Fuel Injection Pump Cam Deformed Section Friction Reduction
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Solution Overview
Problem
Fuel injection pumps face high friction between the roller and shoe components, leading to potential seizure and increased manufacturing costs due to complex structures and high friction coefficients, especially when starting the internal combustion engine or electric motor.
Innovation Solution
Incorporating a deformed section, such as a groove or protrusion, on the cam surface that extends along the rotational axis, which forms an oil film between the shoe and roller through a squeeze effect, reducing friction and allowing the components to transition from a sliding to a rolling state, thereby reducing the shoe braking torque and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the roller and shoe components are designed with conventional contact surfaces, then the structural simplicity is maintained, but high friction occurs leading to potential seizure and increased manufacturing costs
Solution Approach 1:
The cam surface is modified locally by adding deformed sections (grooves or protrusions) only in specific areas where the roller contacts the cam, rather than changing the entire cam structure. This localized modification creates oil film retention zones that reduce friction and prevent seizure, while maintaining the overall simplicity of the cam design.
Solution Approach 2:
Lubricating oil is introduced as an intermediary substance between the roller and cam contact surfaces. The deformed sections on the cam surface are specifically designed to retain and distribute this lubricating oil, creating a protective film that reduces direct metal-to-metal contact and prevents seizure.
2Ease of manufacture
If conventional cam surfaces are used, then manufacturing simplicity is maintained, but high friction coefficients increase manufacturing costs due to complex solutions required
Solution Approach 1:
Instead of redesigning the entire cam surface, only localized deformed sections are added to the cam. These grooves or protrusions are simple geometric features that can be easily manufactured using conventional machining processes, maintaining manufacturing simplicity while providing the necessary friction reduction functionality.
Solution Approach 2:
The surface geometry of the cam is modified by changing parameters such as adding grooves or protrusions with specific dimensions. These parameter changes create oil film retention zones that reduce friction coefficients, solving the reliability issue without requiring complex manufacturing processes.
3Reliability
If the roller slides on the shoe without oil film formation, then the structure remains simple, but friction is high causing shoe braking torque increase
Solution Approach 1:
Deformed sections are added locally to the cam surface at the roller contact area. These localized features create oil film retention zones that reduce friction between the roller and shoe, preventing the increase in shoe braking torque without requiring complex overall structural changes.
Solution Approach 2:
Lubricating oil is introduced into the contact zone between the roller and cam, where the deformed sections create hydraulic-like pressure zones that maintain an oil film. This fluid-based solution reduces direct contact friction and prevents torque increase without complex mechanical modifications.
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
The solution effectively reduces friction between the shoe and roller, preventing seizure and improving the reliability of the fuel injection pump while maintaining a simple structure and manageable manufacturing costs.
Implementation Method 1
forms an oil film between the shoe and roller through a squeeze effect
Implementation Method 2
Lubricating oil is supplied to the housing
Data Source
AI summary
A fuel injection pump pressurizes and injects fuel. A cam rotates about a rotational axis of the cam. A housing includes a cam chamber that houses the cam and a sliding chamber communicated to the cam chamber. A roller rotates while being in contact with a surface of the cam. A shoe reciprocates in the sliding chamber by rotation of the cam and is in contact with and slides on a surface of the roller. A plunger reciprocates with the shoe. A cylinder houses the plunger and includes a pump chamber to pressurize and feed the fuel by reciprocation of the plunger. A deformed section is a groove or a protrusion which extends in a direction of a rotational axis of the cam, on a part of a surface of the cam, and has a shape different from a cam profile of the cam.