GB2315337A - Wheel Balancing - Google Patents

Abstract

A dynamic balancer for wheels, for permanent or transportable use, with fixed mounting and demountable hub assembly is illustrated. For balancing, the demountable hub is removed from the fixed mounting and fitted with mandrels and wheel with tyre, and the overall assembly fitted back onto the fixed mounting, as shown. A static pointer 18, or similar device, highlights the magnitude and angular location of defections due to static imbalance.

Description

DYNAMIC BALANCER FOR WHEELS This invention relates to a dynamic balancer for wheels.

Wheel balancers are used to ensure that vehicle wheels and tyres are balanced for comfort and safety, for reduced wear and tear of the suspension components, and for enhanced tyre life.

Some balancers only take account of the static element of balance thereby providing an approximation to the complete balance solution. To achieve the latter, dynamic balancers, which are significantly more sophisticated, are required.

Nowadays it is common practice for fixed mounted, electronically controlled machines to perform this function but at significant capital outlay and maintenance cost. For this reason the sale of these machines tends to be restricted to specialist wheel and tyre organisations.

This present invention provides a low cost solution to dynamic balancing. It is readily portable and can be used on site, typically by installation on a service vehicle, when wheels and tyres are being repaired.

A specific embodiment of the invention is described below by way of example. This example has been chosen as it relates to the prototype, which was designed for wire wheels - generally considered difficult to balance. Reference should be made to the accompanying drawings.

Figure 1 shows a typical fixed mounting and moveable pointer arrangement.

Figure 2 shows the hub mounting assembly.

Figure 3 shows a typical mandrel with wheel and tyre assembly.

Figure 4 shows an overall view of the dynamic balancer for wheels with mandrel and wheel with tyre assembly installed.

Figure 5 shows a typical arrangement for holding a highlighter on a pivoted arm operated by a lever.

Figure 6 is an alternative arrangement to Figure 5 whereby the arrange is configured for enhanced accuracy.

The dynamic balancer for wheels consists of a fixed mounting (1) onto which a demountable hub assembly (3) is attached in a vertical or near vertical attitude. The hub assembly contains a shaft (4) on the upper end of which there is a means, such as a handle (5), with which to turn the shaft, which is mounted on bearings. On the lower end of the shaft is a free moving universal joint (6) with a long shaft (7) attached.

It should be noted that the long shaft is required for the measurement of deflections due to out of balance effects. Whilst this could also be done at the wheel, the long shaft, being in all likelihood dimensionally greater than the radius of the wheel1 has an amplifying effect on the deflection, thereby enhancing measurement accuracy. It also avoids any deflection measuring problems that could be caused by distortions in the wheel.

The long shaft should be of robust construction and of light weight at its lower end, so as to minimise any contribution it might have to the out of balance effects.

The long shaft hangs freely and has a threaded portion with washer (8), and retaining device (9). If mounted at the lower end of the long shaft, as illustrated in Figure 6, the washer could form part of a light weight, concentrically mounted drum (20) to enhance accuracy at the point of contact of the highlighter. (Accuracy would be enhanced because the highlighter makes a mark of given length, which encloses a smaller angle the bigger the radius of shaft/drum).

With the demountable hub (3) removed from the fixed mounting (1), mandrels (10) and (11) with wheel (13) and tyre (14) are fitted onto the long shaft so that the upper balancing plane, the rim (15) of the wheel, passes through, and is coincident, with the centre point of the universal joint (6). The mandrels ensure that the wheel with tyre are securely mounted onto the long shaft when a suitable spacing arrangement (12) is installed and the fixing device is tightened. The mandrels also ensure that the wheel mounting matches that of the parent vehicle.

The demountable hub with wheel and tyre assembly is then lifted manually or otherwise and fitted to the fixed mounting.

A moveable pointer (2), used in determining static imbalance, is positioned directly beneath the long shaft, plumb below the centre point of the universal joint.

Alternatively the pointer can be replaced by the pivoted arm arrangement shown in Figure 5. This is used to check deflections due to dynamic imbalance, but can also be used for the static mode. It consists of a pivoted arm (17), at the upper end of which there is a lever (19), and on the lower end there is a highlighter (18), such as a piece of chalk. The highlighter can either make contact directly with the long shaft, or indirectly onto the drum (20).

To start the balance process it is first necessary to balance statically the wheel with tyre by applying balance weights to the upper rim (15) of the wheel. The size and location of the balance weights can be determined by the deflection of the end of the long shaft (7) relative to the pointer (2) or high lighter (18). Slow rotation of the shaft (4) using the turning device (5) will identify the deflection and confirm the level, and angular position, of the static imbalance which needs to be corrected.

When statically balanced the shaft (4) should be turned increasingly quickly until it is rotating sufficiently fast for the dynamic balance effects to be apparent. Any sideways deflection of the long shaft (7) means that dynamic balancing is required.

This is achieved by noting the position at which maximum deflection of the long shaft ocurs.

When detecting deflections the pivot arm (17) should be operated by the lever (19) to bring the highlighter (18) close to the base of the long shaft or drum and lightly touch it. The highlighter will mark the long shaft, or drum, thereby indicating where the maximum deflection ocurs.

Once rotation has stopped the angular location of the peak deflection of the long shaft can be identified from the marking left by the highlighter. The centre point of the circumferential marking represents the angular location of the imbalance in the wheel with tyre. In practice this method is surprisingly effective though other, more sophisticated, arrangements could equally apply.

Having identified the point of imbalance, a suitable balance weight should be applied on the lower rim (16) of the wheel at a point diametrically opposite the imbalance. The size of the balance weight should be estimated from the amplitude of the peak deflection of the long shaft.

The wheel with tyre should then be statically re-balanced by applying a suitable weight to the upper rim (15) of the wheel.

The process should then be conducted again until the deflections due to dynamic imbalance of the long shaft reach an acceptable level. When repeating the process it should be noted that the point at which a balance weight needs to be attached to the lower rim (16) has already been established. It is only necessary to reassess the size of the balance weight required.

The wheel and tyre are now fully dynamically balanced and all markings from the highlighter on the long shaft/drum should be removed, and the apparatus readied for the next balancing job.

Claims (14)

1 A dynamic balancer for a wheel comprises a mounting for a universal joint assembly from which is hung a shaft for carrying the wheel, in use the universal joint assembly being suspended from the mounting for rotation about a substantially vertical axis.

2 A dynamic balancer as claimed in claim 1 wherein the wheel is mounted on the shaft hung from the universal joint assembly in a horizontal position level with the centre of the universal joint.

3 A dynamic balancer as claimed in claim 2 wherein the wheel is mounted on the shaft in a position wherein a plane containing a wheel rim passes through the centre of the universal joint.

4 A dynamic balancer as claimed in any preceding claim further comprising means for indicating sideways deflection of the wheel when the universal joint assembly is rotated about the vertical axis.

5 A dynamic balancer as claimed in claim 4 wherein the means for indicating sideways deflection of the wheel comprises the shaft hung from the universal joint assembly upon which the wheel is carried and static means positioned adjacent the lower end of the shaft.

6 A dynamic balancer as claimed in claim 5 wherein the static means positioned adjacent the lower end of the shaft comprises a static pointer situated plumb beneath the centre of the universal joint.

7 A dynamic balancer as claimed in any of the preceding claims wherein the means for indicating sideways deflection of the wheel comprises means to highlight an angular location of peak deflection.

8 A dynamic balancer as claimed in any of the preceding claims wherein the mounting for the universal joint assembly comprises a second shaft rotatably supported in a vertical position and to the lower end of which the universal joint is attached.

9 A dynamic balancer as claimed in claim 8 wherein the second shaft is provided with a handle by means of which it may be rotated.

10 A dynamic balancer as claimed in claim 9 wherein the handle is provided at the upper end of the second shaft.

11 A dynamic balancer as claimed in any of the preceding claims wherein the mounting comprises a fixed mounting which carries a demountable hub assembly for supporting the universal joint.

12 A dynamic balancer as claimed in claim 11 wherein the mounting is adapted to be fixed to a wall, a floor, portable support or otherwise.

13 A dynamic balancer as claimed in any of the preceding claims further comprising a mandrel and spacer arrangement for locating the wheel on the shaft suspended from the universal joint.

14 A dynamic balancer substantially as described with reference to the accompanying drawings.