High-Pressure Pump Bypass Throttle for Piston Cooling
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Solution Overview
Problem
High-pressure pumps used in common rail injection systems face challenges in maintaining piston cooling when the volume flow control valve is closed, leading to a lack of fluid flow in the low-pressure circuit, which is necessary for cooling but not possible in this state.
Innovation Solution
Incorporating a bypass throttle that allows fluid flow even when the volume flow control valve is closed, along with a return throttle downstream of the cooling device to ensure continuous piston cooling, and using a spring-preloaded inlet valve to prevent unwanted high-pressure delivery during leakage, ensuring cooling is maintained across all operating points including '0 delivery'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the volume flow control valve is closed to stop fluid delivery, then the high-pressure delivery function is improved, but the piston cooling function deteriorates due to lack of fluid flow in the low-pressure circuit
Solution Approach 1:
The low-pressure circuit is segmented into two parallel paths: one through the volume flow control valve and another through the bypass throttle. This allows independent control of cooling flow from delivery flow, enabling the cooling function to continue even when the main delivery valve is closed.
Solution Approach 2:
The bypass throttle acts as an intermediary element that provides an alternative flow path for the cooling function. It mediates between the closed state of the volume flow control valve and the continuous cooling requirement, allowing fluid to bypass the controlled valve and still cool the piston.
2Measurement precision
If the volume flow control valve is closed to achieve zero delivery, then the delivery control precision is improved, but the continuous cooling operation deteriorates
Solution Approach 1:
The flow control system is divided into two independent functional segments: the volume flow control valve for precise delivery control and the bypass throttle for continuous cooling. This segmentation allows the precision control function to be fully activated (valve closed) while the cooling function remains active through the bypass path.
Solution Approach 2:
The bypass throttle provides a universal solution that serves the cooling function across all delivery states (zero delivery, partial delivery, full delivery). It ensures the cooling operation can endure continuously regardless of the delivery control valve position.
3Temperature
If a bypass throttle is added to maintain cooling, then the piston cooling function is improved, but the device complexity increases
Solution Approach 1:
The bypass throttle is integrated into the existing low-pressure circuit structure, merging the cooling function with the delivery control system. The bypass path shares common components (fluid source, pump chamber inlet) with the main circuit, reducing the need for entirely separate cooling infrastructure.
Solution Approach 2:
The bypass throttle serves multiple functions: it provides continuous cooling flow, maintains pressure balance in the low-pressure circuit, and enables zero-delivery operation while preserving cooling. This multi-functionality justifies the added component by providing multiple benefits from a single element.
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 ensures continuous piston cooling across all operating points of the high-pressure pump, including '0 delivery', by generating a fluid flow through the bypass throttle and utilizing the return throttle for heat dissipation, even when the volume flow-controlled high-pressure pump does not deliver fluid from the low-pressure side to the high-pressure side.
Implementation Method 1
By providing the bypass throttle, which bypasses the flow control valve, a certain fluid flow is generated even when the flow control valve is closed, which can be used to cool the piston.
Implementation Method 2
Piston cooling is achieved via the flow in the low-pressure circuit upstream of the intake valve. The fuel flowing intermittently into the pump chamber is used as a cooling medium for the heat dissipated by the piston before passing through the intake valve.
Implementation Method 3
The fluid flowing into the pump is discharged via an outlet throttle located downstream of the cooling device.
Data Source
Figure 1
AI summary
The invention relates to a high-pressure pump for raising the pressure level of a fluid, more particularly a fuel, the high-pressure pump comprising: - a movable piston for compressing a pump chamber; - an inlet valve for letting the fluid into the pump chamber; - a cooling device for cooling the piston with the aid of fluid flowing upstream of the inlet valve; and - a volumetric-flow-rate control valve, which is disposed upstream of the cooling device and influences a volumetric flow rate of the fluid through the cooling device toward the inlet valve. The pump is characterized by a bypass throttle for the bypassing of the volumetric-flow-rate control valve and by a return throttle for leading away a fluid downstream of the cooling device.