SAFETY DEVICE FOR VEHICLES

Abstract: The invention relates to a safety device for detecting rotation of a vehicle about its longitudinal or crosswise axis, or about both axes, and the activation of at least one protective device (9) depending on said detection, comprising means (1, 7, 3) for determining the angular position ( phi ) of the vehicle about at least one of said axes, and the angular velocity ( phi , gamma ) of said rotation, and a control unit (3) arranged for said activation if certain predetermined threshold conditions (A-S) regarding the operational condition of the vehicle are fulfilled. The invention is characterized in that at least one of said threshold values (C; P) is variable and depends on at least one predetermined operational state of the vehicle. By means of the invention, an improved device for reliable and quick detection of a roll-over state in a vehicle is obtained.

Description: TITLE : Safety device for vehicles. TECHNICAL FIELD OF THE INVENTION: The present invention relates to a safety device for vehicles, according to the preamble of appended claim 1. In particular, the invention is intended to detect a state in a vehicle which corresponds to the vehicle rotating about its longitudinal axis (so called "roll-over"). The invention also relates to a method when using such a safety device, according to the preamble of appended claim 14. TECHNICAL BACKGROUND: In connection with motor vehicles, there are certain kinds of accidents where the vehicle tilts so heavily that it rolls about its longitudinal axis. This, of course, causes great risks of injuries to those travelling in the vehicle. Recently, safety systems have thus been designed which comprise a sensor arranged to detect the presence of such a "roll-over" state. Such a sensor can suitably be connected to a control unit, which in turn is connected to some kind of protection device, which can be activated to protect those travelling in the vehicle when the vehicle rolls over. An example of such a safety device is a safety bar intended for open-top vehicles, which during roll-over is unfolded from a folded-away position to a position where it extends across the passenger compartment, and thus protects the passengers. For reasons of safety, it is thus desirable to detect this roll-over state in a reliable manner. In particular, it must be possible to detect such a state at an early stage during an accident, and in such a way that it can be separated from other similar states of the vehicle. In this way, it is possible to prevent unnecessary activation of safety devices in the vehicle. In connection with safety systems of the above-mentioned kind, it is previously known to utilize a sensor which detects the angle of inclination of the vehicle relative to the horizontal plane. If the inclination of the vehicle exceeds a certain predetermined threshold value, a signal can be generated which in turn activates a safety device. A previously known system for detecting a roll-over state in a vehicle, and for activation of a safety bar if such a state is present, is shown in document EP 0430813. This system comprises a sensor of the gyrometer-kind, and accelerometers for detecting side and vertical acceleration of the vehicle. Using the signals from the respective sensors, the system can determine whether the vehicle is about to roll over. In particular, the angular or rotational speed of the vehicle is detected using the gyrometer, i.e. relative to the horizontal plane. Additionally, the system is arranged to determine whether the ratio between the side and the vertical acceleration exceeds a certain threshold value. If this is the case, the signal is integrated with respect to the angular speed which is detected using the gyrometer. If the signal which is obtained from this integration, and which indicates a value of the current angle of the vehicle, exceeds a certain threshold value, a safety device in the form of a safety bar will be activated. However, although this previously known system in principle provides efficient function it has a drawback in that it does not always sufficiently reliably detect whether the vehicle is about to roll over. Furthermore, there is also a risk that this state is not detected rapidly enough during the course of an accident. SUMMARY OF THE INVENTION: The object of the present invention is to provide an improved device for quick and reliable detection of a rollover state in a vehicle with, in particular, the above- mentioned drawbacks being eliminated. This object is obtained by means of a safety device, the characteristics of which will become apparent from appended claim 1. The object is also obtained by means of a method, the characteristics of which will become apparent from appended claim 14. The invention is intended to detect rotation of a vehicle about its longitudinal and/or latitudinal axis, and for the activation of at least one safety device depending on said detection. The invention comprises means for determining the angular position of the vehicle about at least one of said axes, and the angular velocity of said rotation, and a control unit which is arranged for the above-mentioned activation if certain predetermined threshold conditions relative to the operational state of the vehicle are fulfilled. The invention is based on the principle that at least one of said threshold conditions is variable, and can be chosen depending on at least one predetermined operational state of the vehicle. In this way, a quick and reliable detection of the roll-over state is obtained. In a preferred embodiment, a micromechanical gyro is utilized to detect the angular velocity of the rotation of the vehicle. Further advantageous embodiments of the invention will become evident from the appended dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS: The invention will in the following be described closer with reference to an example of a preferred embodiment and to the appended drawings, in which: Fig. 1 is a simplified principle diagram, which shows the device according to the present invention, Fig. 2 is a flow chart which shows how the invention works, and Fig. 3 illustrates the function of an alternative embodiment of the invention. PREFERRED EMBODIMENT: The invention is in particular, but not exclusively, suitable for use in connection with motor vehicles, and is intended to detect a state of the vehicle where the vehicle is considered to be about to rotate and roll over, mainly about its longitudinal axis. When detecting this so-called roll-over state, it is desirable that a safety device, for example a safety bar or an airbag, is activated so that injuries to those travelling in the vehicle can be minimized. Fig. 1 shows a principle diagram of the present invention. The invention is intended to be arranged in a motor vehicle, and in a preferred embodiment comprises a sensor in the form of a micromechanical gyro 1. This is a type of sensor which, as such, is previously known from, for example, US patent 5251483 and comprises a resonator with a tuning fork-like component of a piezoelectrical material, comprising two bars which are connected to a base section which is fixedly attached to the vehicle. The bars can be brought to vibrate in the horizontal plane using suitable drive circuits. If the vehicle, and thus also the gyro 1, starts to rotate about its longitudinal axis, a vibration with a component in the vertical direction as well will be generated. This vibration will be a measurement of the current speed of rotation. According to the invention, the gyro 1 is connected to a drive circuit 2 for generating a vibration of a certain frequency in the gyro 1. Additionally, the gyro 1 is connected to a control unit 3, which preferably is computer based, and which comprises circuits by means of which the vibrations of the gyro 1 can be detected (which as such is previously known from the above-mentioned US patent). In this manner, a measurement of the angular velocity φ of a possible twisting or rotational movement of the vehicle about its longitudinal axis can be obtained in the form of a signal in the control unit 3. Instead of a separate drive circuit 2 , the control unit 3 can alternatively comprise the drive electronics needed to generate the vibration of the gyro 1. The control unit 3 is arranged to obtain a value of the current angular position φ of the gyro 1, during a certain period of time by means of integration, i.e. φ = φ dt Jo where the integration from the time 0 to T provides an absolute value of the angular position φ of the gyro 1, and thus also of the vehicle following a rotation with a certain angular velocity φ about its longitudinal axis (in the following referred to as the x-axis). To the control unit 3 there is also connected at least one accelerometer 4, which is arranged to detect the side-acceleration of the vehicle, i.e. acceleration along the y-axis. Furthermore, the system according to the invention preferably comprises a sensor 5, using which the angular position θ of the steering wheel (not shown) of the vehicle can be detected. This sensor 5 for the angle of the steering wheel, which as such is previously known, is connected to the control unit 3. The control unit 3 is arranged to, by means of derivatives, determine a value of the angular speed θ when the wheel is turned. There is also a speed sensor 6 connected to the control unit 3 for detecting the speed x of the vehicle in its longitudinal direction. In the preferred embodiment, the system also comprises a second micromechanical gyro 7. This gyro 1 , to which a drive circuit 8 is connected, is of the same kind as the above-mentioned gyro 1, but is oriented in the vehicle in such a way that the speed of rotation γ of the vehicle about its latitudinal axis (i.e. the y-axis) can be detected. In a manner corresponding to that which has been explained above, the control unit 3 is arranged to, by means of integration, obtain a value of the current angular position γ with respect to the tilt of the vehicle about the y-axis. As will be explained in detail below, the values regarding the measured angular speeds φ and γ respectively, side-acceleration y, steering wheel angle θ , and velocity x (which are measured continuously over time) and calculated values of the vehicle's angular positions φ and γ respectively, and the angular velocity of the steering wheel θ , can be utilized in order to determine whether there is a roll-over state. Additionally, the values regarding the angular acceleration φ about the longitudinal axis of the vehicle (i.e. the x-axis) and the angular acceleration γ about the latitudinal axis of the vehicle (i.e. the y-axis) can be calculated in the control unit 3, and can be utilized to determine whether there is a roll-over state. If that is the case, the control unit 3 will initiate a signal for the activation of at least one protective device 9, which, for example, can be a safety bar, an airbag, a safety belt tightener, or a combination of a plurality of such devices. For example, a number of protective devices can be activated in a certain order during roll-over. Fig. 2 shows a flow chart which illustrates how the invention works. Initially, the gyros 1 and 7 are fixed in a vehicle, and are utilized for measuring the angular speed φ of the rotation of the vehicle about its longitudinal axis, and the angular velocity γ of the rotation about the latitudinal axis (block 10). By integration in the control unit, a value of the current angular positions φ and γ respectively of the vehicle are then calculated (block 11). Following this, the control unit 3 determines whether the angle φ about the x-axis exceeds a predetermined threshold value A (block 12). If this is the case, this is an indication that the vehicle is about to roll over. This causes the control unit to activate the above-mentioned protective device (block 13). If the angular position φ does not exceed the threshold value A, a calculation is made as to whether the current value of the angular velocity φ exceeds a certain predetermined threshold value B (block 14). If that is the case, the value of the angular position φ is compared with a further threshold value C (block 15). If this threshold value C is exceeded, the control unit will activate the protective device (block 13). According to the invention, the latter threshold value C is variable and depends on the measured value of the angular velocity φ. This fact is based on the principle that if the vehicle, for example, rotates about its longitudinal axis with a relatively low angular velocity, a relatively high threshold value C is necessary in order for a roll-over state to be detected reliably. If, on the other hand, the vehicle has a relatively high angular velocity, then the threshold value C can be set relatively low for detecting the roll-over state. In this way, a reliable and early detection of the roll-over state and activation of a protective device is achieved. If neither the angular velocity about the longitudinal axis exceeds the threshold value B nor the angle exceeds the threshold value C, there is a check as to whether the side- acceleration y of the vehicle exceeds a predetermined threshold value D (block 16). If that is the case, there is a check as to whether the current angular position φ exceeds a further threshold value E (block 17). Similarly to that which has been explained above, this threshold value E depends on the level of the side-acceleration y. If, for example, the vehicle has a relatively low side- acceleration, the threshold value E is set relatively high, in order to detect the roll-over state. If, on the other hand, the vehicle has a relatively high side-acceleration, the threshold value E can be set relatively low. If the angular position φ exceeds the threshold value E (block 17), the control unit checks whether the period of time t during which the side-acceleration y has exceeded the threshold value D exceeds an additional threshold value F (block 18). The choice of this latter threshold value F depends on the magnitude of the side-acceleration y and the angular position φ . In case of, for example, a high side- acceleration and a high value of the angular position, a relatively low value of the threshold value F is necessary in order to determine the presence of a roll-over state. If the value of the period of time t exceeds the threshold value F, the control unit will thus activate the protective device (block 13). If the side-acceleration y does not exceed the threshold value D or the angle is larger than the threshold value E or the time period t exceeds the threshold value F, there is a check as to whether the angular position φ exceeds a further threshold value G (block 19). If that is the case, the control unit determines whether the absolute value of the speed x of the vehicle in its longitudinal extension is larger than a further threshold value H (block 20). This latter threshold value H depends on the angular position φ in that, for example, a large value of the angular position only needs a relatively low value of the threshold value H in order for the roll-over state to be detected. If the absolute value of the speed of the vehicle x exceeds the threshold value H, a calculation is made in the control unit to determine whether the angle θ of the steering wheel exceeds a certain threshold value I, which in turn depends on the angular position ψ and the speed x of the vehicle (block 21). In similarity to that which has been explained above, if for example the tilt and the speed of the vehicle are relatively large, a relatively small value of the angle θ of the steering wheel is necessary in order to assume that the roll-over state is present. The direction of the angle θ of the steering wheel (i.e. whether the steering wheel is rotated counter-clockwise or clockwise) is significant, since a vehicle has a higher tendency to roll over when it leans to the left at the same time as the wheels point to the right (or vice versa) than if the vehicle leans in the same direction as the wheels point. If the angle θ of the steering wheel exceeds a certain threshold value I, the protective device will be activated (block 13) . If the angular position φ does not exceed the threshold value G, the absolute value of the speed of the vehicle x is not larger than the threshold value H, or the angle θ of the steering wheel does not exceed the threshold value I, there is a check as to whether the angular position φ exceeds yet a further threshold value J (block 22). If that is the case, there is a check as to whether the absolute value of the speed x of the vehicle exceeds a threshold value K which depends on the angular position of the vehicle (block 23). If this condition is also satisfied, there is a check as to whether the angular speed θ of the steering wheel, i.e. the angular velocity with which the steering wheel is rotated, exceeds a further threshold value L which depends on the angular position of the vehicle and its speed (block 24). If that is the case, the protective device will be activated (block 13). If the angular position φ does not exceed the threshold value J, the absolute value of the speed of the vehicle x does not exceed the threshold value K, or the angular velocity θ of the steering wheel does not exceed the threshold value L, there is a check as to whether the angular position γ regarding the rotation of the vehicle about its longitudinal axis exceeds a further threshold value M (block 25). If that is the case, the control unit will activate the protective device (block 13). If the angular position γ around the latitudinal axis is smaller than the threshold value M, a calculation is made as to whether the current value of the angular velocity γ for the rotation about the longitudinal axis exceeds a certain predetermined threshold value M (block 26). If that is the case, the value of the angular position γ is compared to a further threshold value P (block 27). According to the embodiment, this latter threshold value P is variable and depends on the measured value of the angular velocity γ . This fact is based on the principle that if the vehicle, for example, rotates about its longitudinal axis (the y-axis) at a relatively low angular speed, a relatively high threshold value P is needed in order for the roll-over state to be detected reliably. If, on the other hand, the vehicle has a relatively low angular velocity about its longitudinal axis, the threshold value P can be set relatively low in order for the roll-over state to be determined. If the threshold value P is exceeded, the control unit will activate the protective device (block 13). If the angular velocity γ is not larger than N, or the angular position γ is not larger than P, the control unit checks whether the acceleration x of the vehicle in its longitudinal direction exceeds a certain threshold value Q (block 28). If that is the case, there is a check as to whether the angular position γ exceeds yet another threshold value R (block 29). Similarly to what has been explained above, the threshold value R depends on the level of the acceleration x in the longitudinal direction of the vehicle. If, for example, the vehicle has a relatively low acceleration x, the threshold value R is set relatively high in order to determine the roll-over state. If, on the other hand, the vehicle has a relatively high acceleration x, the threshold value R can be set relatively low. If the angular position γ exceeds the threshold value R (block 29), the control unit calculates whether the period of time t during which the acceleration x has exceeded the threshold value Q exceeds a certain additional threshold value S (block 30). The choice of this threshold value S depends on the magnitude of the acceleration x and the angular position γ . In case of, for example, a high acceleration and a high value of the angular position, a relatively low value of the threshold value S is needed in order to determine the roll-over state. If the value of the time t exceeds the threshold value S, the control unit will thus activate the protective device (block 13). If the acceleration does not exceed the threshold value Q, the angular position γ does not exceed the threshold value R or the time t does not exceed the threshold value S, there is a check as to whether the angular acceleration φ about the latitudinal axis of the vehicle exceeds a further threshold value T (block 31). If that is the case, there is a check as to whether the period of time during which this threshold value T has been exceeded is larger than a further threshold value U (block 32). Similarly to what has been explained above, the threshold value U depends on the angular acceleration φ about the latitudinal axis. If this condition is satisfied as well, there is a check as to whether the current value of the angular velocity φ about the x-axis exceeds a threshold value V (block 33). The choice of this threshold value V depends on the magnitude of the angular acceleration φ about the longitudinal axis and the period of time during which the threshold value U has been exceeded. If the threshold value V is exceeded, there is a check as to whether the angular position φ exceeds a further threshold value X (block 34). This threshold value X depends on the angular velocity φ , the time during which the threshold value U has been exceeded, and the angular acceleration φ. If the threshold value X has been exceeded, the protective device will be activated (block 13). If the angular acceleration φ does not exceed the threshold value T, the time t does not exceed the threshold value U, the angle of velocity φ does not exceed the threshold value V, or the angular position φ does not exceed the threshold value X, there is a check as to whether the angular acceleration γ about the latitudinal axis of the vehicle exceeds a further threshold value Y (block 35). If that is the case, there is a check as to whether the time during which this threshold value Y has been exceeded is greater than a further threshold value Z (block 36). Similarly to what has been explained above, this threshold value Z depends on the magnitude of the angular acceleration γ about the latitudinal axis. If this condition is satisfied as well, there is a check as to whether the current value of the angular velocity γ about the y-axis exceeds a further threshold value AA (block 37), which in turn depends on the magnitude of the angular acceleration γ about the crosswise axis and the time during which the threshold value Z has been exceeded. If the threshold value AA has been exceeded, there is a check as to whether the angular position γ exceeds a further threshold value AB (block 38), which in turn depends on the angular velocity γ , the time during which the threshold value Z has been exceeded and said angular acceleration γ. If the threshold value AB has been exceeded, the protective device will be activated (block 13). If the angular acceleration γ does not exceed the threshold value Y, the time t does not exceed the threshold value Z, the angular velocity γ does not exceed the threshold value AA, or the angular position γ does not exceed the threshold value AB, the system reverts to its initial position, in which the angular velocity φ and γ is measured (block 10). The above-mentioned variable threshold values C, E, F, H, I, K, L, P, R and S are thus determined depending on the current values of the certain chosen operational conditions of the vehicle, preferably the angular positions of the vehicle φ and γ respectively, angular speed φ and γ respectively, acceleration y and x respectively and speed x , as has been described above. The relationship between the variable threshold values and said operational conditions are preferably stored in the form of tables in the control unit. Furthermore, the threshold values A-AB can be adapted to the kind of vehicle in question, when detection of the roll-over state is desired, and similar conditions. In a particular version of the invention, a measurement of the side-acceleration y of the vehicle is utilized as the main parameter when determining whether the roll-over state is present or not. This corresponds to the conditions according to blocks 16 and 18 being utilized. Fig. 3 schematically shows how such a detection can be carried out. The figure shows a plurality of diagrams, which each indicate a relationship between the side-acceleration y and the time during which a certain side-acceleration y is present, with each curve corresponding to the current tilt (i.e. angular position φ ) of the vehicle. A large tilt of the vehicle corresponds to a curve which is close to the origin in Fig. 3, while a low angle of tilt corresponds to a curve which is farther away from the origin. From the figure, it can be seen that a state where the side- acceleration y has a certain value y, during a certain time tr (at a certain angle of tilt) corresponds to the presumed presence of the roll-over state. If the tilt decreases (which corresponds to another curve in Fig. 3), a longer period of time t 2 with maintained side-acceleration γ λ is instead necessary in order for the roll-over state to be presumed present. In a further possible version of the invention, the invention can utilize measurement of the rotational energy of the vehicle about its crosswise axis which passes through the centre of gravity of the vehicle. This measurement is then utilized to determine whether a rollover state is presumed present. The control unit can then be arranged to determine whether this rotational energy exceeds the position of energy in a rest state where the vehicle does not tilt with respect to its horizontal axis. This condition can also be written as 5 (I xx + mL 2 )φ 2 ( ) /2 > mg(h 2 -h 1 ) where I xx is the inertia of the vehicle in the current direction of rotation, m is the mass of the vehicle, L is 10 the distance between the longitudinal axis which runs through the vehicle's centre of gravity and the vehicle's point of contact with the ground during rotation, φ is the angular acceleration, and (h 2 -h,) is the difference in height of the centre of gravity of the vehicle at rest and 15 when the vehicle has rotated so far that it cannot return to its resting position, respectively. If the control unit thus determines that the rotational energy of the vehicle exceeds a threshold value which corresponds to the positional energy of the vehicle which it is necessary to 20 overcome in order for the vehicle to roll over, the protective device will be activated. In a further version of the invention, such a rotational state can be determined using two transducers for 25. determining the angular acceleration about the longitudinal axis of the vehicle. If these transducers are placed sufficiently far out at the sides of the vehicle, and if they simultaneously indicate positive and negative acceleration respectively, this is an indication that the 30 vehicle is rotating about its longitudinal axis. By combining such a measurement with a measurement of the angular position φ of the vehicle about the longitudinal axis and the angular speed φ about the longitudinal axis, the system can determine whether the roll-over state 35 is present. The invention is not limited to the examples of embodiments described above and shown in the drawings, but can be varied within the scope of the appended claims. For example, different kinds of protective devices can be utilized to protect those travelling in the vehicle. Furthermore, different kinds of sensors can be utilized for detection of the various operational states in question of the vehicle. For example, other types of inclination sensors than micromechanical gyros can be utilized. Furthermore, the control unit does not necessarily need to be arranged to check all the conditions which are indicated with reference to Fig. 2. A system which, for example, does not utilize the conditions according to blocks 16-30 can also provide a reliable and quick detection of the rollover state. According to a possible version of the invention, the gyro for detecting the rotation about the crosswise axis of the vehicle can also be left out, in which case the conditions according to blocks 25-30 will not be included. Furthermore, the conditions according to blocks 31-38, i.e. those which relate to determining the angular acceleration about the x- and y-axis, respectively, can be left out.

Claims: CLAIMS : 1. Safety device for detecting rotation of a vehicle about its longitudinal or crosswise axis, or about both axes, and for activation of at least one protective device (9) depending on said detection, comprising means (1, 7, 3) for determining the angular position (φ) of the vehicle about at least one of said axes and the angular speed (φ, γ) of said rotation, and a control unit (3) arranged for said activation if certain predetermined threshold values (A-AB) with respect to the operational state of the vehicle are fulfilled, c h a r a c t e r i z e d i n that at least one of said threshold values (C; P) is variable and depends on at least one predetermined operational condition of the vehicle. 2. Safety device according to claim 1, c h a r a c t e r i z e d i n that the control unit (3) is arranged to detect whether the current angular velocity (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (B), and if that is the case, to determine whether the current angular position (φ) about the longitudinal axis exceeds a further threshold value (C), which is chosen depending on the magnitude of the current angle of velocity (φ) , and if that is the case, to activate said protective device (9). 3. Safety device according to claim 1 or 2, c h a r a c t e r i z e d i n that it additionally comprises a transducer (4) for determining the side- acceleration (y) of the vehicle, with the control unit (3) being arranged to determine whether the current value of the side-acceleration (y) exceeds a predetermined threshold value (D), and if that is the case, to determine whether the current angular position (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (E), which is chosen depending on the current value of the side-acceleration (y), and if that is the case to calculate whether the time (t) during which the first threshold value (D) has been exceeded is higher than a further threshold value (F), which is chosen depending on the current value of the side-acceleration (y) and the current angular position (φ ) , and if that is the case, to activate said protective device ( 9 ) . 4. Safety device according to any of the previous claims, c h a r a c t e r i z e d i n that it comprises a transducer (5) for determining the angular position of the steering wheel of the vehicle and a transducer (6) for determining the velocity of the vehicle (x) , with the control unit ( 3 ) being arranged to determine whether the current angular position (φ ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (G), and if that is the case, to determine whether the absolute value of the current speed (x) exceeds a predetermined threshold value (H) which is chosen depending on the current angular position (φ ) , and if that is the case, to determine whether the current angular position ( θ ) of the steering wheel exceeds a further threshold value (I) which is chosen depending on the current angular position (φ ) , and the absolute value of the current velocity (x) , and if that is the case, to activate said protective device (9). 5. Safety device according to claim 4, c h a r a c t e r i z e d i n that the control unit (3) is arranged to calculate the angular velocity (θ) of the steering wheel with respect to the turning of a steering wheel of the vehicle, and is arranged to determine whether the current angular position (φ ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (J), and if that is the case, to determine whether the absolute value of the current speed (x) exceeds a further predetermined threshold value (K), which is chosen depending on the current angular position ( φ ) , and if that is the case, to calculate whether the current angular speed (6) of the steering wheel exceeds a further threshold value (L) chosen depending on the current angular position (ψ ) and the absolute value of the current speed (x) , and if that is the case, to activate said protective device (9). 6. Safety device according to any of the previous claims, c h a r a c t e r i z e d i n that the control unit (3) is arranged to determine whether the current angular velocity (γ) about the crosswise axis of the vehicle exceeds a predetermined threshold value (N), and if that is the case, to determine wether the current angular position ( γ ) around the crosswise axis of the vehicle exceeds a further threshold value (P), which is chosen depending on the magnitude of the current angular velocity (γ) , and if that is the case, to activate said protective device (9). 7. Safety device according to claim 6, c h a r a c t e r i z e d i n that it comprises a transducer for determining the acceleration (x) of the vehicle in its longitudinal direction, with the control unit (3) being arranged to determine whether the current value of said acceleration (x) exceeds a predetermined threshold value (Q), and if that is the case, to determine whether the current angular position ( γ ) about the crosswise axis of the vehicle exceeds a predetermined threshold value which is chosen depending on the current value of the acceleration (x), and if that is the case, to calculate whether the time (t) during which the first threshold value (Q) has been exceeded is larger than a further threshold value (S) which is chosen depending on the current value of the acceleration (x) and the current angular position (y), and if that is the case, to activate said protective device (9). 8. Safety device according to any of the previous claims, c h a r a c t e r i z e d i n that the control unit ( 3 ) is arranged to determine whether the current angular acceleration (φ) about the crosswise axis of the vehicle exceeds a predetermined threshold value (T), and if that is the case, to determine whether the time (t) during which said threshold value (T) has been exceeded is larger than a further threshold value (U) which is chosen depending on the current value of said angular acceleration (φ), and if that is the case, to determine whether the current angular velocity (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (V) which is chosen depending on the angular acceleration (φ) and said time (t), during which said threshold value (T) has been exceeded, and if that is the case, to determine whether the current angular position (φ ) about the longitudinal axis of the vehicle exceeds a further threshold value (X) which is chosen depending on the angular acceleration (φ) , said time (t) and the angular velocity (φ) , and if that is the case, to activate said protective device (9). 9. Safety device according to any of the previous claims, c h a r a c t e r i z e d i n that the control unit ( 3 ) is arranged to determine whether the current angular acceleration (φ) about the crosswise axis of the vehicle exceeds a predetermined threshold value (Y), and if that is the case, to determine whether the time (t) during which said threshold value (Y) has been exceeded is larger than an additional threshold value (Z) which is chosen depending on the current value of said angular acceleration (φ), and if that is the case, to determine whether the current angular velocity (γ) about the crosswise axis of the vehicle exceeds a predetermined threshold value (AA) which is chosen depending on the angular acceleration (φ) and said time (t), during which said threshold value (Y) has been exceeded, and if that is the case, to determine whether the current angular position (γ) about the crosswise axis of the vehicle exceeds a further threshold value (AB) which is chosen depending on the angular acceleration (γ) , said time (t) and the angular velocity (γ) , and if that is the case, to activate said protective device (9). 10. Safety device according to any of the previous claims, c h a r a c t e r i z e d i n that said means (1, 7, 3) comprise at least one micromechanical gyro (1, 7) for detecting the angular velocity (φ, γ), which gyro (1, 7) is connected to said control unit (3). 11. Safety device for detecting the rotation of a vehicle about its longitudinal or crosswise axis or about both axes, and for the activation of at least one safety device (9) depending on said detection, c h a r a c t e r i z e d i n that it comprises a transducer (4) for determining the side-acceleration of the vehicle (y), and a control unit (3) arranged to determine whether the current value of the side-acceleration (y) exceeds a predetermined threshold value (D), and if that is the case, to calculate whether the time (t) during which said threshold value (D) has been exceeded is larger than an additional threshold value (F), and if that is the case, to activate said protective device (9). 12. Safety device according to claim 11, c h a r a c t e r i z e d i n that said further threshold value (F) is chosen depending on at least the current value of the side-acceleration (y). 13. Safety device for detecting the rotation of a vehicle about its longitudinal axis and for the activation of at least one protective device depending on said detection, c h a r a c t e r i z e d i n that it comprises a transducer for determining the angular acceleration (φ) about said axis and a control unit arranged to determine whether the current value of the rotational energy of the vehicle about said axis exceeds a predetermined threshold value which corresponds to the positional energy of the vehicle which it is necessary to overcome in order for the vehicle to roll over, and if that is the case, to activate said protective device. 14. Method in a safety device in a vehicle comprising the detection of the rotation of the vehicle about its longitudinal or crosswise axis or both axes at least by determining the angular position (φ, γ) of the vehicle about either of said axes and the angular velocity (φ, γ) of said rotation, the activation of at least one protective device (9) in case of said detection if certain predetermined threshold conditions (A-S) relating to the operational condition of the vehicle are fulfilled, c h a r a c t e r i z e d i n that at least one of said threshold conditions (C; P) are chosen depending on at least one predetermined operational state of the vehicle. 15. Method according to claim 14, c h a r a c t e r i z e d i n that it comprises determining whether the current angular velocity (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (B), and if that is the case, determining whether the current angular position (φ) about the longitudinal axis of the vehicle exceeds a further threshold value (C) which is chosen depending on the magnitude of said angular velocity (φ) , and if that is the case, the activation of said protective device (9). 16. Method according to claims 14 or 15, c h a r a c t e r i z e d i n that it comprises: determining whether the current value of the side- acceleration (y) of the vehicle exceeds a predetermined threshold value (D), and if that is the case, determining whether the current angular position (φ) about the crosswise axis of the vehicle exceeds a predetermined threshold value (E) which is chosen depending on the current value of the side-acceleration (y), and if that is the case, the calculation of whether the time (t) during which the first threshold value (D) has been exceeded is longer than an additional threshold value (F) which is chosen depending on the current value of the side- acceleration (y) and the current angular position (φ) , and if that is the case, the activation of said protective device (9). 17. Method according to any of claims 14-16, c h a r a c t e r i z e d i n that it comprises: determining whether the current angular position (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (G), and if that is the case, determining whether the absolute value of the current velocity (x) in the longitudinal direction of the vehicle exceeds a predetermined threshold value (H) which is chosen depending on the current angular position (φ) about the longitudinal axis of the vehicle, and if that is the case, calculating whether the current angular position (θ) of the steering wheel exceeds a further threshold value (I) which is chosen depending on the current angular position (φ) and the absolute value of the current velocity (x) , and if that is the case, the activation of said protective device (9). 18. Method according to any of claims 14-17, c h a r a c t e r i z e d i n that comprises : determining whether the current angular position (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (J), and if that is the case, determining whether the absolute value of the current velocity (x) in the longitudinal extension of the vehicle exceeds a further predetermined threshold value (K) which is chosen depending on the current angular position (φ) , and if that is the case, calculating whether the current angular velocity (θ) of the steering wheel exceeds a further threshold value (L) which is chosen depending on the current angular position (φ) and the absolute value of the current velocity (x) , and if that is the case, the activation of said protective device (9). 19. Method according to any of claims 14-18, c h a r a c t e r i z e d i n that it comprises: determining whether the current angular velocity (γ) about the crosswise axis of the vehicle exceeds a predetermined threshold value (N), and if that is the case, determining whether the current angular position (φ) about the crosswise axis of the vehicle exceeds a further threshold value (P) which is chosen depending on the size of said angular velocity (γ), and if that is the case, the activation of said protective device ( 9 ) . 20. Method according to any of claims 14-19, c h a r a c t e r i z e d i n that it comprises: determining whether the current value of the acceleration (x) in the longitudinal extension of the vehicle exceeds a predetermined threshold value (Q), and if that is the case, determining whether the current angular position (φ ) about the crosswise position of the vehicle exceeds a predetermined threshold value (R) which is chosen depending on the current value of the acceleration (x), and if that is the case, calculating whether the time (t) during which the first threshold value (Q) has been exceeded is longer than a further threshold value (S) which is chosen depending on the current value of the acceleration (x) and the current angular position (y), and if that is the case, the activation of said protective device (9). 21. Method according to any of claims 14-20, c h a r a c t e r i z e d i n that it comprises: determining whether the current value of the angular acceleration (φ) in the longitudinal extension of the vehicle exceeds a predetermined threshold value (T), and if that is the case, calculating whether the time (t) during which said threshold value (T) has been exceeded is longer than a further threshold value (U) which is chosen depending on the current value of said angular acceleration (φ) , and if that is the case, determining whether the current angular velocity (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (V) which is chosen depending on the angular acceleration (φ) and said time (t) during which said threshold value (T) has been exceeded, and if that is the case, determining whether the current angular position (φ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (X) which is chosen depending on the angular acceleration (φ) , said time (t) and the angular velocity (φ) , and if that is the case, the activation of said protective device (9). 22. Method according to any of claims 14-21, c h a r a c t e r i z e d i n that it comprises : determining whether the current value of the angular acceleration (γ) in the crosswise direction of the vehicle exceeds a predetermined threshold value (Y), and if that is the case, determining whether the time (t) during which said threshold value (Y) has been exceeded is longer than a further threshold value (Z) which is chosen depending on the current value of said angular acceleration (γ) , and if that is the case, determining whether the current angular velocity (γ) about the longitudinal axis of the vehicle exceeds a predetermined threshold value (AA) which is chosen depending on the angular acceleration and said time (t) during which said threshold value (Y) has been exceeded, and if that is the case, determining whether the current angular position (y) about the crosswise axis of the vehicle exceeds a predetermined threshold value (AB) which is chosen depending on the angular acceleration (γ) , said time (t) and the angular velocity (γ) , and if that is the case, the activation of said protective device (9). 23. Method for detecting rotation of a vehicle about its longitudinal or crosswise axis or about both axes and the activation of at least one protective device ( 9 ) depending on said detection, c h a r a c t e r i z e d i n that it comprises : determining the side-acceleration (y) of the vehicle, determining whether the current value of the side- acceleration (y) exceeds a predetermined threshold value (D), and if that is the case, calculating whether the time (t) during which said threshold value (D) has been exceeded is greater than a further threshold value (F), and if that is the case, the activation of said protective device (9). 24. Method for detecting rotation of a vehicle about its longitudinal axis and the activation of at least one protective device depending on said detection, c h a r a c t e r i z e d i n that it comprises: determining the angular acceleration (φ) of the vehicle about said axis, determining a value which corresponds to the vehicle's rotational energy about said axis, and determining whether the current value of the vehicle's rotational energy exceeds a predetermined threshold value which corresponds to the positional energy of the vehicle which must be overcome in order for the vehicle to roll over, and if that is the case, the activation of said protective device.

Inventors: PALMERTZ CAMILLA, SAMEUS JOERGEN, PALMERTZ, CAMILLA, SAMEUS, JOERGEN
Applicants: PALMERTZ CAMILLA, SAMEUS JOERGEN, VOLVO AB, AB VOLVO, PALMERTZ, CAMILLA, SAMEUS, JOERGEN
Application year: 1997
Main classification: B60R21
IPC codes: B60G17, B60R21, G01C19, G01P15