Diesel Engine Cam Profile Prevents Reverse Rotation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Single-cylinder diesel engines face the challenge of preventing reverse rotation during operation, which can continue due to inertial forces and timely fuel injection, disrupting normal engine function.
Innovation Solution
The diesel engine incorporates a fuel injection pump driving cam with specific radius portions and a slant portion configuration on the camshaft, ensuring that the intermediate portion shifts to the slant portion after the intake valve is opened to at least half of its maximum lift, thereby preventing reverse rotation by ensuring proper fuel injection timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fuel injection pump driving cam is used, then the engine can operate normally during forward rotation, but reverse rotation may continue due to timely fuel injection caused by inertial force of the flywheel
Solution Approach 1:
The fuel injection pump driving cam employs local quality by creating distinct radius portions (maximum, intermediate, and minimum) at specific locations along the cam profile. The intermediate radius portion is strategically positioned between the maximum and minimum radius portions in the reverse rotation direction, providing localized geometric features that prevent reverse rotation continuation while maintaining normal forward rotation operation.
Solution Approach 2:
The cam profile is designed with the intermediate radius portion that acts in advance to prevent reverse rotation. By positioning the intermediate portion such that it contacts the follower before the minimum radius portion during reverse rotation, the system performs a preliminary action that interrupts the reverse rotation cycle before it can complete and cause harmful effects.
2Reliability
If the intermediate portion shifts to the slant portion early in reverse rotation, then reverse rotation can be stopped quickly, but fuel injection timing may become incorrect
Solution Approach 1:
The cam profile utilizes parameter changes by varying the radius from maximum to intermediate to minimum in a controlled sequence. The intermediate radius portion serves as a transition zone that modifies the geometric parameters of the cam profile, enabling controlled interaction with the follower to prevent reverse rotation while maintaining proper fuel injection timing through carefully designed radius transitions.
Solution Approach 2:
The cam profile incorporates dynamic characteristics through its varying radius portions that interact differently with the follower during forward and reverse rotation. The intermediate radius portion creates a dynamic response that adapts to the rotation direction, providing appropriate mechanical interaction to prevent reverse rotation continuation while ensuring correct fuel injection timing through the slant portion's angular relationship with the intermediate portion.
3Reliability
If the slant portion is positioned before the intermediate portion in reverse rotation direction, then reverse rotation can be prevented, but the intake valve opening timing becomes incorrect
Solution Approach 1:
The cam profile employs asymmetry by arranging the maximum, intermediate, and minimum radius portions in a specific sequence that differs for forward and reverse rotation. The intermediate radius portion is positioned between the maximum and minimum radius portions when viewed in the reverse rotation direction, creating an asymmetric geometry that provides different functional effects for forward operation versus reverse rotation prevention, thereby preventing reverse rotation while maintaining correct intake valve timing.
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 configuration effectively prevents reverse rotation from continuing during engine operation, ensuring stable engine function by ensuring appropriate fuel injection and valve operation.
Implementation Method 1
a reverse rotation may occur not only at a time of starting but also during operation. For example, in a case where a flywheel returns (rotates in a reverse direction) due to an inertial force
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a diesel engine configured so that, when reverse rotation occurs during operation, the reverse rotation will not continue. A diesel engine (1) is provided with: a camshaft (13) driven by a crankshaft (5); a fuel injection pump-driving cam (14) provided on the camshaft (13) and driving a fuel injection pump (12), the fuel injection pump-driving cam (14) having formed thereon a maximum-diameter section (53), a minimum-diameter section (51), an intermediate section (55) which is smaller in diameter than the maximum-diameter section (53) and larger in diameter than the minimum-diameter section (51), and a sloped section (56) in which transition from the intermediate section (55) to the minimum-diameter section (51) occurs, the intermediate section (55), the sloped section (56), and the minimum-diameter section (51) being arranged in this order in the reverse rotational direction; and an intake cam (22) provided on the camshaft (13) and driving an intake valve (31). The fuel injection pump-driving cam (14) is formed so that the point where transition from the intermediate section (55) to the sloped section (56) occurs will be reached after the intake valve (31) opens an amount greater than or equal to half the maximum amount of lift of at least the intake valve (31).