Fluid Pump Assembly Cam Plunger Wear Reduction
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Solution Overview
Problem
Existing fluid pump assemblies, particularly those in common rail fuel injection systems, face issues such as high volume occupation and tappet wear due to side loads and inadequate lubrication, which can lead to significant damage.
Innovation Solution
A fluid pump assembly design featuring a driven cam and reciprocating member that translates axially and rotates continuously, utilizing beveled faces and lubricating coatings to reduce friction and wear, with axial and radial bearings that promote hydrodynamic lubrication and accommodate side loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radial pump design with tappets is used, then fuel can be pressurized and delivered to the common rail, but the pump occupies a relatively high volume and the tappets are prone to wear due to side loads and inadequate lubrication
Solution Approach 1:
The invention extracts and eliminates the tappet component from the pump system. Instead of using a cam with tappets, the patent employs a cam directly actuating the plunger, thereby removing the source of side load wear and lubrication problems associated with tappets
Solution Approach 2:
The invention introduces rotational motion to the plunger through a curved cam surface. The cam profile is designed to convert the reciprocating motion into simultaneous reciprocating and rotational motion of the plunger, reducing friction and wear through continuous surface contact
2Power
If a radial pump design is used, then fuel pressurization can be achieved, but the pump occupies a relatively high volume
Solution Approach 1:
The invention transitions from a traditional radial pump layout to a more compact arrangement by integrating the cam mechanism directly with the plunger actuation. This dimensional reorganization allows for reduced overall pump volume while maintaining pressurization capability
Solution Approach 2:
The invention merges the cam mechanism and plunger actuation into a single integrated system. The cam directly actuates the plunger without intermediate components, combining functions and reducing the overall volume required for the pump assembly
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 design enhances lubrication, reduces wear, and effectively manages side loads, resulting in a more efficient and durable fluid pump assembly suitable for high-pressure fuel injection systems.
Implementation Method 1
interface means between the cam and the reciprocating member which cause the reciprocating member to be driven to translate in a first, axial direction within the bore and driven to rotate continuously within the bore in a second, rotational direction, as the cam is driven
Implementation Method 2
As the reciprocating member rotates within its bore, the constant relative velocity between the parts aids lubrication so as to reduce the effects of wear due to friction
Data Source
Figure 1
Figure 2~7
Figure 3(a)~4(b)
AI summary
A fluid pump assembly comprising a driven cam (18) and a reciprocating member (26, 28; 126, 226, 326; 32, 34) reciprocal within a bore provided in a pump housing (12, 30) as the cam (18) is driven, in use, to cause pressurisation of fluid within a pump chamber (33, 35). The pump assembly further comprises interface means (26a, 18c) between the cam (18) and the reciprocating member, preferably in the form of bevelled surfaces (18c, 26a, 28a; 32a, 34a) of the cam and the reciprocating member, which serve to drive the reciprocating member (26, 28) (i) to translate in a first, axial direction within the bore and (ii) to rotate within the bore in a second, rotational direction. A preferred feature of the fluid pump assembly is that the pump housing (12, 30) defines a bearing (22) for the cam (18) which is provided with a region of weakness (50) to allow the bearing (22) to deflect, in use, thereby to provide an increased lubrication volume between the cam and the bearing (22). The reciprocating member may take the form of a tappet (26, 28) which cooperates with a pumping plunger to pressurise fluid within the pump chamber (33, 35).