Overhead Camshaft Fuel Pump Mounting
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Solution Overview
Problem
Existing fuel injection systems for internal combustion engines face challenges such as increased cost and complexity due to the need for rocker arms to drive fuel pumps, which result in undesirable side-loads and noise, and the integration of pump components with injectors, limiting space and efficiency.
Innovation Solution
The arrangement of unit pump assemblies in an overhead-camshaft engine where each pump is driven directly by a pump cam on the camshaft, mounted transversely across the cylinder head assembly, avoiding integration with injectors and reducing the need for dedicated drive mechanisms, allowing for a compact and space-efficient configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If rocker arms are used to drive fuel pumps in overhead camshaft engines, then fuel pumps can be positioned close to injectors, but system complexity and cost increase due to additional drive mechanisms
Solution Approach 1:
The invention extracts the fuel pump drive mechanism from the traditional rocker arm system. Instead of using rocker arms to drive both valves and pumps, the patent implements direct cam-driven fuel pumps that are independently actuated by cams on the camshaft, eliminating the need for separate rocker arm drive mechanisms for pumps.
Solution Approach 2:
The camshaft serves multiple functions: it actuates both the inlet and exhaust valves through traditional cams, and it directly drives the fuel pumps through integrated pump cams. This multi-functional approach consolidates the drive system, reducing overall complexity while maintaining compact positioning.
2Volume of moving object
If rocker arms are used to drive fuel pumps, then pumps can be mounted close to injectors, but undesirable side-loads and noise are generated
Solution Approach 1:
The invention replaces the rocker arm mechanical transmission system with a direct cam-follower mechanism for driving fuel pumps. This substitution eliminates the intermediate rocker arm linkage that generates side-loads and noise, providing a more direct and cleaner drive path from cam to pump.
3Volume of moving object
If unit injectors with integrated pumps are used, then space is optimized, but pump and injector components are integrated limiting flexibility
Solution Approach 1:
The invention segments the fuel delivery system by providing separate fuel pumps and separate fuel injectors. Each component is independently mounted and actuated, allowing flexible configuration and positioning without requiring integration. The pumps are mounted in the cylinder head but remain distinct from the injectors, providing both space efficiency and configurability.
4Device complexity
If separate fuel pumps are mounted on engine block, then space is available, but distance to injectors increases and system complexity increases
Solution Approach 1:
The invention changes the mounting dimension by positioning fuel pumps within the cylinder head assembly rather than on the engine block. This vertical integration within the head's available space reduces the horizontal distance to injectors, minimizing fuel line length while maintaining mounting simplicity through standardized head integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces system complexity and cost by eliminating the need for rocker arms and dedicated drive mechanisms, minimizing side-loads, and optimizing space usage within the cylinder head assembly, while maintaining efficient fuel delivery to injectors.
Implementation Method 1
a camshaft mounted longitudinally with respect to the cylinder head assembly, the camshaft being rotatable about a camshaft axis
Implementation Method 2
each pump being driven directly by a respective pump cam provided on the camshaft
Implementation Method 3
A high-pressure fuel pump generally includes a plunger that is driven for reciprocal movement within a bore provided in the pump housing by means of a cam drive arrangement
Data Source
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AI summary
An overhead-camshaft internal combustion engine is disclosed, in which the fuel pumps are arranged to use efficiently the space within a cylinder head assembly (100) of the engine. The cylinder head assembly (100) includes a cylinder head block (102), and the engine comprises a camshaft (106) mounted longitudinally with respect to the cylinder head assembly (100), the camshaft (106) being rotatable about a camshaft axis (A) and having a plurality of inlet and exhaust cams for actuating associated inlet and exhaust valves (116a; 116b) of the engine, and at least one fuel pump comprising a unit pump assembly (110) driven directly by a respective pump cam (130) provided on the camshaft (106), the unit pump assembly (110) being elongate to define a pump axis (P). The engine further comprises a plurality of rocker arms (118) driven by the inlet and exhaust cams and arranged to actuate the inlet and exhaust valves (116a, 116b). Each rocker arm (118) is pivotable about a rocker arm axis (R) which is substantially parallel to the camshaft axis (A). The or each pump assembly (110) is mounted between the rocker arm axis (A) and the cylinder head block (102).