Cam Shaft Bolt Polygonal Torque Transmission
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Solution Overview
Problem
Conventional pump driving devices in engines face difficulties in transmitting large driving torque to pump shafts without reducing the effective support surface of the cam shaft, making them unsuitable for heavy-load applications.
Innovation Solution
A pump driving device that uses a polygonal hole on the cam shaft and a corresponding polygonal shaft portion on the pump shaft for torque transmission, along with a bolt that is threadedly engaged with the cam shaft and features a wrench-fitting hole, allowing for efficient torque transfer and simplified structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a drive pin with large diameter is used to transmit large torque, then the torque transmission capability is improved, but the effective support surface area of the journal portion is reduced
Solution Approach 1:
The driving member is divided into separate functional components: a polygonal hole portion for torque transmission and a threaded portion for axial fixation. This segmentation allows the polygonal hole to be sized for optimal torque transmission while the threaded portion provides secure mounting without compromising the journal portion's support surface area.
Solution Approach 2:
The driving member utilizes three-dimensional spatial arrangement by positioning the polygonal hole in a plane perpendicular to the cam shaft axis, while the threaded portion extends along the axis. This dimensional separation allows independent optimization of torque transmission (via polygonal hole size) and mounting functionality (via thread length) without compromising the journal portion's support surface.
2Reliability
If a dedicated joint member is added to couple the pump shaft to the cam shaft, then the torque transmission reliability is improved, but the device complexity increases
Solution Approach 1:
The driving member is designed as a multi-functional component that simultaneously performs three functions: (1) coupling the pump shaft to the cam shaft through the polygonal hole and polygonal shaft portion fitting, (2) providing axial fixation through the threaded portion engaging with the cam shaft, and (3) serving as the primary torque transmission element. This eliminates the need for separate joint members while maintaining reliable torque transmission.
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
Enables the transmission of large driving torque to the pump shaft without compromising the support surface of the cam shaft, improving durability and reducing component complexity, thus enhancing the device's ability to handle heavy loads while minimizing costs.
Implementation Method 1
a bolt which is threadedly engaged with the cam shaft
Implementation Method 2
the bolt and the pump shaft opposed to the bolt are provided with fitting portions, respectively, which are fitted to each other to allow a torque transmission therebetween
Data Source
AI summary
In a pump driving device in an engine, driving a pump shaft of a pump mounted to an engine body by a valve-operating cam shaft supported by the engine body, a bolt is threadedly engaged with one end of the cam shaft, the bolt having a head portion in which a polygonal hole is formed, and a polygonal shaft portion is formed at one end of the pump shaft so as to be fitted into the polygonal hole. The pump shaft is driven by the cam shaft via the polygonal hole and the polygonal shaft portion. Thus, a large driving torque can be transmitted from the cam shaft to the pump shaft without reducing any effective support surface of a journal portion of the cam shaft.