Fuel Pump Pressure Compensation via Stroke-Controlled Outlet

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Solution Overview

Problem

High-pressure fuel pumps experience pressure fluctuations in the interior space due to the stroke movement of the pump piston, which cannot be fully compensated by existing overflow valves, affecting fuel delivery, especially when the inlet is connected to multiple pump elements.

Innovation Solution

An additional connection between the interior space and the outlet is controlled as a function of the pump piston's stroke, allowing for better pressure compensation by opening during the middle stroke and closing at other times, either through the drive shaft or the roller tappet, to manage fuel flow effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If an overflow valve is used to limit pressure in the interior space, then the maximum pressure is controlled, but pressure fluctuations during piston stroke cannot be compensated

Engineering Contradiction:
Improvepressure controlVSAvoidfuel delivery stability
Core Design Contradiction:
Stress or pressureVSReliability

Solution Approach 1:

The invention introduces a dynamic pressure compensation mechanism where a compensation channel connects the interior space to the outlet, allowing the system to adaptively respond to pressure fluctuations during piston stroke. This dynamic adjustment compensates for the static limitation of the overflow valve, maintaining stable fuel delivery while controlling maximum pressure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The compensation channel acts as an intermediary between the interior space and the outlet, providing an additional pathway for fuel flow that mediates pressure fluctuations. This intermediary mechanism allows gradual pressure equalization during piston movement, preventing the pressure variations that would otherwise affect fuel delivery stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Quantity of substance

If the inlet is connected to multiple pump elements, then fuel supply capacity is increased, but pressure fluctuations affect delivery more significantly

Engineering Contradiction:
Improvefuel supply capacityVSAvoiddelivery stability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The compensation channel serves multiple functions: it compensates for pressure fluctuations, maintains stable delivery across multiple pump elements, and works universally regardless of the number of pump elements connected to the inlet. This multi-functional mechanism ensures that increasing fuel supply capacity through multiple pump elements does not compromise delivery stability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If a controlled connection between interior space and outlet is added, then pressure fluctuations are compensated, but device complexity increases

Engineering Contradiction:
Improvepressure compensationVSAvoidsystem structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The compensation channel is merged with the existing outlet structure, integrating the pressure compensation function into the already-present fuel outlet pathway. This merging approach allows pressure fluctuation compensation without adding completely separate components, thereby reducing the increase in device complexity while still achieving reliable pressure compensation.

Inventive Principle:
Principle #5Merging (Combining)

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 solution effectively compensates for pressure fluctuations, improving fuel delivery stability and reducing the impact of piston movement on pressure dynamics within the pump system.

Implementation Method 1

The drive shaft 14 has a cam 18 or eccentric for driving the pump piston 12

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

The drive shaft 14 has a cam 18 or eccentric for driving the pump piston 12

Methodology Applied
Scientific EffectEccentric mechanism: Excentric

Implementation Method 3

The pump has at least one pump element 10, which in turn has a pump piston 12, which is driven at least indirectly by a drive shaft 14 in a stroke movement

Methodology Applied
Scientific EffectReciprocating pump mechanism: Pump

Implementation Method 4

The connection between the interior and the drain is controlled by an overflow valve which, when its opening pressure is reached, opens the connection between the interior and the drain so that the pressure in the interior is limited

Methodology Applied
Scientific EffectPressure-controlled valve: Valve

Data Source

PatentEP2795095B1Pump, in particular a fuel pump for a fuel injection system
Publication Date: 2016.03.16 ROBERT BOSCH GMBH
  • EP2795095B1 patent drawingFigure 1
  • EP2795095B1 patent drawingFigure 2
  • EP2795095B1 patent drawingFigure 3

AI summary

The pump has at least one pump element (10) with a pump piston (12) driven in a stroke movement and a pump housing (22, 40) which has an interior space (42) in which a drive area (14, 18, 36) is arranged. The pump piston (12) moves alternately into the interior space (42) and out of the interior space (42) in the pump's stroke movement. The interior space (42) has at least one supply (28) and at least one outlet (50) for fluid medium. The connection of the interior space (42) to the at least one outlet (50) is controlled depending on the stroke of the piston pump (12).