EP1563270A1

EP1563270A1 - A collision test device and a method of breaking a collision test device

Info

Publication number: EP1563270A1
Application number: EP03776112A
Authority: EP
Inventors: Haakan Lindqvist
Original assignee: Asea Brown Boveri AB; ABB AB
Current assignee: ABB AB
Priority date: 2002-11-19
Filing date: 2003-11-18
Publication date: 2005-08-17
Also published as: WO2004046677A1; SE524771C2; SE0203416D0; AU2003283900A1; SE0203416L

Abstract

A collision test device, comprising a tow rope (3), a means (9-14) for driving the tow rope (3), and a means (20) for connecting the tow rope to an object (1) that is to be accelerated by means of the moving tow rope (3) and subjected to a collision test. The collision test device further comprises a second means (21, 22) for connecting the tow rope (3) to said object (1) and operating as a brake device for subsequent deceleration of the object (1), and the second connecting means (21, 22) comprises a trolley (21) that is attached to the tow rope (3), to be able to conduct a pre-crash deceleration impact test.

Description

A collision test device and a method of breaking a collision test device.

TECHNICAL FIELD

The present invention relates to a collision test device, comprising a tow rope, a means for driving the tow rope, a first means for connecting the tow rope to an object that is to be accelerated by means of the moving tow rope and subjected to a collision test.

The invention also relates to a method of braking a collision test device in which the test device is accelerated and subsequently decelerated before colliding, the test object being accelerated by means of a tow rope, a means for driving the tow rope, and a means for connecting the tow rope to the object.

The term "tow rope" should be regarded in a broad sense, and may include a wire, a rope, a chain, a belt or any similar elongated object that can be coiled onto a drum or the like or guided and directed by a pulley.

The object to be tested may be any object, such as any constructional element like a beam or a rod, but is preferably a vehicle, in particular a vehicle for transporting human beings, such as a car, a bus or a truck.

The means for driving the tow rope may typically comprise a drum or the like onto which the tow rope is coiled or from which the tow rope is uncoiled, or a driving pulley, and a motor for rotating the drum, pulley or the like. Typically, the motor is an electric or hydraulic motor. Braking of the movement of the tow rope can be achieved by means of the motor or by means of specific brakes for braking the drum, pulley or the like. BACKGROUND OF THE INVENTION

Crash test plants for the purpose of testing the safety properties of vehicles such as cars and trucks are facing new and tougher requirements as new standards are being set for the conditions under which crash tests are to take place.

Accordingly, the test plants of the future must provide the possibility of more realistically representing real crash conditions, including a representation of the deceleration stage that normally foregoes a real crash due to active braking thereof. Thus, after release of the car or the like from the means (tow rope, motor, and trolley) that are used for accelerating it, the car should be subjected to a deceleration during which a braking force is actively applied thereto.

Active braking by means of the brakes of the car itself will not be sufficient since it does not provide the required controllability and repeatability of the test conditions.

Therefore, already existing plants should be upgraded to be able to perform such active deceleration or be replaced by new plants capable of performing said active deceleration.

THE OBJECT OF THE INVENTION

It is an object of the invention to provide a device and a method by means of which an object that is to be subjected to a collision test is efficiently and actively decelerated such that the deceleration corresponds to the deceleration that the object would be subjected to under normal operation, upon a collision situation. It is also an object of the invention to present a method and a device that permits very accurate deceleration of the test object. The accurate deceleration should be repeatable, meaning that the same deceleration conditions should be possible to achieve for different tests in a controllable manner.

The device and method shall also permit continued deceleration up to the very point when the object collides.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is achieved by means of the initially defined collision test device, which is characterised in that it comprises a second means for (separately) connecting the tow rope to said object and operating as a brake device for subsequent deceleration of the object, to be able to conduct a pre-crash deceleration impact test.

Preferably, the second connecting means comprises a trolley that is attached to the tow rope, whereby said second means is arranged so as to separately connect the tow rope to said object. However, the second connecting means may comprise any kind of element that establishes a rigid connection between the tow rope and the object during the deceleration thereof, but does not affect the behaviour of the test object at the moment the latter collides. Accordingly, braking the object by means of the first connecting means, which is normally a trolley attached to a front portion of the test object, will not be a good solution since such a trolley either has to be removed shortly before the collision moment or will unavoidably affect the behaviour of the test object at the collision moment. "Rigid connection" is referred to as a connection where the length of the second connecting means will not at all or only slightly alter during the deceleration. In other words, the position of the object in relation to the first tow rope remains generally the same during deceleration until the collision moment. Accordingly, the deceleration of the object is achieved by a corresponding braking or deceleration of the movement of the tow rope that is used for the previous acceleration thereof. Thereby, the same driving equipment (motor, brakes, tow rope, etc.) is used both for accelerating and decelerating the test object.

According to a preferred embodiment of the invention the second connecting means comprises a second tow rope, and the second tow rope is arranged to be connected at one end to the test object and at the other end to said trolley.

Further preferred embodiments of the device according to the invention are defined in the dependent claims 5-9.

The object of the invention is also achieved by means of the initially defined method, which is characterised in that a decelerating force is applied to the object by means of a separate second connecting means that is connected to the tow rope and the object, and by decelerating the moving first tow rope. The second connecting means may be designed as described earlier in the text. The position of the object in relation to the tow rope is maintained by means of the second connecting means.

In a preferred embodiment of the method according to the invention the second connecting means comprises a second tow rope, which is attached to the first tow rope in one end and to the object in the other end, and which is pre-strained before the object is decelerated by means thereof. Preferably the second tow rope is pre-strained before the acceleration of the object is started. According to the invention, the second connecting means is attached to the first tow rope at a point behind the rear part of the object as seen in the moving direction thereof.

Further advantages and features of the present invention will be presented in the following detailed description of a preferred embodiment and in the annexed patent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention shall now be presented by way of example, with reference to the annexed drawings, on which:

Fig. 1 is a schematic perspective view of a collision test device according to the invention comprising a double-drum arrangement,

Fig. 2 is a schematic side view of a part of the collision device according to Fig. 1,

Fig. 3 is a schematic view of a collision test device comprising a driving pulley, and

Fig. 4 is a schematic view of a collision test device comprising a single-drum arrangement.

DETAILED DESCRIPTION OF THE INVENTION

The present invention shall now be described as applied to three main types of arrangements for accelerating and decelerating a collision test object. A first embodiment, as shown in Fig. 1 , in which the device comprises a double motor and double drum arrangement of modern design will be described more in detail below. However, the inventive idea could as well be applied to that kind of contemporary crash test devices that only use one motor and/or drum and that is shown in Fig. 3. In this kind of arrangement the first tow rope is both coiled onto and uncoiled from one and the same drum during operation.

An equally possible third embodiment, in which the device comprises a driving pulley arrangement instead of a drum arrangement, is shown in fig. 4. Here, a tow rope is arranged like an endless wire that is redirected by two opposite pulleys, at least one of which is driven by a motor. This kind of driving pulley arrangement is maybe the most common one today for the purpose of accelerating and guiding collision test objects.

Fig. 1 shows a collision test device according to a first embodiment of the invention. The device is arranged for the purpose of executing collision tests between a first and a second test object 1, 2. Here, the objects 1, 2 comprise a first and a second vehicle, or, more precisely, a first and a second car.

The device comprises first tow ropes 3, 4 for the purpose of pulling and accelerating the first and the second objects 1, 2 towards each other until they meet and collide at a predetermined spot. The tow ropes 3,4 form parts of a first and a second track 5, 6 for pulling and guiding the objects 1,2 towards each other. Each track 5, 6 comprises a first trolley 20 (see Fig. 2) via which the object 1, 2 is pulled by the respective tow rope 3, 4. The trolley is clamped to the rope 3, 4 associated thereto and has a pin or the like via which it engages the object 1, 2. It runs in a suitably shaped groove or recess arranged within, on or under a floor, said groove or recess permitting a guiding of the trolley in two directions, vertically and horizontally to the direction of movement of the object 1, 2 pulled thereby.

The first and second track 5, 6 extend in the horizontal plane and are arranged so as to permit adjustment of the angle α between them, that is the angle between the moving directions of the first and second objects 1, 2 is variable. It might be considered to arrange the tracks 5, 6 such that at least one of them presents an optional inclination, preferably an adjustable inclination, for the purpose of permitting tests in which at least one of the objects 1, 2 confronts the other object while moving in a sloping direction.

The device also comprises a first and a second drum 9, 10 for the purpose of coiling and uncoiling the first tow rope 3 during the pulling of the first object 1. Each track 5, 6 further comprises a pair of guiding rolls 7, 8 via which the rope is guided to the respective drum. The device comprises a corresponding third and fourth drum 11, 12 for the second tow rope 4. Motors 13, 14, 15, 16 that are torque, speed and position controlled drive a respective one of the drums 9-12. At least one of the drums 9-12 is equipped with brakes, preferably disk brakes for the purpose of permitting a rapid speed reduction or stopping. As the first and second tracks 5, 6 with their respective tow ropes 3, 4, drums 9-12 and motors 13-16 are generally identical as to the arrangement, only the first track will be described in detail hereinafter.

The first drum 9 is arranged at an end region of the track 5 and driven by a first motor 13. The second drum 10 is arranged at the opposite start end region of the track and driven by a second motor 14. During pulling of the first object 1, the first tow rope 3 is coiled onto the first drum 9, while it is uncoiled from the second drum 10. However, it should be emphasised that the drums can be driven in the opposite directions if necessary, for example in order to carry out a collision test at the other end of the test track. A control system known per se (including suitable computer software) controls the motors 13, 14 such that a predetermined rope tension is obtained throughout the test course, from initial acceleration to final stopping of the tow rope movement during a collision test. The same principles applies for the second track 6. The tracks 5,6 are independent in the sense that the tow ropes 3,4 are individually guided (not via any common roll or the like), and so, consequently, the speeds of the first and second object 1,2 can follow very different position-speed profiles during one and the same test collision course.

Apart from the elements used for accelerating and keeping speed of a test object, the device also comprises a second, braking trolley 21 that is connected to the tow rope 3 at a position behind the first trolley 20 as seen in the moving direction of the trolleys during a crash test (see Fig. 2). The second trolley is positioned at such a distance from the first trolley 20 that it will be positioned behind a rear end of the pulled object 1, preferably 10-20 meters behind said rear end. Preferably, the second trolley is guided in the same groove and in a way as described above for the first trolley 20. However, the second trolley may, alternatively, be positioned much closer, preferably in the order of 1 meter, behind the rear end of the pulled object. In this case the second trolley comprises a release function similar to that of the driving trolley 20 as mentioned below.

As shown in Fig. 2, a second tow rope or wire 22, preferably made of steel, is connected to the second trolley 21 in one end and arranged to be connected to the pulled object 1, possibly to a rear part of the object 1, such as a tow hook or a tow eyelet. However, in order to achieve a best possible resemblance of normal breaking conditions, in which the vehicle front drops somewhat, the second tow rope 22 could, as an alternative, be attached to the front part of the vehicle, for example close to the front wheel axle or the front bumper. Before acceleration of the object 1, the second tow 22 rope is connected to the object 1 and pre-strained to a certain amount.

During a crash test, the object 1, is accelerated as described above. At a certain point when a sufficient pre-selected speed has been obtained, the first, pulling trolley 20 is released from its engagement with the object 1. Upon release of the first trolley 20, a braking force is applied to the moving first tow rope 3 to which the second trolley 21 is attached. Thereby, a braking force will be applied to the object 1 via the first tow rope 3, the second trolley 21 and the second tow rope 22.

The braking force is controlled by means of controlling the machinery, here comprised by the second drum 10 and the second motor 14. The braking force is controlled such in order to make the deceleration of the object 1 resemble a specific operating condition of the object. Here the object 1 is a car, and the deceleration is to resemble a deceleration during heavy braking of the car, as would be the case upon an incident such as a car crash.

In those preferred cases when a test dummy is positioned in the car, the dummy will experience a more realistic speed change before crashing. For example the head of the dummy will be in a different position than if only free-wheeling is applied during deceleration, making it possible to study a more realistic effect of activated air bags on the dummy. Thus, the braking trolley decelerates the object without the dummy being subjected to other stresses than during normal panic braking immediately before crashing. Braking by means of the second trolley 21 and the second tow rope 22 is performed until the very moment when the first object 1 hits the second object 2. The speed of the second trolley 21 and second tow rope 22 is then rapidly reduced in order to prevent them from crashing into the crashed object 1, further affecting the test result and getting damaged.

Preferably, position and speed of the test object 1 is measured continuously during acceleration and deceleration in order to achieve a very precisely controlled impact condition upon crash. The speed and position measurements could, for example, be performed by means of a laser device 17, 18 (as indicated in Fig. 1), the output of which is transmitted and used as input to a control unit and treated by means of a computer soft- ware. Control signals to the motors, such as the second motor 14, and possibly to the brakes of the drums, such as the second drum 10 (or driving pulley, see below), are then delivered from the control unit based on the input from the position and speed measurements.

The second tow rope 22 should be pre-strained before the start of a test in order to prevent the rope from excessive elongation during braking of the object 1 by means thereof. Excessive elongation of the second tow rope 22 during the deceleration would result in difficulties in exactly controlling the speed and position of the test object by means of the second motor 14 and second drum 10, and, accordingly, in difficulties in obtaining precisely controlled impact conditions.

In Fig. 3 a single motor and single drum arrangement is shown in which, during acceleration and deceleration of collision test object 1, a first tow rope 23 is uncoiled from one half of a drum 24, guided to a pulley 25 or the like at an opposite end of the collision test path, redirected by the pulley 25 and returned to drum 24, and coiled onto the other half of the drum 24. A first trolley 20, a second trolley 21 and a second tow rope 22 are arranged in the same manner with regard to the first tow rope 23 as in the first embodiment that has been describe above. A single motor 26 is provided for the purpose of driving the drum 24. The operation of the motor 26 is controlled with regard to measured speed and position of the test object during a test. It should be understood that the device could include further . arrangements as known in the state of art, for example a further pulley arrangement for controlling the tension of the first tow rope during acceleration and deceleration.

In Fig. 4 there is shown an embodiment in which the device comprises a first and a second pulley 27, 28 one of which is driven by a schematically shown motor 29. The operation of the motor 29 is controlled with regard to measured speed and position of the test object during a test. Each pulley is a rotating disc-shaped element that is provided with a groove or the like (not shown) for guiding a first tow rope 30. The first tow rope is arranged as an endless rope running between and directed by the pulleys 27, 28. Accordingly, there is no coiling and uncoiling of the rope like in the previously described embodiments. A first trolley 20, a second trolley 21 and a second tow rope 22 are arranged in the same manner with regard to the first tow rope 30 as in the first embodiment that has been describe above.

It should be realised that the above presentation of the invention has been made by way of example, and that alternative embodiments will be obvious for a man skilled in the art. However, the scope of protection claimed is defined in the patent claims supported by the description and the annexed drawings. For example the term "trolley" should be regarded in its widest sense, and should include all kinds of mechanical couplings that could be used to connect a tow rope to an object as described above.

Claims

PATENT CLAIMS

1. A collision test device, comprising a tow rope (3), a means (9-14) for driving the tow rope (3), a first means (20) for connecting the tow rope to an object (1) that is to be accelerated by means of the moving tow rope (3) and subjected to a collision test, characterised in that it comprises a second means (21, 22) for connecting the tow rope (3) to said object (1) and operating as a brake device for subsequent deceleration of the object (1).

2. A collision test device according to claim 1, characterised in that the second connecting means (21 , 22) comprises a trolley (21) that is attached to the tow rope (3).

3. A collision test device according to claim 1 or 2, characterised in that the second connecting means (21, 22) comprises a second tow rope (22).

4. A collision test device according to claim 3, characterised in that the second tow rope (22) is arranged to be connected at one end to the test object (1) and at the other end to said trolley.

5. A collision test device according to any one of claims 1-4, characterised in that the second connecting means (21, 22) defines a generally non-elastic connection between the driven, first tow rope (3) and the test object (1).

6. A collision test device according to claim 4 or 5, characterised in that the second tow rope (22) is in a pre-strained condition before and upon start of its braking operation.

7. A collision test device according to any one of claims 1-6, characterised in that the second connecting means is attached to the tow rope (3) at a point behind the rear end of the test object (1) as seen in the moving direction thereof.

8. A collision test device according to any one of claims 1-7, characterised in that it comprises a braking arrangement (10, 14) for braking the first tow rope (3) in order to decelerate the test object (1).

9. A collision test device according to any one of claims 1-8, characterised in that the object (1) is a vehicle, preferably a vehicle for carrying human beings, and more preferably a car, bus or a truck.

10. A method of braking a collision test device in which the test device is accelerated and subsequently decelerated before colliding, the test object (1) being accelerated by means of a tow rope (3), a means (9-14) for driving the tow rope, and a means (20) for connecting the tow rope (3) to the object (1), characterised in that a decelerating force is applied to the object by means of a separate second connecting means (21, 22) that is connected to the tow rope (3) and the object (1), and that the moving first tow rope (3) is decelerated.

11. A method according to claim 10, characterised in that the second connecting means comprises a second tow rope (22), which is attached to the first tow rope (3) in one end and to the object in the other end, and which is pre-strained before the object (1) is decelerated by means thereof.

12. A method according claim 10 or 11, characterised in that the second connecting means (21, 22) is attached to the first tow rope (3) at a point behind the rear part of the object (1) as seen in the moving direction thereof.