Power Tool Axial Sealing Lubrication via Gear Housing Openings
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Solution Overview
Problem
Conventional power tools, such as grinders, face a challenge with the degradation of axial sealings around the pinion shaft due to lack of lubrication, leading to fluid leakage into the motor room and reduced reliability over time, especially given the high rotational speed of the pinion shaft.
Innovation Solution
The solution involves a fluid-tight arrangement where the bearing supporting the pinion shaft is located close to the bevel gear, with a hollow support member outside the pinion shaft, and fluid conveying openings between the bearing and the gear housing, ensuring continuous lubrication to the axial sealing, preventing drying out and maintaining sealing functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the axial sealing around the pinion shaft is used to prevent lubrication fluid leakage, then sealing function is provided, but the sealing degrades over time due to lack of lubrication and high rotational speed
Solution Approach 1:
The patent introduces fluid conveying openings (tracks or channels) in the support member that proactively deliver lubrication fluid from the gear space to the confined space around the axial sealing before the sealing degrades. This preliminary lubrication action prevents the sealing from drying out and maintains its functionality throughout the operational lifetime of the power tool.
Solution Approach 2:
The support member acts as an intermediary structure that not only supports the bearing but also serves as a conduit for lubrication fluid delivery. The fluid conveying openings in the support member mediate the transfer of lubrication fluid from the gear space to the axial sealing area, ensuring continuous lubrication without compromising the fluid-tight separation between gear space and motor room.
2Force
If the bearing is located close to the bevel gear for optimal force distribution, then mechanical performance is improved, but the axial sealing may dry out due to insufficient lubrication access
Solution Approach 1:
The patent solves the lubrication access problem by introducing a new dimensional pathway through the support member. The fluid conveying openings create a third-dimensional route for lubrication fluid to reach the axial sealing, bypassing the spatial constraint imposed by the bearing's close proximity to the bevel gear. This allows the bearing to remain optimally positioned while ensuring sealing lubrication.
Solution Approach 2:
The support member is designed with integrated fluid conveying openings that segment the structure into functional zones: a bearing support zone and a fluid delivery zone. This segmentation allows the support member to simultaneously fulfill mechanical support and lubrication delivery functions, resolving the contradiction between bearing positioning and sealing lubrication.
3Reliability
If the gear space is sealed off to prevent lubrication fluid leakage, then fluid containment is achieved, but the axial sealing degrades due to inability to receive lubrication fluid
Solution Approach 1:
The patent ensures continuous lubrication of the axial sealing by maintaining an open fluid pathway from the gear space through the support member to the sealing area. The fluid conveying openings enable continuous flow of lubrication fluid, preventing the sealing from drying out while maintaining the fluid-tight containment of the gear space. This continuous lubrication action extends the service life of the sealing.
Solution Approach 2:
The support member with its fluid conveying openings serves as an intermediary structure that reconciles the apparent contradiction between fluid containment and sealing lubrication. It allows controlled fluid access to the sealing while maintaining the overall fluid-tight separation between the gear space and motor room, enabling both containment and lubrication functions to coexist.
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 arrangement prolongs the lifespan of the axial sealing, maintains its functionality, and enhances the overall reliability of the power tool by ensuring continuous lubrication and cooling, preventing leakage and maintaining optimal sealing performance.
Implementation Method 1
The provision of lubrication to the sealing prevents burning and maintains the function of the sealing throughout its operational lifetime
Implementation Method 2
the confined space of the gear space is open to the fluid tight axial sealing via at least one opening to a region between the sealing and the bearing
Implementation Method 3
both the output shaft and the pinion shaft are supported by bearings
Data Source
Figure 1~2
Figure 3~4
AI summary
A hand held power tool (10), which comprises: a motor room (19) that houses a motor that drives an output shaft; a bevel gear (12, 13) comprising an interconnected pinion gear (12) and crown gear (13), wherein the pinion gear (12) is connected to a pinion shaft (11) that is drivingly connected to the output shaft and the crown gear (13) is drivingly connected to a tool holding shaft (14); a gear housing (18) that delimits a fluid tight gear space (26) around the bevel gear (12, 13); a bearing (15) arranged around the pinion shaft (11), close to the pinion gear (12), which bearing (15) delimits a confined space (25) around the pinion shaft (11) and within the gear space (26); and a fluid tight axial sealing (20) arranged around the pinion shaft (11) inside the confined space (25) of the gear space (26), which sealing (11) seals off the gear space (26) from the motor room (19). At least one fluid conveying opening (24a, 24b) is arranged to put the confined space (25) of the gear space (26) in fluid contact with the rest of the gear space (26). Thereby, the lubrication fluid present in the gear space (26) will provide both lubrication and cooling to the axial sealing (20).