Vehicle Hydraulic System Pump Segmentation
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Solution Overview
Problem
The existing vehicle hydraulic systems face challenges in ensuring sufficient supply of working fluid to both high-hydraulic-pressure and low-hydraulic-pressure required parts, especially when the rotational speed of the vehicle drive source is low, leading to increased pump size and reduced fuel economy due to elevated load on the main pump and sub pump.
Innovation Solution
A hydraulic system with a hydraulic pump device having two outlet ports, a first line passage with regulated pressure, a downstream-side passage with lower pressure, and a path-switching valve device that allows fluid flow between these passages based on pressure conditions, reducing the load on the main pump and improving fuel efficiency by switching the supply destination of the working fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the main pump size is increased to ensure sufficient working fluid supply to the high-hydraulic-pressure required part when the vehicle drive source rotational speed is low, then the ejection capacity is improved, but the device complexity and fuel economy deteriorate
Solution Approach 1:
The hydraulic pump device is segmented into a main pump and a sub pump, each with separate outlet ports. The main pump supplies the high-hydraulic-pressure required part, while the sub pump supplies both the high-hydraulic-pressure required part and the low-hydraulic-pressure required part. This segmentation allows each pump to be sized appropriately for its specific function rather than requiring one oversized pump to handle all scenarios.
Solution Approach 2:
The sub pump is designed with multi-functionality to supply working fluid to both the high-hydraulic-pressure required part and the low-hydraulic-pressure required part. This universal capability allows the system to maintain adequate supply to both types of required parts without requiring the main pump to be oversized, thereby resolving the contradiction between ejection capacity and pump size.
2Productivity
If the sub pump continues to supply working fluid to the high-hydraulic-pressure required part when the rotational speed is high, then the ejection capacity is maintained, but the load on the sub pump increases and fuel economy deteriorates
Solution Approach 1:
The system dynamically adjusts the supply configuration based on the rotational speed of the vehicle drive source. When the rotational speed is high and the main pump's ejection capacity is sufficient, the sub pump's supply to the high-hydraulic-pressure required part is stopped or reduced. This dynamic adjustment optimizes energy usage by minimizing the load on the sub pump during high-speed operation while maintaining adequate supply during low-speed operation.
3Quantity of substance
If the sub pump supplies working fluid to the low-hydraulic-pressure required part when the rotational speed is low, then the supply requirement is met, but the load on the sub pump increases and prevents fuel economy improvement
Solution Approach 1:
The system dynamically adjusts the sub pump's supply configuration based on rotational speed. At low rotational speeds, the sub pump supplies both high-hydraulic-pressure and low-hydraulic-pressure required parts. At high rotational speeds, the sub pump's supply to low-hydraulic-pressure required part is optimized or stopped when the main pump's ejection capacity becomes sufficient, thereby reducing the sub pump load and improving fuel economy while maintaining adequate working fluid supply.
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 system ensures adequate fluid supply to both pressure types without increasing the main pump's size, reducing the load on the sub pump, and enhancing fuel economy by optimizing fluid distribution based on rotational speed.
Implementation Method 1
a hydraulic pump device which is to be driven by a vehicle drive source of the vehicle to eject a working fluid through first and second outlet ports of the hydraulic pump device
Implementation Method 2
a first path-switching valve device which is configured to allow the working fluid ejected through the second outlet port, to flow into the first line passage, when the hydraulic pressure in the first line passage is lower than a first predetermined pressure value
Data Source
AI summary
A vehicle hydraulic system includes: (a) a hydraulic pump device to be driven by a vehicle drive source to eject a working fluid through first and second outlet ports; (b) a first line passage that guides the working fluid ejected through the first outlet port, with a hydraulic pressure being regulated to a relatively high value; (c) a downstream-side passage in which the hydraulic pressure is regulated to a relatively low value; (d) a path-switching valve device configured to allow the working fluid ejected through the second outlet port, to flow into the first line passage, when the hydraulic pressure is lower than a predetermined value, and configured to allow the working fluid ejected through the second outlet port, to flow into the downstream-side passage, when the hydraulic pressure is higher than the predetermined value; and (e) a bypass passage provided between the second outlet port and the downstream-side passage.