# Patent

## Title
Vehicle door

## Abstract

A vehicle door (10) includes a door frame (20), hinges (32) for attaching the door frame to a vehicle body (31) therethrough in such a manner that the door frame moves between open and closed positions, a door lock section (35) for holding the vehicle door in a closed position, and door beams (70) connected between the hinges and the door lock section. Each door beam includes a series a plural dividing members. The plural dividing members have their respective end portions (71b, 72a) overlapped with each other in a widthwise direction of the vehicle body and joined with each other in such a manner that the dividing members are movable relative to each other by a predetermined distance when a collision force acts on the doorbeam.

## Background
TECHNICAL FIELD
The present invention relates to a technique for improving performance of a door to protect a passenger or driver (hereinafter, generically referred to as a passenger) in a motor vehicle.
BACKGROUND ART
In recent years, techniques have been developed for protecting a passenger of a vehicle from a collision force acting on the vehicle. For enhanced passenger protecting performance, there has been a demand for reconsideration of the overall vehicle body structure including doors. As an example of a vehicle door designed to enhance the passenger protecting performance, there is known a “vehicle door structure” disclosed in Japanese Patent Laid-open Publication No. HEI-7-25236.
The disclosed vehicle door has an inner door panel mounted via upper and lower hinges to a vehicle body to move between open and closed positions. The vehicle door has a door lock device for holding the door closed. The inner door panel includes an impact bar extending between the hinges and the door lock device.
When an impact load is applied to the door in a widthwise direction of the vehicle body, that is, when the vehicle body collides with a certain object at either of right and left sides thereof, the impact bar transfers collision energy from front and rear ends thereof to the hinges and the door lock device to thereby alleviate or reduce the collision.
However, the disclosed vehicle door designed to transfer the collision energy towards the door lock device and the hinges does not take any measure against collision occurring at (or a collision force applied to) a front side of the vehicle body. There is a need to ensure the enhanced passenger protecting performance even when the vehicle body collides with a certain object at a front side thereof.
One may propose to make such a vehicle door deformable to absorb the impact load when a vehicle body collides with the object at a front side thereof. Even in such a case, the door lock device needs to reliably unlock the vehicle door.
What has been needed is a vehicle door which provides an improved performance of protecting passengers from a collision occurring at a front side of a vehicle and which includes a door lock section designed to ensure that the vehicle door is unlocked even after subjected to a collision force.
DISCLOSURE OF THE INVENTION
According to one aspect of the present invention, there is provided a vehicle door comprising: a door frame attachable via hinges to a vehicle body to move between open and closed positions; a door lock section secured to the door frame to hold the vehicle door in a closed position; door beams connected between secured positions of the hinges and the door lock section; the door beams each comprising a series of plural dividing members, the plural dividing members having respective end portions thereof overlapped with each other in the widthwise direction of the vehicle body and joined with each other in such a manner that the dividing members are movable relative to each other by a predetermined distance when a compression force greater than predetermined intensity acts on the door beam.
The collision force acting on the door from ahead of the vehicle body is transmitted, as a compression force acting on the door beam in the longitudinal direction thereof, from a region at and around the hinge of the door frame, via the door beam, to a region at and around the door lock section. If the collision force acting on the door beam is greater than predetermined intensity, each end portion moves rearward with respect to the end portion provided in overlapping relation thereto by the predetermined distance to thereby absorb the collision energy. Therefore, the collision energy applied from ahead of the vehicle body can be alleviated significantly by being absorbed promptly and sufficiently by the door beam. Further, because the collision energy applied from ahead of the vehicle body is absorbed by the door beam, an impact force transmitted from the door beam to the door lock section can be greatly reduced. Since the door lock section is subjected to only a small impact force, it can still remain in its predetermined state where the door lock can be released as desired. Therefore, even after the door has undergone the impact force, it is possible to operate the door lock section to reliably release the locking state.
Preferably, the dividing members comprise a first dividing member positioned closer to the hinge and a second dividing member positioned closer to the door lock section, and mutually-joined areas of the end portions are located near the hinge, and the first dividing member is located closer to the interior of a vehicle compartment than the second dividing member. The mutually-joined dividing areas of the end portions are located near the hinge, namely near the high-rigidity door frame. The first dividing element has only a small length from the hinge to the dividing area, and thus it has greater rigidity than the second dividing element. Because the higher-rigidity first dividing element is located closer to the interior of the vehicle compartment, the first dividing element is more difficult to deform plastically toward the interior of the vehicle compartment. As a consequence, it is possible to suppress plastic deformation of the second dividing element toward the interior of the vehicle compartment. In this way, there can be minimized plastic deformation, toward the interior of the vehicle compartment, of the first and second dividing elements having undergone a collision force from ahead of the vehicle body. Thus, it becomes possible to lessen an impact applied to the passenger and thereby even further enhance the passenger protecting performance of the door.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a vehicle door in accordance with an embodiment of the present invention;
FIG. 2 is a side view showing a lower half of an inner door panel of the vehicle door of the present invention;
FIG. 3 is a sectional view taken along 3—3 line of FIG. 2;
FIG. 4 is a sectional view taken along line 4—4 of FIG. 2;
FIG. 5 is a sectional view taken along line 5—5 of FIG. 2;
FIG. 6A is a sectional plan view of first and second elongated members having fragile sections, and FIG. 6B is a view showing one of the first and second elongated members having fractured in the fragile section;
FIG. 7 is a sectional view taken along line 7—7 of FIG. 2; and
FIG. 8A is a schematic side view of the vehicle door having a door beam, FIG. 8B is a view showing a state of the vehicle door at a moment when a collision force has acted on the door beam, and FIG. 8C is a view showing a state of the vehicle door immediately after the collision force has acted on the door beam and a first dividing element has moved rearward relative to a second dividing element.



BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a structure of a left front door 10 of a full-door type vehicle as viewed from a left side of the door 10. The door 10 is composed of an inner door panel 11 having a window sash 12 formed integrally with an upper end portion thereof, and an outer door panel 13 joined with an outer side—i.e., a side facing a viewer of the figure—of the inner door panel 11. The door 10 is mounted for opening and closing movement with a door frame 20 of the inner door panel 11 attached via upper and lower hinges 32 to a vehicle body 31 denoted by a phantom line in the figure, and it is held in the closed position by means of a door lock section 35 secured to the door frame 20.
The window sash 12 is a component holding therein a door glass (not shown) in such a manner that the glass can be raised and lowered along the sash 12. In this description, the terms “inner door panel” collectively refer to a combination of the panel 11 and window sash 12.
The door frame 20 of the inner door panel 11 includes a horizontal lower frame member 21, a front frame member 22 extending upward from the front end of the lower frame member 21, a rear frame member 23 extending upward from the rear end of the lower frame member 21, and an upper frame member 24 extending between the respective top ends of the front frame member 22 and rear frame member 23.
The inner door panel 11 is formed of a magnesium alloy material with a view to reducing its weight; for example, the inner door panel 11 is made by casting (preferably, die-casting) such a magnesium alloy material. This is because a magnesium alloy material has a low melting point and presents a good fluid flow capability. For example, a magnesium alloy diecasting of Type B (JIS H5303, MD2B) is preferable.
The outer door panel 13 is made by press-forming a sheet-shaped material, such as a magnesium alloy sheet, aluminum alloy sheet or steel sheet.
Further, in FIG. 1, there is also shown a relationship between the door 10 and a seat 40 for a passenger Ma (i.e., driver's or passenger's seat). The passenger seat 40, denoted by a phantom line in the figure, includes a seat cushion 41 and a seat back 42. The seat cushion 41 is disposed near a rear lower portion of the door frame 20, while the seat back 42 is disposed near a rear portion of the door frame 20.
The door frame 20 includes a first elongated member 25 extending substantially horizontally and facing a side surface of the seat back 42 retained in an upright position. Thus, the first elongated member 25 substantially faces a shoulder Sh of the passenger Ma. The first elongated member 25 is a reinforcing member extending between the top end of the front frame member 22 and a height-wise middle portion of the rear frame member 23.
FIG. 2 shows a lower half of the inner door panel 11, which includes the door frame 20 and a plurality of elongated members (the above-mentioned first elongated member 25 and a second elongated member 26) extending in the front-and-rear direction of the vehicle body within the door frame 20. Specifically, the first elongated member 25 and second elongated member 26 are elongated door beams formed integrally with the door frame 20. The second elongated member 26 extends from a front lower portion (i.e., a corner between the lower frame member 21 and the front frame member 22) of the door frame 20 obliquely toward a rear end portion of the first elongated member 25.
The first elongated member 25 has one fragile section 60 at its front end, and the second elongated member 26 has two fragile sections 60 at its front end and one fragile section 60 at its rear end. These fragile sections 60 are located at given distances from the passenger Ma seated on the seat 40 shown in FIG. 1. Details of the fragile sections 60 will be discussed later.
The front frame member 22 has two hinges 32 secured to its upper and lower portions. The rear frame member 23 has the door lock section 35 secured to a height-wise or vertically middle portion thereof that corresponds generally to a midpoint between the upper and lower hinges 32 of the front frame member 22.
The door frame 20 includes a door beam 70 connected between the secured positions of the upper hinge 32 and door lock section 35, and another door beam 70 connected between the secured positions of the lower hinge 32 and door lock section 35.
FIG. 3 is a sectional plan view of the rear frame member 23 and first elongated member 25. The first elongated member 25 has an inner wall surface 25a facing the interior of a vehicle compartment In and a passenger protecting cover 51 secured to the surface 25a in overlapped relation thereto. The passenger protecting cover 51 is a press-formed sheet of a relatively lightweight aluminum alloy that has greater toughness than the magnesium alloy used in the inner door panel 11. The “toughness” represents how tenacious and how difficult the material is to fracture or break due to an external impact.
Front end portion 51a of the passenger protecting cover 51 is secured locally to a front portion of the first elongated member 25 of the inner door panel 11 in overlapped relation by means of a plurality of rivets 52. Rear end portion 51b of the passenger protecting cover 51 is secured locally to a bracket 53, along with the first elongated member 25, in overlapped relation to the bracket 53, by means of a plurality of rivets 54. The bracket 53 is secured locally to the rear frame member 23 of the door frame 20 by means of a plurality of rivets 55.
FIG. 4 shows in detail how the front end portion 51a of the passenger protecting cover 51 is secured to the first elongated member 25 in overlapped relation by means of the plurality of rivets 52.
FIG. 4 also shows a door glass 58 accommodated in an opening 57 between the first elongated member 25 and the outer door panel 13 for closing/opening vertical movement through the opening 57.
FIG. 5 shows in detail how the rear end portion 51b of the passenger protecting cover 51 is secured to the bracket 53, together with the first elongated member 25, in overlapped relation to the bracket 53, by means of the plurality of rivets 54.
Referring back to FIG. 1, because the first elongated member 25 faces the seat 40, the passenger protecting cover 51 is also positioned in a portion of the inner door panel 11 which faces at least the seat 40 or vicinity thereof. Further, the inner door panel 11 and passenger protecting cover 51 are secured together to the bracket 53 in overlapped relation thereto in the portion facing the seat 40 or vicinity thereof.
FIGS. 6A and 6B show sections of the first and second elongated members 25 and 26, and FIG. 6B particularly shows the fragile section 60 in a fractured state.
The fragile section 60 is a portion that is designed to be fractured by a fracturing stress when a compression force greater than predetermined intensity acts on the first and second elongated members 25 and 26 in a longitudinal direction thereof. The fragile section 60 is formed integrally with the first and second elongated members 25 and 26.
Specifically, each of the fragile sections 60 is a stepped portion formed by a short connecting portion (fracturing portion) 63 extending, in the widthwise direction of the vehicle body, between a pair of first and second elements 61 and 62 extending generally serially in the front-and-rear direction of the vehicle body. The second element 62, as a longitudinally-middle portion of each of the first and second elongated members 25 and 26, is located closer to the outside Ou of the vehicle (farther from the vehicle compartment) than the first element 61. Respective wall thicknesses t1, t2 and t3 of the first element 61, second element 62 and fracturing portion 63 are generally identical to each other.
Behavior of each of the fragile sections 60 will now be described with reference to FIGS. 6A and 6B. The fracturing portion 63 can fracture when a compression force greater than predetermined intensity acts on the first and second elongated members 25 and 26 in the longitudinal direction thereof as seen in FIG. 6A. Namely, when a collision force Fo acts on the inner door panel 11 from ahead of the vehicle body, the fracturing portion 63 fractures due to the collision force Fo. As a consequence, the first element 61 moves rearward relative to the second element 62 as illustrated in FIG. 6B, so that the collision energy from ahead of the vehicle body can be absorbed and lessened by the inner door panel 11 promptly and even more effectively.
FIG. 7 shows a sectional structure of the door beam 70 referred to earlier in relation to FIG. 2. The door beam 70 in the instant embodiment includes a series of dividing members (first and second dividing members 71 and 72), which have their respective end portions 71b and 72a overlapped with each other in the widthwise direction of the vehicle body and joined with each other in such a manner that the dividing members are movable relative to each other by a predetermined distance when a compression force greater than predetermined intensity acts on the door beam 70.
Specifically, in the illustrated example, the dividing members include the first dividing member 71 positioned closer to the hinge 32 and second dividing member 72 positioned closer to the door lock section 35, and the mutually-joined areas of the end portions 71b and 72a are located near the hinge 32. The first dividing member 71 is located closer to the interior of the vehicle compartment In than the second dividing member 72.
One element of the hinge 32 is fixed, via a bolt and nut fastener 33, to the vehicle body 31 denoted by a phantom line, while the other element of the hinge 32 is fixed, via a bolt 73, to the front frame member 22 along with a front end portion 71a of the first dividing member 71. The front end portion 72a of the second dividing member 72 is overlapped over the rear end portion 71b of the first dividing member 71 in the widthwise direction of the vehicle body and joined, via a bolt 74, with the rear end portion 71b of the first dividing member 71. Further, a rear end portion 72b of the second dividing member 72 and a bracket 36 of the door lock section 35 are overlapped with each other in the widthwise direction of the vehicle body and joined with each other by a rivet 75. The bracket 36 and rear frame member 23 are coupled with each other by a rivet 76 and bolt and nut fastener 77.
The rear end portion 71b of the first dividing member 71 is located closer to the interior of the vehicle compartment In than the front end portion 72a of the second dividing member 72.
The door lock section 35 comprises a conventional mechanism including a latch member (not shown) that is fixed to the bracket 36 and engages a striker (not shown) fixed to the vehicle body 31. The bracket 36 and first and second dividing members 71 and 72 are each a press-formed sheet of an aluminum alloy material.
More specifically, the corresponding end portions 71b and 72a of the first and second dividing members 71 and 72 are joined with each other in either of two manners to be explained in (1) and (2) below.
(1) Round hole 78 is formed in the rear end portion 71b of the first dividing member 71 to extend therethrough in the widthwise direction of the vehicle body, and a hole 79, elongated in the longitudinal direction of the door beam 70, is formed in the front end portion 72a of the second dividing member 72 to extend therethrough in the widthwise direction of the vehicle body. Then, the end portions 71b and 72a are coupled with each other by the bolt 74 extending through the round hole 78 and elongated hole 79.
(2) Hole 79, elongated in the longitudinal direction of the door beam 70, is formed in the rear end portion 71b of the first dividing member 71 to extend therethrough in the widthwise direction of the vehicle body, a round hole 78 is formed in the front end portion 72a of the second dividing member 72 to extend therethrough in the widthwise direction of the vehicle body, and the end portions 71b and 72a are joined together via the bolt 74.
The elongated hole 79 has a length L1, which determines a range over which the first and second dividing elements 71 and 72 are movable relative to each other.
FIG. 8A is a schematic side view of the door 10, FIG. 8B shows a state of the vehicle door when a collision force Fo has acted on the door beam 70, and FIG. 8C shows a state of the vehicle door immediately after the collision force Fo has acted on the door beam 70.
In FIGS. 8A and 8B, when a compressing force greater than predetermined intensity has acted on the door beam 70 in the longitudinal direction thereof, the compressing force exceeds friction occurring between the end portions 71b and 72a through the tightening by the bolt 74. As a consequence, the first and second dividing elements 71 and 72 can move relative to each other.
When the collision force FO acts on the door beam 70 by way of the hinge 32 from ahead of the vehicle body, the collision force Fo is transmitted from the first element 71, via the round hole 78, to the bolt 74. Once the collision force Fo exceeds the friction between the end portions 71b and 72a, the first dividing element 71 moves rearward relative to the second dividing element 72 as illustrated in FIG. 8C. Note that a distance L2 over which the first and second dividing elements 71 and 72 can move relative to each other depends on the length L1 (see FIG. 7) of the elongated hole 79. In the above-described manner, the collision energy can be absorbed.
To sum up the foregoing, the collision force Fo acting on the door 10, from ahead of the vehicle body is transmitted, as a compression force acting on the door beam 70 in the longitudinal direction thereof, from a region at and around the hinge 32 of the door frame 20 (see FIG. 2), via the door beam 70, to a region at and around the door lock section 35 (see FIG. 2). If the collision force Fo acting on the door beam 70 is greater than predetermined intensity, the end portion 71b of the first dividing element 71 moves rearward by the predetermined distance L2 to thereby absorb the collision energy. Therefore, the collision energy applied from ahead of the vehicle body can be alleviated significantly by being absorbed promptly and sufficiently by the door beam 70.
Further, because the collision energy applied from ahead of the vehicle body is absorbed by the door beam 70, an impact force transmitted from the door beam 70 to the door lock section 35 can be greatly reduced. Since the door lock section 35 is subjected to only a small impact force, it can still remain in its predetermined state where the door lock can be released as desired. Therefore, even after the door 10 has undergone the impact force Fo, it is possible to operate the door lock section 35 to reliably release the locking state.
Namely, the instant embodiment can enhance the passenger protecting performance of the vehicle door 10 against the collision force Fo applied from ahead of the vehicle body, and, even after the door 10 has undergone the impact force Fo, it can reliably release the locking state of the door lock section 35.
Further, the door frame 20 has relatively great rigidity. The mutually-joined dividing areas of the end portions 71b and 72a are located near the hinge 32, namely near the high-rigidity door frame 20. The first dividing element 71 has only a small length from the hinge 32 to the dividing areas, and thus it has greater rigidity than the second dividing element 72. Because the higher-rigidity first dividing element 71 is located closer to the interior of the vehicle compartment In (see FIG. 7), the first dividing element 71 is more difficult to deform plastically toward the interior of the vehicle compartment In. As a consequence, it is possible to suppress plastic deformation of the second dividing element 72 toward the interior of the vehicle compartment In. In this way, the instant embodiment can minimize plastic deformation, toward the interior of the vehicle compartment In, of the first and second dividing elements 71 and 72 having undergone a collision force Fo from ahead of the vehicle body. Thus, the instant embodiment can lessen an impact applied to the passenger and thereby even further enhance the passenger protecting performance of the door 10.
Further, because the mutually-joined areas of the end portions 71b and 72a are located near the hinge 32 and hence apart from the seat 40 (see FIG. 1) or its vicinity in the forward direction of the vehicle body, the instant embodiment can even further lessen the impact applied to the passenger and thereby even more effectively enhance the passenger protecting performance of the door 10.
It should be appreciated that the vehicle door 10 embodying basic principles of the present invention is not limited to the left front door and may be the right front door, left rear door or right rear door.
Further, the vehicle door 10 embodying the present invention is not limited to the full door type; for example, it may be a sash-equipped door having a separate sash body secured to an upper portion of the inner door panel or a sash-less door.
Furthermore, the inner door panel 11 in the present invention is not limited to one made of a magnesium alloy material; for example, it may be made of an aluminum alloy or steel. Moreover, the inner door panel 11 may be made by press-forming rather than by casting.
Moreover, the passenger protecting cover 51 may be made of any other suitable material than a nonferrous material like an aluminum alloy, such steel, hard rubber or engineering plastics, as long as the material of the protecting cover 51 has greater “toughness” than the inner door panel 11.
In addition, the arrangement for fixing the passenger protecting cover 51 to the inner door panel 11 may be chosen as appropriate taking the material of the cover 51 into consideration; for example, the passenger protecting cover 51 may be fixed to the inner door panel 11 by bolts, spot-welding rather than by rivets.
INDUSTRIAL APPLICABILITY
According to the present invention, when the collision force acts on the door from ahead of the vehicle body, the end portions of the dividing elements of the door beams move rearward by the predetermined distance to thereby absorb the collision energy. Further, impact force transmitted from the door beams to the door lock section can be reduced, and hence the door lock can be released. Therefore, in addition to enhancing the passenger protecting performance of the vehicle door against the collision force applied from ahead of the vehicle body, it becomes possible to reliably release the locking state of the door lock section even after the door has undergone the impact force. Accordingly, the present invention is useful in applications to the automobile industry.

## Claims

1. A vehicle door comprising:
a door frame attachable via hinges to a vehicle body to move between open and closed positions;
a door lock section secured to said door frame to hold said vehicle door in a closed position;
door beams connected between secured positions of said hinges and said door lock section;
said door beams each comprising a series of plural dividing members, said plural dividing members having respective end portions thereof overlapped with each other in the widthwise direction of the vehicle body and joined with each other in such a manner that the dividing members are movable relative to each other by a predetermined distance when a compression force greater than predetermined intensity acts on said door beam.

2. A vehicle door according to claim 1, wherein said dividing members comprise a first dividing member positioned closer to said hinge and a second dividing member positioned closer to said door lock section, and mutually-joined areas of said end portions are located near said hinge, and said first dividing member is located closer to the interior of a vehicle compartment than said second dividing member.