Method and assembly for absorbing energy from loads being applied during an overload event in order to prevent damage

Abstract

A method and an assembly for absorbing energy during an overload event. An energy absorber reduces loads on an object being transported on a loading unit during a single overload event, which introduces such a high degree of energy that there is an overwhelming likelihood the object would be damaged without an energy absorber. Measurement values on the current state of the loading unit are sensed. A control device determines an overload event and a damping of the energy absorber is set to a high value after the detection of the overload event. The damping is maintained for a specified prolonged time period and controlled dependent on the measurement values during the overload event to increase the load for objects during the specified time period initially to a specified threshold load and after the specified time dependent on the measurement values detected during the overload event.

Claims

1. A method for absorbing energy during an overload event using an energy absorber in order to reduce loads on an object being transported on a loading unit, the method comprising: providing an energy absorber that is suitable for absorbing energy during a single overload event, which introduces such a degree of energy into the loading unit that would cause the object to be damaged without an energy absorber, in order to reduce the resulting load on the object during the overload event by way of the energy absorption of the energy absorber, the energy absorber having a maximum value of damping and a minimum value of damping; detecting measurement values with a sensor device about a current state of the loading unit; receiving the measurement values in a control device and determining an overload event from the recorded measurement values; and at least immediately after the overload event is detected, setting a damping of the energy absorber to a relatively high value that is closer to the maximum value than to the minimum value and maintaining the damping for a specified time period; setting the specified time period such that during the specified time period a plurality of successive measurement values are detected, and controlling the damping after the specified time period dependent on the measurement values detected during the overload event, in order to initially increase the load on the object being transported on the loading unit up to a specified threshold load during the specified time period and, after the specified time period, to control the load in dependence on the measurement values detected during the overload event.

2. The method according to claim 1, wherein the control device periodically derives characteristic parameters for a load on the loading unit from the measurement values.

3. The method according to claim 1, which comprises providing a shear device in the loading unit, which is sheared off when the load being applied to the loading unit exceeds a predetermined amount, and wherein the control device detects an overload event when a shear sensor detects the shear device being sheared.

4. The method according to claim 1, wherein the control device detects an overload event when a characteristic parameter exceeds a predetermined amount.

5. The method according to claim 4, which comprises reducing the damping to a lesser value of the damping immediately after the specified time period, and then controlling the damping in dependence on the characteristic parameter.

6. The method according to claim 1, which comprises maintaining the damping at the relatively high value beyond the specified time period.

7. The method according to claim 1, which comprises setting a damping of the energy absorber during the specified time period after an overload event is detected to the maximum value.

8. The method according to claim 1, which comprises, after the specified time period has ended, controlling the energy absorber time-dependently in dependence on the respective currently derived characteristic parameter.

9. The method according to claim 1, which comprises reducing the damping of the energy absorber when the characteristic parameter reaches or exceeds a specified threshold load.

10. The method according to claim 1, wherein the acceptable threshold load is predetermined for a person.

11. The method according to claim 1, which comprises taking into consideration sensor values of a sensor unit located on the object.

12. The method according to claim 1, wherein a sensor device is coupled with the loading unit, in order to determine a weight of an object being transported and an acceleration of the loading unit.

13. The method according to claim 1, which comprises providing for a comfort function and damping minor impacts below an overload event threshold.

14. The method according to claim 1, wherein the energy absorber has an absorber valve, and the method comprises damping the absorber valve by way of a strength of an applied magnetic field.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) Further advantages and features of the present invention can be seen from the description of the embodiment examples that are explained below with reference to the attached figures.

(2) The figures show:

(3) FIG. 1 a schematic perspective view of an assembly according to the invention;

(4) FIG. 2 a front view of the assembly according to FIG. 1;

(5) FIG. 3 a side section of the assembly according to FIG. 1 in the damping state;

(6) FIG. 4 a front section of the assembly according to FIG. 1 in the resting state;

(7) FIG. 5 a vehicle with assemblies according to the invention for protecting passengers from explosions;

(8) FIG. 6 a chronological sequence of a damping force of the assembly according to FIG. 1 during an overload event; and

(9) FIG. 7 a schematic flowchart of the assembly's control during an overload event according to FIG. 6.

DESCRIPTION OF THE INVENTION

(10) FIG. 1 shows a schematic perspective view of an assembly 1 according to the invention. The assembly comprises an absorber cylinder 5, on one end of which an attachment device 3 and on the other end of which a retention device 4 is provided. The retention device 4 and the attachment device 3 each have two laterally protruding arms, with a preloading spring 43 of a preloading device 38 placed on either of them, in order to reset the assembly after an overload event 63 to the resting state 40, which is also shown in FIG. 1.

(11) The assembly 1 is provided to absorb energy or damp relative movements between the attachment device 3 and the retention device 4. For such purpose, the retention device 4 is connected with the piston device 6 of the energy absorber, while the attachment device 3 is securely connected with the absorber cylinder 5. At the upper end, an end cap 39 can be seen that closes off from the outside and limits the second chamber of the absorber chamber 9 concealed in the interior. The assembly 1 is in particular inserted in a loading unit 100 between a mounting unit 101 and a bearing unit 102 (see FIG. 5).

(12) FIG. 2 shows the assembly 1 in a front view. A symmetry axis 30 extends centrally through the absorber cylinder 5, the section in FIG. 3 running through said symmetry axis.

(13) FIG. 3 shows a section according to FIG. 2 in a resting state 40. In addition, a seat assembly 21 is schematically shown as a loading unit 100. The loading unit 100 has a mounting unit 101 or seating surface 21a, on which an object 103 such as a person 105, e.g. a soldier in a personnel carrier, can be seated.

(14) In the interior of the absorber cylinder 5, the section shows the absorber piston 7 and the piston rod 8 of the piston device 6 connected therewith. The absorber piston 7 divides the absorber chamber 9 located in the interior of the absorber cylinder 5 into a first chamber 10 and a second chamber 11. The second chamber 11 is limited from the outside by the end cap 39 and sealed airtight.

(15) In the resting state, the first chamber 10 is at least partially and in particular entirely filled with absorber fluid 12. When an overload event 63 occurs, the piston rod 8 is retracted from the absorber cylinder 5, so that the absorber fluid 12 in the first chamber 10 passes through the absorber channel 14 in the absorber piston 7 and into the second chamber 11. In the resting state, the second chamber 11 can already be filled to a certain extent with absorber fluid 12. However, it is also possible that in the resting state, the second chamber 11 is filled with only little absorber fluid 12 or none at all, but with air or another compressible gas or medium.

(16) It is clearly visible that the piston rod 8 has a very large diameter, so that for the first chamber 10 only a relatively small annular gap remains around the piston rod. Thus, when the absorber piston 7 is extended, only a relatively small volume of absorber fluid 12 is displaced from the first chamber 10. Therefore, the flow velocities of the absorber fluid 12 in the absorber channel 14 remain low even during overload events 63 caused by explosions, so that the length of the absorber pistons 7 is sufficient to influence the flow as desired using the magnetic field of the electric coil as the field generation device 16.

(17) When the flowing fluid 12 passes from the first chamber 10 into the second chamber 11, the absorber fluid 12 is diverted towards the interior by the radial flow openings 44 that radially obliquely extend towards the interior from the outside. This means that the flow channel or absorber channel 14 is radially placed further inside than the first chamber 10. This enables the effective use of the interior of the absorber piston 7 for generating the required magnetic field and for the absorber channel 14.

(18) The piston rod 8 is shown here with a considerably greater thickness than would be necessary for ensuring stability. Therefore, an empty space 22 is provided in the piston rod 8, which is shown here as a blind hole. The blind hole 22 extends from the end 26 opposite the piston into the piston rod 8. The empty space 22 can extend up to just in front of the absorber piston 7, so that the length of the empty space 22 extends over three-quarters or more of the length of the piston rod 8 up to the absorber piston 7. The empty space 22 can be used accordingly. The control device 48 and an energy device 47 are located here in the interior of the empty space 22. The control device 48 is connected to the electric coil 16, in order to control it. Moreover, the control device 48 is connected to a sensor device 61 in order to accept and process the load on the loading unit 100 identified as a seat assembly 21.

(19) The energy storage device 47 ensures that even in the event of a loss of power on board the means of transport, the assembly 1 holds sufficient energy to control the energy absorber 2. The energy storage device can be a capacitor or a rechargeable battery.

(20) The absorber piston 7 not only separates the first chamber 10 from the second chamber 11, but also forms a flow valve 13, which can be controlled by means of the control device 48.

(21) FIG. 4 shows another cross section of assembly 1, whereas in this case it also shows the preloading device 38 as the resetting device 32 to 43 in section. For the sake of clarity, the energy storage device 47 and the control device 48 in the empty space 22 are not shown in this figure. The first chamber 10 forms an annular gap 28 around the piston rod 8. In this case, a radial extension of the annular gap 28 is smaller of than the wall thickness of the hollow piston rod 8.

(22) FIG. 5 shows a schematic view of a means of transport 50, such as a personnel carrier, provided with assemblies 1 according to the invention, in order to protect the passengers during explosions. The means of transport 50 has a body 51, with mine blast protection seats 60 attached thereto as assemblies 1. The vehicle 50 can be driven using wheels with tyres 52. During an overload event 63, e.g. an explosion, the vehicle 50 is launched into the air, a damped movement occurs of the loading unit 100 of the assemblies 1 which, identified here as a seat assembly 21, in order to protect the persons seated on it from permanent damage.

(23) FIG. 6 shows the chronological progression 70 of the relative adjusted electric current of the energy absorber 2 during an overload event 63. Said overload event occurs, as an example, when an armoured personnel carrier moves over a land mine and said mine detonates.

(24) The overload event 63 is detected, for example, when the shear pin of the shear device 42 is sheared, because the load being applied to it exceeds the shear force. This results in the electrically conductive contact being interrupted by the shear device 42, which is detected by the control device 48. A corresponding control sequence is then activated. This point in time is designated t0.

(25) Alternatively, or additionally, the control device 48 can also run an alternative routine for detecting an overload event. The control device 48 can also poll and evaluate the respective current measurement values in certain intervals from the sensor device 61 and the sensor unit 68 and further sensor means, to periodically derive a parameter 65 from a single measurement value from one sensor or multiple measurement values from different sensors. The parameter 65, as an example, can be determined every 10 ms or other suitable intervals. After an overload event 63 is detected, it is preferable that a shorter interval be selected.

(26) At the point in time to, a strong electric current is directly applied to the electric coil 16. In particular, the maximum possible current is immediately applied to the electric coil 16, in order to preferably immediately block the energy absorber 2. The magnetic field generated by the electric coil 16 chains up the magnetorheological particles in the magnetorheological absorber fluid 12 within the absorber channel 14. In order to force the absorber fluid 12 through the absorber channel 14, the force being applied must be sufficiently great so that the chained up magnetorheological particles (reversibly) shear off. The maximum force is therefore adjusted in such a way that during an overload event it is normally also sufficient to prevent the relative movement of the retention device 4 relative to the attachment device 3. The electrical current remains at 100% for a pre-set time period 67. The length of the specified period 67 can be pre-set, however, it can also be variable depending on, for example, the weight of the person 105 seated on the seat assembly 21. It is also possible that the weight of a device 104 as the object 103 is recorded and taken into consideration. By such means, the forces being applied can be determined for a detected acceleration. In many cases, an acceptable maximum force may not be exceeded. The force is calculated as the product of acceleration and mass.

(27) The specified period 67 is preferably chosen based on measurements, calculations and experience in a way that within said period 67, the load on the back or the spine of a typical person is not exceeded in the case of damage 63. The previously unloaded spine of a person 105, seated on the seat assembly 21, is then preloaded during an overload event 63. Likewise, various springs and cushions of the seat assembly 21 and mechanical components acting as springs are also preloaded. If articles 104 are being transported, this will be taken into consideration accordingly, in order to enable the protection of sensitive devices during transport.

(28) After the time period 67 has ended, the load on the person at the point in time t1 may have reached the maximum specified load threshold 81. At the same time, the threshold load 64 is also reached, which may not be exceeded. In order to achieve optimal control, the electrical current of the electric coil 16 is heavily reduced down to a reduced value 72. In particular, the electric current of the electric coil 16 is abruptly reduced to zero. This prevents the load progression 80 from overshooting.

(29) Initially, the load progression 80 rises rapidly and then reaches a plateau 82. The energy absorber 2 now allows a relative movement of the seat assembly 21 to the body 51 of the vehicle 50. At the point in time t2, the electric current is first increased to the value 78 and from that moment on the current of the electric coil 16 progresses in a ramp-like manner. The damping increases correspondingly, so that the movement speed of the absorber piston 7 is reduced and the load is maintained at the high plateau 82. By this method, the load is constantly maintained as high as is acceptable. This ensures that the largest possible reserves remain available at all times, in order to damp the overload event without any permanent damage to a person seated on the mine blast protection seat. If an energy absorber or damper abuts, the load increases abruptly and can continue to increase beyond acceptable thresholds. The invention significantly reduces risks of injury. At the point in time t3, the overload event is over and the current is switched off again.

(30) During the time interval starting at the point in time t1, the damping is controlled in a regulated manner. For this purpose, the measurement values from the sensors 61 and 68 are periodically retrieved. A parameter 65 is periodically derived from the measurement results, which is used for subsequent control. A current load is derived from the parameter 65, if the parameter does not directly reflect the current load. By means of the current load the electric current is controlled so that the load is preferably maintained just under the threshold load 64 and preferably does not exceed it.

(31) If it is detected that the maximum load of the overload event has been exceeded, the damping can be adjusted to a softer setting in order to increase comfort.

(32) FIG. 6 additionally contains a dot-dashed line 83 that reflects a different load progression. The progression of the line 83 also begins at the point in time t0, when an overload event 63 is detected. The electric current is increased to 100% once again and at the point in time t1 it is reduced to zero. At the point in time t2, the electric current is increased up to the value 78 and subsequently, it is increased in a ramp-like manner (73) until the point in time t2a. The load then decreases, so that the damping can be adjusted to a softer setting and the electric current can be reduced.

(33) In one version, the parameter 65 is periodically determined at least from the point in time t0 also during the specified period 67 at its respective current value. Control is then carried out at all times by means of the respective determined parameter 65, until, for example, it falls back below an overload event threshold 69.

(34) If no shear device 42 is provided, the overload event threshold 69 can also be used as the threshold for detecting an overload event 63. For loads smaller than the overload event threshold 69, the energy absorber can be used in a comfort function and absorb minor impacts. A certain proportion of the vertical lift may be reserved for overload events. The proportion reserved can be dependent on the current level of hazard.

(35) FIG. 7 shows a highly schematic representation of a control progression in a specific embodiment. The process is initiated at the starting point 84. In this case, for example, the shear device 42 is polled in an endless loop in order to detect an explosion. If an explosion or similar disruption was detected during step 85, the endless loop is interrupted at the branching 94 and the control 48 is initialised. This is carried out in step 86. At this time, the control algorithm 87 is also caused to then apply the maximum damping 66 or 71 to the energy absorber during the specified time period 67. Said time period 67 is used to preload all (mechanical) components involved, including the object 103. Starting from the point in time t0 and in particular after the time period 103 has ended, characteristic parameters 65 are periodically derived from measurement values from measurement 89 in a parameter determination 90. The parameters 65 and, in this case, also the measurement values themselves are passed on to the regulation algorithm 88. The regulation algorithm 88 passes on the data and a control variable is calculated in step 91. In order to calculate the control variable and, in this case, the value of the current, data from the control algorithm 87, which is also provided the measurement values, are used in addition. Finally, the actor in step 92 is powered. The control circuit is then run through again, then returning to step 88. At this time, the current measurement values are received. The actual value is compared with the desired value and re-adjusted when appropriate. If it is detected during step 95 that the overload event or explosion has ended, the end 93 of the control is initiated by means of the branching 95. The end 93 can lead directly back to the start 84, in order to detect further disruptions.

(36) In all embodiments, the object being transported on a loading unit can be directly or indirectly coupled on and/or with the loading unit and/or placed thereon. The connection can be permanent and/or releasable. Or, the object is placed on the loading unit and held in place by the force of its weight.

LIST OF REFERENCE NUMERALS

(37) TABLE-US-00001 1 assembly 2 energy absorber 3 attachment device 4 retention device 5 absorber cylinder 6 piston device 7 absorber piston 8 piston rod 9 absorber chamber 10 first chamber 11 second chamber 12 absorber fluid 13 absorber valve 14 absorber channel 16 electric coil 16a permanent Magnet 21 seat assembly 21a seating surface 22 empty space (in 8) 25 wall 26 end 28 annular gap 30 symmetry axis (from 5, 8) 32 resetting device 38 preloading device 39 end cap 40 resting state 41 absorber state 42 shear device 43 preloading spring 45 guide bushing 46 seal 47 energy storage device 48 control device 50 means of transport, vehicle 51 body 52 tyre 60 mine blast protection seat 61 sensor device 62 measurement values 63 overload event 64 threshold load 65 parameter 66 predetermined amount 67 specified time period 68 sensor unit 69 overload event threshold 70 electric current progression 71 maximum amount 72 reduced amount 73 ramp 80 load progression 81 maximum load 82 plateau 83 decreasing load 84 start 85 detection of explosion 86 initialisation 87 control algorithm 88 regulation algorithm 89 measurement 90 parameter determination 91 determining control variable 92 applying current to actor 93 end 94 branching 95 branching t0 point in time t1 point in time t2 point in time t2a point in time t3 point in time 100 loading unit 101 mounting unit 102 bearing unit 103 object 104 article 105 person