IL117121A - Evaluation of motor car safety systems under driving conditions - Google Patents

Abstract

A system for evaluating a number of important safety systems of motor cars under actual high-speed driving conditions, comprising means for actuating such systems while the motor vehicle is positioned on a stationary test stand, where the systems tested are more than one of the following: (a) high-speed, up to about 120 km/h, simulated brake test, (b) suspension test determining lateral deviations at up to high driving speeds, (c) simultaneous scuff determination; (d) determination of possible overheating of brakes during repeated brake sequence; (e) retarder efficiency test; (f) ABS effectivity test, where the parameters are determined separately and preferably simultaneously for each wheel of a wheel pair, said system comprising rollers (1) actuated by either the motor car engine or by electrical motors (3) on which the motor car is positioned, with a floating roller (2) between roller pairs; and a pneumatic flat spring (6) actuated by a high pressure gas container, said system being adapted to measure individual parameters and also the interaction of various safety means of a motor car when same is driven at a high speed. 3601 כ" ח בשבט התשס" ב - February 10, 2002

Description

EVALUATION OF MOTOR CAR SAFETY SYSTEMS UNDER DRIVING CONDITIONS w nm'Di niuiyB np^a The present invention relates to a device for measuring quantitatively, under road conditions, important parameters of vehicle safety systems and their influence on each other under road conditions, and especially parameters of the suspension and of the braking system.

The novel testing device makes possible the quantitative measurement of the important parameters of the suspension and the braking system under road condition, such as : suspension and wheel geometry , suspension play , influence of brake forces at high speed on suspension geometry and driving direction, wheel vibration, vehicle brake forces, brake fading caused by overheating downhills at high speed, retarder's efficiency, vehicle brake functions at high speed, ABS system efficiency and brake performance parameters.

The present invention complies fully with the INTEREUROPE E.E.C. (European Economic Community - 92/55/EEC, 77/143/EEC, 71/320/EEC) standard concerning road worthiness brake testing under road conditions.

The novel system is adapted to measure the various parameters under road condition terms.

The novel system and the records obtained by same are of value for use in road worthiness test stations, diagnostic test stations, vehicle prototype laboratories etc.

Contrasted with conventional means for establishing and measuring various parameters of car performance, wherein each of the above mentioned vehicle safety systems and parameters is tested in a static condition, making use of a separate device for each system, and therefore without their relation on each other and thus not fulfilling the E.E.C. regulations, the novel system enables a complete simultaneous evaluation of various parameters and of their interdependence.

According to the present invention it is possible to obtain simultaneously a continuous record of a number of parameters at a range of velocities, acceleration and deceleration, and such record is of considerable value for the evaluation of car safety systems.

Other and further features of the present invention will become apparent hereinafter.

Brief Description of the Invention : The novel testing system according to the present invention comprises two pairs of heavy weight aligned parallel inertia grooved rollers (1).

Each pair of rollers (1) is interconnected between each other with a chain and by sprockets (4).

Each pair of rollers (1) simulates predetermined inertia in order to decelerate and accelerate the vehicle wheels (18) for road condition simulation.

Between each pair of rollers (1), there is a floating roller (2) which has the ability of moving up and down, as well as right and left. It is connected (by means of a pneumatic spring (6) ) to the vehicle wheels (18) in order to follow the vehicle wheels (18) position and movement continuously and to record its position and send the information to the computer in order to interpret the vehicle wheels (18) parameters and changes (Figure 5).

The inertia rollers (1) are rotated by means of the tested vehicle's driven wheels (18) or by electrical motors (3).

The vehicle wheels (18) measurements are recorded continuously at all desired speeds, from 0 to maximum speed.

After the maximum speed is reached, the vehicle brakes are applied against the rollers' inertia by pushing and releasing the brake pedal.

During the test, while the brakes are applied, the change of the vehicle wheel geometry (Figure 5) shows that there exists a play or distortion or flexibility in the suspension.

Brief description of the drawings (A): The test device and its accessories, the method of measurements carried out therewith and the records thus obtained are described by way of illustration only with reference to the enclosed schematical drawings, which are not according to scale, and in which : Fig. 1A is a schematical top view of the device according to the invention.

Fig. 2A is a sectional side view of the device and a vehicle in a test position.

Fig. 3A is a schematical top view of the wheel scuff-incli nation measuring system.

Fig. 4A illustrates the control panel equipped with monitor screen, PC computer interface and pneumatic control.

Fig. 5 is a view of the suspension, wheel geometry and wheel behaviour tests.

Fig. 6 shows brake parameters and curves under road condition terms, showing the brake balance, brake fading, ABS system, retarders test and parking brakes.

Fig. 7 is a schematical top view of the 4x4 double set testing device.

Description of the preferred Embodiment: Figure (1A) shows the novel system which comprises inertia rollers (1), a wheel scaff-inclination measuring system (13) with its floating rollers (2), leaf springs (12), compression-tension leaf spring sensor (9) and the pneumatic spring constant controlled pressure (6).

Figure (2A) is a side view of the device and vehicle being tested.

Figure (3A) shows the wheel scaff-inclination measuring system (13).

Figure (4A) shows the control panel (14).

Function Description of the Device: The car is positioned between the rollers (1), pressing against the pneumatic spring (6) for a constant contact between them. The pneumatic spring (6) lifts the floating rollers (2) by the wheel scaff-inclination measuring system at a constant pressure.

The pressure of the pneumatic spring (6) is regulated to a certain value that will not change while the wheel scaff-inclination measuring system (13) changes the height of the floating roller (2) due to a different vehicle wheel (18) diameter. Thus the floating roller (2) pressure will be always the same and this system prevents changing the results of the wheel scaff when different tyre sizes are measured.

The lateral scaff of the floating roller (2) acts against the floating roller leaf spring (12).

The floating roller leaf spring (12) is highly accurate and is connected to the compression-tension leaf spring sensor (9) in order to measure the lateral force of the floating roller (2).

The compression-tension leaf spring sensor (9) sends the information to the computer which interprets the results and calculates the lateral force of the vehicle wheels (18) and its direction.

At the edge of each pair of rollers there is provided an acceleration-deceleration speed sensor (10) which measures the speed deceleration during the braking period .

The acceleration-deceleration rate sensor (10) sends the information to the computer which interprets the results and calculates the speed and the deceleration force actuated by the vehicle.

After testing the front wheels, the rear wheels are driven between the rollers (1 ) in order to test them. If the rear wheels are not driven by the vehicle engine, they will be driven by the device electrical motors (3) of the device up to the maximum speed, and the test will be carried out in the same manner.

There exists a possibility to test the lateral scaff change using an automatic load simulator (8), by running the vehicle wheels (18), loading and unloading the vehicle and determining the wheels' lateral scaff.

Comprehensive Description of the Brake Test: Brake test - Brake parameters to be tested are: a. Brake force per wheel - the brake force test is performed by using the "second law of Newton", where the moment of inertia (I) of the rollers (1) is known and fed into the computer memory. This moment of inertia (I) is multiplied by ^ .

The dv measured continuously by the acceleration-deceleration speed sensor (10), and the computer calculates the brake force using its own chronograph for calculating the dt in each and every readout of the dv .

The results are displayed by [KN] or [Kgf] force units in a very accurate manner. b. Brake Gain - brake gain is the ratio between the pedal pressure force and the brake force.

In order to measure the brake gain, the system uses a brake pedal force sensor attached to the brake pedal and an interface attached to the computer, and the computer continuously calculates the brake gain c. Road conditioned brake efficiency - brake efficiency is the ratio between the brake force of the vehicle and the brake vehicle total F weight — .

The computer is fed with the value of the weight of the car, either from its memory or from a weighing system which is connected to the computer. d. Brake balance - brake balance is the ratio between left and right ρ wheels brake force >1 , calculated continuously by the computer. e. Brake time and Brake distance - the acceleration-deceleration speed sensor (10) sends the information to the computer in order to calculate the distance starting at a predetermined speed or when the brakes are being applied, in the same manner the computer will measure the time. The result is multiplied by the ratio of the vehicle weight and the rollers simulated weight ' V ROL Speed Measurment: The speed is measured continuously all along the test by the acceleration-deceleration speed sensor (10) which transfers the information to the computer for speed calculation.

Brake Fading: While braking the wheels against the inertia force, the braking energy is transferred to result in overheating of the vehicle brakes material.

The overheating of the brakes material causes fading of the brake force.

The fading of the brake force is measured as follows: a complete brake test is performed several times (preferably four times) from 80 to 0 Km\H to a complete stop. After several times of applying the brakes, the fading should not be less than a certain percentage from the first time of applying the brakes.

All the parameters are displayed as digital display and/or graphic display on a monitor screen continuously all along the test.

All the information of all the tests that were performed, is accumulated in the computer memory and can be printed.

Retarders Function Test - the retarders task is to decelerate vehicles, specially downhills.

The range of the retarder efficiency is specially at high and medium speeds and its operation is to absorb the vehicle inertia.

Till today there was no way to measure and to test the retarders efficiency. This novel system gives the possibility to measure and test in a very accurate manner the efficiency and performance of the retarders.

Test Description - the vehicle enters with the driven vehicle wheels (18) between the rollers (1). The vehicle is running by its engine up to its maximum speed, at which moment the gear is being shifted to neutral and the retarder is operated by shifting the retarder lever to its effort stages. The deceleration force and efficiency will be measured continuously at each stage by the same procedure according to the second Law of Newton as described previously, including calculation of brake efficiency according to vehicle weight.

Testing ABS Systems - the ABS task is to prevent wheel lock at high and medium speeds.

The test and measurement at the ABS functions must be done at high and medium speeds.

Test description (testing ABS at one or two wheels or axles separately): The vehicle enters with its driven wheels between the rollers (1). The vehicle is run to a chosen speed and at this moment, the emergency brake is applied on the brake pedal (30-40 Kg pedal force) until the wheels are coming to a full stop.

The ABS brakes curve on the monitor screen will show a curve with "saw teeth" according to the time and the brake force parameters which are displayed due to the ABS characteristics.

If the curve is flat and the tested wheels were locked, the ABS system is malfunctioning.

Note: in case the ABS is functioning on 4 wheels together or the vehicle has a 4x4 wheel drive or the vehicle is equipped with an ASR system (Traction Control System), there is a need to use a 4x4 testing device which is a double set of the novel device.

Such a Device is illustrated by Figure 7 which comprises 4 double-roller pairs, 71, 72, 73 74, one of each pair being actuated by driving means. The use of this device is similar to that illustrated with reference to the preceding Figures, and especially to Fig 1, which illustrates "half of such a device.

LIST OF COMPONENTS

Claims (7)

CLAIMS:

1. A system for evaluating a number of important safety systems of motor cars under actual high-speed driving conditions, comprising means for actuating such systems while the motor vehicle is positioned on a stationary test stand, where the systems tested are more than one of the following: a. High-speed, up to about 120 km/h, simulated brake test, b. Suspension test determining lateral deviations at up to high driving speeds, c. Simultaneous scuff determination; d. Determination of possible overheating of brakes during repeated brake sequence; e. Retarder efficiency test; f. ABS effectivity test, where the parameters are determined separately and preferably simultaneously for each wheel of a wheel pair, said system comprising rollers actuated by either the motor car engine or by electrical motors on which the motor car is positioned, with a floating roller between roller pairs; and a pneumatic flat spring actuated by a high pressure gas container, said system being adapted to measure individual parameters and also the intercation of various safety means of a motor car when same is driven at a high speed. 14 * 15

2. A system accoding to claim 1, where the floating roller is arranged in such a manner that it can move up and down as well as left and right.

3. A system according to claim 1 or 2, wherein there is provided a flat pneumatically actuated spring adapted to follow the movement of the wheels of the vehicle, and to indicate their position at any given point of time.

4. A system according to any of claims 1 to 3, where the inertia rollers are rotated by the driven wheels of the vehicle.

5. A system according to any of claims 1 to 3, where the inertia rollers are driven by electric motors.

6. A system according to any of claims 1 to 5, comprising wheel scaff-inclination measuring means.

7. A system according to any of claims 1 to 6, where a floating roller leaf is connected to a compression tension leaf spring sensor, adapted to measure the lateral force on the floating roller.