WO2003027628A1

WO2003027628A1 - Apparatus for testing a headrest

Info

Publication number: WO2003027628A1
Application number: PCT/SE2002/001719
Authority: WO
Inventors: Gunnar Baltzer
Original assignee: Gunnar Baltzer
Priority date: 2001-09-24
Filing date: 2002-09-23
Publication date: 2003-04-03
Also published as: SE0103163D0

Abstract

The invention refers to an apparatus for testing a headrest (13) for a vehicle. The apparatus includes a support member (1) defining a path and a carriage (6) movably provided on the support member to be movable along the path. The carriage has a weight and includes a model (11) having a neck portion similar to a human's neck. A holding member (12) is mounted on the support member (1) for holding the headrest (13) to be tested in a test position. An ejecting member (25) accelerates the carriage to move along the path with a forward velocity (∩) towards the holding member (12) . The model will then hit the headrest, penetrate into the headrest and be given a return velocity (∩) .A measuring device (30-42) measures at least one parameter reflecting the quality of the headrest (13) .

Description

APPARATUS FOR TESTING A HEADREST

THE BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention refers to an apparatus for testing a headrest for a vehicle. In this application, a headrest is given a broad definition as a support device, which is mounted on the top of a vehicle chair and arranged to support the head of a person sitting in the chair in case of a vehicle collision. It also exits other names for the headrest such as a head rest, a head restraint etc.

A freguent kind of injuries caused by traffic collisions is the so-called whiplash injury. Whiplash injuries may be caused by a rear-end collision already at relatively low speed. This kind of injuries arises in the area of the neck of the driver and or passenger of the vehicle hit from behind, and frequently results in life-long suffering and large costs for the society.

Research has been made in order to try to explain the occurrence of whiplash injuries. Although there are yet no definite explanations available as to which organs are injured and how the injury exactly arises, many researcher believe that these explanations are to be found in the movement of the head into the headrest and the rebound of the head against the headrest . The rebound causes the head to be violently accelerated in a direction opposite to said movement into the headrest. It therefore appears as an essential task to be able to design a headrest in such a manner that the effects of the rebound are reduced and that the head is softly retarded during the movement into the headrest. Such a design could be obtained by a different structure of the headrest and by using different shock absorbing materials in the headrest.

In order to accomplish this task, it is important to be able to test different headrest constructions and different headrest materials. There are various apparatuses developed for testing the resiliency and hardness of different materials, see US-A-3, 965, 727, for instance. This document shows a device for manually measuring the hardness of a plastic foam material by pressing a blade-shaped indentor into the material to be tested. This prior art is not concerned with the specific problem of testing headrests for vehicles .

The Swedish Patent Application No. 0100324-3, which was filed on 2 February, 2001, discloses various materials developed to be used as a shock absorbing material in headrests. This document also discloses, in a schematic manner, an apparatus for evaluating the deformation behaviour of headrests due to the impact of a solid body.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an apparatus for permitting a relevant testing of the quality properties of a headrest for a vehicle.

This object is obtained by an apparatus for testing a headrest for a vehicle, including: a support member defining a path, a carriage movably provided on the support member to be movable along the path, said carriage having a weight and including a model having a neck portion similar to a human' s neck, a holding member mounted on the support member and arranged to hold the headrest to be tested in a test position, an ejecting member arranged to accelerate the carriage in such a way that the carriage will move along the path with a forward velocity towards the holding member, wherein the said model will hit the headrest, penetrate into the headrest and be given a return velocity, and a measuring device arranged to measure at least one parameter reflecting a property quality of the headrest.

By such an apparatus, it is possible to test various headrests and various headrest materials in an appropriate manner. The apparatus permits testing of properties, such as the deformation behaviour as well as the rebound properties of the headrest in a convenient and reliable manner. The tests can be repeated with maintained test conditions. Consequently, the test results from different headrest are comparable. The apparatus permits a realistic simulation of a car crash, and especially a rear-end car collision, i.e. the headrest can be tested under conditions similar to a real collision.

According to an embodiment of the invention, said parameter includes the forward velocity of the model before the model hits the headrest and the return velocity of the model when the model has left the headrest. Hence, it is possible to obtain a parameter indicating the relation between the forward velocity and the return velocity.

According to a further embodiment of the invention, said parameter includes the level of the retardation of the model when penetrating into the headrest. According to a further embodiment of the invention, said parameter includes the time period during which the model is in contact with the headrest.

According to a further embodiment of the invention, said parameter includes a distance corresponding to the extent of the penetration of the model into the headrest.

According to a further embodiment of the invention, the measuring device includes an evaluation unit arranged to display said parameter. The evaluation unit may include a processing member for making an appropriate calculation of sensed parameters, and a display member. It is thus possible to display the actual value of said parameter.

According to a further embodiment of the invention, the measuring device includes an accelerometer arranged to sense the retardation or the acceleration of the model. By such an accelerometer, the retardation mentioned above may be sensed. By the accelerometer, it is also possible to sense when and/or at which position the acceleration is zero, i.e. when the movement is continuing towards the headrest, when the movement has stopped, and when the model has left the contact with the headrest.

According to a further embodiment of the invention, the measuring device includes a timer. The evaluation unit may then be arranged to display the forward and return movement of the model as function of the time.

According to a further embodiment of the invention, the measuring device includes a position sensor arranged to sense the position of the model in relation to the headrest. In that connection, the measuring device may be arranged to calculate said velocities by means of the position sensed by the position sensor and the timer. Furthermore, said position sensor includes an optical sensor mounted on the support member and a scale member mounted on the carriage, wherein said optical sensor may be adjustably movable along the support member in a direction extending in parallel with the path.

According to a further embodiment of the invention, the measuring device includes a registering member arranged to register a first position of the model when the model gets in contact with the headrest and a following, second position of the model when the acceleration is zero, wherein said first and second positions being sensed by said position sensor. The registering member includes a marker member mounted on the support member and a marking member mounted on the carriage. The marker member is arranged to make a mark on said marking member at said first position and at said second position.

According to a further embodiment of the invention, the apparatus includes an elongated plate member mounted on the carriage and extending in parallel to the path, wherein said plate member carries said scale member and said marking member.

According to a further embodiment of the invention, the path extends along a substantially horizontal direction.

According to a further embodiment of the invention, the support member includes a rail member forming the path. Such rail member may, for instance, include two parallel rails extending in a substantially horizontal direction.

According to a further embodiment of the invention, the holding member is mounted on the support member to be located in an angular test position with respect to the path, wherein said angular test position is adjustable around an axis extending substantially perpendicularly to the path. By such an adjustment possibility, the headrest may be tested in different simulated crash situations.

According to a further embodiment of the invention, the ejecting member includes a cylinder mounted on the support member and a piston, which is movable in the cylinder and arranged to provide said acceleration of the carriage.

According to a further embodiment of the invention, the weight of the carriage is adjustable. Consequently, the apparatus is adaptable to test a headrest for different individuals .

According to a further embodiment of the invention, the ejecting member is adjustable to accelerate the carriage to selected forward velocity. Said forward velocity may correspond to the hitting speed of a passenger' s head on a headrest in a real crash event, and may lie in the range from 0,5 m/s to 10 m/s, for instance 1, 2, 3, 4, 5 or 10 m/s .

BRIEF DESCRIPTION OF THE DRAWING

The present invention is now to be explained more closely by a description of an embodiment and with reference to the drawings attached.

Fig. 1 discloses schematically a view from above of an apparatus according to the invention.

Fig. 2 discloses schematically a sectional view along the lines II-II in Fig. 1. Fig. 3 discloses schematically a side view of a forward part of the apparatus according ^'to the invention. Fig. 4 discloses a diagram indicating the acceleration of a carriage of the apparatus, wherein the carriage has a forward initial velocity of 1 m/s.

Fig. 5 discloses a diagram indicating the acceleration of said carriage having a forward initial velocity of

2 m/s.

Fig. 6 discloses a diagram indicating the acceleration of said carriage having a forward initial velocity of

3 m/s .

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

Fig s 1 - 3 disclose an apparatus according to the present invention. The apparatus includes a support member 1, which includes a base element 2 adapted to rest on a substantially horizontal floor 3 and two lateral support pieces 4 and 5. The lateral support pieces 4, 5 extend substantially perpendicularly to the base element 2, i.e. substantially vertically upwards from the base element 2.

The apparatus also includes a carriage 6, which is movable along a path defined by the support member 1 and extending in a substantially horizontal direction. Each of the lateral support members 4 and 5 carries an elongated rail 7 and 8. The rails 7, 8 extend along and are attached to the lateral support pieces 4, 5 in a substantially horizontal longitudinal direction x. The rails 7, 8 form said path. Each rail 7, 8 is arranged to engage a corresponding ball member 9 and 10 attached to the carriage 6 in such a manner that the carriage is movable along the rails 7, 8.

The carriage 6 includes a model 11 having a neck portion similar to a human's neck. The carriage 6 has a certain weight, which advantageously is adjustable. For instance, the weight may be adjustable by replacement of the model 11 to another model having a differing weight or by replacement of a special weight member (not disclosed) .

Furthermore, the apparatus includes a holding member 12, which is mounted on the lateral support pieces 5 and 6 of the support member 1 at a forward end of the apparatus . The holding member is arranged to hold, in a releasable manner, a headrest 13 to be tested in a test position. In the embodiment disclosed, the headrest 13 includes two legs 14, one of which is disclosed in Fig 3. The legs 14 are clamped between a rear transversal beam 15 and a forward transversal beam 16 by means of one or two clamping screws 17. The rear transversal beam 15 is, at its lateral ends, attached to a respective longitudinal beam 18, one of which is disclosed in Fig 3. The longitudinal beams 18 are connected to the lateral support pieces 4 and 5 by means of a transversal shaft 19, which extends substantially perpendicularly to the direction x and around which the longitudinal beams 18 are rotatable. Consequently, also the holding member 12 is rotatable to permit an angular adjustment of the test position of the headrest 13 with respect to the longitudinal path, see arrow c in Fig 3. The rear ends of the longitudinal beams 18 are joined to a respective vertical beam 20, one of which is disclosed in Fig 3 and carries a third locking screw 21. The third locking screw 21 engages a guide beam 22, which in its turn is rotatable around a fourth locking screw 23. The fourth locking screw 23 permits locking of the position of the guide beam 22 with respect to one of the lateral support pieces 5, whereas the third locking screw 21 permits locking of the position of the guide beam 22 with respect to the vertical beam 20. Consequently, the holding member 12 and the headrest 13 may be locked in a desired angular position by means of the locking screws 21 and 23. The apparatus also includes an ejecting member 25 provided at the rear end of the apparatus and arranged to accelerate the carriage 6 to move along the path with a forward velocity, see arrow a in Fig 1. The ejecting member 25 is thus arranged to accelerate the carriage 6 towards the holding member 12 and the headrest 13 in such a manner that the model 11 will hit the headrest 13, penetrate into the headrest 13 and be given a return velocity, see arrow b in Fig 1.

The ejecting member 25 includes a cylinder 26 mounted on the support member 1 and a piston 27, which is movable in the cylinder 26 and arranged to provide said acceleration of the carriage 6. The ejecting member 25 may be pneumatically, hydraulically or electrically driven. The ejecting member 25 is adjustable to accelerate the carriage 6 to a selected forward velocity a in the range from 0,5 m/s to 10 m/s, for instance 1, 2, 3, 4, 5 or 10 m/s.

As appears from Fig 1, the apparatus also includes a shock absorbing device having two forward shock absorbing elements 28' arranged to stop the carriage 6 after the rebound against the head rest 13. The shock absorbing device also includes two rear shock absorbing elements 28'' co-acting with a stop member 29 mounted on the piston 27. The rear shock absorbing elements 28'' are arranged to stop the forward movement of the piston 27 after the piston 27 has accelerated the carriage 6. The shock absorbing elements 28', 28'' are rigidly mounted to the support member 1.

Furthermore, the apparatus includes a measuring device arranged to measure at least one parameter reflecting quality properties of the headrest 13. The measuring device includes an evaluation unit 30, including a processing member 31 for making the necessary calculations and a display member 32 arranged to display said parameter. For instance, the evaluation unit 30 may be realised by means of an oscilloscope.

The measuring device also includes an accelerometer 33, which is mounted on the carriage 6 and thus arranged to sense the acceleration of the model 11. The accelerometer 33 is connected to the processing member 31. Moreover, the measuring device includes a timer 34 forming a part of the evaluation unit 30. Consequently, the display member 32 may display the acceleration of the model 11, which is sensed by the accelerometer, as function of the time.

The measuring device also includes a position sensor arranged to sense the position of the model 11 in relation to the headrest 13. The position sensor includes a sensor support 35, which is mounted on one of the lateral support pieces 5 of the support member 1. The sensor support 35 carries an optical sensor 36, which is connected to the processing member 31. The position sensor also includes a scale member 37 provided on the carriage 6. The scale member 37 is carried by an elongated plate member 38, which is mounted on the carriage 6 and extends in parallel to the path and to the direction x. The scale member 37 includes vertical lines, for instance, which are positioned at a regular interval and with an equal distance from each other of 50 mm, for instance. When the carriage 6 moves along the path the optical sensor 36 may thus sense the vertical lines of the scale member 37 as they pass the sensor 36. For each such vertical line an electric pulse is generated by the optical sensor 36 and transferred to the evaluation unit 30.

Consequently, by means of the positions sensed by the position sensor, the evaluation unit 30 can calculate the forward velocity a of the model 11 and the rearward velocity b of the model 11. The sensor support 35 is movable along the lateral support piece 5 in a direction extending in parallel with the path and the direction x. The sensor support 35 may be lock in an arbitrary position by means of a locking screw 39.

Furthermore, the measuring device includes a registering member. The registering member 40 is connected to the processing member 31 and includes a marker member 40, including a pen 41, for instance, and a marking member 42 in the form of a paper, for instance. The marker member 40 is mounted on the sensor support 35. The paper 42 is arranged on the plate member 38. The registering member is, in cooperation with the position sensor, arranged to register a first position of the model 11 when the model 11 gets into contact with the headrest 13 and a following, second position of the model 11 when the acceleration is zero, i.e. when the model 11 changes direction from the forward direction a to the rearward direction b. In order to obtain such a registration, the sensor support 35 may be adjusted to a position along the lateral support member 5, where the optical sensor 36 is located opposite to a specific line of the scale member 37. Especially, the pen 41 may then be arranged to be be lowered to the paper 42 when the model 11 gets into contact with the headrest 13 and to remain in contact with the paper at least until the acceleration is zero. Consequently a line is created, which is a measure of the penetration depth of the model 11 into the headrest 13.

Figs 4 - 6 disclose the test result, which can be obtained by the apparatus described in this application for three different forward velocities, namely 1, 2 and 3 m/s. In these figures, the horizontal axis T illustrates the time, whereas the line 50 illustrates the retardation and acceleration of the model 11. In other words, Figs 4 - 6 indicate the velocity changes of the carriage 6 and the model 11, when hitting the headrest 13 held by the holding member 12. The line 51 illustrates the position of the model 11, and more precisely the peaks 53-58 illustrates each time the model 11, or sensor 36, passes a vertical line of the scale member 37.

The present invention is not limited to the embodiment disclosed but may be varied and modified within the scope of the following claims.

Claims

1. An apparatus for testing a headrest for a vehicle, including: a support member (1) defining a path, a carriage (6) movably provided on the support member (1) to be movable along the path, said carriage (6) having a weight and including a model (11) having a neck portion similar to a human' s neck, a holding member (12) mounted on the support member (1) and arranged to hold the headrest (13) to be tested in a test position, an ejecting member (25) arranged to accelerate the carriage (6) in such a way that the carriage will move along the path with a forward velocity (a) towards the holding member (12) , wherein the said model will hit the headrest (13), penetrate into the headrest and be given a return velocity (b) , and measuring device (30-42) arranged to measure at least one parameter reflecting a property of the headrest (13) .

2. An apparatus according to claim 1, wherein said parameter includes the forward velocity (a) of the model

(11) before the model hits the headrest (13) and the return velocity (b) of the model when the model has left the headrest (13) .

3. An apparatus according to any one of the preceding claims, wherein said parameter includes the level of the retardation of the model (11) when penetrating into the headrest (13) .

4. An apparatus according to any one of the preceding claims, wherein said parameter includes the time period during which the model (11) is in contact with the headrest

5. An apparatus according to any one of the preceding claims, wherein said parameter includes a distance corresponding to the extent of the penetration of the model (11) into the headrest (13) .

6. An apparatus according to any one of the preceding claims, wherein the measuring device (30-42) includes an evaluation unit (30) arranged to display said parameter

7. An apparatus according to any one of the preceding claims, wherein the measuring device includes an accelerometer (33) arranged to sense the retardation or acceleration of the model (11) .

8. An apparatus according to any one of the preceding claims, wherein the measuring device (30-42) includes a timer (34) .

9. An apparatus according to claims 6, 7 and 8, wherein the evaluation unit (30) is arranged to display the forward and return movement of the model (11) as function of the time.

10. An apparatus according to any one of the preceding claims, wherein the measuring device (30-42) includes a position sensor (36, 37) arranged to sense the position of the model (11) in relation to the headrest.

11. An apparatus according to claims 2, 8 and 10, wherein the measuring device (30-42) is arranged to calculate said velocities (a, b) by means of the position sensed by the position sensor (36, 37) and the timer (34) .

12. An apparatus according to claim 11, wherein said position sensor (36, 37) includes an optical sensor (36) mounted on the support member (1, 2, 4, 5) and a scale member (37) mounted on the carriage (6).

13. An apparatus according to claim 12, wherein said optical sensor (36) is movably adjustable along the support member (5) in a direction (x) extending in parallel with the path.

14. An apparatus according to any one of claims 10 to 13, wherein the measuring device (30-42) includes a registering member (40-42) arranged to register a first position of the model (11) when the model gets in contact with the headrest

(13) and a following, second position of the model (11) when the acceleration is zero, said first and second positions being sensed by said position sensor (36, 37) .

15. An apparatus according to claim 14, wherein said registering member (40-42) includes a marker member (40) mounted on the support member (5) and a marking member (42) mounted on the carriage (6), wherein said marker member (40) is arranged to make a mark on said marking member (42) at said first position and at said second position.

16. An apparatus according to claims 12 and 15, wherein the apparatus includes an elongated plate member (38) mounted on the carriage and extending in parallel to the path, wherein said plate member (38) carries said scale member (37) and said marking member (42) .

17. An apparatus according to any one of the preceding claims, wherein the path extends along a substantially horizontal direction (x) .

18. An apparatus according to any one of the preceding claims, wherein the support member (1) includes a rail member (7, 8) forming the path.

19. An apparatus according to any one of the preceding claims, wherein the holding member (12) is mounted on the support member (1) to be located in an angular test position with respect to the path, wherein said angular test position is adjustable around an axis (19) extending substantially perpendicular to the path (x) .

20. An apparatus according to any one of the preceding claims, wherein the ejecting member (25) includes a cylinder

(26) mounted on the support member and a piston (27) , which is movable in the cylinder and arranged to provide said acceleration of the carriage (6) .

21. An apparatus according to any one of the preceding claims, wherein the weight of the carriage (6) is adjustable.

22. An apparatus according to any one of the preceding claims, wherein the ejecting member (25) is adjustable to accelerate the carriage (6) to a selected forward velocity (a) .