Refuse Vehicle Tailgate CNG Integration for Space and Weight Balance
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Solution Overview
Problem
Existing refuse vehicles with CNG systems face issues such as space constraints, weight distribution, damage risk, and aesthetic concerns, particularly with chassis-mounted, roof-mounted, and POD tailgate designs, which affect capacity and ease of inspection.
Innovation Solution
A CNG system integrated into the tailgate of a refuse vehicle, with tanks positioned between hinges and following the contour of the tailgate, reducing height and weight, providing an aesthetic appearance, and enabling easy inspection and service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CNG system is mounted to the chassis frame, then the system has stable installation, but it requires a large amount of space which limits the capacity of the refuse vehicle and adds significant weight to the front axle
Solution Approach 1:
The CNG tanks are relocated from the chassis frame to the tailgate structure, utilizing the vertical and depth dimensions of the tailgate space. This dimensional shift allows the system to occupy space that would otherwise be unused, reducing the impact on vehicle capacity while maintaining stable installation through integration with the tailgate framework.
Solution Approach 2:
The CNG tanks are nested within the tailgate structure, with tanks positioned between the tailgate hinges and following the contour of the curved tailgate. This nesting approach allows the CNG system to occupy space within the existing tailgate geometry without extending beyond the vehicle's external dimensions, thereby preserving vehicle capacity.
2Reliability
If a CNG system is mounted to the chassis frame, then the system has stable installation, but it adds a large percentage of weight to the chassis front axle
Solution Approach 1:
The CNG system is relocated from the front chassis area to the rear tailgate structure, changing the spatial distribution of weight from front to rear. This dimensional relocation balances the weight distribution across the vehicle, reducing the excessive weight on the front axle while maintaining stable installation through the tailgate's structural integration.
3Ease of operation
If a CNG system is mounted on the roof, then the system is easily accessible, but it exposes the CNG unit to damage by low bridge overpasses, shop doors, tree limbs, etc. and adds significant weight to the front axle
Solution Approach 1:
The CNG system is relocated from the vertical roof surface to the horizontal tailgate structure at the rear of the vehicle. This dimensional change protects the tanks from overhead obstacles like low bridges and tree limbs while maintaining accessibility through the rear access design, eliminating the damage risks associated with roof mounting.
Solution Approach 2:
The CNG system is extracted from the vulnerable roof location and relocated to the protected tailgate area. This extraction removes the tanks from the harmful environment of overhead obstacles while preserving the functionality and accessibility of the CNG system through the rear-mounted configuration.
4Reliability
If preassembled PODs are installed on the tailgate, then the CNG system is integrated, but the units are relatively large providing an overhang with the center of gravity measured from the tailgate hinge, creating a large moment on the tailgate raised cylinder and structure
Solution Approach 1:
Instead of using a single large POD unit, the design employs multiple smaller CNG tanks distributed within the tailgate structure. This local distribution of tank units reduces the concentrated overhang mass, thereby reducing the moment arm and the resulting moment force on the tailgate raised cylinder and structure while maintaining system integration.
Solution Approach 2:
The CNG storage system is segmented into multiple individual tanks rather than a single large POD. This segmentation distributes the mass throughout the tailgate structure, reducing the center of gravity overhang and the resulting moment forces on the tailgate mechanism while achieving integrated installation.
5Reliability
If preassembled PODs are installed on the tailgate, then the CNG system is integrated, but the CNG fuel line routing is exposed due to the routing over the tailgate top cross member, and the aesthetics are not most desirable
Solution Approach 1:
The design uses a contoured cover that follows the curvature of the tailgate, creating a smooth aesthetic appearance. This cover conceals the CNG fuel line routing and tank connections, hiding the mechanical components behind a streamlined exterior surface that matches the vehicle's design while maintaining system integration.
Solution Approach 2:
The contoured cover is designed to match the aesthetic appearance of the tailgate, creating a uniform visual appearance that conceals the underlying CNG system components and fuel line routing. This visual integration enhances the overall aesthetic while maintaining the functional integration of the CNG system.
6Reliability
If preassembled PODs are installed on the tailgate, then the CNG system is integrated, but the tanks in the POD tailgate are stacked, making inspection and service of the tanks difficult
Solution Approach 1:
The CNG system uses multiple individual tanks rather than a single stacked POD unit. This segmentation allows each tank to be independently accessed and serviced, eliminating the difficulty of inspecting and maintaining tanks that are stacked within a confined POD structure while maintaining system integration.
Solution Approach 2:
The tanks are extracted from the enclosed POD structure and individually positioned within the tailgate framework. This extraction allows each tank to be independently accessible for inspection and service, removing the maintenance difficulties associated with stacked tanks while preserving the integrated appearance and function of the CNG system.
7Reliability
If preassembled PODs are installed on the tailgate, then the CNG system is integrated, but the POD assembly is quite heavy adding additional weight to the refuse vehicle reducing its capacity
Solution Approach 1:
The CNG system is segmented into multiple smaller tanks distributed within the tailgate structure, replacing the heavy single-unit POD assembly. This segmentation reduces the overall weight while maintaining the integrated appearance and function, thereby preserving vehicle capacity while achieving system integration.
Solution Approach 2:
The CNG tanks are positioned within the three-dimensional space of the tailgate structure, utilizing available volume rather than adding external mass. This spatial integration reduces the overall weight compared to external POD assemblies while maintaining system integration and aesthetic appearance.
Data Source
AI summary
A refuse vehicle has a tailgate. The tailgate has a framework to secure CNG tanks. A cover overlays the frame work to provide an aesthetic appearance to the vehicle.