Fuel Pump Spill Valve Assembly for Accurate Stroke Setting
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Solution Overview
Problem
The conventional method of assembling a spill valve in a fuel pump generates blowoff and spatters that interfere with performance, and the setting of the stroke length can be inaccurate due to robot arm slip during the welding process.
Innovation Solution
A method involving an assembly tool with a stepped portion to set the stroke length accurately, using a fixture surface to secure the spill valve body and sleeve, followed by welding them together, and then integrating the assembly into the fuel pump housing without generating blowoff or spatters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the spill valve body is welded to the inlet valve sleeve using conventional methods, then the assembly is secured, but welding blowoff and spatters penetrate into the spill valve body and interfere with performance
Solution Approach 1:
The assembly process is divided into two separate welding operations: first welding the inlet valve sleeve to the fuel pump housing, then welding the spill valve body to the inlet valve sleeve. This segmentation allows the first weld to be completed without risking spatter contamination of the spill valve body, as the body is not yet attached. The second weld occurs after the sleeve is already secured to the housing, isolating the spill valve body from harmful welding effects.
Solution Approach 2:
The inlet valve sleeve is welded to the fuel pump housing before the spill valve body is attached. This preliminary action secures the sleeve in position and protects it from subsequent welding operations, preventing any welding blowoff or spatters from penetrating into the spill valve body cavity and interfering with its performance.
2Manufacturing precision
If the robot gripper arms grip the spill valve body to pull it out for stroke setting, then the stroke can be adjusted, but the grip may slip during the pulling step and result in improper stroke distance
Solution Approach 1:
A purpose-built assembly tool with a gripper mechanism serves as an intermediary between the robot and the spill valve body. This specialized tool provides reliable, slip-free gripping surfaces designed specifically for the spill valve body geometry, ensuring consistent and accurate stroke setting without the reliability issues of generic robot grippers.
Solution Approach 2:
The conventional robot gripper system is replaced with a dedicated assembly tool that has mechanically optimized gripping features. This tool provides more reliable and precise control during the stroke setting operation, eliminating the slippage problems associated with standard robot grippers.
3Manufacturing precision
If the spill valve body is pulled out a small defined distance by a robot with micrometer precision, then the stroke can be set, but the process is complex and time-consuming
Solution Approach 1:
The assembly tool incorporates a stepped portion with predetermined height that automatically sets the stroke distance when the spill valve body is positioned against it. This self-service feature eliminates the need for complex robot-controlled pulling and micrometer adjustments, as the tool itself provides the precise positioning through its fixed geometric features.
Solution Approach 2:
The assembly tool uses fixed geometric parameters (the height of the stepped portion) to define the stroke distance, replacing the need for dynamic, complex control systems. This simplifies the overall process by converting an active, controlled operation into a passive, geometry-based solution.
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
Ensures precise setting of the stroke length and prevents welding spatters from interfering with the spill valve's performance, enhancing the assembly process's reliability and efficiency.
Implementation Method 1
welding the inlet valve sleeve of the body sub-assembly to the fuel pump housing adjacent the bore
Data Source
AI summary
A method of assembling a spill valve of a high-pressure fluid pump includes disposing an inlet valve sleeve on an assembly tool such that the inlet valve sleeve contacts a fixture surface of the assembly tool. A pole piece is disposed within a cavity of a spill valve body. An open end of a spill valve body with the pole piece therein is inserted into the inlet valve sleeve that is on the assembly tool. The spill valve body is welded to the inlet valve sleeve to form a body sub-assembly. Subsequent to welding the spill valve body to the inlet valve sleeve, the body sub-assembly is removed from the assembly tool and inserted into a bore in an outer surface of a fuel pump housing. The inlet valve sleeve of the body sub-assembly is then welded to the fuel pump housing adjacent the bore.