Vehicular resin back door structure

A vehicular resin back door structure includes an inner panel that is made of resin and defines a frame of a resin back door configured to be supported by a vehicle body, and that is formed with an opening through which a vehicle driver can view rearwardly at an upper portion of the inner panel; an outer panel that is made of resin and disposed at a periphery of the opening, and that is joined to the inner panel by a first adhesive to form, together with the inner panel, a frame section including an internal chamber; a glass sheet that is joined to the inner panel by a second adhesive; and a contact wall portion that forms part of a portion of the inner panel, and that directly or indirectly contacts the vehicle body in a closed state of the vehicular resin back door.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent application No. 2014-252921 filed on Dec. 15, 2014, the disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

Preferred embodiments relate to a vehicular resin back door structure.

Related Art

Japanese Patent Application Laid-Open (JP-A) No. 2014-131896 describes a vehicular resin back door structure in which an inner panel made of resin and an outer panel made of resin are joined together by an adhesive. To explain this vehicular resin back door structure simply, a bent portion is formed at a vehicle width direction inside end portion of the outer panel, and the bent portion is joined by adhesive to an inside wall of the inner panel. A vehicle width direction outside end portion of the outer panel is joined by adhesive to a flange portion of the inner panel. A closed cross-section is thereby formed by the inner panel and the outer panel. That is, once the inner panel and the outer panel are joined to each other, the inner and outer panels form a chamber that, when viewed in cross section, is surrounded on all sides by walls of the inner and outer panels.

However, there is room for improvement in the vehicular resin back door structure described above, with regard to the following point. In the vehicular resin back door structure described above, back window glass (a glass sheet) is joined by adhesive to a vehicle width direction outside end portion of the outer panel. An adhesive layer is thereby interposed between the flange portion of the inner panel and the back window glass at two locations, such that there is room for improvement with regard to stably supporting the back window glass.

SUMMARY

In consideration of the above circumstances, an object of preferred embodiments is to provide a vehicular resin back door structure capable of stably supporting a glass sheet.

A vehicular resin back door structure of a first aspect of the disclosure includes: an inner panel that is made of resin and defines a frame of a resin back door that is configured to be supported by a vehicle body so as to be capable of opening and closing, an upper portion of the inner panel having an opening through which a driver of the vehicle can view rearwardly out of the vehicle; an outer panel that is made of resin and disposed on a vehicle outer side of the inner panel at a periphery of the opening, the outer panel joined to the inner panel by a first adhesive to form, together with the inner panel, a frame section including an internal chamber; a glass sheet that is joined to the inner panel at the frame section by a second adhesive, and that covers the opening; and a contact wall that forms part of a portion of the inner panel at the frame section, and that is configured to directly or indirectly contact the vehicle body in a closed state of the vehicular resin back door.

In the vehicular resin back door structure of the first aspect, the frame of the vehicular resin back door, configured to be supported by the vehicle body so as to be capable of opening and closing, is configured by the inner panel made of resin, and the opening used for viewing rearwardly out of the vehicle is formed in the inner panel. The outer panel made of resin is disposed at the periphery of the opening on the vehicle outer side of the inner panel, and the outer panel is joined to the inner panel by the first adhesive. The frame section including the internal chamber is thereby formed at the periphery of the opening by the inner panel and the outer panel.

The glass sheet is joined to the vehicle outer side of the inner panel at the frame section by the second adhesive, and closes off (covers) the opening. Since the glass sheet is directly joined to the inner panel, the glass sheet can be directly supported by the inner panel that mainly secures the rigidity of the vehicular resin back door.

A part of the portion of the inner panel forming the frame section defines the contact wall portion, and the contact wall portion is configured to directly or indirectly contact the vehicle body. This enables load acting on the inner panel from the glass sheet (such as load acting on the inner panel due to the weight of the glass sheet itself) to be distributed to the vehicle body, while being distributed across the entire vehicular resin back door. This enables the glass sheet to be stably supported.

A vehicular resin back door structure of a second aspect of the disclosure further includes the frame section having a first joint section that faces the glass sheet and that joins the inner panel and the outer panel together, and a second joint section that is disposed closer to the opening than the first joint section and that joins the inner panel and the outer panel together; and the first joint section and the glass sheet are joined together by the second adhesive.

In the vehicular resin back door structure of the second aspect, the frame section includes the first joint section and the second joint section joining the inner panel and the outer panel to each other. Namely, the inner panel and the outer panel are joined together at two locations in the frame section, these two locations being the first joint section and the second joint section. The first joint section and the glass sheet are joined together by the second adhesive. Thus when an impact load, occurring when the vehicular resin back door is being closed, is input from the vehicle body to the inner panel, the impact load is distributed at the two locations that are the first joint section and the second joint section and transmitted to the outer panel, and is also transmitted to the glass sheet through the second adhesive. This enables impact load occurring during opening and closing of the vehicular resin back door to be effectively distributed.

A vehicular resin back door structure of a third aspect of the disclosure further includes the first joint section having an inner side flange portion that is provided at the inner panel and extends outwardly of the chamber, and an outer side flange portion that is provided at the outer panel, that extends outwardly of the chamber, and that is joined to the inner side flange portion; and an extension portion extending further outwardly of the chamber than the outer side flange portion is formed at a portion at a leading end side of the inner side flange portion, and the glass sheet is joined to the extension portion by the second adhesive.

In the vehicular resin back door structure of the third aspect, the first joint portion includes the inner side flange portion of the inner panel and the outer side flange portion of the outer panel, and the inner side flange portion and the outer side flange portion extend outwardly of the chamber. Namely, the first joint portion extends outwardly of the chamber. The extension portion extending further outwardly of the chamber than the outer side flange portion is formed at the portion at the leading end side of the inner side flange portion, and the glass sheet is joined to the extension portion by the second adhesive. This enables a location for disposing the second adhesive to be secured on the inner panel, while providing for a sufficiently long joint length of the first joint section.

A vehicular resin back door structure of a fourth aspect of the disclosure further includes the first joint section extending parallel to the glass sheet in a cross-section viewed along the length direction of the frame section.

In the vehicular resin back door structure of the fourth aspect, a high joint strength can be secured for the first adhesive at the first joint section between the inner panel and the outer panel, during opening and closing of the vehicular resin back door, for example. Namely, during opening and closing of the vehicular resin back door, load toward the vehicle inside acts on the first joint section from the glass sheet, and load along the glass surface acts on the first joint section from the glass sheet. The load along the glass surface forms a load in a direction of shear between the inner panel and the outer panel with respect to the first adhesive. The fourth aspect enables a higher joint strength to be secured for the first adhesive at the inner panel and the outer panel than in cases in which load acts in a peeling direction between the inner panel and the outer panel with respect to the first adhesive. This enables a high joint strength to be secured for the first adhesive at the first joint portion between the inner panel and the outer panel during opening and closing of the vehicular resin back door.

A vehicular resin back door structure of a fifth aspect of the disclosure is any one of the second aspect to the fourth aspect, wherein the second joint section extends along a vehicle up-down direction in a cross-section viewed along the length direction of the frame section.

In the vehicular resin back door structure of the fifth aspect, a high joint strength can be secured for the first adhesive at the second joint section between the inner panel and the outer panel in a state in which the frame section supports the glass sheet. Namely, since the second joint section extends along the vehicle up-down direction in cross-section viewed along the length direction of the frame section, due to the weight of the glass sheet itself, a load in a direction of shear between the inner panel and the outer panel acts on the first adhesive of the second joint section. This enables a higher joint strength to be secured for the first adhesive at the second joint section between the inner panel and the outer panel than in cases in which load acts in a peeling direction between the inner panel and the outer panel with respect to the first adhesive. This enables a high joint strength to be secured for the first adhesive at the second joint section between the inner panel and the outer panel, in the state in which the frame section supports the glass sheet.

A vehicular resin back door structure of a sixth aspect of the disclosure is any one of the third aspect to the fifth aspect, wherein the second adhesive is disposed along both side edge portions in a vehicle width direction of the glass sheet, and both end portions in the vehicle width direction of the glass sheet are joined to the inner side flange portion.

In the vehicular resin back door structure of the sixth aspect, both end portions in the vehicle width direction of the glass sheet are joined to the inner side flange portion along both side edge portions in the vehicle width direction of the glass sheet, thereby enabling the glass sheet to be even more stably supported.

A vehicular resin back door structure of a seventh aspect of the disclosure is any one of the first aspect to the sixth aspect, wherein the second adhesive is disposed along an outer peripheral edge portion of the glass sheet around the entire periphery of the glass sheet, and an outer peripheral portion of the glass sheet is joined to the inner panel.

In the vehicular resin back door structure of the seventh aspect, the outer peripheral portion of the glass sheet is joined to the inner panel around the entire periphery of the glass sheet, thereby enabling the glass sheet to be even more stably supported in this case also.

A vehicular resin back door structure of a eighth aspect of the disclosure is the second aspect, wherein: the first joint section includes an inner side flange portion that is provided at the inner panel and that extends outwardly of the chamber, and an outer side flange portion that is provided at the outer panel, that extends outwardly of the chamber, and that is joined to the inner side flange portion; and the outer side flange portion has substantially the same length as the inner side flange portion, a hole is formed at the outer side flange portion, the inner side flange portion is exposed to the glass sheet through the hole, the second adhesive is disposed inside the hole, and the glass sheet is joined to the inner side flange portion through the hole.

The vehicular resin back door structure of the eighth aspect also enables a location for disposing the second adhesive to be secured on the inner panel, while securing the joint length of the first joint section.

A vehicular resin back door structure of a ninth aspect of the disclosure is the second aspect, wherein the first joint section is provided at an exterior of the chamber of the frame section and extends outwardly in the vehicle width direction.

The vehicular resin back door structure of the ninth aspect also enables a location for disposing the second adhesive to be secured on the inner panel, while securing the joint length of the first joint section.

A vehicular resin back door structure of a tenth aspect of the disclosure is the second aspect, wherein the first joint section is provided at the chamber of the frame section and extends inwardly in the vehicle width direction.

The vehicular resin back door structure of the tenth aspect also enables a location for disposing the second adhesive to be secured on the inner panel, while securing the joint length of the first joint section, and also enables the capacity of the chamber to be increased.

The vehicular resin back door structure of the first aspect enables the glass sheet to be stably supported.

The vehicular resin back door structure of the second aspect enables impact load occurring during opening and closing of the vehicular resin back door to be effectively distributed.

The vehicular resin back door structure of the third aspect enables a location for disposing the second adhesive to be secured on the inner panel, while securing the joint length of the first joint section.

The vehicular resin back door structure of the fourth aspect enables a high joint strength to be secured for the first adhesive at the first joint portion between the inner panel and the outer panel during opening and closing of the vehicular resin back door.

The vehicular resin back door structure of the fifth aspect enables a high joint strength to be secured for the first adhesive at the second joint section between the inner panel and the outer panel, in the state in which the frame section supports the glass sheet.

The vehicular resin back door structure of the sixth aspect and the seventh aspect enables the glass sheet to be even more stably supported.

The vehicular resin back door structure of the eighth aspect to the tenth aspect enables a location for disposing the second adhesive to be secured on the inner panel, while securing the joint length of the first joint section.

DETAILED DESCRIPTION

Explanation follows regarding a vehicular resin back door12(hereafter simply referred to as back door (or rear hatch)12) applied with a vehicular resin back door structure10according to an exemplary embodiment, with reference to the drawings. Note that in each of the drawings as appropriate, the arrow FR indicates the vehicle front side, and the arrow UP indicates the vehicle upper side, of a vehicle (automobile) applied with the back door12. The arrow OUT indicates the vehicle width direction outside.

FIG. 2is a perspective view illustrating the back door12viewed diagonally from the rear left side. As illustrated inFIG. 2, the back door12is provided at the rear end section of the vehicle. An upper end portion of the back door12is joined by hinges to a vehicle body with its axial direction along the vehicle width direction, and the back door12is supported by the vehicle body so as to be capable of opening and closing.

The back door12is formed substantially L-shaped in a vehicle side view, and is configured by a door upper section16extending with a gentle slope from the upper end portion of the back door12toward the vehicle rear side, and a door lower section18hanging down from a rear end portion of the door upper section16toward the vehicle lower side. Detailed explanation follows regarding the door upper section16, installed with rear window glass20.

The door upper section16includes a frame section22configured in a substantially rectangular frame shape. An opening24, used by a driver to view rearwardly out of the vehicle rear, is formed inside the frame section22. The rear window glass20, serving as a glass sheet closing off (covering) the opening24from the vehicle outside, is provided at the door upper section16, and the rear window glass20is supported by the frame section22. The rear window glass20is formed in a substantially rectangular flat plate shape curving gently toward the vehicle outside.

FIG. 1is a cross-section of a side portion of the frame section22, cut away along the vehicle width direction. The frame section22is configured by a door inner panel26serving as an inner panel disposed at the vehicle inside, and door outer panels28serving as outer panels disposed at the vehicle outside. Both the door inner panel26and the door outer panels28are made of resin. Specifically, the door inner panel26and the door outer panels28are configured by carbon fiber reinforced plastic (CFRP).

As illustrated inFIG. 3, the door inner panel26is configured as a relatively large panel member forming the overall frame of the back door12, and the opening24is formed at the door inner panel26. The pair of left and right door outer panels28are disposed at the periphery of the opening24. The pair of door outer panels28are configured with left-right symmetry to each other, and the door outer panels28are disposed at both vehicle width direction sides and the vehicle upper side of the opening24. As described above, the frame section22is configured by the door outer panels28and the door inner panel26. The back door12is thereby configured such that the rigidity of the back door12is mainly secured by the door inner panel26. A lower portion of the door inner panel26is covered from the vehicle outside by a lower outer panel or the like, not illustrated in the drawings.

Returning toFIG. 1, each door outer panel28is configured by an outer upper wall portion28A disposed parallel to the rear window glass20, an outer side wall portion28B bending in substantially a right angle from a vehicle width direction inside end portion of the outer upper wall portion28A in a direction away from the rear window glass20, and an outer lower wall portion28C bending in an obtuse angle from an extension direction side end portion of the outer side wall portion28B toward the vehicle lower side.

The door inner panel26includes an inner side wall upper portion26A disposed further toward the vehicle width direction outside than the outer side wall portion28B and disposed parallel to the outer side wall portion28B, and an inner side wall lower portion26B serving as a “contact wall portion” extending in an L-shape from a vehicle lower side end portion of the inner side wall upper portion26A. The inner side wall upper portion26A extends as far as the outer upper wall portion28A, then bends toward the vehicle width direction outside, configuring an inner side flange portion26C. A vehicle width direction outside end portion of the inner side flange portion26C bends toward the rear window glass20side in substantially a right angle, configuring an outer end portion26D. The inner side wall lower portion26B extends as far as the outer lower wall portion28C, then bends toward the vehicle upper side, configuring an inner lower wall portion26E.

Note that a ball joint30of a damper stay, not illustrated in the drawings, formed with a male thread at a leading end portion, is fastened (fixed) to the inner side wall upper portion26A using a nut32. The inner side wall upper portion26A is accordingly formed with a thicker plate thickness than other locations. In a closed state of the back door12, a weather strip52, attached to a vehicle body54, is in contact with the inner side wall lower portion26B. In this state, the weather strip52is pressed by the inner side wall lower portion26B and undergoes resilient deformation. The inner side wall lower portion26B is in contact with the vehicle body54through the weather strip52in this manner. Note that although the weather strip52is attached to the vehicle body54as described above, the weather strip52may be integrally formed to the door inner panel26(inner side wall lower portion26B). In such cases, the inner side wall lower portion26B is in direct contact with the vehicle body54through the weather strip52.

Note that the outer upper wall portion28A described above extends along the rear window glass20substantially straight along the vehicle width direction. A vehicle width direction outside portion of the outer upper wall portion28A (specifically, a portion that extends toward the vehicle width direction outside of a closed cross-section portion (chamber)38, described later) configures an outer side flange portion34.

The inner side flange portion26C described above is configured by an inner side joint portion26C1overlapping the outer side flange portion34, and an extension portion26C3extending from a vehicle width direction outside end portion of the inner side joint portion26C1, through a step portion26C2, toward the vehicle width direction outside (a leading end side of the inner side flange portion26C). The height of the step portion26C2is set substantially the same as a dimension of the thickness of a cured structural adhesive36, described below, added to the plate thickness of the outer side flange portion34. Thus in a state in which the outer side flange portion34is joined to the inner side joint portion26C1, the surfaces of both portions are positioned in the same planar face (in the same plane).

The structural adhesive36, serving as a first adhesive, is applied to the inner side joint portion26C1described above and the outer side flange portion34is superimposed thereon, thereby joining the outer side flange portion34to the inner side flange portion26C (inner side flange portion26C1). Similarly, the outer lower wall portion28C is joined to the inner lower wall portion26E using the structural adhesive36. The closed cross-section portion (chamber)38is thereby formed at the interior of the frame section22by the door inner panel26and the door outer panels28. That is, closed cross-section portion38is an internal chamber formed by door inner panel26and door outer panels28. Note that a high-strength, low elongation two component liquid urethane-based adhesive, for example, may be employed as the structural adhesive36.

The inner side flange portion26C (inner side joint portion26C1) of the frame section22and a portion of the outer side flange portion34configure a first joint section40. The first joint section40is disposed at the exterior of the closed cross-section portion (chamber)38, specifically at the vehicle width direction outside (the opposite side to the opening24) of the closed cross-section portion (chamber)38, and extends parallel to the rear window glass20. A portion of the frame section22at the outer lower wall portion28C and the inner lower wall portion26E configures a second joint section42, and the second joint section42is disposed at the vehicle width direction inside (the opening24side) of the first joint section40. The second joint section42extends along the vehicle up-down direction, and is configured as a wall section partitioning the interior and exterior of the closed cross-section portion (chamber)38.

In a state in which the outer side flange portion34is joined to the inner side flange portion26C, a gap44is formed at a seam between the inner side flange portion26C and the outer upper wall portion28A. An end44A of the gap44is positioned between a leading end portion of the outer side flange portion34and the step portion26C2of the inner side flange portion26C. A peripheral component adhesive46, serving as a second adhesive, is disposed so as to close off the end44A of the gap44. Three components, these being the extension portion26C3of the inner side flange portion26C, the outer side flange portion34, and the rear window glass20, are joined together by the peripheral component adhesive46.

Specifically, the peripheral component adhesive46is disposed along both side edge portions in a vehicle width direction of the rear window glass20, and both side end portions in the vehicle width direction of the rear window glass20are joined to the inner side flange portion26C. The rear window glass20is thereby directly joined to the extension portion26C3of the door inner panel26, and supported by the frame section22. As illustrated by the bold lines inFIG. 2, the peripheral component adhesive46is also disposed along an upper edge portion and a lower edge portion of the rear window glass20, and an upper end portion and a lower end portion of the rear window glass20are joined to the door inner panel26. Namely, an outer peripheral portion of the rear window glass20is joined around the entire periphery of the rear window glass20to the door inner panel26using the peripheral component adhesive46. A one component urethane-based adhesive, for example, may be employed as the peripheral component adhesive46.

The peripheral component adhesive46has a higher water resistance than the structural adhesive36. Testing of high or low water resistance is performed according to JIS K6850 (Adhesives: Determination of tensile lap-shear strength of rigid-to-rigid bonded assemblies). Specifically, two test pieces (for example, of 25 mm in width, 200 mm in length, and 0.8 mm in height), equivalent to a first panel and a second panel, are prepared, and the test pieces are joined together with a joint overlap of 10 mm using the adhesive subject to test. The adhered test pieces are then immersed in warm water of a specific temperature (such as 60° C.) for a specific duration (such as 10 days), after which tensile water resistance testing (tensile shear testing) is performed at room temperature. After testing is complete, the generated load when breaking of the joined test pieces occurred and the state of damage thereof are checked, and the degree of water resistance is determined based on this. For a given generated load, the assumed input load differs according to the component used (component application), such that no single determination can be made; however determination can be established (per manufacturer) as long as the components used are determined. There are three types of damaged states. If interface damage, in which damage occurs to an interface between either of the test pieces and the adhesive, occurs, then water resistance is evaluated to be low. However, if cohesion failure, in which the adhesive itself is damaged, as well as material damage in which one of the test pieces themselves are damaged, occurs, then water resistance is evaluated to be high. When the high-strength, low elongation two component urethane-based adhesive, given as an example of the structural adhesive36, is employed to adhere the two test pieces to each other, interface peeling occurs. Thus the water resistance of the high-strength, low elongation two component urethane-based adhesive is evaluated to be low. In contrast thereto, when the one component urethane-based adhesive, given as an example of the peripheral component adhesive46, is employed to adhere the test pieces to each other, cohesion failure occurs. Thus the water resistance of the one component urethane-based adhesive is evaluated to be high.

A dam member48(a waterproofing member) is provided disposed at the extension portion26C3so as to be adjacent to the vehicle width direction outside of the peripheral component adhesive46. The dam member48thereby seals between the extension portion26C3and the rear window glass20. Note that an upper portion of the frame section22illustrated inFIG. 2is similarly configured to the above configuration.

Explanation next follows regarding operation and advantageous effects of the present exemplary embodiment.

In the back door12configured as described above, the frame section22supporting the rear window glass20is configured by the door inner panel26and the door outer panels28. Specifically, the inner side flange portion26C of the door inner panel26and the outer side flange portion34of each door outer panel28are joined together by the structural adhesive36, forming the first joint section40of the frame section22. The outer lower wall portion28C of each door outer panel28and the inner lower wall portion26E of the door inner panel26are joined together by the structural adhesive36, forming the second joint section42of the frame section22. The frame section22forms a closed cross-section structure including the closed cross-section portion (chamber)38at the interior.

The rear window glass20is joined to the door inner panel26configuring the frame section22by the peripheral component adhesive46, and the opening24is closed off from the vehicle width direction outside. Specifically, the rear window glass20is directly joined to the extension portion26C3of the inner side flange portion26C of the door inner panel26by the peripheral component adhesive46. Since the rear window glass20is directly joined to the door inner panel26, the rear window glass20can be directly supported by the door inner panel26that mainly secures the rigidity of the back door12.

The inner side wall lower portion26B of the door inner panel26contacts the vehicle body54through the weather strip52. This enables load from the rear window glass20acting on the door inner panel26(such as load acting on the door inner panel26due to the weight of the rear window glass20itself, or load from the rear window glass20toward the vehicle inside acting on the door inner panel26when the back door12is being closed) to be distributed to the vehicle body54, while also being distributed across the entire back door12. This enables the rear window glass20to be stably supported.

In the present exemplary embodiment, since the rear window glass20is directly joined to the door inner panel26, configuration is such that a single adhesive layer, formed by the peripheral component adhesive46, is interposed between the rear window glass20and the door inner panel26. This enables the rear window glass20to be stably joined and enables the rigidity of the back door12to be increased, compared to a configuration in which two adhesive layers are interposed between an inner panel and a glass sheet, as in technology hitherto.

The frame section22also includes the first joint section40and the second joint section42that joint together the door inner panel26and each door outer panel28as described above. Namely, in the frame section22, the door inner panel26and the door outer panel28are joined together at joint sections in two locations, these being the first joint section40and the second joint section42. The rear window glass20is joined to the extension portion26C3of the inner side flange portion26C at the first joint section40by the peripheral component adhesive46. Thus when an impact load, occurring during opening and closing of the back door12(mainly when the back door12is being closed), is input from the vehicle body54to the door inner panel26configuring the frame section22, the impact load is distributed at the two locations that are the first joint section40and the second joint section42and transmitted to the door outer panel28, and is also transmitted to the rear window glass20through the first joint section40. This enables the impact load to be effectively distributed, while suppressing stress from concentrating at the joint sections between the door inner panel26and the door outer panel28, during opening and closing of the back door12. This enables impact resistance to be improved during opening and closing of the back door12, for example, and enables opening and closing durability of the back door12to be improved.

The first joint section40is configured including the inner side flange portion26C and the outer side flange portion34, and the inner side flange portion26C and the outer side flange portion34extend toward the vehicle width direction outside of the closed cross-section portion (chamber)38. The extension portion26C3is formed at a portion at the leading end side of the inner side flange portion26C, and the extension portion26C3extends further toward the vehicle width direction outside than the outer side flange portion34. The rear window glass20is joined to the extension portion26C3by the peripheral component adhesive46. This enables a location for disposing the peripheral component adhesive46to be secured on the door inner panel26, while securing the joint length of the first joint section40.

The first joint section40extends parallel to the rear window glass20. This enables a high joint strength to be secured for the structural adhesive36at the first joint section40between the inner side flange portion26C and the outer side flange portion34during opening and closing of the back door12. Namely, during opening and closing of the back door12, load toward the vehicle inside acts on the first joint section40from the rear window glass20, and load along the glass surface of the rear window glass20(see the arrow A inFIG. 1) acts on the first joint section40from the rear window glass20. The load along the glass surface forms load in a direction of shear between the inner side flange portion26C and the outer side flange portion34with respect to the structural adhesive36. This enables a higher joint strength to be secured for the structural adhesive36at the inner side flange portion26C and the outer side flange portion34than in cases in which load acts in a direction of peel between the inner side flange portion26C and the outer side flange portion34with respect to the structural adhesive36. This enables a high joint strength to be secured for the structural adhesive36at the first joint section40between the inner side flange portion26C and the outer side flange portion34during opening and closing of the back door12.

In a cross-section viewed along the length direction of the frame section22, the second joint section42of the frame section22extends along the vehicle up-down direction. This enables a high joint strength to be secured for the structural adhesive36at the second joint section42between the inner lower wall portion26E and the outer lower wall portion28C, in a state in which the frame section22supports the rear window glass20. Namely, since the second joint section42extends along the vehicle up-down direction, due to the weight of the rear window glass20itself, load in a direction of shear between the inner lower wall portion26E and the outer lower wall portion28C acts on the structural adhesive36of the second joint section42. This enables a higher joint strength to be secured for the structural adhesive36at the second joint section42between the inner lower wall portion26E and the outer lower wall portion28C than in cases in which load acts in a direction of peel between the inner lower wall portion26E and the outer lower wall portion28C with respect to the structural adhesive36. This enables a high joint strength to be secured for the structural adhesive36at the second joint section42between the inner lower wall portion26E and the outer lower wall portion28C, in the state in which the frame section22supports the rear window glass20.

The second joint section42of the frame section22is configured as a wall section partitioning (separating) the interior and exterior of the closed cross-section portion (chamber)38. This enables the surface area of the closed cross-section portion (chamber)38of the frame section22to be increased, and torsional rigidity and bending rigidity of the frame section22to be increased, in the door inner panel26and the door outer panels28configured by resin material.

Explanation follows regarding this point, with comparison to a back door configured by metal, as illustrated inFIG. 10. Since a door inner panel926and a door outer panel928, illustrated inFIG. 10, are both made of metal, the door inner panel926and the door outer panel928need to be joined together by welding or the like. Thus in a Comparative Example, similarly to a first joint section940, a joint section942corresponding to the second joint section42of the present specification is disposed at the exterior of a closed cross-section portion938, and a weld gun G is used to make the joint. Placement space for the weld gun G therefore needs to be secured in the door inner panel926and door outer panel928that are made of metal, and the surface area of the closed cross-section portion (chamber)938is decreased proportionately.

In contrast thereto, in the present exemplary embodiment, the door inner panel26and the door outer panels28are configured by resin material, and the second joint section42of the frame section22configures the wall section partitioning the interior and exterior of the closed cross-section portion (chamber)38. The surface area of the closed cross-section portion (chamber)38of the frame section22is therefore larger than in the Comparative Example, thereby enabling the torsional rigidity and bending rigidity of the frame section22to be increased.

The outer peripheral end portion of the rear window glass20is joined to the door inner panel26by the peripheral component adhesive46around the entire periphery of the rear window glass20. This enables the rear window glass20to be even more stably supported.

Explanation next follows regarding variations to the structure of the first joint section40, and the joint structure between the first joint section40and the rear window glass20, in the present exemplary embodiment, with reference toFIG. 4toFIG. 9. Note thatFIG. 4toFIG. 9mainly illustrate variations in the structure of the first joint section40, and so the overall shape of the frame section22is illustrated simplified as a substantially rectangular shape.

As illustrated inFIG. 4, a variation 1 is configured similarly to the present exemplary embodiment, with the exception of the following points. In the variation 1, an inner side flange portion126C of a door inner panel126bends toward the vehicle width direction inside of an inner side wall upper portion126A, and is disposed substantially parallel to the rear window glass20. An outer side flange portion134of a door outer panel128overlaps a portion at a leading end side of the inner side flange portion126C at the vehicle outside of the inner side flange portion126C. Namely, in the variation 1, the outer side flange portion134does not extend toward the vehicle width direction outside of a closed cross-section portion (chamber)138, and a first joint section140is configured as a wall section partitioning between the interior and exterior of the closed cross-section portion (chamber)138. The rear window glass20is directly joined to a portion at a base end side of the inner side flange portion126C by the peripheral component adhesive46. In other words, the rear window glass20is only joined to the door inner panel126. Thus the rear window glass20is directly supported by the door inner panel126in the variation 1 also, thereby enabling the rear window glass20to be stably supported. Reference numerals110,122,128,128A and128B represent structures similar to the structures associated with reference numerals10,22,28,28A and28B, respectively, inFIG. 1.

As illustrated inFIG. 5, a variation 2 is configured similarly to the variation 1, with the exception of the following points. In the variation 2, an inner side flange portion226C is disposed at the vehicle outside (the rear window glass20side) of an outer side flange portion234at a first joint section240. The rear window glass20is directly joined to the inner side flange portion226C by the peripheral component adhesive46. In other words, the rear window glass20is only joined to a door inner panel226. Thus the rear window glass20is directly supported by the door inner panel226in the variation 2 also, thereby enabling the rear window glass20to be stably supported.

In the variation 2, the inner side flange portion226C is disposed at the vehicle outside (the rear window glass20side) of the outer side flange portion234, thereby enabling an adhesion surface area between the inner side flange portion226C and the rear window glass20to be increased. This enables joint strength between the rear window glass20and the door inner panel226by the peripheral component adhesive46to be increased. Reference numerals210,222,226A,228,228A,228B and238represent structures similar to the structures associated with reference numerals10,22,26A,28,28A,28B and38, respectively, inFIG. 1.

As illustrated inFIG. 6, a variation 3 is configured similarly to the present exemplary embodiment, with the exception of the following points. In the variation 3, the step portion26C2is omitted from an inner side flange portion326C of a door inner panel326, and an inner side joint portion326C1and an extension portion326C3are directly joined together. The extension portion326C3has a longer extension toward the vehicle width direction outside than in theFIG. 1exemplary embodiment, and the rear window glass20is directly joined to the extension portion326C3of the inner side flange portion326C by the peripheral component adhesive46. In other words, the rear window glass20is only joined to the door inner panel326. Thus the rear window glass20is directly supported by the door inner panel326in the variation 3 also, thereby enabling the rear window glass20to be stably supported. Reference numerals310,322,326A,328,328A,328B,334,338and340represent structures similar to the structures associated with reference numerals10,22,26A,28,28A,28B,34,38and40, respectively, inFIG. 1.

As illustrated inFIG. 7, a variation 4 is configured similarly to theFIG. 1exemplary embodiment, with the exception of the following points. In the variation 4, similarly to in the variation 3, an extension portion426C3of an inner side flange portion426C has a longer extension toward the vehicle width direction outside than in theFIG. 1exemplary embodiment. The rear window glass20is directly joined to the extension portion426C3of the inner side flange portion426C by the peripheral component adhesive46. In other words, the rear window glass20is only joined to a door inner panel426. Thus the rear window glass20is directly supported by the door inner panel426in the variation 4 also, thereby enabling the rear window glass20to be stably supported. This also enables an adhesion surface area between the rear window glass20and the door inner panel426to be larger than in the present exemplary embodiment. Reference numerals410,422,426,426A,426C1,426C2,428,428A,428B,434,438and440represent structures similar to the structures associated with reference numerals10,22,26,26A,26C1,26C2,28,28A,28B,34,38and40, respectively, inFIG. 1.

As illustrated inFIG. 8, a variation 5 is configured similarly to the variation 3, with the exception of the following points. In the variation 5, a leading end portion of an outer side flange portion534of a door outer panel528extends as far as an extension portion of an inner side flange portion526C of a door inner panel526. In other words, configuration is such that substantially the entire outer side flange portion534and substantially the entire inner side flange portion526C overlap with each other. A hole portion50is formed at the outer side flange portion534, and the inner side flange portion526C is exposed to the rear window glass20side by the hole portion50. The peripheral component adhesive46is disposed inside the hole portion50, and the rear window glass20is directly joined to the inner side flange portion526C by the peripheral component adhesive46. In other words, the rear window glass20is only joined to the door inner panel526. Thus the rear window glass20is directly supported by the door inner panel526in the variation 5 also, thereby enabling the rear window glass20to be stably supported. Reference numerals510,522,526A,528A,528B and540represent structures similar to the structures associated with reference numerals10,22,26A,28A,28B and40, respectively, inFIG. 1.

As illustrated inFIG. 9, a variation 6 is configured similarly to the variation 1, with the exception of the following points. In the variation 6, a leading end portion of an outer side flange portion634of a door outer panel628extends as far as a base end side of an inner side flange portion626C of a door inner panel626. The hole portion50is formed at the outer side flange portion634, similarly to in the variation 5, and the inner side flange portion626C is exposed to the rear window glass20side by the hole portion50. The peripheral component adhesive46is disposed inside the hole portion50, and the rear window glass20is directly joined to the inner side flange portion626C by the peripheral component adhesive46. In other words, the rear window glass20is only joined to the door inner panel626. Thus the rear window glass20is directly supported by the door inner panel626in the variation 6 also, thereby enabling the rear window glass20to be stably supported. Reference numerals622,626A,626B,628A,638and640represent structures similar to the structures associated with reference numerals22,26A,26B,28A,38and40, respectively, inFIG. 1.

In the variation 1 to the variation 6 as described above, the rear window glass20is only joined to the door inner panel26,126to626by the peripheral component adhesive46. This enables the position of the rear window glass20with respect to the door inner panel26,126to626(the inner side flange portion26C,126C to626C) to be made even more stable than in a configuration in which the rear window glass20is joined to the door inner panel26(inner side flange portion26C) through the door outer panel28(outer side flange portion34).

Note that in the variation 5 and the variation 6, the peripheral component adhesive46may be disposed such that the peripheral component adhesive46is joined to a peripheral edge portion of the hole portion50.