Patent Application
20150375791
The present disclosure relates to body-in-white pickup truck floor pans that include holes for facilitating the flow of e-coat liquids.
Pickup trucks are motor vehicles with a rear open top cargo area that is often referred to as a cargo box. Pickup trucks are popular largely because the bed allows the vehicle to be utilized in many different ways, including caring a variety of types of cargo and towing various types of trailers. Traditionally, the majority of body structures on pickup trucks have been formed from steel alloys. Through years of experience, pickup truck designers have learned how to design steel truck body parts that withstand the variety of demanding pickup truck applications. The current regulatory and economic environment have increased the importance of making pickup trucks more fuel efficient while maintaining or improving functionality and durability. One way to reduce the fuel consumption of a vehicle is to reduce vehicle structure weight.
Aluminum alloys typically have a higher strength to weight ratio than steel alloys. Consequently, replacing steel with aluminum offers the potential for weight reduction. However, the elastic modulus of aluminum is generally lower than elastic modulus of steel. Additionally, fabrication techniques and methods for joining parts that work well for steel parts may not work well for the same aluminum part. Due to these and other differences, simple material substitution does not necessarily produce acceptable design.
Aluminum alloys are generally identified by a four digit number, the first digit of which typically identifies the major alloying element. When describing a series of aluminum alloys based on the majority alloying element, the first number may be followed by three x's or three zero's. For example, the major alloying element in 6xxx (or 6000) series aluminum alloy is magnesium and silicone, while the major alloying element of 5xxx series is magnesium and for 7xxx series is zinc. Additional numbers represented by the letter ‘x’ (or zero) in the series designation define the exact aluminum alloy.
According to an aspect of the present disclosure, a floor pan for a body-in-white vehicle includes a front seat footwell portion and a rear seat footwell portion. The front seat footwell portion defines a front fluid passage hole configured to port a surface treatment liquid during submersion of the floor pan in a surface treatment bath. The rear seat footwell portion defines a rear fluid passage hole configured to port the surface treatment liquid during submersion of the floor pan in the bath.
According to an another aspect of the present disclosure, a method of submerging a body-in-white vehicle into a tank containing surface treatment liquid is disclosed. The method includes forming at least one front footwell hole and at least one rear footwell hole into a floor pan of the vehicle. Then conveying the vehicle into the tank and porting the liquid initially through the front hole and subsequently through the rear hole to reduce the buoyancy of the vehicle and increase a sinking rate of the vehicle.
The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts.
Referring to
Once the surface treatment is applied, the vehicle is removed from the tank 22 and excess liquid is drained from the vehicle back into the tank 22. The vehicle 34 then enters a bake oven to cure the surface treatment liquid.
For successful e-coating, the vehicle 34 must be fully submerged within the surface treatment liquid. E-coating lines may rely on vehicle weight for sinking the vehicle and may not apply an external downward force to the vehicle. E-coating line 20, for example, includes chains 36 and relies on vehicle weight for submersion. The line speed for the e-coating line 20 is partially dependent upon the time required to fully immerse the vehicle, also known as “sinking time”. If the sinking time increases, the line speed must be slowed down to account for this increased sinking time reducing efficiency and productivity of the line. Buoyancy of the vehicle is caused by air pockets and displacement of the liquid as the vehicle is immersed. Buoyancy is also affected by the viscosity of the surface treatment liquid.
Vehicle weight is one factor that affects buoyancy. A lighter vehicle has increased buoyancy as compared to a heavier vehicle if all other factors remain constant. The demand for lightweight vehicles has increased due to increasing emphasis on fuel efficiency. For example, the pickup truck 34 may include aluminum alloy body structures in order to decrease the weight of the pickup truck. Aluminum alloy pickup trucks may have increased fuel efficiency and driving dynamics but may also cause several problems during the e-coating process.
Referring to
The floor pan 52 includes a driver footwell portion 66 that defines a driver side fluid passage hole, or “driver hole” 62. The driver hole 62 extends between the interior surface 51 and the exterior surface 53 forming a hole completely through the floor pan 52. The floor pan 52 may also include a passenger footwell portion 68 that defines a front passenger side fluid passage hole, or “passenger hole” 64. The passenger hole 64 extends between the interior surface 51 and the exterior surface 53 forming a hole completely through the floor pan 52. A transmission tunnel 74 may be disposed between the driver footwell portion 66 and the passenger footwell portion 68 and approximately located along a longitudinal centerline of the floor pan 52. In the illustrated embodiment, the transmission tunnel defines a transmission tunnel hole 76, but this may not be essential.
A plurality of beads 70 may be formed in the floor pan 52 around the driver hole 62 to compensate for reduced strength due to the creation of the hole 62. A plurality of beads 72 may be formed in the floor pan 52 around the front passenger hole 64 to compensate for reduced strength due to the creation of the hole 64. The configuration and the number of the beads 70, 72 will depend upon the size of the hole and specific design requirements of the floor pan 52. This disclosure contemplates a plurality of different bead configurations.
The floor pan 52 also includes a rear footwell portion 78. The rear footwell portion 78 may include a driver-side area 80 and a passenger-side area 82. The driver-side area 80 may define a first fluid passage hole, or “first hole” 84. The first hole 84 extends between the interior surface 51 and the exterior surface 53 forming a hole completely through the floor pan 52. The passenger-side area 82 may define a second fluid passage hole, or “second hole” 86. The second hole 86 extends between interior surface 51 and the exterior surface 53 forming a hole completely through the floor pan 52. A plurality of beads 88 may be formed in the floor pan 52 around the first hole 84 to compensate for reduced strength due to the creation of the hole 84. A plurality of beads 90 may be formed in the floor pan 52 around the second hole 86 to compensate for reduced strength due to the creation of the hole 86.
Each of the holes includes a length and a width. If the length is larger than the width it may be referred to as an “elongated rectangular hole”. For example, each hole may be an elongated rectangle that is 192 millimeters (mm) long and 82 mm wide. In another embodiment, the rectangular holes may be between 175 mm-210 mm long and may be between 60 mm-100 mm wide. The length 92 of the driver hole 62 is parallel to the driver longitudinal side 54 of the floor pan 52. The width 94 of the driver hole 62 is parallel to the front 58 of the floor pan 52 and substantially perpendicular to the driver longitudinal side 54.
The length 96 of the passenger hole 64 is parallel to the passenger longitudinal side 56 of the floor pan 52. The width 98 of the front hole 64 is parallel to the front area 58 of the floor pan 52 and perpendicular to the passenger longitudinal side 56.
The length 100 of the first hole 84 is perpendicular to the driver longitudinal side 54 of the floor pan 52. The width 102 of the first holes 84 is perpendicular to the rear 60 of the floor pan 52 and parallel to the driver longitudinal side 54.
The length 104 of the second hole 86 is perpendicular to the passenger longitudinal side 56 of the floor pan 52. The width 106 of the second hole 86 is perpendicular to the rear area 60 of the floor pan 52 and parallel to the passenger longitudinal side 54. The present disclosure contemplates other orientations of holes 62, 64, 84 and 86.
In some embodiments, a recessed area, or “racetrack” may be disposed around at least one of the holes. The racetrack provides additional strength to reinforce the area around the hole and also allows the hole to be covered to provide a smooth surface as will be described below.
After the vehicle is surface treated, the holes may be covered to seal the floor pan. Referring to
The body-and-white vehicle 34 is attached to a skid 32 at step 208 after the fluid passage holes are formed. The skid 32 supports the vehicle 34 during the e-coat dipping process and conveys the vehicle along the line 20. At step 210, the vehicle is conveyed forward along the guide rail 28 and is dipped into the tank 22.
As the vehicle 34 enters the tank 22 the surface treatment liquid 26 is initially received through the driver hole 62 and the passenger hole 64 at step 212. The liquid 26 may also be received through the transmission hole 76. The fluid passage holes allow the liquid 26 to enter into the vehicle 34 more quickly and reduce the buoyancy of the vehicle 34. The aluminum alloy components may reduce the vehicle weight so much that the vehicle 34 tends to float. The addition of the fluid holes allows the surface treatment liquid 26 to enter into the vehicle 34 immediately and reduce the tendency of the vehicle to float. As the vehicle moves further into the tank 22, the liquid 26 enters into the vehicle through the first and second holes 84, 86 to further reduce the buoyancy of the vehicle. The holes cooperates to prevent the vehicle 34 from floating and also increase the sinking rate of the vehicle 34. Preventing floating minimizes the potential for the vehicle to become detached from its carriage 30 and cause damage to the line. The increased sinking rate allows for increased line speed.
The vehicle 34 is conveyed out of the tank 22 after the surface treatment is fully applied. The surface treatment liquid 26 inside the vehicle 34 drains through the fluid passage holes (62, 64, 84, 86) at step 214 and reduces the time required to fully drain the surface treatment liquid 26 from the vehicle 34. At step 216, a cap is installed over each hole to seal the floor pan 52.
In another embodiment, the method is simplified to include forming at least one front footwell hole into the floor pan at step 218. At step 220, at least one rear footwell hole is formed into the floor pan of the vehicle. After forming the holes, the vehicle is conveyed into the tank containing the surface treatment liquid at step 222. When the vehicle enters the tank, surface treatment liquid is initially received through the front hole and subsequently received through the rear hole at step 224. The holes allow liquid to enter into the cab of the vehicle to reduce buoyancy and increase the sinking rate of the vehicle.
The embodiments described above are specific examples that do not describe all possible forms of the disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and also includes modifications of the illustrated embodiments.
