the car since at 2009.

With this insight have proposed a Fluid using both the inertia of the and a spinning mass. By making the device more like a where by a damper rod displaces this fluid is then into a circuit to spin the There by both effects can be

It is the inertance of the fluid that the LRGP patent to the conventional proposed by Dr Malcolm Smith.

is a new term and I’ll quote the for LRGP’s explanation of the effect.

fluid inertance means#8221; an arrangement in which the presence of a fluid provides an inertance, inertance is a measure of the fluid which is required to bring a change in fluid flow in a system. Between the terminals translates to an inertial force resists acceleration.

LRGP that the fluid used was to the efficiency of the design. In particular to it effective for the lightweight and small volume required to make the work within the tight of an F1 footwell or gearbox. Needing to be and low viscosity, they have several fluids, such as and oil, but the preference appears to be for Although a metal, it’s at ambient temperatures and very

This means smaller lines filled with will provide the necessary compared to larger amounts of dense fluids. Passing one chamber in the damper body via the line to the other chamber, the design of the length and diameter of the lines are key in creating the correct inertance effect. Just “1 to of fluid is required to get the desired

The range of inertial reaction is as “10 to 500kg, which is a typical required in Formula One racing

As a side note McLaren this inertial reaction into different measured Rather than Kg of Inertial McLaren use the term “Zog”, allows them to hide the units set up on their Inerter.

suggests winding the lines the damper body as one solution for the of the fluid circuit. Additionally a or shim stack in the damper rod also alter the amount of displaced, to further tailor the effect.

With Mercury a high coefficient of thermal the patent suggests using a valve emptying into chamber is used to ensure the has a constant volume of fluid.

the emphasis is on the fluid to provide the effect, the patent citing a 50%, up to as much as 90% of the inertance from the fluid.

The device the left hand casing as the cylinder the right hand for bump rubbers

Not only the Patent contain the conceptual on the Inerter, but also detailed sections. I have simplified to explain the Inerters construction. have been able to the entire solution into a self contained component, fits into the same as the conventional Inerter.

The device is up of a main body and a damper The main body split left and right sections together. The left hand forms the cylinder, not only the fluid, but also channels in the outer casing form the lines. Such that no pipework is required.

The right hand casing allows the rod to pass through and also bump stops to prevent the bottoming at the end of its 16mm of bump or 23mm of droop travel. In the device is just 220mm (eye to eye).

In cross we can see the casing is a complex machined With the right hand formed with bushes, and endplates to create the cylinder for the rods to pass through. The rod along with its shim valve pass through the like piston as the suspension and rebounds.

The mercury within is and passes through channels the channels machined into the of the body.

The Inerter (yellow) is between the rockers

LRGP a diagram for the Inerters mounting. being a typical position the pushrod rockers. No doubt a mounting is found between the pull rod rockers. Externally it be hard distinguish the Fluid from a Mechanical version.

the Renault front bulkhead shows almost nothing of the inside the footwell. The steering and anti roll bar getting in the way of the aperture inside the front of the Thus we cannot be clear if the has raced.

One benefit is the technology is to LRGP and not used under via Penske or Dr Malcolm Smith. LRGP are free to use and develop technology freely.

I couldn’t state whether the Inerter has any compliance benefits a mechanical one. Perhaps easier to tune via the shim in the damper rod, rather the fixed specification of the mechanical Equally it may be easier to maintain, needing to strip clean and their Mechanical Inerters to maintain their smooth

It seems one advantage to this might be lightweight. The tiny of fluid required would be than an equivalent spinning As Inerters tend to be mounted high a weight saving aid CofG height, as well as placement.

One negative issue is Mercury is a hazardous material. the unit is positioned ahead of the legs, any mercury leakage as a of a major accident will complicate the health issues for the and Marshalls. I am not aware of Mercury specifically restricted by the FIA approved list.

Although with a few CC’s of the liquid contained the cylinder, this might not be as an issue by the FIA.


the team came across solution, it is a new direction for Inerter The solution is totally legal, as set by the of the mechanical Inerter being to race, even when the TMD

It will be interesting other come forward with new or linked suspension solutions. The problem is few teams patent design to allow us such to their design.

A view of the casing

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