Hydraulic Pump Speed Ramp-Down for Stable Pressure Switching
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Solution Overview
Problem
In hydraulic control devices, the transition from using a second pump to a first pump results in a drastic decrease in hydraulic pressure, leading to reduced fuel efficiency when the second pump is stopped, especially when determining the operation state of the second pump is challenging, affecting the operation of hydraulic systems like continuously variable transmissions.
Innovation Solution
The hydraulic control device implements a control mechanism that differentiates the rate of rotation speed decrease for the second pump based on its operation state, allowing a slower decrease in the operation-allowed region to maintain fuel efficiency and a faster decrease in the operation-disallowed region to ensure hydraulic function, using sensors to determine the operation state and adjust the rotation speed accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the second pump is stopped quickly to switch to the first pump, then the hydraulic pressure drops drastically, but fuel efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the rotation speed decrease rate of the second pump variable rather than fixed. The control device adjusts the decrease rate dynamically based on the operation state of the second pump, allowing faster decrease when the pump is in an operation-disallowed region and slower decrease when in an operation-allowed region, thus resolving the contradiction between quick switching and fuel efficiency
Solution Approach 2:
The patent changes the parameter of rotation speed decrease rate based on the operation state of the second pump. By determining whether the pump is in an operation-allowed or operation-disallowed region and adjusting the decrease rate accordingly, the system optimizes both switching speed and fuel efficiency through parameter adaptation
2Reliability
If the second pump is stopped quickly to shorten operation time in operation-disallowed region, then hydraulic function is maintained, but fuel efficiency is reduced
Solution Approach 1:
The control device changes the rotation speed decrease rate parameter based on the determined operation state. When the second pump is in an operation-disallowed region, a faster decrease rate is applied to maintain hydraulic function, while when in an operation-allowed region, a slower rate preserves fuel efficiency
Solution Approach 2:
The system dynamically adjusts the pump shutdown behavior based on real-time operation state assessment, making the rotation speed decrease rate adaptive rather than static, thereby balancing reliability and energy efficiency requirements
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 approach facilitates improved fuel efficiency by managing the second pump's rotation speed decrease, ensuring the hydraulic system's functionality and energy efficiency by determining the appropriate stop period and operation state, thereby optimizing the hydraulic control device's performance.
Implementation Method 1
pressurizes the first oil supplied from the first pump, and supplies the pressurized first oil as the second oil
Implementation Method 2
when the discharge amount of the second oil from the second pump exceeds the flow rate of the first oil passing through the bypass valve, the hydraulic pressure in the downstream oil passage of the bypass valve becomes higher than the hydraulic pressure in the upstream oil passage
Data Source
AI summary
In a hydraulic control device switchable between a first state in which a first oil is supplied from a first pump to a hydraulic operation part via a bypass valve and a second state in which the first oil supplied from the first pump is pressurized by using the second pump and the pressurized first oil is supplied, as a second oil, to the hydraulic operation part, when the second pump is stopped in the second state, control that gradually decreases a target rotation speed of the second pump is performed, and rates at which the target rotation speed of the second pump decreases differ in a case where the second pump is stopped in an operation-allowed region and in a case where the second pump is stopped when the second pump is determined as in an operation-disallowed region.