APPARATUS AND METHOD FOR TESTING VEHICLE SUSPENSION SYSTEMS

Abstract: Apparatus is provided which enables the testing of a vehicle's suspension systems under workshop conditions and includes one or more platforms (2) which, while supporting one or more respective wheels (9) of the vehicle (8), may be moved both upwardly and downwardly to simulate vertical irregularities in a road surface. Means (12, 13) may be provided for measuring the movement or maximum movement of the vehicle body so as to enable analysis of the performance of the suspension damping. Deactivating safety devices (10) may also be incorporated.

Description: "Apparatus and method for testing vehicle suspension systems" This invention is in the field of vehicle suspension systems, and more particularly relates to a means for testing the wear and condition of such suspension systems. All common road motor vehicles are equipped with some form of suspension mechanism to cushion the body/chassis from shocks due to, for example, imperfections on the road surface on which they are travelling. Vehicle suspension systems generally consist of a spring to support the weight of the vehicle and some method of damping the oscillations of the spring. Damping is necessary to prevent the vehicle body from bouncing excessively and also to prevent the wheels from bouncing away from the road upon hitting a bump. Over a period of time, the dampers in any given suspension system will deteriorate in their performance due to normal wear. In other circumstances, a damper may be faulty due to a manufacturing defect or the like. Deteriorating or otherwise underperforming dampers give rise to the foregoing mentioned effects, thereby causing the vehicle handling characteristics to become adversely affected. For this reason the service or maintenance of road vehicles desirably includes frequent monitoring of the condition of the vehicle's suspension system. However, it is recognised in the present invention that no suitable or consistent apparatus or methodology is available for satisfactorily conducting such tests. In many circumstances the replacement of suspension systems, including dampers, can be recommended either unnecessarily or prematurely in consequence to unsatisfactory testing procedures or equipment. In other cases a real need for the replacement of all or part of a suspension system may be overlooked for similar reasons. An object of the present invention is to obviate or at least mitigate these shortcomings by providing a means for testing the condition and performance of vehicle suspension systems. A further object of the invention described herein, although not necessarily essential to it, is to visually indicate the said condition or performance. According to the present invention there is provided apparatus for testing the condition of a vehicle's suspension system, the apparatus comprising a platform capable of supporting one or more wheels of the vehicle and actuating means for providing controlled upward and downward movement of the platform while supporting or partially supporting a vehicle so as to enable an assessment of the performance of the suspension system. Preferably the apparatus further comprises a visual indicator which enables a visual reading of the performance of the vehicle suspension system. The actuating means may incorporate hydraulic rams or cylinders. Alternatively, mechanical or electromechanical lifts may be used. Preferably the actuating means is designed to move the platform in a vertical direction so as to simulate the vehicle hitting a bump in the road while travelling. Preferably also, the actuating means is capable of moving the platform in low frequency vertical oscillations. The actuating means may be associated with a control panel to allow for the remote control of the actuating means by an operator. Optionally the apparatus may further comprise a safety device wherein the safety device includes a detector means for detecting whether the vehicle is oscillating beyond predetermined limits of amplitude and a switch adapted to be triggered upon said detection by the detector means, thereby deactivating the actuation means. The platforms may include guide means for assisting in the appropriate location of the vehicle ' s wheels thereon. Preferably the one or more platforms are mounted on the one or more respective actuating mechanisms such that the platforms may be generally level with a surrounding floor surface. Alternatively, the one or more platforms may be accessed via one or more respective ramp means. Preferably a plurality of platforms may be linked together to enable the simultaneous testing of a plurality of independent or related suspension systems on a vehicle or for the testing of an axle or all four wheels on a car. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying Figures, in which: Fig. 1 shows in elevation a schematic representation of an embodiment of the invention: and Fig.2 shows a pair of linked platforms in accordance with the invention. Referring firstly to Fig. 1, apparatus for testing the performance or condition of a vehicle's suspension system has a platform 2 moveable between an upper position (as shown in Fig. 1) and a lower position whereat the upper surface of the platform is substantially level with the surrounding floor 3. Movement of the platform 2 is enabled by an actuating mechanism which includes hydraulic rams 4 grounded on a fixed housing 5. The housing 5 anchors the apparatus and typically might incorporate provision for being securely fixed to the floor. It is recognised in the invention that the apparatus will be most commonly used in garages and workshops where the floor normally comprises of a concrete slab, allowing for the use of well known anchor bolts or the like. The hydraulic rams 4 are empowered by an hydraulic system, generally referenced 6 in the drawings; the system 6 being controlled by a remote control panel 7. The platform 2 is designed to support the vehicle, or at least that proportion of the weight of the vehicle 8 which is transmitted through the wheel 9. Guides (not shown) may be used on the platform to appropriately locate the wheel 9 on the platform 2. In one possible embodiment the wheel 9 could be clamped to the platform 2 to ensure that the vehicle 8 at the wheel 9 does not dislodge from or at least is caused to return to its rightful position on the platform 2 during a test. Such a clamp would improve the safety of the apparatus, particularly where the platform 2 was provided in an elevated position, it being accessed by the vehicle via a ramp. Another optional safety device is shown in Fig. 1 in the form of a sensor 10. In this particular example embodiment the sensor transmits a horizontal beam to detect whether the bonnet 14 (or other predetermined datum point) on the vehicle 8 is caused to oscillate to a particular and predetermined amplitude limit. If the sensor 10 detects the datum point on the vehicle body reaching the said limit it deactivates the actuating mechanism such that the platform and thereafter the vehicle are allowed to come to rest. In a more sophisticated design, the actuating mechanism, when prompted by the sensor 10, could move the platform 2 in a direction to counter the oscillations of the vehicle 8, thereby causing the vehicle to come to rest more quickly. Also, in a preferred embodiment, the safety device may be constructed such that if it is not correctly set up prior to the commencement of a test, the apparatus will not operate, that is the actuating mechanism will be deactivated. Alternatively, the set up of the safety device could be automated on powering up the apparatus. In the embodiment shown in Fig.l the sensor 10 is mounted on a vertical post 11 which also supports a slide 12. An arm 13 is clamped to the body of the vehicle 8 and extends in a manner which causes it to interact with the slide 12 such that the slide is nudged up the post 11 by the arm 13: the arm 13 itself rising and falling in accordance with movement of the body of the vehicle 8. A scale is marked on to the support 11 to enable a reading or measurement to be taken in respect of the position of the slide 12 after a test has been completed. This arrangement allows for the maximum amplitude of oscillation to be measured and related to the input oscillations of the platform 2 caused by the actuating mechanism. It is appreciated in the invention that far more sophisticated equipment could be used to track and monitor the movement of the body of the vehicle in relation to the platform movement. Similarly advanced and detailed software could be employed to analyse the performance of the suspension system in light of the readings obtained. Turning now to Fig. 2, an example is given depicting a typical situation whereby two or more test platforms could be linked together and used to test either an axle pair of wheels or a complete vehicle. The vehicle 8 would be driven onto the pair of platforms 2a, 2b which are placed at a suitable distance apart, such that both wheels 9a, 9b of the same axle are supported on respective platforms. A means of linking and synchronising the two test platforms 2a. 2b is provided in the form of a mechanical link 15. The link 15 allows for the simultaneous control of both platforms 2 by the one operator and control panel. In order to use the testing apparatus of the invention, a vehicle is positioned, typically being driven, such that one or more wheels are located on one or more respective platforms. In one example test, the actuating mechanism would then cause the one or more platforms and respective wheel or wheels to move up and down at a relatively low frequency. The frequency may be variable by the operator. In this example, the vehicle wheel would be subjected to motion which was approximately equivalent to simple harmonic motion at a frequency designed to give rise to resonance within the suspension system, should there be a fault in the damping component of the suspension system under test. Movement of the vehicle body in response to the motion of the wheel may then be analysed by visual, mechanical or electrical means. Further tests may be designed and incorporated in order to provide a more informed analysis of the condition or performance of the suspension system. For example, the apparatus may be used to simulate the vehicle hitting a pot-hole or bump in the road. This could be performed by lowering the platform to its lowest position and then rapidly raising it to its highest position, thereby subjecting the suspension system to a step input of energy. This test may cause the tyre of the wheel to lose contact with the platform and perhaps "patter" should the suspension damper be faulty. Once the test has been performed it may be suitable to reposition the vehicle such that an alternative wheel or wheels are located on the respective one or more platforms. This may involve driving the vehicle forward or reversing the vehicle in to the apparatus for example. The test may then be repeated. Further modifications and improvements may be incorporated without departing from the scope of the invention herein intended.

Claims: Claims: 1. Apparatus for testing the condition of a vehicle's suspension system, the apparatus comprising a platform capable of supporting one or more wheels of the vehicle and actuating means for providing controlled upward and downward movement of the platform while supporting or partially supporting a vehicle so as to enable an assessment of the performance of the suspension system. 2. Apparatus as claimed in Claim 1 further comprising a visual indicator which enables a visual reading of the performance of the vehicle suspension system. 3. Apparatus as claimed in Claim 1 or Claim 2 wherein the actuating means incorporates hydraulic rams or cylinders. 4. Actuating means as claimed in any one of the preceding Claims designed to move the platform in a vertical direction so as to simulate the vehicle hitting a bump in the road while travelling. 5. Actuating means as claimed in any one of the preceding Claims capable of moving the platform in low frequency vertical oscillations. 6. Actuating means as claimed in any one of the preceding Claims associated with a control panel to allow for the remote control of the actuating means by an operator. 7. Apparatus as claimed in any one of the preceding Claims further comprising a safety device wherein the safety device includes a detector means for detecting whether the vehicle is oscillating beyond predetermined limits of amplitude and a switch adapted to be triggered upon said detection by the detector means, thereby deactivating the actuation means. 8. Apparatus as claimed in any one of the preceding Claims wherein the one or more platforms include guide means for assisting in the appropriate location of the vehicle's wheels thereon. 9. Apparatus as claimed in any one of the preceding Claims wherein the one or more platforms are mounted on the one or more respective actuating mechanisms such that the platforms may be generally level with a surrounding floor surface. 10. Apparatus as claimed in any one of Claims 1 to 8 wherein the one or more platforms may be accessed via one or more respective ramp means. 11. Apparatus as claimed in any one of the preceding Claims wherein two or more of the platforms are linked together to enable the simultaneous testing of a plurality of independent or related suspension systems on a vehicle or for the testing of an axle or all four wheels on a car. 12. A method of testing a vehicle's suspension system comprising the steps of : a) locating at least one wheel of the vehicle on a platform, b) imparting vertical movement to the platform to simulate the vertical irregularites in a road surface, and c) measuring at least one parameter or characteristic of the resultant movement of the vehicle's body relative to the movement of the wheel and platform.

Inventors: BROWNE ALASTAIR, BROWNE, ALASTAIR
Applicants: BROWNE ALASTAIR, BROWNE, ALASTAIR
Application year: 1997
Main classification: G01M17
IPC codes: G01M17