Vehicle bumper structure with pedestrian collision detection sensor

Abstract

Vehicle bumper structure comprising: a bumper reinforcement (20) whose longitudinal direction extends along a vehicle width direction and which is arranged on an inner side in the longitudinal direction of a bumper cover (12) arranged at an outer end in the longitudinal direction of the vehicle, wherein outer end sections (26) of the bumper reinforcement (20) are inclined rearward in the width direction in a top view, with respect to the direction of force application in the longitudinal direction of the vehicle; an absorber (30) which adjoins an outer side in the longitudinal direction of the bumper reinforcement (20) and whose longitudinal direction extends along the vehicle width direction, wherein outer end sections (30S) of the absorber (30) are bent diagonally towards a rear corresponding to corner sections (14) of a vehicle (V) and outer end sections (26) of the bumper reinforcement (20) are bent diagonally;and a pedestrian collision detection sensor (40) which includes a pressure tube (42) which is housed in the absorber (30) in the vehicle width direction, which outputs a signal according to a pressure change of the pressure tube (42), characterized in that a total volume of the pressure tube (42) which is housed in one of the outer end sections (30S) of the absorber (30) in the vehicle width direction is larger than the total volume of the pressure tube (42) which is housed in a central section (31) of the absorber (30) in the vehicle width direction, wherein the pressure tube (42) is a single tube which has a substantially constant cross-sectional profile in its longitudinal direction.

Description

BACKGROUND Technical field This publication concerns a vehicle bumper structure with a pedestrian collision detection sensor. State of the art In a vehicle bumper structure with a pedestrian collision detection sensor, as described in publication WO 2012 / 113 362 A1, an absorber is arranged adjacent to the front of a bumper reinforcement. A groove opening towards the rear of the vehicle is formed in the absorber, and a pressure tube is fitted into this groove. In the event of a collision between the vehicle and a collision object, the absorber, due to the impact load, pushes the pressure tube towards the rear of the vehicle, causing the pressure tube to deform. Pressure sensors located at both longitudinal ends of the pressure tube output signals corresponding to the pressure change within the tube, and an ECU distinguishes whether the collision object is a pedestrian. The generic patent JP 2010-76525A discloses an impact detection device for a vehicle. This device comprises a chamber component arranged in the vehicle bumper, with an inner chamber space and a pressure sensor for detecting internal pressure. The chamber component extends transversely to the vehicle and has curved sections where the lateral ends are bent backwards to follow the shape of the bumper. To ensure the same deformation volume, the height of the chamber component is adjusted in the curved sections in JP 2010-76525A. JP 2010-179668A and JP 2007-153073A also describe vehicle bumper structures with a pedestrian collision detection sensor. DE 10 2013 201 592 A1 discloses a sensor unit for impact detection on a vehicle, which is designed and intended to detect the position of an impact in a vehicle width direction. However, the aforementioned vehicle bumper structures with a pedestrian collision detection sensor offer room for improvement with regard to the following point. Specifically, in plan view, both outer end sections of the bumper reinforcement, viewed from the front, slope towards the rear of the vehicle. Thus, these outer end sections are inclined relative to the direction of the collision load in plan view. Consequently, the pressure tube tends to be compressed with less force when the collision load is applied towards the rear of the vehicle to a corner section (a bumper cover) than when the collision load is applied to a section of the bumper cover in the middle of the vehicle's width.The output from the pressure sensors is lower when a collision object collides with the corner section (bumper cover) of the vehicle. Therefore, it is desirable to increase the sensitivity of the pedestrian collision detection sensor with regard to the corner sections of the vehicle in vehicle bumper structures equipped with a pedestrian collision detection sensor. SUMMARY In view of the foregoing circumstances, the object of the present invention is to provide a vehicle bumper structure with pedestrian collision detection sensor which can increase the sensitivity of the pedestrian collision detection sensor with respect to a corner section of a vehicle. This problem is solved by a vehicle bumper structure with the features of the main claim. Advantageous embodiments of the invention are the subject of dependent claims. One aspect of the present invention is a vehicle bumper structure comprising: a bumper reinforcement whose longitudinal direction runs along a vehicle width direction and which is arranged on an inner side (in the vehicle length direction) of a bumper cover arranged at an outer end (in the vehicle length direction), wherein outer end sections of the bumper reinforcement are inclined rearward in a plan view with respect to the direction of force application (vehicle length direction); an absorber adjacent to an outer side (in the vehicle length direction) of the bumper reinforcement, the longitudinal direction of which runs along the vehicle width direction, wherein outer end sections of the absorber are bent diagonally toward a rear corresponding to corner sections of a vehicle, and outer end sections of the bumper reinforcement are bent diagonally;and a pedestrian collision detection sensor comprising a pressure tube embedded in the absorber in the vehicle width direction, which outputs a signal according to a pressure change of the pressure tube, and wherein a total volume of the pressure tube embedded in one of the outer end sections of the absorber in the vehicle width direction is greater than the total volume of the pressure tube embedded in a central section of the absorber in the vehicle width direction, wherein the pressure tube is a single tube having a substantially constant cross-sectional profile in its longitudinal direction. In this aspect, the bumper cover is located at the outer end of the vehicle in the longitudinal direction (either the front or rear). The bumper reinforcement, whose longitudinal direction runs along the vehicle's width, is located on the inner side of the bumper cover in the longitudinal direction (the rear of the vehicle if the bumper cover is located at the front, and the front of the vehicle if the bumper cover is located at the rear). The absorber, whose longitudinal direction runs along the vehicle's width, is located adjacent to the outer side of the bumper reinforcement in the longitudinal direction, and the pressure tube is incorporated into the absorber so that they extend as a whole along the vehicle's width. In the event of a collision between the vehicle and a collision object, a collision load is applied to the absorber in the direction of the vehicle's inner longitudinal axis, causing the absorber to compress the pressure tube. The pressure tube deforms accordingly, and a signal corresponding to the pressure change within the tube is output by the pedestrian collision detection sensor. In the pedestrian collision detection sensor, the total volume of the pressure tube housed in the outer end section of the absorber (in the direction of vehicle width) is set to be larger than the total volume of the pressure tube housed in the middle section of the absorber (in the direction of vehicle width). Therefore, the deformation of the pressure tube housed in the outer end section of the absorber (in the direction of vehicle width) can be greater than the deformation of the pressure tube housed in a middle section of the absorber (in the direction of vehicle width). This allows the sensitivity of the pedestrian collision detection sensor to the corner sections of the vehicle to be increased. Furthermore, the length of the pressure pipe that is received in one of the outer end sections of the absorber in the direction of vehicle width can be longer than the length of the pressure pipe that is received in the middle section of the absorber in the direction of vehicle width. In the configuration described above, the length of the pressure tube housed in the outer end section of the absorber (in the direction of vehicle width) can be made longer than the length of the pressure tube housed in the middle section of the absorber (in the direction of vehicle width), for example by bending the pressure tube located in the outer end section of the absorber (in the direction of vehicle width). This allows the sensitivity of the pedestrian collision detection sensor with respect to the corner sections of the vehicle to be increased using a simple configuration. The vehicle bumper structure can be designed such that, in a cross-section of the absorber viewed along a vehicle side surface direction, a number of sections of the pressure tube arranged in the absorber in the vehicle height direction are larger on the outer side in the vehicle width direction than in the middle section of the absorber in the vehicle width direction. This allows the sensitivity of the pedestrian collision detection sensor to the corner sections of the vehicle to be increased using a simple configuration. According to one aspect, the pressure pipe can be a single pipe arranged to be guided back to itself in the vehicle width direction, vehicle height direction or vehicle length direction at one of the outer end sections of the absorber in the vehicle width direction. In this way, the sensitivity of the pedestrian collision detection sensor to the corner sections of the vehicle can be increased using a simple configuration. Furthermore, in an alternative embodiment, which is not covered by the scope of protection of independent claim 1 and serves only for illustration, the cross-sectional area of ​​the pressure pipe which is received in one of the outer end sections of the absorber in the direction of vehicle width may be larger than the cross-sectional area of ​​the pressure pipe which is received in the middle section of the absorber in the direction of vehicle width. In the configuration described above, for example, the vehicle height and longitudinal dimensions of the pressure pipe located in the outer end section of the absorber (in the vehicle width direction) can be greater than those of a pressure pipe located in the middle section of the absorber (in the vehicle width direction). Therefore, the position of an outer end of the pressure pipe located in the outer end section of the absorber (in the vehicle width direction) can be further towards the outer side of the vehicle than the position of an outer end of the pressure pipe located in the middle section of the absorber (in the vehicle width direction). Accordingly, the deformation of the pressure pipe can be efficiently increased when the collision load acts on the outer end section of the absorber (in the vehicle width direction). BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the present inventions are described in detail with reference to the following figures, wherein: Fig. 1 is a schematic front view which, viewed from the front of a vehicle, shows an arranged state of a pressure tube used in a front bumper equipped with a vehicle bumper structure incorporating a pedestrian collision detection sensor according to a first exemplary embodiment; Fig. 2 is a partially cut-away schematic top view which shows an entire front bumper equipped with the vehicle bumper structure according to the first exemplary embodiment; Fig. 3 is a schematic side cross-sectional view (an enlarged cross-section along line 3-3 in Fig. 2) which, viewed from the left side of the vehicle, shows a section central in the vehicle width direction of a component shown in Fig. 2.2 represents the central absorber section shown; Fig. 4 is a schematic side cross-sectional view (an enlarged cross-section along line 4-4 in Fig. 2) which, viewed from the left side of the vehicle, represents a side absorber section; Fig. 5A is a schematic front view corresponding to Fig. 1, which represents a modified example of the arranged state of the pressure tube shown in Fig. 1; Fig. 5B is a schematic front view corresponding to Fig. 1, which represents another modified example of the arranged state of the pressure tube shown in Fig. 1; Fig. 6A is a top view which represents the surroundings of a side absorber section of a modified example in which the pressure tube shown in Fig. 2 is arranged in a grooved section formed on an upper surface of an absorber; Fig.Fig. 6B is a schematic side cross-sectional view (a partially enlarged cross-section along line 6B-6B in Fig. 6A) of an upper part of the side absorber section shown in Fig. 6A, viewed from the left side of the vehicle; Fig. 7 is a schematic top view showing an entire front bumper equipped with a vehicle bumper structure incorporating a pedestrian collision detection sensor according to an unclaimed example; Fig. 8A is a schematic side cross-sectional view (an enlarged cross-section along line 8A-8A in Fig. 7) showing a central section in the vehicle width direction of a central absorber section shown in Fig. 7, viewed from the left side of the vehicle, according to an unclaimed example; and Fig. 8B is a schematic side cross-sectional view (an enlarged cross-section along line 8B-8B in Fig. 7) showing a section shown in Fig.7 shows the lateral absorber section as viewed from the left side of the vehicle. DETAILED DESCRIPTION First exemplary embodiment The following describes, with reference to Figures 1, 2, 3 to 4, a front bumper 10 of a vehicle (automobile) V, which is equipped with a vehicle bumper structure S1 with a pedestrian collision detection sensor 40 according to a first exemplary embodiment. It should be noted that in the drawings, the FRONT arrow indicates the front of the vehicle, the LEFT arrow indicates the left side of the vehicle (a side in the vehicle's width direction), and the UP arrow indicates the top of the vehicle. Unless otherwise specified, simple references to the front-rear, vertical, and left-right directions in the following description refer to front and rear in the vehicle's longitudinal direction, top and bottom in the vehicle's vertical direction, and left and right of the vehicle (when viewed from the front). As shown in Fig. 2, the front bumper 10 is arranged at a front end section of the vehicle V. In the present exemplary embodiment, the “front side” is referred to as the “outer side in the longitudinal direction of the vehicle” and the “rear side” is referred to as the “inner side in the longitudinal direction of the vehicle”. The front bumper 10 includes a bumper cover 12 formed at a front end of the vehicle V, a bumper reinforcement 20 forming a bumper frame component, and an absorber 30 arranged between the bumper cover 12 and the bumper reinforcement 20. The front bumper 10 includes the pedestrian collision detection sensor 40 for detecting a collision between the vehicle V and a collision object. Configurations of each of the foregoing are described below. Bumper cover 12 As shown in Fig. 2, the bumper reinforcement 12 is made of resin (plastic). The bumper reinforcement 12 extends along the width of the vehicle and is supported by being fixed to a section of the vehicle body not shown in the drawings. Both lateral sections 12A of the bumper cover 12, extending in the width of the vehicle, slope in plan view towards the rear side, forming corner sections 14 of the vehicle V. Bumper reinforcement 20 The bumper reinforcement 20 is formed in a hollow, substantially rectangular column shape, and its longitudinal direction runs along the vehicle's width. The bumper reinforcement 20 is made of a metal such as aluminum and is manufactured by a process such as extrusion. As shown in Fig. 3, plate-shaped reinforcement sections 22 are provided within the bumper reinforcement 20. The reinforcement sections 22 are arranged with their plate thickness direction along the vertical direction and are connected to a front wall and a rear wall of the bumper reinforcement 20 (i.e., the reinforcement sections 22 connect the front and rear walls). The cross-sectional structure of the bumper reinforcement 20 is designed such that several (three in the present exemplary embodiment) substantially rectangular closed cross-sections are arranged in a row along the vertical direction.In the present exemplary embodiment, a pair of reinforcing sections 22 are arranged in a row along the vertical direction within the bumper reinforcement 20. The closed cross-section located at an upper part of the bumper reinforcement 20 is a top-closed cross-section 24A, the closed cross-section located in an intermediate part of the bumper reinforcement 20 in the vertical direction is an intermediate closed cross-section 24B, and the closed cross-section located in a lower part of the bumper reinforcement 20 is a bottom-closed cross-section 24C. As shown in Fig. 2, a pair of left and right front sections FS, which form frame components on the vehicle body side, extend along the longitudinal direction on the rear side of the bumper reinforcement 20. Both end sections of the bumper reinforcement 20, viewed in the vehicle width direction, are connected to the front ends of the front sections FS. Both end sections of the bumper reinforcement 20, viewed in the vehicle width direction, project towards the outer sides of the front sections FS and are bent diagonally towards the rear in accordance with both lateral sections 12A of the bumper cover 12 (the corner sections 14 of the vehicle V). These bent sections are referred to as bending sections 26. Absorber 30 The absorber 30 is made of a foamed resin material, namely urethane foam or the like. The absorber 30 is arranged adjacent to the front side of the bumper reinforcement 20, between the bumper cover 12 and the bumper reinforcement 20. The absorber 30 is elongated, with its length running along the width of the vehicle to follow the shape of the bumper cover 12 in plan view. The outer end sections of the absorber 30, in the width of the vehicle, are bent diagonally towards the rear, corresponding to the corner sections 14 of the vehicle V and the bending sections 26 of the bumper reinforcement 20. The absorber 30 contains a middle absorber section 30C, which is an intermediate section of the absorber 30 in the direction of vehicle width, and a pair of left and right lateral absorber sections 30S, which are the outer end sections of the absorber 30 in the direction of vehicle width. As shown in Fig. 3, the absorber 30, when viewed in cross-section along its longitudinal direction, is formed in a substantially rectangular shape, its longitudinal direction running along the vertical direction, and a rear surface 30R of the absorber 30 is fixed to a front surface 20F of the bumper reinforcement 20. The length of the central absorber section 30C is defined as being longer than the length of the lateral absorber sections 30S (see Fig. 2). It should be noted that the length of the lateral absorber sections 30S can be appropriately modified according to the inclination angle of the corner sections 14 of the vehicle V, etc., and, for example, the lengths of the central absorber section 30C and the lateral absorber sections 30S can be defined as equal. The rear surface 30R of the absorber 30 is formed with a grooved section 32 for receiving a pressure pipe (or pressure hose) 42, which will be described later. The grooved section 32 extends along the width of the vehicle and is formed as an essentially C-shaped groove (more precisely, one with a partially open circular shape), which, viewed in cross-section along the longitudinal direction of the grooved section 32, opens towards the rear. The cross-sectional profile of the grooved section 32 is uniform along its longitudinal direction. As shown in Fig. 1, the grooved section 32 includes a central grooved section 32C, which is formed in the central absorber section 30C, and a pair of left and right lateral grooved sections 32S, which are formed in the respective lateral absorber sections 30S. The central groove section 32C extends in a substantially straight line along the vehicle width direction and is located adjacent to the front side of the upper part (especially the part forming the top-closed cross-section 24A) of the bumper reinforcement 20 (see Fig. 3 ). The lateral groove sections 32S each contain a first groove part 34A, a second groove part 34B, a third groove part 34C, and a fourth groove part 34D, each extending along the vehicle width direction. The first 34A to fourth groove parts 34D are arranged in a row with a specific distance between them in the vertical direction (see Fig. 4). The first 34A to third groove parts 34C have substantially the same length in the vehicle width direction, and the fourth groove part 34D has a shorter length in the width direction than the lengths of the first 34A to third groove parts 34C (substantially half the length of the first 34A to third groove parts 34C in the present exemplary embodiment). A vertical position of the first groove section 34A aligns with a vertical position of the middle groove section 32C, and an inner end of the first groove section 34A (in the direction of vehicle width) is connected to an outer end of the middle groove section 32C (in the direction of vehicle width). An outer end of the first groove section 34A (in the direction of vehicle width) and an outer end of the second groove section 34B (in the direction of vehicle width) are connected to each other by a first coiled (returned) section 36A, and the first coiled section 36A is formed in a substantially C-shape (essentially semicircular arc shape) that opens in the front view towards the inner side (in the direction of vehicle width).An inner end (in the direction of vehicle width) of the second groove section 34B and an inner end (in the direction of vehicle width) of the third groove section 34C are connected to each other by a second coiled section 36B, and the second coiled section 36B is formed in a substantially C-shape (semicircular arc shape) that opens in the front view towards the outer side (in the direction of vehicle width). An outer end (in the direction of vehicle width) of the third groove section 34C and an outer end (in the direction of vehicle width) of the fourth groove section 34D are connected to each other by a third coiled section 36C, and the third coiled section 36C is formed in a substantially C-shape (semicircular arc shape) that opens in the front view towards the inner side (in the direction of vehicle width).Note that the first 36A to third coiled parts 36C are each set with an appropriate radius so that, viewed from the front, the pressure tube 42 described later is gently bent back in the first 36A to third coiled parts 36C. An inner side section of the fourth groove section 34D, in the direction of vehicle width, is bent towards the rear, and the fourth groove section 34D opens downwards. Thus, in each side groove section 32S, groove sections at three locations (the first 34A to the third groove section 34C) are arranged vertically in a row in an inner side section of the side absorber section 30S, and groove sections at four locations (the first 34A to the fourth groove section 34D) are arranged vertically in a row in an outer side section of the side absorber section 30S. Pedestrian collision detection sensor 40 As shown in Fig. 2, the pedestrian collision detection sensor 40 includes the pressure tube 42, which is designed in an elongated shape, and pressure sensors 44 (elements which are generally understood as "pressure detectors") which output signals according to the pressure change in the pressure tube 42. As shown in Figures 3 and 4, the pressure tube 42 is designed as a hollow body structure with a substantially annular cross-section, and the cross-sectional profile of the pressure tube 42 is substantially the same along its length. The outer diameter of the pressure tube 42 is slightly smaller than the inner diameter of the groove section 32, and the length of the pressure tube 42 is defined as longer than the length of the groove section 32. The pressure tube 42 is installed (fitted) within the groove section 32. Thus, as shown in Figure 1, the pressure tube 42 is arranged along the groove section 32, and the pressure tube 42 extends overall along the width of the vehicle. Specifically, the pressure tube 42 is arranged such that there is a tube section extending along the width of the vehicle within the central absorber section 30C.In contrast, the pressure pipe 42 is arranged such that there are three pipe sections extending in a row along the vehicle width direction in the inner side part of the lateral absorber section 30S in the vehicle width direction, four pipe sections extending in a row along the vehicle width direction in the outer side part of the lateral absorber section 30S in the vehicle width direction, and the pressure pipe 42 is essentially U-shaped in the first 36A to third coiled parts 36C. The length of the pressure tube 42 enclosed by each lateral absorber section 30S (specifically, its total volume) is correspondingly longer (greater) than the length of the pressure tube 42 enclosed in a section 31 of the absorber 30 located centrally in the direction of the vehicle's width (specifically, its total volume). In other words, the volume density of the pressure tube 42 enclosed in the lateral absorber section 30S is greater with respect to the lateral absorber section 30S than the volume density of the pressure tube 42 enclosed in the section 31 of the absorber 30 located centrally in the direction of the vehicle's width (specifically, its total volume).It should be noted that the section 31 of the absorber 30, which is central in the direction of the vehicle's width, is a section of the absorber 30 that contains a center line CL of the central absorber section 30C in the direction of the vehicle's width, and a width dimension W1 of the section 31, which is central in the direction of the vehicle's width, is defined as equal to a width dimension W2 of each lateral absorber section 30S. In a state in which the pressure tube 42 is installed within the grooved section 32, an outer circumferential surface of the pressure tube 42 contacts the front surface 20F of the bumper reinforcement 20, or a small gap is formed between the outer circumferential surface of the pressure tube 42 and the front surface 20F (see Fig. 3 and Fig. 4). Both longitudinally viewed side sections of the pressure tube 42 extend from the absorber 30 towards the lower side through the fourth groove sections 34D of the lateral groove sections 32S. As shown in Fig. 4, in the side view the pressure tube 42, which extends from the absorber 30 towards the lower side, is essentially U-shaped at the lower side of the bumper reinforcement 20, and both longitudinally viewed end sections of the pressure tube 42 are arranged at the rear side of the bumper reinforcement 20. As shown in Figs. 2 and 4, the pressure sensors 44 are provided at both ends of the pressure tube 42, viewed in the direction of the vehicle's width. Each pressure sensor 44 is fixed to a substantially L-shaped, plate-like bracket BR, which is fixed to an upper surface of the bumper reinforcement 20, and is located on the rear side of the upper part of the bumper reinforcement 20. The pressure sensors 44 are electrically connected to an ECU 46 (an element generally understood as a "collision detection section"). In response to the deformation of the pressure tube 42, signals corresponding to the pressure change within the pressure tube 42 are output by the pressure sensors 44 to the ECU 46. A collision speed sensor (not shown in the drawings) is also electrically connected to the aforementioned ECU 46, and the collision speed sensor outputs a signal to the ECU 46 corresponding to the collision speed with a collision object. The ECU 46 then calculates the collision load based on the signals output by the previously described pressure sensors 44 and also calculates the collision speed based on the signal output by the collision speed sensor. From the calculated collision load and collision speed, the ECU 46 derives an effective mass of the collision object, determines whether the effective mass exceeds a threshold value, and decides whether the collision object striking the front bumper 10 is a pedestrian or an object other than a pedestrian (e.g., a car).an obstacle on the road, such as a road edge marking or a guidepost). The operation and advantageous effects of the first exemplary embodiment are described below. In the front bumper 10, designed as described above, the pressure tube 42 is installed (fitted) within the groove section 32 formed in the absorber 30, and the pressure tube 42 extends along the entire width of the vehicle. In the event of a collision between the vehicle V (front bumper 10) and a collision body I (see Fig. 2), the bumper cover 12 is pushed towards the rear by the collision body I. The bumper cover 12, in turn, pushes the absorber 30 towards the rear, and a collision load F in the rear direction (see Fig. 2) is transferred from the bumper cover 12 to the absorber 30.A reaction force opposing the collision force F acts from the front surface 20F of the bumper reinforcement 20 onto the absorber 30. The absorber 30 undergoes compression deformation, and the pressure tube 42 is forced through the absorber 30 and the bumper reinforcement 20. Consequently, the pressure tube 42 deforms, and the pressure inside the pressure tube 42 changes. When the pressure within the pressure tube 42 changes, the pressure sensors 44 output signals to the ECU 46 corresponding to the pressure change in the pressure tube 42, and the ECU 46 calculates the collision load based on the signals output by the pressure sensors 44. The ECU 46 also calculates the collision speed based on an output signal from the collision speed sensor. The ECU 46 then derives the effective mass of the collision body I from the calculated collision load and collision speed, determines whether the effective mass exceeds a threshold value, and decides whether the collision body I, which collided with the front bumper 10, is a pedestrian. It should be noted that, in plan view, the bending sections 26 of the bumper reinforcement 20 are bent diagonally towards the rear, corresponding to the corner sections 14 at the rear of the corner sections 14 (both side sections 12A of the bumper cover 12 in the vehicle width direction) of the vehicle V. Thus, in plan view, the bending section 26 of the bumper reinforcement 20 is inclined with respect to the direction of the collision load F. Therefore, the force of the collision load F, which pushes the pressure tube 42 in a direction perpendicular to the front surface 20F of the bumper reinforcement 20, is smaller at the corner section 14 of the bumper cover 12 than at a section of the bumper cover 12 located in the middle of the vehicle width direction.Furthermore, since both side sections 12A of the bumper cover 12 (corner sections 14) in the vehicle width direction slope in the direction of the outer sides towards the rear when the collision body I strikes the corner section 14, the collision body I slides (shifts) towards the outer side in the vehicle width direction. If, as a result, the collision body I collides with the corner section 14 of the vehicle V, the pressure tube tends to be pressed with a smaller load than if the collision body I collides with the middle section of the bumper cover 12 in the vehicle width direction (e.g., approximately 60% of the force that the pressure tube 42 presses on the middle section of the bumper cover 12 in the vehicle width direction). However, the pressure pipe 42 is arranged such that one pipe section extends along the vehicle width direction in the central absorber section 30C. Furthermore, the pressure pipe 42 is arranged such that three pipe sections arranged in a row in the vertical direction extend along the vehicle width direction in the inner side section of the lateral absorber section 30S, and four pipe sections arranged in a row in the vertical direction extend along the vehicle width direction in the outer side section of the lateral absorber section 30S. Specifically, the pressure pipe 42 is arranged such that the number of pipe sections along the vertical direction in the absorber 30 on the outer side (in the vehicle width direction) is greater than in the central section of the absorber 30 (in the vehicle width direction).Thus, the total volume (longitudinal length) of the pressure pipe 42, which is contained in the lateral absorber section 30S, is larger (longer) than the total volume (longitudinal length) of the pressure pipe 42, which is contained in the section 31 of the absorber 30 which is located in the middle of the vehicle width. Thus, when the collision load F is applied to the central absorber section 30C, a section of the pressure tube 42 deforms, while three sections (or four sections of the tube) of the pressure tube 42 deform when the collision load F is applied to the inner (or outer) side section of the lateral absorber section 30S. This allows the (total) amount of deformation of the pressure tube 42 when the collision load F is applied to the lateral absorber section 30S to be increased compared to the (total) amount of deformation of the pressure tube 42 when the collision load F is applied to the central section 31 of the absorber 30. This correspondingly increases the sensitivity of the pedestrian collision detection sensor 40 with respect to the corner sections 14 of the vehicle V.Even if the load pressing on the pressure tube 42 when the collision body I collides with the corner section 14 of the vehicle V is small, it can prevent the output from the pressure sensors 44 from decreasing, thereby improving the detection precision of the pedestrian collision detection sensor 40. In the present exemplary embodiment, the length of the pressure tube 42, which is accommodated in each lateral absorber section 30S, is longer than the longitudinal length of the pressure tube 42, which is accommodated in the section 31 of the absorber 30 that is central in the vehicle width direction. Thus, the curved arrangement of the pressure tube in the lateral absorber section 30S allows the total volume of the pressure tube 42 accommodated in the lateral absorber section 30S to be made larger than the total volume of the pressure tube 42 accommodated in the section 31 of the absorber 30 that is central in the vehicle width direction. Therefore, the sensitivity of the pedestrian collision detection sensor 40 with respect to the corner sections 14 of the vehicle V can be increased using a simple configuration. Furthermore, the same cross-sectional profile of the pressure pipe 42 can be determined via the longitudinal direction of the pressure pipe 42. This makes it possible to increase the sensitivity of the pedestrian collision detection sensor 40 with respect to the corner sections 14 of the vehicle V while using an existing pressure pipe 42. It should be noted that in the first exemplary embodiment, the pressure pipe 42 is arranged such that three pipe sections are arranged in a row in the vertical direction in the inner side part of the lateral absorber section 30S (in the direction of the vehicle's width), and four pipe sections are arranged in a row in the vertical direction in the outer side part of the lateral absorber section 30S (in the direction of the vehicle's width). However, the arrangement of the pressure pipe 42 in the lateral absorber section 30S is not limited to this. As shown in Fig. 5A, for example, the pressure pipe 42 in each lateral absorber section 30S can be configured in a zigzag shape, forming bulges in the vertical direction when viewed from the front.It is sufficient that the pressure pipe 42 is arranged in the absorber 30 such that the length of the pressure pipe 42 received in each lateral absorber section 30S is longer than the length of the pressure pipe 42 received in the section 31 of the absorber 30 that is central in the direction of the vehicle's width. It should be noted that in such cases, a section of the pressure pipe 42 which is arranged in the central absorber section 30C (especially a part which is arranged on an outer side part of the central absorber section 30C in the direction of the vehicle's width) may be bent. As shown in Fig. 5B, the pressure tube 42, which is arranged in each lateral absorber section 30S, can be bent into a substantially U-shape, opening towards the inner side in the direction of the vehicle width, and two sections of the pressure tube 42 can be arranged in a row in the vertical direction in the lateral absorber section 30S. In such cases, the pressure tube 42 can be efficiently arranged in the absorber 30 in vehicles in which the vertical extent of the absorber 30 is relatively short. In the first exemplary embodiment, the pressure tube 42 is arranged in a row in the vertical direction in each lateral absorber section 30S. However, the embodiments are not limited to this, and the pressure tube 42 can be arranged in a row in the longitudinal direction in the lateral absorber section 30S. As shown in Fig. 6A and Fig. 6B, the grooved section 32 can, for example, be formed on an upper surface of the absorber 30, and the first 34A to fourth grooved sections 34D can be formed in a row along the longitudinal direction on an upper surface of the lateral absorber section 30S. Furthermore, in such cases, the length of the pressure tube 42 accommodated in each lateral absorber section 30S is longer than the longitudinal length of the pressure tube 42 accommodated in the section 31 of the absorber 30 that is central in the vehicle width direction. It should be noted that in the embodiment shown in Fig. 6A and Fig.In the modified example shown in Fig. 6B, the longitudinally outer side parts of the pressure tube 42 can extend outwards from the absorber 30 towards the upper side and then bend towards the rear side. In the modified example shown in Fig. 6A and Fig. 6B, the grooved section 32 is formed on the upper surface of the absorber 30; however, the grooved section 32 can also be formed on a lower surface of the absorber 30. Description of an unclaimed example The embodiment described below has a variable cross-sectional profile and is therefore not covered by the scope of the patent claims. It serves only to better understand the technical background. With reference to Figures 7, 8A, and 8B, a vehicle bumper structure S2 with a pedestrian collision detection sensor 40 according to a second exemplary embodiment is described below. This example is similar to the first exemplary embodiment, except for the points shown below. It should be noted that the components which are similar to those of the first exemplary embodiment are provided with the same reference numerals. In the second exemplary embodiment, the central absorber section 30C and the lateral absorber sections 30S are defined with the same longitudinal dimension. The groove section 32 formed in the absorber 30 is arranged adjacent to the front face of the vertically interposed part (especially the part forming the interposed closed cross-section 24B) of the bumper reinforcement 20 and extends along the vehicle width direction. The lateral groove sections 32S formed in the lateral absorber sections 30S are each formed by a single groove section extending along the vehicle width direction.An inner end (in the vehicle width direction) of each lateral groove section 32S is connected to the outer end (in the vehicle width direction) of the central groove section 32C, and an outer end (in the vehicle width direction) of the lateral groove section 32S opens towards the outer side (in the vehicle width direction). The inner diameter dimension of the lateral groove section 32 increases towards the outer side (in the vehicle width direction) according to an outer profile of the pressure tube 42, as described below (i.e., the inner diameter dimension of the lateral groove section 32S becomes larger towards the outer side (in the vehicle width direction). The pressure tube 42 is arranged along the central groove section 32C and the lateral groove section 32S formed in the absorber 30 and extends along the vehicle width direction. The outer diameter dimension of the pressure tube 42, which is accommodated in each lateral absorber section 30S, increases towards the outer side in the vehicle width direction (i.e., the outer diameter dimension of the pressure tube 42 becomes larger towards the outer side in the vehicle width direction). In other words, the cross-sectional area of ​​the pressure tube 42 accommodated in the lateral absorber section 30S is such that it is larger than the cross-sectional area of ​​the pressure tube 42 accommodated in the central absorber section 30C (see Fig. 8A and Fig. 8B). The pressure sensors 44 are provided at both ends of the pressure tube 42 in the direction of the vehicle width and are arranged on the outer sides of the absorber 30 in the direction of the vehicle width.It should be noted that the pressure sensors 44 may be fixed to components not shown in the drawings, which form the vehicle body of vehicle V. Thus, in the second exemplary embodiment, the total volume of the pressure pipe 42 contained in each lateral absorber section 30S is also greater than the total volume of the pressure pipe 42 contained in the section 31 of the absorber 30 located centrally in the vehicle width direction. Specifically, the volumetric density of the pressure pipe 42 contained in the lateral absorber section 30S is higher with respect to the lateral absorber section 30S than the volumetric density of the pressure pipe 42 contained in the section 31 of the absorber 30 located centrally in the vehicle width direction with respect to the section 31 located centrally in the vehicle width direction.As a result, the deformation of the pressure tube 42 when the collision load F is applied to the lateral absorber section 30S can be increased compared to the deformation of the pressure tube 42 when the collision load F is applied to the section 31 of the absorber 30 located centrally in the vehicle width direction. Thus, the second exemplary embodiment can also increase the sensitivity of the pedestrian collision detection sensor 40 with respect to the corner sections 14 of the vehicle V, just as in the first exemplary embodiment. Since, in the second exemplary embodiment, the cross-sectional profile of the pressure tube 42 essentially forms an annular shape, the vertical and longitudinal dimensions of the pressure tube 42 received in the lateral absorber section 30S are greater than the vertical and longitudinal dimensions of the pressure tube 42 received in the central absorber section 30C. This allows the front end 42A of the pressure tube 42 received in the lateral absorber section 30S to be located at the front face of the front end 42A of the pressure tube 42 received in the central absorber section 30C. In other words, the front end 42A of the pressure tube 42 is located in the lateral absorber section 30S to be closer to a front surface of the absorber 30.This allows the amount of deformation of the pressure tube 42, which is contained in the lateral absorber section 30S, to be effectively increased when the collision load F is applied to the lateral absorber section 30S. Certain details regarding this point follow. Specifically, when the collision load F is applied to the absorber 30, the absorber 30 tends to be subjected to compression deformation at its front portion due to the collision load F. Since, in the second exemplary embodiment described above, the front end 42A of the pressure tube 42 is located in the lateral absorber section 30S to be closer to the front surface of the absorber 30, the front end 42A of the pressure tube 42 can be effectively compressed due to the collision load F. Thus, the amount of deformation of the pressure tube 42 contained within the lateral absorber section 30S can be efficiently increased. In the second exemplary embodiment, the pressure tube 42 (the grooved section 32 of the absorber 30) is arranged on the front side of the vertically interposed section of the bumper reinforcement 20; however, the vertical position of the pressure tube 42 (the grooved section 32 of the absorber 30) can be determined as desired according to each vehicle type. In the first exemplary embodiment and the second exemplary embodiment, the intermediate section of the bumper reinforcement 20 (the section excluding the curved sections 26) extends in a straight line along the vehicle's width; however, the intermediate section of the bumper reinforcement 20 may be curved according to factors such as the design of each vehicle type to form a slight bulge in plan view towards the front of the vehicle. In such cases, the central absorber section 30C may be similarly curved to form a slight bulge in plan view towards the front of the vehicle. In the first exemplary embodiment (as well as the unclaimed example), examples were given in which the vehicle bumper structures S1 and S2 with the pedestrian collision detection sensor 40 are provided in the front bumper 10; however, the embodiments are not limited thereto. For example, the front and rear of the above configurations can be reversed, and the vehicle bumper structures S1 and S2 with the pedestrian collision detection sensor 40 can be provided in a rear bumper.

Claims

Vehicle bumper structure comprising: a bumper reinforcement (20) whose longitudinal direction extends along a vehicle width direction and which is arranged on an inner side in the longitudinal direction of a bumper cover (12) arranged at an outer end in the longitudinal direction of the vehicle, wherein outer end sections (26) of the bumper reinforcement (20) are inclined rearward in the width direction in a top view, with respect to the direction of force application in the longitudinal direction of the vehicle; an absorber (30) which adjoins an outer side in the longitudinal direction of the bumper reinforcement (20) and whose longitudinal direction extends along the vehicle width direction, wherein outer end sections (30S) of the absorber (30) are bent diagonally towards a rear corresponding to corner sections (14) of a vehicle (V) and outer end sections (26) of the bumper reinforcement (20) are bent diagonally;and a pedestrian collision detection sensor (40) which includes a pressure tube (42) which is accommodated in the absorber (30) in the vehicle width direction, which outputs a signal according to a pressure change of the pressure tube (42), characterized in that a total volume of the pressure tube (42) which is accommodated in one of the outer end sections (30S) of the absorber (30) in the vehicle width direction is larger than the total volume of the pressure tube (42) which is accommodated in a central section (31) of the absorber (30) in the vehicle width direction, wherein the pressure tube (42) is a single tube which has a substantially constant cross-sectional profile in its longitudinal direction. Vehicle bumper structure according to claim 1, wherein a length of the pressure tube (42) which is received in one of the outer end sections (30S) of the absorber (30) in the direction of the vehicle width is longer than a length of the pressure tube (42) which is received in the middle section (31) of the absorber (30) in the direction of the vehicle width. Vehicle bumper structure according to claim 1 or 2, wherein, in a cross-section of the absorber (30) viewed along a vehicle side surface direction, a number of sections of the pressure tube (42) arranged in the vehicle height direction in the absorber (30) is larger in the outer side in the vehicle width direction than in the middle section (31) of the absorber (30) in the vehicle width direction. Vehicle bumper structure according to one of claims 1 to 3, wherein the pressure tube (42) is a single tube arranged such that it is guided back to itself in the vehicle width direction, vehicle height direction or vehicle longitudinal direction at one of the outer end sections (30S) of the absorber (30) in the vehicle width direction, vehicle height direction or vehicle length direction.

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