DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0056] These embodiments are vehicle collision state detecting devices configured to detect the collision state of a vehicle with respect to certain prescribed moving bodies. With these vehicle collision state detecting devices, the tensile force in a tension member changes when the colliding object contacts the bumper reinforcement at the beginning of a collision. The tensile force in the tension member is measured by the tensile force sensors connected at both ends of the wire and the collision state is determined based on the measurement data obtained from the tensile force sensors. As a result, a wide range of collision states can be identified.

First Embodiment

[0057] Referring initially to FIG. 1 (A), a front section of a vehicle is illustrated that is configured and arranged with a vehicle collision state detecting device 10 in accordance with a first embodiment of the present invention. In particular, the front section includes the main elements of the vehicle collision state detecting device 10 in accordance with the first embodiment. FIG. 1 (B) shows the entire front section of the vehicle that forms a part of the vehicle collision state detecting device 10 , while FIG. 1 (C) is a detailed enlargement of the front section showing the details of a selected portion of the front section of the vehicle.

[0058] The vehicle collision state detecting device 10 basically includes a right side structural member 11 R, a left side structural member 11 L, a right bumper stay 12 R, a left bumper stay 12 L, a bumper reinforcement 13 , a right tensile force sensor 14 R, a left tensile force sensor 14 L, a tension member or wire 15 , a right lock mechanism 16 R and a left lock mechanism 16 L.

[0059] The side structural members 11 R and 11 L are arranged and configured on the left and right sides of the front section of the vehicle so that they are paced laterally apart and extend in a substantially longitudinal direction of the vehicle. The bumper stays 12 R and 12 L are easily deformable members, which are arranged on the forward tip ends of the side members 11 R and 11 L, respectively. The bumper reinforcement 13 is arranged crosswise in the widthwise direction of the vehicle with its end portions fixedly coupled the front end parts of the bumper stays 12 R and 12 L, respectively. The right and left tensile force sensors 14 R and 14 L are arranged on the outside of the approximate tip ends of the side structural members 11 R and 11 L, respectively. The tensile force sensors 14 R and 14 L serve to measure the tensile force. The wire 15 is fixedly connected between the right tensile force sensor 14 R and the left tensile force sensor 14 L and arranged to extend along the forward facing surface of the bumper reinforcement 13 between the side members 11 R and 11 L. The wire 15 is placed under tension to have a prescribed initial tensile force. The right and left lock mechanisms 16 R and 16 L are arranged on the bumper reinforcement 13 in the general vicinity of the front ends of the bumper stays 12 R and 12 L, respectively. The lock mechanisms 16 R and 16 L are configured to grip the wire 15 so as to divide and fix the wire 15 into individual sections when a collision occurs.

[0060] As shown in FIG. 1 (B), the vehicle collision state detecting device 10 includes a floor tunnel 17 and a floor sensor 18 , which is arranged on the floor tunnel 17 and functions as a deceleration sensor to measure the deceleration of the vehicle. As shown in FIG. 1 (C), the vehicle collision state detecting device 10 also includes a pair of corner guides 19 R and 19 L and a plurality of front guides 20 . The two corner guides 19 R and 19 L are arranged on the corner parts where the bumper stays 12 R and 12 L are connected to the bumper reinforcement 13 . The corner guides 19 R and 19 L serve to prevent excess friction force from acting on the wire 15 at the corner part of the bumper reinforcement 13 . The front guides 20 are arranged on the front surface of the bumper reinforcement 13 and serve to support the wire 15 , which passes therethrough.

[0061] The front section also has a pair of deformation areas (a pair of notches) 21 R and 21 L located on the side structural members 11 R and 11 L to control collapsing of the side structural members 11 R and 11 L during a collision affect those areas. The deformation areas 21 R and 21 L are configured to give the side structural members 11 R and 11 L such a rigidity balance that when a load acts on the tip of one or both of the side members 11 R and 11 L in the widthwise direction of the vehicle, such as during an oblique collision, the side member collapses inward to some degree at the front or rear of the right tensile force sensor 14 R and/or the left tensile force sensor 14 L while momentarily collapsing axially.

[0062] Preferably, a control unit box is provided for housing the floor sensor 18 and a control unit 22 (collision state identifying section) that serves to determine when to trigger the passenger restraining devices (described later) are configured in an integral manner.

[0063] As shown in the system block diagram of FIG. 2 , the control unit 22 has a central processing unit or CPU 31 , a triggering control section 32 that controls triggering of the passenger retraining devices 35 , and a threshold value setting section 33 that sets a threshold value for triggering the passenger restraining devices 35 . The control unit 22 preferably includes a microcomputer as the CPU 31 which runs a control program that controls the deployment of the passenger restraining devices as discussed below. The control unit 22 can also include other conventional components such as an input interface circuit, an output interface circuit, and storage devices such as a ROM (Read Only Memory) device and a RAM (Random Access Memory) device. The memory circuit stores processing results and control programs for the operations that are run by the processor circuit. The internal RAM of the control unit 22 stores statuses of operational flags and various control data. It will be apparent to those skilled in the art from this disclosure that the precise structure and algorithms for the control unit 22 can be any combination of hardware and software that will carry out the functions of the present invention. In other words, “means plus function” clauses as utilized in the specification and claims should include any structure or hardware and/or algorithm or software that can be utilized to carry out the function of the “means plus function” clause.

[0064] The vehicle collision state detecting device 10 is configured such that the tensile force in the wire 15 measured by the right tensile force sensor 14 R and left tensile force sensor 14 L (which are arranged on the outside of the approximate tip ends of the side members 11 R and 11 L, respectively) and the deceleration measured by the floor sensor 18 (which is arranged on the floor tunnel 17 ) are fed to the control unit 22 . Controlled by the CPU 31 of the control unit 22 , the vehicle collision state detecting device 10 identifies the collision state based on the balance between the left and right tensile forces of the wire 15 measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L. Based on the identified collision state, the triggering control section 32 executes calculations for executing triggering control of the passenger restraining devices 35 (e.g., seatbelts and airbags), the threshold value setting section 33 calculates and sets a threshold value for triggering the passenger restraining devices 35 , and the passenger restraining devices 35 are controlled through a triggering circuit 34 .

Structure of the Lock Mechanism

[0065] The structure of the right lock mechanism 16 R and the left lock mechanism 16 L (which divide and fix the wire 15 during a collision) will now be described using FIG. 3 . The right and left lock mechanisms 16 R and 16 L are identical in the illustrated embodiment. For the sake of brevity, only the right lock mechanism 16 R will be discussed and illustrated in detail herein.

[0066] As shown in the perspective view of FIG. 3 (A), the lock mechanism 16 R comprises a plurality of stopper parts 41 coupled to the wire 15 at spaced apart locations, a plurality of protruding parts 42 positioned such that they can fit into the stopper parts 41 , and a pair of deformable end plates 43 , and a pair of support plates 44 that are connected to the deformable end plates 43 . The forward most one of the support plates 44 supports the protruding parts 42 .

[0067] The stopper parts 41 are provided with bores 45 for connecting the wire 15 to the stopper parts 41 . The wire 15 is fixedly connected to the stopper parts 41 of the lock mechanism 16 through the bores 45 . The center stopper part 41 is also provided with a notch or groove for receiving one of the protruding parts 42 therein.

[0068] The protruding parts 42 are shaped to fit into the notches or grooves provided in the stopper parts 41 or the spaces therebetween. Thus, the protruding parts 42 are configured and arranged closer to the front of the vehicle than the stopper parts 41 .

[0069] The support plates 44 are longer than the stopper parts 41 and the protruding parts 42 in the widthwise direction of the vehicle. Also, two deformation structures (notches) are provided in the deformable end plates 43 . The protruding parts 42 are supported for movement upon deformation of the deformable end plates 43 .

[0070] In a lock mechanism 16 R so constituted, a prescribed clearance exists between the protruding parts 42 and the stopper parts 41 when a collision is not occurring, as shown in FIG. 3 (B). As a result, the wire 15 can move freely in the widthwise direction of the vehicle relative to the stopper parts 41 . Thus, the lock mechanism 16 allows equal tensile forces to exist in the left and right portions of the wire 15 extending from the stopper parts 41 .

[0071] When a collision occurs, the support plates 43 of the lock mechanism 16 buckle due to the contact of the colliding object against the protruding parts 42 , as shown in FIG. 3 (C). The protruding parts 42 fit into the notches or grooves provided in the stopper parts 41 to deflect stopper parts 41 against the wire 15 so as to grip the wire 15 . Thus, movement of the stopper parts 41 in the widthwise direction of the vehicle is restrained. As a result, the wire 15 can no longer move in the widthwise direction of the vehicle and the lock mechanism 16 causes independent tensile forces to exist in the left and right portions of the wire 15 extending from the stopper parts 41 .

[0072] By operating as described below, a vehicle collision state detecting device 10 equipped with such a lock mechanism 16 can identify various vehicle collision states or types.

Operation of the Vehicle Collision State Detecting Device

[0073] The operation of the previously described vehicle collision state detecting device will now be explained. In particular, the method of identifying the vehicle collision state based on the balance between the tensile forces on the left and right of the vehicle will now be explained.

Identification of Front Collision

[0074] Referring to FIGS. 4 (A)- 4 (C), plots of the tensile forces are illustrated that show the tensile forces measured in the wire 15 during a front collision with a rigid wall. The plots show the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L during the period from the beginning of the collision to the end of the collision. In particular, FIG. 4 (A) shows plots of the tensile forces before the front collision. FIG. 4 (B) shows plots of the tensile forces for a 15-km/h collision speed, while FIG. 4 (C) shows plots of the tensile forces for a 64-km/h collision speed.

[0075] Since the wire 15 of the vehicle collision state detecting device 10 is tensioned to a prescribed initial tensile force, the tensile force measured by the right tensile force sensor 14 R and the tensile force measured by the left tensile force sensor 14 L are substantially constant and equal during normal travel before the front collision, as shown in FIG. 4 (A).

[0076] When a front collision occurs at a collision speed of 15 km/h, the right lock mechanism 16 R and the left lock mechanism 16 L provided on the surface of the bumper reinforcement 13 both utilize the collision load to fix the wire 15 simultaneously. Afterwards, the bumper reinforcement 13 deforms and the right and left bumper stays 12 R and 12 L simultaneously collapse due to collision pressure.

[0077] Since the bumper stays 12 R and 12 L collapse substantially simultaneously, the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L decrease from the initial tensile force substantially simultaneously at slopes β R and β L , as shown in FIG. 4 (B).

[0078] When a front collision occurs at a collision speed of 64 km/h, the collapsing pressure level is higher than in the case of the 15-km/h collision, but the collision state is substantially the same. The tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L decrease from the initial tensile force substantially simultaneously, as shown in FIG. 4 (C). The absolute values of the slopes (i.e., time rates) β R and β L at which the tensile forces decrease from the initial tensile force are larger for the 64-km/h collision than for the 15-km/h collision.

[0079] During a front collision, the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L decrease substantially simultaneously. Therefore, when the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L decrease substantially simultaneously, the control unit 22 identifies the collision state as a front collision.

Identification of Simple Offset Collision

[0080] Referring now to FIGS. 5 (A)- 5 (C), plots of the tensile forces are illustrated that show the tensile forces measured in the wire 15 during a simple offset collision with a rigid wall. The plots show the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L during the period from the beginning of the collision to the end of the collision. FIG. 5 (A) shows plots of the tensile forces before the simple offset collision. FIG. 5 (B) shows plots of the tensile forces for a 15-km/h collision speed, while FIG. 5 (C) shows plots of the tensile forces for a 64-km/h collision speed.

[0081] Since the wire 15 of the vehicle collision state detecting device 10 is tensioned to a prescribed initial tensile force, the tensile force measured by the right tensile force sensor 14 R and the tensile force measured by the left tensile force sensor 14 L are substantially constant during normal travel before the simple offset collision, as shown in FIG. 5 (A).

[0082] When a simple offset collision occurs at a collision speed of 15 km/h, one of the lock mechanisms 16 R and 16 L provided on the surface of the bumper reinforcement 13 utilizes the collision load to fix the wire 15 . More specifically, as shown in FIG. 5 (B), the right lock mechanism 16 R fixes the wire 15 when the collision occurs on the right side of the vehicle. Afterwards, the bumper reinforcement 13 deforms and the bumper stay on the side where the collision occurred, i.e., the bumper stay 12 R in this example, collapses due to the collision pressure.

[0083] Due to the collapse of the bumper stay 12 R and the fixing of the wire 15 by the right lock mechanism 16 R, the tensile force measured by the tensile force sensor provided on the side member on the side where the collision occurred, i.e., the right tensile force sensor 14 R, decreases from the initial tensile force at slope β R as shown in FIG. 5 (B).

[0084] Meanwhile, the tensile force measured by the tensile force sensor provided on the side member on the side where the collision did not occur, i.e., the left tensile force sensor 14 L, increases from the initial tensile force at slope β L as shown in FIG. 5 (B). This occurs because the right lock mechanism 16 R moves toward the rear of the vehicle due to the deformation of the bumper stay 12 R while continuing to fix the wire 15 and the bumper stay and side member on the side where the collision did not occur, i.e., the bumper stay 12 L and the side member 11 L, do not readily deform. Thus, the wire 15 is pulled toward the side where the collision occurred.

[0085] When a simple offset collision occurs at a collision speed of 64 km/h, the pressure collapse level is higher than in the case of the 15-km/h collision but the collision state is substantially the same. As shown in FIG. 5 (C), the tensile force measured by the tensile force sensor provided on the side member on the side where the collision occurred, i.e., the right tensile force sensor 14 R, decreases from the initial tensile force and the tensile force measured by the tensile force sensor provided on the side member on the side where the collision did not occur, i.e., the left tensile force sensor 14 L, increases from the initial tensile force. The absolute values of the slopes (i.e., time rates) β R and β L at which the tensile forces decrease or increase from the initial tensile force are larger for the 64-km/h collision than for the 15-km/h collision.

[0086] Thus, during a simple offset collision, the tensile force measured by the tensile force sensor provided on the side member on the side where the collision occurred decreases from the initial tensile force and the tensile force measured by the tensile force sensor provided on the side member on the side where the collision did not occur increases from the initial tensile force. Therefore, when the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L are such that one decreases while the other increases, the control unit 22 identifies the collision state as a simple offset collision on the side where the tensile force decreased.

Identification of Pole Collision

[0087] Referring now to FIGS. 6 (A)- 6 (C), plots of the tensile forces are illustrated that show the tensile forces measured in the wire 15 during a pole collision. The plots show the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L during the period from the beginning of the collision to the end of the collision. FIG. 6 (A) shows plots of the tensile forces before the pole collision. FIG. 6 (B) shows plots of the tensile forces for a 15-km/h collision speed, while FIG. 6 (C) shows plots of the tensile forces for a 64-km/h collision speed.

[0088] Since the wire 15 of the vehicle collision state detecting device 10 is tensioned to a prescribed initial tensile force, the tensile force measured by the right tensile force sensor 14 R and the tensile force measured by the left tensile force sensor 14 L are substantially constant during normal travel before the pole collision, as shown in FIG. 6 (A).

[0089] As shown in FIG. 6 (B), when a pole collision occurs at a collision speed of 15 km/h, first the pole collides with the bumper reinforcement 13 and moves toward the engine while deforming the bumper reinforcement 13 .

[0090] Since the pole does not contact them, the right and left side members 11 R and 11 L do no readily deform and the wire 15 is pulled by the pole. Consequently, the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L both increase from the initial tensile force at slopes of β R and β L , respectively, as shown in FIG. 6 (B).

[0091] When a pole collision occurs at a collision speed of 64 km/h, the pressure collapse level is higher than in the case of the 15-km/h collision but the collision state is substantially the same. The tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L increase from the initial tensile force as shown in FIG. 6 (C). The absolute values of the slopes (i.e., time rates) β R and β L at which the tensile forces decrease from the initial tensile force are larger for the 64-km/h collision than for the 15-km/h collision.

[0092] During a pole collision, the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L both increase. Therefore, when the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L both increase, the control unit 22 identifies the collision state as a pole collision.

Identification of Oblique Offset Collision

[0093] Referring now to FIGS. 7 (A)- 7 (C), plots of the tensile forces are illustrated that show the tensile forces measured in the wire 15 during an oblique offset collision. The plots show the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L during the period from the beginning of the collision to the end of the collision.

[0094] FIG. 7 (A) shows plots of the tensile forces before the oblique offset collision. FIG. 7 (B) shows plots of the tensile forces for a 15-km/h collision speed, while FIG. 7 (C) shows plots of the tensile forces for a 64-km/h collision speed.

[0095] Since the wire 15 of the vehicle collision state detecting device 10 is tensioned to a prescribed initial tensile force, the tensile force measured by the right tensile force sensor 14 R and the tensile force measured by the left tensile force sensor 14 L are substantially constant during normal travel before the oblique offset collision, as shown in FIG. 7 (A).

[0096] When an oblique offset collision occurs at a collision speed of 15 km/h, a lock mechanism provided on the surface of the bumper reinforcement 13 utilizes the collision load to fix the wire 15 . More specifically, as shown in FIG. 7 (B), the right lock mechanism 16 R fixes the wire 15 when the collision occurs on the right side of the vehicle. Afterwards, the bumper reinforcement 13 deforms and the bumper stay on the side where the collision occurred, i.e., the bumper stay 12 R in this example, collapses due to the collision pressure. Also, since a load is imparted in the widthwise direction of the vehicle, the bumper stay and the tip of the side member on the side where the collision occurred, i.e., the bumper stay 12 R and the tip of the side member 11 R in this example, collapse inward.

[0097] Due to the collapse of the bumper stay 12 R and the fixing of the wire 15 by the right lock mechanism 16 R, the tensile force measured by the tensile force sensor provided on the side member on the side where the collision occurred, i.e., the right tensile force sensor 14 R, decreases from the initial tensile force at slope β R as shown in FIG. 7 (B).

[0098] Meanwhile, the tensile force measured by the tensile force sensor provided on the side member on the side where the collision did not occur, i.e., the left tensile force sensor 14 L, decreases from the initial tensile force at a slope β L that is proportional to the speed at which the bumper stay 12 R and the side member 11 R collapse inward and more gradual than the slope β R , as shown in FIG. 7 (B). This occurs because, while the wire 15 is fixed by the right lock mechanism, the portion the side member 11 R with the right lock mechanism 16 R moves toward the inside of the vehicle due to the inward deformation of the bumper stay 12 R and the tip of the side member 11 R, thus causing the wire 15 to loosen relative to the left tensile force sensor 14 L.

[0099] When an oblique offset collision occurs at a collision speed of 64 km/h, the pressure collapse level is higher than in the case of the 15-km/h collision but the collision state is substantially the same. As shown in FIG. 7 (C), the tensile force measured by the tensile force sensor provided on the side member on the side where the collision occurred, i.e., the right tensile force sensor 14 R, decreases from the initial tensile force and the tensile force measured by the tensile force sensor provided on the side member on the side where the collision did not occur, i.e., the left tensile force sensor 14 L, decreases gradually from the initial tensile force in a manner that is proportional to the speed at which the bumper stay 12 R and the tip of the side member 11 R collapse inward. The absolute values of the slopes (i.e., time rates) β R and β L at which the tensile forces decrease from the initial tensile force are larger for the 64-km/h collision than for the 15-km/h collision.

[0100] Thus during an oblique offset collision, the tensile force measured by the tensile force sensor provided on the side member on the side where the collision occurred decreases from the initial tensile force and the tensile force measured by the tensile force sensor provided on the side member on the side where the collision did not occur decreases gradually from the initial tensile force. Therefore, when the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L provided on the side members 11 R and 11 L are such that one decreases and the other decreases gradually, the control unit 22 identifies the collision state as an oblique offset collision on the side where the rate of decrease in the tensile force is larger.

Processing Executed by Control Unit 22

[0101] Next, the processing the control unit 22 executes during a collision up until it triggers the passenger restraining devices 35 will be explained with reference to FIGS. 8, 9 and 10 . As shown in FIG. 8 , when the front of the vehicle collides with an object, the object contacts the bumper reinforcement 13 of the vehicle collision state detecting device 10 in step S 1 .

[0102] In step S 2 , the right tensile force sensor 14 R and the left tensile force sensor 14 L of the vehicle collision state detecting device 10 measure a change in the tensile force and send their measurement data to the CPU 31 of the control unit 22 . In step S 3 , the floor sensor 18 measures the vehicle deceleration and sends the measured vehicle deceleration to the CPU 31 .

[0103] In step S 4 , the CPU 31 recognizes the pattern of change in the tensile forces obtained from the right tensile force sensor 14 R and the left tensile force sensor 14 L and identifies the collision state or type using the methods described in FIGS. 4 to 7 . In step S 5 , the threshold value setting section 33 of the control unit 22 determines the threshold value for triggering the passenger restraining devices 35 in accordance with the collision state identified in step S 4 . Each type of collision preferably has a different threshold value for triggering the passenger restraining devices 35 .

[0104] In step S 6 , the CPU 31 calculates the velocity ΔV by determining the first derivative of the deceleration obtained from the floor sensor 18 in step S 3 and based on the relationship between the velocity ΔV and time t.

[0105] In step S 7 ; the control unit 22 of the vehicle collision state detecting device 10 compares the threshold value calculated in step S 5 to the velocity ΔV calculated in step S 6 . In step S 8 , the control unit 22 determines if the velocity ΔV exceeds the threshold value. If the CPU 31 determines that the velocity ΔV does not exceed the threshold value, there is no need to trigger the passenger restraining devices 35 and the processing of step S 8 is repeated.

[0106] Meanwhile, if the CPU 31 determines that the velocity ΔV does exceed the threshold value, based on controls executed by the triggering control section 32 , it triggers one or more of the passenger restraining devices 35 by sending a signal for triggering the corresponding one or more of the passenger restraining devices 35 through the triggering circuit 34 .

[0107] More specifically, if the CPU 31 determines that the velocity ΔV exceeds the threshold value in step S 8 , it proceeds to step S 9 of FIG. 9 . In step S 9 , the CPU 31 starts the passenger restraining device routine. Preferably, the CPU 31 first activates the seatbelt retractors of the vehicle in step S 10 .

[0108] In step S 11 a , the CPU 31 determines if the collision state identified in step S 4 of FIG. 8 was a front collision. If the collision state or mode identified in step S 4 was a front collision, the CPU 31 proceeds to step S 12 a where the CPU 31 sets an airbag timing for deploying the front airbags (passenger restraining devices 35 ) based on the collision state identified (front collision).

[0109] Then, in step S 13 a , the CPU 31 determines if the airbag deployment timing set in step S 12 a has elapsed. If the airbag deployment timing has elapsed, the CPU 31 by using the triggering control section 32 deploys the front airbags as the passenger restraining devices 35 in step S 14 a and ends the control sequence.

[0110] In step S 11 b , the CPU 31 determines if the collision state identified in step S 4 of FIG. 8 was a simple offset collision. If the collision state or mode identified in step S 4 was a simple offset collision, the CPU 31 proceeds to step S 12 b where the CPU 31 sets an airbag timing for deploying the front airbags (passenger restraining devices 35 ) based on the collision state identified (simple offset collision).

[0111] Then, in step S 13 b , the CPU 31 determines if the airbag deployment timing set in step S 12 b has elapsed. If the airbag deployment timing has elapsed, the CPU 31 by using the triggering control section 32 deploys the front airbags as the passenger restraining devices 35 in step S 14 b and ends the control sequence.

[0112] Meanwhile, if the collision state identified in step S 4 was neither a front collision nor a simple offset collision, the CPU 31 proceeds to step S 11 c where it determines if the collision state identified in step S 4 of FIG. 8 was a pole collision.

[0113] If a pole collision was detected, the CPU 31 proceeds to step S 12 c where the CPU 31 sets an airbag timing for deploying the front airbags based on the collision state identified (pole collision). Then, in step S 13 c , the CPU 31 determines if the airbag deployment timing set in step S 12 b has elapsed. If the airbag deployment timing has elapsed, the CPU 31 by using the triggering control section 32 deploys the front airbags as the passenger restraining devices 35 in step S 14 c . In a pole collision, the CPU 31 deploys the front airbags (passenger restraining devices 35 ) such that they are inflated to a higher internal pressure than would be used in the case of a front collision or a simple offset collision. Then the control sequence ends.

[0114] Meanwhile, if a pole collision was not detected, the CPU 31 proceeds to step S 11 d where determines if the collision state identified in step S 4 of FIG. 8 was an oblique offset collision.

[0115] If an oblique offset collision was detected, the CPU 31 proceeds to step S 12 d where the CPU 31 sets an airbag timing for deploying the front airbags (passenger restraining devices 35 ) based on the collision state identified (oblique offset collision). Then, in step S 13 d , the CPU 31 determines if the airbag deployment timing set in step S 12 d has elapsed. If the airbag deployment timing has elapsed, the CPU 31 by using the triggering control section 32 deploys the front airbags as the passenger restraining devices 35 in step S 14 d.

[0116] In step S 14 d , the CPU 31 proceeds to step S 12 d where the CPU 31 sets an airbag timing for deploying the passenger curtain or side airbags (passenger restraining devices 35 ) based on the collision state identified (oblique offset collision). Then, in step S 16 , the CPU 31 determines if the airbag deployment timing set in step S 15 has elapsed. If the airbag deployment timing has elapsed, the CPU 31 by using the triggering control section 32 deploys the front airbags as the passenger restraining devices 35 in step S 17 .

[0117] In step S 17 , the vehicle collision state detecting device 10 deploys the passenger curtain or side airbags (passenger restraining devices 35 ) approximately 20 milliseconds after the passenger front airbags were deployed and then the control sequence ends.

[0118] By executing this kind of control sequence, the vehicle collision state detecting device 10 identifies the collision state and triggers the passenger restraining devices 35 in an appropriate manner based on collision state or type. When it does so, the vehicle collision state detecting device 10 selects the passenger restraining devices 35 it will trigger as appropriate based on the collision state.

[0119] The way the velocity ΔV found in step S 6 in FIG. 8 changes with time changes greatly depending on the collision state and the vehicle collision speed, as shown in FIGS. 10 (A)- 10 (D). FIG. 10 (A) shows a plot of the velocity for front collisions at collision speeds of 15 km/h and 64 km/h, FIG. 10 (B) shows a plot of the velocity for simple offset collisions at collision speeds of 15 km/h and 64 km/h, FIG. 10 (C) shows a plot of the velocity for pole collisions at collision speeds of 15 km/h and 64 km/h, and FIG. 10 (D) shows a plot of the velocity for oblique offset collisions at collision speeds of 15 km/h and 64 km/h.

[0120] As illustrated in FIGS. 10 (A)-(D), the way the velocity ΔV changes over time changes greatly depending on the collision state and the vehicle collision speed and this difference greatly affects the passenger behavior. Therefore, it is extremely important to determine the threshold value used for triggering the passenger restraining devices 35 in accordance with the particular collision state.

[0121] More specifically, when the CPU 31 detects a front collision, as in FIG. 10 (A), or a simple offset collision, as in FIG. 10 (B), based on the signals received from the right tensile force sensor 14 R and the left tensile force sensor 14 L, it executes control to start triggering the airbag provided in the center of the steering wheel, the knee airbags in front of the passengers, and the pretensioners of the passenger restraining belts at the moment the velocity ΔV exceeds the threshold value.

[0122] Similarly, when the CPU 31 detects a pole collision, as in FIG. 10 (C), based on the signals received from the right tensile force sensor 14 R and the left tensile force sensor 14 L, it executes control to start triggering the airbag provided in the center of the steering wheel, the knee airbags in front of the passengers, and the pretensioners of the passenger restraining belts at the moment the velocity ΔV exceeds the threshold value. Furthermore, the CPU 31 executes control to inflate the airbags to a higher internal pressure than in the case of a front collision or offset collision. This is done because in a pole collision there is little material available at the front of the vehicle body to absorb the enormous energy of the collision and the collision energy is transferred directly to the cabin. Thus, with this vehicle collision state detecting device 10 , the kinetic energy of the passengers can be absorbed effectively by increasing the internal pressure of the airbags to the maximum pressure that can be permitted without injuring the passengers.

[0123] Meanwhile, when the CPU 31 detects an oblique offset collision, as in FIG. 10 (D), based on the signals received from the right tensile force sensor 14 R and the left tensile force sensor 14 L, again, it executes control to start triggering the airbag provided in the center of the steering wheel, the knee airbags in front of the passengers, and the pretensioners of the passenger restraining belts at the moment the velocity ΔV exceeds the threshold value. Then, approximately 20 milliseconds later, the CPU 31 executes control to deploy the side airbags and the curtain airbags located to the sides of the passengers. This is done because in an oblique offset collision, the behavior of the passengers' upper bodies is such that they fall forward and then fall to the seat. Thus, with this vehicle collision state detecting device 10 , the kinetic energy of the passengers can be absorbed effectively by first deploying the front airbags located in front of the passengers and then deploying the side airbags at a later time.

[0124] FIG. 11 illustrates how the deployment timing of the passenger restraining devices 35 relates to the collision state. FIG. 12 illustrates the collision state-specific manner in which the threshold value is set.

[0125] When the vehicle undergoes a low-speed collision at, for example, approximately 15 km/h, it is preferable not to deploy the airbags. However, the seatbelt retractor will be activated at this velocity. Therefore, although the velocity ΔV can be calculated for each collision state, it is necessary to have the threshold value setting section 33 set the threshold value such that the airbags will not be deployed when a collision occurs at a collision speed of approximately 15 km/h or less, as shown in FIGS. 10 (A)-(D).

[0126] When a front collision occurs, the two side members 11 R and 11 L provided on the left and right sides of the vehicle absorb the collision energy of the vehicle. Since the strength of the engine compartment, which includes the side members 11 R and 11 L, is high, a high collision G-force is generated against the cabin at the initial stage of the collision. Therefore, the threshold value setting section 33 sets the threshold ΔV value for a front collision to the highest value of all the collision states, as shown in FIG. 12 . The high collision G-force generated in the cabin at the initial stage of a front collision causes the timing at which the passengers' upper bodies begin to fall forward to occur earlier. Therefore, the triggering control section 32 deploys the airbags at an earlier timing for a front collision than for the other collision states, as shown in FIG. 11 .

[0127] When a simple offset collision occurs, one or the other of the right and left side members 11 R and 11 L absorbs the vehicle collision energy. Consequently, the collision G-force is smaller than for a front collision. Therefore, the threshold value setting section 33 sets the threshold ΔV value for a simple offset collision to a lower value than for a front collision, as shown in FIG. 12 . Meanwhile, in the case of a simple offset collision, the triggering control section 32 deploys the airbags at the latest timing of all the other collision states, as shown in FIGS. 11 and 12 .

[0128] When a pole collision or oblique offset collision occurs, there is little material to absorb the enormous energy and a comparatively small collision G-force is generated in the cabin at the initial stage of the collision. Then, in the latter half of the collision, a high collision G-force is generated. Since the upper bodies of the passengers fall forward abruptly when a pole collision or oblique offset collision occurs, it is necessary to trigger the airbags and pretensioners early. Therefore, the threshold value setting section 33 sets the threshold value lower for a pole collision or an oblique offset collision than for a simple offset collision, as shown in FIG. 12 , and the triggering control section 32 deploys the airbags earlier than for a simple offset collision, as shown in FIG. 11 .

[0129] The simple offset collision and oblique offset collision mentioned here are described under the assumption that the vehicle collides with a deformable barrier.

[0130] Thus, extremely effective collision protection can be achieved by selectively changing the passenger restraining devices 35 that will be triggered in accordance with the identified collision state or type and also determining both the threshold value for triggering and the timing for deploying the passenger restraining devices 35 in accordance with the identified collision state.

Vehicle Collision State Identification Center

[0131] Next, a different method of identifying the vehicle collision state will be described. This method is based on the tensile force balance between the left and right tensile forces of the wire 15 .

[0132] Assuming the initial tensile force is F′, the tensile force FL obtained from the left tensile force sensor 14 L and the tensile force FR obtained from the right tensile force sensor 14 R take on the following relationships depending on the collision state: in a front collision FL<F′, FR<F′, and FR≈FL; in a right simple offset collision FL>F′ and FR<F′; in a left simple offset collision FL<F′ and FR>F′; in a pole collision FL>F′ and FR>F′; in an right oblique offset collision FL<F′, FR<F′, and FR<FL and in a left oblique offset collision FL<F′, FR<F′, and FR>FL.

[0133] The vehicle collision state detecting device 10 identifies the collision state by matching these relationships between the tensile forces to the respective collision state. When the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L have not changed with respect to the initial tensile force, the vehicle collision state detecting device 10 has the right tensile force sensor 14 R and the left tensile force sensor 14 L measure the tensile force again.

[0134] The vehicle collision state detecting device 10 distinguishes between front collisions and oblique offset collisions by identifying collisions that occur with an angle of 15 degrees or more between the vehicle and the colliding object as oblique offset collisions and identifying collisions that do not satisfy this angle requirement as front collisions. It accomplishes this by defining the relationship between the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L (which are provided on the side members 11 R and 11 L) as follows: the relationship “|FR−FL|<a prescribed value” indicates a front collision and the relationship “|FR−FL|≧a prescribed value” indicates an oblique offset collision.

[0135] In order to accomplish this method of identifying the vehicle collision state, the vehicle collision state detecting device 10 executes the control sequence shown in FIG. 13 when it identifies the vehicle mode in step S 4 of FIG. 8 .

[0136] Thus, as shown in FIG. 13 , in step S 21 the CPU 31 determines if the tensile force FL obtained from the left tensile force sensor 14 L is larger than the initial tensile force F′.

[0137] If the CPU 31 determines that the tensile force FL is not larger than the initial tensile force F′, it proceeds to step S 22 where it determines if the tensile force FL obtained from the left tensile force sensor 14 L is smaller than the initial tensile force F′.

[0138] If the CPU 31 determines that the tensile force FL is not smaller than the initial tensile force F′, the relationship FL=F′ exists and the CPU 31 proceeds to step S 2 of FIG. 8 to execute measurement of the tensile forces by the right tensile force sensor 14 R and the left tensile force sensor 14 L again. Meanwhile, if the CPU 31 determines that the tensile force FL is smaller than the initial tensile force F′, it proceeds to step S 25 where it determines if the tensile force FR obtained from the right tensile force sensor 14 R is smaller than the initial tensile force F′.

[0139] If the CPU 31 determines that the tensile force FR is smaller than the initial tensile force F′, it proceeds to step S 30 where it determines if the absolute value of the difference between the tensile force FR obtained from the right tensile force sensor 14 R and the tensile force FL obtained from the left tensile force sensor 14 L, i.e., |FR−FL|, is smaller than a prescribed value. The prescribed value is set such that it is larger than the absolute value |FR−FL| when the angle between the vehicle and the colliding object is 15 degrees or larger.

[0140] If the CPU 31 determines that the absolute value |FR−FL| is smaller than the prescribed value, then the relationships FL<F′, FR<F′, FR≈FL, and |FR−FL|<prescribed value exist and the CPU 31 proceeds to step S 32 , where it identifies the collision as a front collision and proceeds to step S 5 of FIG. 8 . Meanwhile, if the CPU 31 determines that the absolute value |FR−FL| is not smaller than the prescribed value, it proceeds to step S 31 where it determines if the tensile force FR obtained from the right tensile force sensor 14 R is larger than the tensile force FL obtained from the left tensile force sensor 14 L.

[0141] If the CPU 31 determines that the tensile force FR is larger than the tensile force FL, then the relationships FL<F′, FR<F′, FR>FL, and |FR−FL|≧prescribed value exist and the CPU 31 proceeds to step S 33 , where it identifies the collision as a left oblique offset collision and proceeds to step S 5 of FIG. 8 . Meanwhile, if the CPU 31 determines that the tensile force FR is not larger than the tensile force FL, then the relationships FL<F′, FR<F′, FR<FL, and |FR−FL|≧prescribed value exist and the CPU 31 proceeds to step S 34 , where it identifies the collision as a right oblique offset collision and proceeds to step S 5 of FIG. 8 .

[0142] If the CPU 31 determines that the tensile force FR is not smaller than the initial tensile force F′ in step S 25 , then it proceeds to step S 26 where it determines if the tensile force FR obtained from the right tensile force sensor 14 R is larger than the initial tensile force F′.

[0143] If the CPU 31 determines that the tensile force FR is not larger than the initial tensile force F′, then the relationship FR=F′ exists and the CPU 31 proceeds to step S 2 of FIG. 8 to execute measurement of the tensile forces by the right tensile force sensor 14 R and the left tensile force sensor 14 L again. Meanwhile, if the CPU 31 determines that the tensile force FR is larger than the initial tensile force F′, then the relationships FL<F′ and FR>F′ exist and the CPU 31 proceeds to step S 29 , where it identifies the collision as left simple offset collision and proceeds to step S 5 of FIG. 8 .

[0144] If the CPU 31 determines that the tensile force FL is larger than the initial force F′ in step S 21 , then it proceeds to step S 23 and determines if the tensile force FR obtained from the right tensile force sensor 14 R is larger than the initial tensile force F′.

[0145] If the CPU 31 determines that the tensile force FR is larger than the initial tensile force F′, then the relationships FL>F′ and FR>F′ exist and the CPU 31 proceeds to step S 27 , where it identifies the collision as a pole collision and proceeds to step S 5 of FIG. 8 . Meanwhile, if the CPU 31 determines that the tensile force FR is not larger than the initial tensile force F′, then it proceeds to step S 24 where it determines if the tensile force FR obtained from the right tensile force sensor 14 R is smaller than the initial tensile force F′.

[0146] If the CPU 31 determines that the tensile force FR is not smaller than the initial tensile force F′, then the relationship FR=F′ exists and the CPU 31 proceeds to step S 2 of FIG. 8 to execute measurement of the tensile forces by the right tensile force sensor 14 R and the left tensile force sensor 14 L again. Meanwhile, if the CPU 31 determines that the tensile force FR is smaller than the initial tensile force F′, then the relationships FL>F′ and FR<F′ exist and the CPU 31 proceeds to step S 28 , where it identifies the collision as a right simple offset collision. The CPU 31 then proceeds to step S 5 of FIG. 8 .

[0147] By executing this kind of control sequence, the vehicle collision state detecting device 10 can identify the collision state based on the balance between the left and right tensile forces of the wire 15 and selectively change which passenger restraining devices 35 it will trigger based on the identified collision state.

[0148] As described in detail heretofore, in a vehicle collision state detecting device 10 in accordance with the first embodiment, at the beginning of a vehicle collision the contact of the colliding object with the bumper reinforcement 13 causes the tensile force in the wire 15 to change. The right tensile force sensor 14 R and the left tensile force sensor 14 L connected to opposite ends of the wire 15 measure the tensile force in the wire 15 and the vehicle collision state detecting device 10 identifies the collision state based on the balance between the left and right tensile forces of the wire 15 measured by the sensors. In this way, a wide range of collision states can be identified. More particularly, the vehicle collision state detecting device 10 uses an extremely simple system in which a wire 15 is arranged at approximately the tip end of the vehicle and the tensile force as well as the occurrence of changes in tensile force are detected. This system can identify the collision state accurately and easily at the initial stage of a collision and, even though it is simple, it can identify many different collision states. The vehicle collision state detecting device 10 is provided with a right tensile force sensor 14 R and a left tensile force sensor 14 L that measure the tensile force in the wire 15 , which is arranged crosswise between the side members 11 R and 11 L. The right tensile force sensor 14 R and the left tensile force sensor 14 L measure changes in the tensile force, enabling reliable identification of the collision state. Also, since the vehicle collision state detecting device 10 has a wire 15 arranged on the approximate tip end of the vehicle and identifies the collision state based on the balance between the left and right forces in the wire 15 , it can detect a collision immediately after it occurs and identify the collision state right away. By designing the control unit 22 to identify the collision state based on the balance between the tensile forces on the left and right of the vehicle, the vehicle collision state detecting device 10 can serve as a simple and cost-effective system capable of identifying a variety of collision states (e.g., front collision, simple offset collision, pole collision, and oblique offset collision) based solely on the balance between the tensile forces on the left and right of the vehicle.

[0149] By using the control unit 22 , the vehicle collision state detecting device 10 can identify the collision state as that of a front collision by detecting that the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L have both decreased below the initial tensile force existing before the collision and that the two tensile forces are approximately equal to each other.

[0150] By using the control unit 22 , the vehicle collision state detecting device 10 can identify the collision state as that of a simple offset collision by detecting that the tensile force measured by the tensile force sensor on the side where the collision occurred has decreased below the initial tensile force that existed before the collision and the tensile force measured by the tensile force sensor on the side where the collision did not occur has increased above the initial tensile force that existed before the collision.

[0151] By using of the control unit 22 , the vehicle collision state detecting device 10 can identify the collision state as that of a pole collision by detecting that the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L have both increased above the initial tensile force existing before the collision.

[0152] By using the control unit 22 , the vehicle collision state detecting device 10 can identify the collision state as that of an oblique offset collision by detecting that the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L both decreased below the initial tensile force existing before the collision and that the two tensile forces are not approximately equal to each other. Thus, the vehicle collision state detecting device 10 can accurately identify a variety of collision states (e.g., front collision, simple offset collision, pole collision, and oblique offset collision) by using the control unit 22 to identify the patterns of change in the tensile forces measured by the right tensile force sensor 14 R and the left tensile force sensor 14 L.

[0153] By using the control unit 22 to identify the collision state based on the balance between the tensile forces on the left and right of the vehicle and determine a threshold value for triggering the passenger restraining devices 35 in accordance with the identified collision state, the vehicle collision state detecting device 10 can eliminate late triggering of the passenger restraining devices 35 and trigger passenger restraining devices 35 that are well suited to the particular collision state can be triggered, thus enabling extremely effective collision protection to be contrived.

[0154] The vehicle collision state detecting device 10 can also avoid unnecessary triggering of the passenger restraining devices 35 by using the control unit 22 to calculate a velocity waveform with respect to time based on the deceleration measured by the floor sensor 18 provided in the cabin and operating the passenger restraining devices 35 based on the calculated velocity waveform and the determined threshold value. </