AU702728B2 - Vibration control - Google Patents

Description

Regulation 3.2 -1-

AUSTRALIA

Patents Act 1990 CFIJPcJ71 SFE C 1 F I GAT 1QN S TAIDARD FA2PdA E bT' r r r r e r a e

APPLICANT:

NUMBER:

FILING DATE: RICKY ANDREW WASON PM 5749/94 20/ 5/94 Invention Title: VIBRATION CONTROL The following statement is a full description of this invention, including the best method of performing it known to me/us: -e 2 VIBRATION CONTROL This invention relates to a vibration control method and product and, in particular, to such control when used in vehicles.

It does, however, have substantial applications in vibration control in other applications.

The general description of the invention will be in relation to vehicles but reference will be made to the 'other applications to which the invention may be applied.

It has been recognised for many years that there is a symbiosis between the chassis of a vehicle and the engine and also the situation as far as the inter relationship between components of non powered vehicles, such as bicycles and even other structures.

S In general terms, when considering driven vehicles, there can be a different relationship between the motor and the chassis depending upon the manner of mounting between the two. For example, cars and other substantial vehicles normally have rubber mountings between the two whereas, say, a go kart has the engine directly mounted to the chassis.

Technically, the inter reaction can vary what is known as the WP51/SPEC/WASON.CAP/AT.KM/26 May, 1995 3 balance factor which has a relationship with the speed of the motor and vibration.

In general terms, the more directly a motor can be mounted relative to the chassis, the more the balance factor will increase whilst the looser the motor is mounted, the more the balance factor will decrease. This is not directly applicable, only to the rotation of the motor, but also to all other rotatable components in the vehicle, such as wheels and tyres, the axles, the brakes and any gears or chains in the .e drive train.

Because of their simplicity, I will discuss the matter in relation to a go kart and, in these, there is a two stroke S motor which has no clutch and no gear box and drives the vehicle directly from the crankshaft.

Considering the go kart motor, the crankshaft is normally balanced statically when out of the motor, and not S" dynamically.

When the crankshaft is in the motor, and is rotating, then dynamic rather than static balancing becomes the critical aspect and at each engine speed, there will be a change in the balance factor, largely because of the difference between static and dynamic balance and because of the inertia developed by the crankshaft on rotation.

UP51/SPEC/WASON.CAP/AT.KM/26 May, 1995

B

There will be one particular speed of rotation of the motor at which the motor and the chassis inter-react and there will be resonant vibration between the two. At any speed below this, the vibration becomes less and less noticeable and once the motor speed goes beyond the speed of resonance, the vibration tends again to drop away quickly.

It is an object of the invention to provide a system whereby unwanted vibrations can be minimised and a complimentary object is to provide such a system where, when a motor is S• used, it is operated most efficiently.

eo oo The invention includes a means of limiting resonant vibration S: between two components by providing dampening in at least one of the components which can be effected by such vibration.

The invention is particularly applicable to applications having two components, one of which is rotating, whereby the other component is damped to minimise vibration.

o.

The concept of the invention includes a means of reducing resonant vibration between a vehicle chassis, substantially constructed of tubular members, and a propulsion providing mechanism fixed directly onto the chassis and having a rotary motion associated with it and which mechanism can itself vibrate, by filling said tubular members with a vibration damping material to minimise vibration of said members.

I I rr~rar~MEMS1.

rotating member is a vehicle chassis or the like, the chassis components are covered with a bituminous or rubber type paint to provide a dampening load on the chassis.

The invention can also be applied to components which move, but do not rotate, and even connected components which, together, can have a resonant frequency.

In order that the invention may be more readily understood, we shall describe particular forms of the invention in different applications.

In the first application, I shall consider a go kart which has as tubular frame.

Normally, once the frame is assembled, there will be at least co: one particular speed of motor revolution which would tend to set up a sympathetic, resonant vibration with the chassis which, I have found, not only makes the go kart more difficult S" to handle, but can also restrict the speed of the engine as it moves through this resonant area and even the top speed of rotation.

I have found that if I apply a damping material to the chassis components, then I tend not to have resonant vibration between the chassis or the motor or, at worst, the vibration is very limited.

WP51/SPEC/WASON.CAP/ATKM/26 May, 19-5 14 _r ~Pp r 6 In a first, preferred, form of the invention, I can use a non toxic self foaming material which I can place into the tubes to be used to form the chassis, and permit this material to foam to fill the tubes with a foam.

The tubes can then be cut to length and worked, for example by being welded together, flattened to receive a bolt therethrough or the like. This is not prevented by the provision of the foam material and the completed chassis then has its tubes largely filled with the foam material.

Alternatively, I could build up the chassis and then fill the tubes with a fluid, either a liquid or a gas, and seal the tubes and again, there will be a resistance to vibration.

In, say, a go kart or the like, it is preferred that whatever material is used to fill the tubes is a non flammable or fire retardant material and non toxic, as particularly where components are to be welded together, the closely adjacent S foam will normally be vaporised.

As an alterative, I could dip or otherwise coat the chassis with a material which limits vibration thereof.

The same principal could be used in other applications. For example, a motor vehicle chassis could be provided with a sufficiently thick layer of a bituminous or rubber based paint IP51/SPEC/WASON.CAP/AT.KM/26 May, 1995 I IL~s 7 to act as a deadening agent, and, of course, this could also act as an agent to protect the chassis from stones or the like.

Bicycles could be made with frames which are tubular and which have a foam or other material therein or, again, could be coated with a material to prevent vibration.

In each case, I have found substantial benefit as any resonant ~vibration is substantially reduced from a non-treated frame or chassis.

As mentioned earlier, whilst the invention is particularly applicable to vehicles, the same benefits can be achieved in S other areas having rotating componentry, for example only, windmills.

The invention can also be used in areas where there is no relative rotation, such as tennis racquet, hammers, axes and S" splitters and baseball bats and golf clubs.

For example, the use of the invention in a tennis racquet or such is of great importance. When the tennis ball hits the racquet the strings stretch and then rebound. This motion always carries a certain amount of lost force travelling out of the racquet head and through the handle to the arm of the person using the racquet. The only way energy can be lost WP51/SPEC/WASON.CAP/AT.KM/26 May, 1995 8 from the system is through the handle as the user's body is the damped mounting system for the racquet. Using this invention the force cannot travel through the racquet handle as the handle itself can no longer transmit that force due to it being damped. The energy previously lost out of the strings and through the racquet is now held within the strings and can therefore deliver more power in return.

Also structures which could have a sympathetic vibration at certain wind speeds could use damping in accordance with the invention.

S. Of course the benefits generally discussed are equally applicable to sea and aircraft as well as land vehicles.

WP51/SPEC/WASON.CAP/AT.KM/26 May, 1995 I I, I

Claims (3)

1. A means of reducing resonant vibration between a vehicle chassis, substantially constructed of tubular members, and a propulsion providing mechanism fixed directly onto the chassis and having a rotary motion associated with it and which mechanism can itself vibrate, by filling said tubular members with a vibration damping material to minimise vibration of said members.

2. A means as claimed in claim 1 wherein the damping material is a synthetic foam material. 0

3. A vehicle chassis, substantially constructed of tubular members, vibration of which tubular members is damped by the means described in any preceding claim. DATED THIS 26 DAY OF May 1995 RICKY ANDREW WASON By His Patent Attorneys A. Tatlock Associates Dc.bl-, 199l -r ABSTRACT The specification describes a means of limiting resonant vibration between two components, whether fixed or separate, whether rotating or stationary, one relative to the other which includes providing damping in at least one of the components. The invention is particularly applicable to areas where one of the components is rotating or has rotating parts and such can be in vehicles or the like having a rotary engine fixed to a a *i chassis. 9* C S *a C 00 w UP51/SPEC/WASON.CAP/AT.KM/26 May, 1995 s I