Collision detection device

Abstract

To enable a collision detection device to determine whether a form of a frontal collision is a bilaterally symmetric collision or a non bilaterally symmetric collision even if a vehicle includes only one acceleration sensor at a center in a lateral direction of a front end.SOLUTION: A collision detection device includes: an acceleration sensor disposed at a center in a vehicle lateral direction at a front end of a vehicle; a pressure sensor unit; and one or multiple processors. The pressure sensor unit includes: an air tube extending in the vehicle lateral direction at the inner side of a front bumper; and a pair of pressure sensors respectively connected to ends of the air tube to detect the change of the pressure in the air tube occurring in response to deformation of the air tube caused by a frontal collision. The one or multiple processors determine whether a frontal collision occurs on the basis of the output of the acceleration sensor and then determines whether a form of the frontal collision is a bilaterally symmetric collision or a non bilaterally symmetric collision according to a difference of timing, at which pressure values respectively detected by the pair of pressures sensors exceed a determination threshold value, after it is determined that the frontal collision occurs.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a technique for determining whether a type of frontal collision of a vehicle is a symmetrical collision or an asymmetrical collision. [Background technology]

[0002] Patent Document 1 discloses a vehicle collision type determination device. When a peak in left or right deceleration is detected during a collision by two deceleration sensors arranged on the left and right front sides of the vehicle, this determination device determines whether the vehicle collision type is symmetrical or asymmetrical based on an integrated value of the left and right decelerations. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-9830 A Summary of the Invention [Problem to be solved by the invention]

[0004] The determination method described in Patent Document 1 requires two deceleration sensors (acceleration sensors) at the front end of the vehicle to determine whether the front collision type is a symmetrical collision or an asymmetrical collision. Therefore, it is difficult to apply this determination method to a vehicle that has only one acceleration sensor at the center in the left-right direction of the front end of the vehicle to reduce costs in order to determine the type of front collision.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a collision detection device that is capable of determining whether a frontal collision is a symmetrical collision or an asymmetrical collision, even in a vehicle that has only one acceleration sensor located in the center of the front end of the vehicle in the left-right direction. [Means for solving the problem]

[0006] The collision detection device according to the present disclosure is configured to detect a frontal collision of a vehicle. The collision detection device includes an acceleration sensor, a pressure sensor unit, and one or more processors. The acceleration sensor is disposed at the center of the front end of the vehicle in the left-right direction of the vehicle. The pressure sensor unit includes an air tube extending in the left-right direction of the vehicle inside the front bumper of the vehicle, and a pair of pressure sensors connected to each end of the air tube to detect a change in pressure in the air tube according to deformation of the air tube caused by the frontal collision. The one or more processors determine whether a frontal collision has occurred based on the output of the acceleration sensor, and after determining that a frontal collision has occurred, determine whether the type of the frontal collision is a symmetrical collision or an asymmetrical collision according to the difference in timing at which the pressure values ​​detected by each of the pair of pressure sensors exceed a determination threshold. Effect of the Invention

[0007] According to the present disclosure, by utilizing the fact that the pressure detection timing by a pair of pressure sensors differs depending on the collision location, it becomes possible to determine whether the type of frontal collision is a symmetrical collision or an asymmetrical collision, even in a vehicle that has only one acceleration sensor located in the center of the vehicle's left-right direction at the front end of the vehicle. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of a configuration of a vehicle equipped with a collision detection device according to an embodiment; [Diagram 2] 10A and 10B are diagrams for explaining differences in output waveforms of a pair of pressure sensors caused by differences in collision modes; [Diagram 3] 5 is a flowchart showing a process for detecting a frontal collision and determining a collision type according to the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1. Vehicle configuration FIG. 1 is a diagram showing an example of the configuration of a vehicle 10 equipped with a collision detection device 1 according to an embodiment.

[0010] The vehicle 10 is equipped with a first acceleration sensor 12. The first acceleration sensor 12 is disposed at the center of the front end of the vehicle 10 in the left-right direction of the vehicle as shown in Fig. 1. The first acceleration sensor 12 detects acceleration (more specifically, longitudinal acceleration) A1 occurring at an attachment site of the first acceleration sensor 12. The first acceleration sensor 12 corresponds to an example of an "acceleration sensor" according to the present disclosure.

[0011] The vehicle 10 is equipped with a second acceleration sensor 14. The second acceleration sensor 14 is disposed rearward of the first acceleration sensor 12. For example, the second acceleration sensor 14 is disposed at the center of the vehicle body in the longitudinal and lateral directions of the vehicle as shown in FIG. 1. As an example, the second acceleration sensor 14 is housed in a device (e.g., an airbag ECU included in the ECU 30 described below) attached to a vehicle body component. The second acceleration sensor 14 detects acceleration (more specifically, longitudinal acceleration) A2 occurring at the attachment position of the second acceleration sensor 14.

[0012] The vehicle 10 includes a pressure sensor unit 16. The pressure sensor unit 16 includes an air tube 18 and a pair of pressure sensors 20L and 20R. The air tube 18 is disposed inside a front bumper 22 so as to extend in the left-right direction of the vehicle. More specifically, the air tube 18 is disposed so as to extend in the left-right direction of the vehicle while being sandwiched between the front bumper 22 and a vehicle body component (e.g., a bumper reinforcement) 24 via an absorber 26 (e.g., a foam material). The pair of pressure sensors 20L and 20R are connected to each end of the air tube 18. Each of the pair of pressure sensors 20L and 20R detects a change in pressure in the air tube 18 in response to the deformation of the air tube 18 accompanying the deformation of the absorber 26 at the time of a frontal collision of the vehicle 10.

[0013] The vehicle 10 includes an electronic control unit (ECU) 30. The ECU 30 is a computer that controls the vehicle 10. The ECU 30 includes one or more processors 32 (hereinafter simply referred to as the processor 32) and one or more storage devices 34 (hereinafter simply referred to as the storage device 34). The processor 32 executes various processes. The various processes include processes related to "frontal collision detection" and "collision type discrimination" described below, and processes related to the operation of the airbag device 40. The storage device 34 stores various information required for the processes by the processor 32. The processor 32 executes a computer program, thereby realizing various processes by the ECU 30. The computer program is stored in the storage device 34. Alternatively, the computer program may be recorded in a computer-readable recording medium. The ECU 30 may be configured by combining multiple ECUs that can communicate with each other, for example, by CAN (Controller Area Network) communication.

[0014] The vehicle 10 is equipped with an airbag device 40. The airbag device 40 is configured to deploy an airbag in response to detection of a frontal collision, which will be described later, based on a command from the ECU 30. More specifically, the airbag device 40 is a dual airbag device equipped with an airbag for each of the driver's seat and the passenger seat, and is configured to be capable of igniting in two stages so that the airbag deployment pressure can be adjusted.

[0015] 2. Identifying the type of collision in a frontal collision In order to detect a frontal collision of the vehicle 10 (i.e., a collision from the front of the vehicle 10) and further to determine the collision type in the frontal collision, the "collision detection device 1" according to this embodiment is configured to include a first acceleration sensor 12, a second acceleration sensor 14, a pressure sensor unit 16, and a processor 32.

[0016] The processor 32 detects a frontal collision in the following manner. That is, the processor 32 determines that a frontal collision has occurred when the condition that the acceleration A1 detected by the first acceleration sensor 12 is higher than a predetermined first collision determination threshold and the acceleration A2 detected by the second acceleration sensor 14 is higher than a predetermined second collision determination threshold is satisfied. Note that only the first acceleration sensor 12 may be used to detect a frontal collision. That is, the processor 32 may determine that a frontal collision has occurred when the condition that the acceleration A1 is higher than the first collision determination threshold is satisfied.

[0017] Here, in a vehicle 10 equipped with an airbag device 40 of dual airbag specification as a frontal collision airbag, it is required to determine whether the type of frontal collision is a symmetrical collision or an asymmetrical collision. The reason is that it is necessary to adjust the second stage ignition timing according to the difference in occupant behavior resulting from whether the type of frontal collision is a symmetrical collision or an asymmetrical collision. However, in a vehicle 10 equipped with only one first acceleration sensor 12 at the front end of the vehicle 10, located at the center in the left-right direction of the vehicle for cost reduction, it is difficult to determine the type of frontal collision using the output of the first acceleration sensor 12.

[0018] Therefore, in this embodiment, a pair of pressure sensors 20L and 20R (pedestrian protection pressure sensors) included in a pressure sensor unit 16 provided on the vehicle 10 to provide pedestrian protection function are used together with the first acceleration sensor 12 (and the second acceleration sensor 14) to determine the type of frontal collision.

[0019] Fig. 2 is a diagram for explaining the difference in output waveforms of the pair of pressure sensors 20L and 20R caused by the difference in the collision type. In Fig. 2, the pressure change amount ΔP with respect to a predetermined reference value when no collision occurs is used as an example of the pressure value detected by each of the pair of pressure sensors 20L and 20R.

[0020] First, Fig. 2(A) shows output waveforms (waveforms of pressure changes ΔP1 and ΔP2) of a pair of pressure sensors 20L and 20R when a "symmetrical collision" occurs. The "symmetrical collision" here refers to a collision that is symmetrical with respect to a vehicle center line L extending in the vehicle longitudinal direction. Symmetrical collisions include, for example, a collision with a collision object X located on the vehicle center line L as shown in Fig. 2(A), and a collision between the entire front of the vehicle and the collision object (full-lap collision).

[0021] The pair of pressure sensors 20L and 20R communicate with each other through the air tube 18, i.e., they share the space (pressure detection space) inside the air tube 18. When a collision occurs, the air tube 18 is crushed at the collision location, causing the pressure inside the air tube 18 to rise. In an example where a symmetrical collision occurs, the distances from the position where the air tube 18 is crushed by the collision to each pressure sensor 20L and 20B are equal. Therefore, the change (including the increase) in pressure inside the air tube 18 due to the collision is detected by the left and right pressure sensors 20L and 20R at the same timing as shown in FIG. 2(A). That is, the pressure change amount ΔP1 of the pressure sensor 20L on the left side of the vehicle and the pressure change amount ΔP2 of the pressure sensor 20R on the right side of the vehicle progress in a similar waveform as shown in FIG. 2(A).

[0022] Next, Fig. 2(B) shows output waveforms (waveforms of pressure changes ΔP1 and ΔP2) of a pair of pressure sensors 20L and 20R when an "asymmetric collision" occurs. The asymmetric collision here refers to a collision that is asymmetric with respect to the vehicle center line L. Asymmetric collisions include, for example, a collision with a collision object X at a position offset from the vehicle center line L as shown in Fig. 2(B) and an oblique collision of the front of the vehicle with the collision object.

[0023] When an asymmetric collision occurs, a difference (left-right difference Δt) occurs in the timing of detection of the pressure change in the air tube 18 by the left and right pressure sensors 20L and 20R due to the difference in distance from the position where the air tube 18 is crushed by the collision. As a result, for example, when a collision occurs on the left side of the vehicle 10 with respect to the vehicle center line L as shown in FIG. 2(B), the timing at which the pressure change amount ΔP due to the collision exceeds the predetermined judgment threshold value THp is delayed for the pressure sensor 20R on the right side of the vehicle compared to the pressure sensor 20L on the left side of the vehicle, which is closer to the collision site. The left-right difference Δt in the timing is, for example, about 3 to 5 ms.

[0024] In this embodiment, the type of frontal collision is determined by utilizing the principle described with reference to Figures 2(A) and 2(B). That is, the processor 32 first determines whether or not a frontal collision has occurred using the above-mentioned method based on the output of the first acceleration sensor 12 (and the second acceleration sensor 14). After determining that a frontal collision has occurred, the processor 32 determines whether the type of frontal collision is a symmetrical collision or an asymmetrical collision according to the difference (left-right difference Δt) in the timing at which the pressure values ​​(e.g., pressure changes ΔP1 and ΔP2) detected by each of the pair of pressure sensors 20L and 20R exceed the determination threshold value THp.

[0025] 3 is a flowchart showing a process for detecting a frontal collision and determining a collision type according to the embodiment of the present invention. The process of this flowchart is executed by the processor 32 of the ECU 30 while the system of the vehicle 10 is running.

[0026] In step S100, the processor 32 acquires acceleration sensor information based on the outputs of the first and second acceleration sensors 12, 14. Specifically, the acceleration sensor information here is both the accelerations A1 and A2, but may be only the acceleration A1 as described above.

[0027] In step S102 following step S100, the processor 32 determines whether or not a frontal collision has occurred based on the acquired acceleration sensor information. If it is determined that a frontal collision has not occurred (step S102; No), the process returns to step S100. On the other hand, if it is determined that a frontal collision has occurred (step S102; Yes), the process proceeds to step S104.

[0028] In step S104, the processor 32 acquires pressure sensor information (pressure sensor information for pedestrian protection) based on the outputs of the pair of pressure sensors 20L and 20R. Specifically, the pressure sensor information is pressure values ​​(e.g., pressure changes ΔP1 and ΔP2) detected by each of the pair of pressure sensors 20L and 20R.

[0029] In step S106 following step S104, the processor 32 determines whether or not the left-right difference Δt in the timing at which each of the pressure change amounts ΔP1 and ΔP2 exceeds a predetermined determination threshold THp due to the occurrence of a frontal collision is equal to or greater than a predetermined determination threshold THt. The determination threshold THt is determined, for example, by performing an experiment or a simulation in advance.

[0030] When the left-right difference in timing Δt is equal to or greater than the determination threshold value THt (step S106; Yes), the processor 32 determines that the type of the currently occurring frontal collision is an asymmetric collision (step S108).

[0031] On the other hand, if the left-right timing difference Δt is less than the determination threshold THt (step S106; No), the processor 32 determines that the type of the currently occurring frontal collision is a left-right symmetric collision (step S110).

[0032] 3.Effects As described above, according to the collision detection device 1 of this embodiment, after it is determined that a frontal collision has occurred using the first acceleration sensor 12, the type of the frontal collision is determined by utilizing the fact that the pressure detection timings by the pair of pressure sensors 20L and 20R differ depending on the collision location. Thus, according to this embodiment, even in a vehicle 10 that has only one acceleration sensor (first acceleration sensor 12) at the center in the vehicle left-right direction at the front end of the vehicle 10, it is possible to determine whether the type of the frontal collision is a symmetrical collision or an asymmetrical collision. [Explanation of symbols]

[0033] REFERENCE SIGNS LIST 1 collision detection device, 10 vehicle, 12 first acceleration sensor, 14 second acceleration sensor, 16 pressure sensor unit, 18 air tube, 20L, 20R pressure sensor, 22 front bumper, 24 vehicle body component, 26 absorber, 30 electronic control unit (ECU), 32 processor, 34 storage device, 40 airbag device

Claims

[Claim 1] A collision detection device for detecting a frontal collision of a vehicle, An acceleration sensor disposed at a center in a left-right direction of the front end of the vehicle; a pressure sensor unit including an air tube extending in the left-right direction of the vehicle inside a front bumper of the vehicle, and a pair of pressure sensors connected to each end of the air tube to detect a change in pressure within the air tube in response to deformation of the air tube caused by the frontal collision; one or more processors; Equipped with The one or more processors: determining whether or not the front collision has occurred based on an output of the acceleration sensor; After determining that the frontal collision has occurred, the system determines whether the type of the frontal collision is a symmetrical collision or an asymmetrical collision depending on a difference in timing at which the pressure values ​​detected by each of the pair of pressure sensors exceed a determination threshold. A collision detection device comprising:

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