Hydraulic Control Device for Transmission Reverse Clutch Engagement
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Solution Overview
Problem
In belt type continuously variable transmissions, the responsiveness of the reverse clutch is low when switching from the Drive range (D range) to the Reverse range (R range) during idling stop due to insufficient hydraulic pressure, as the hydraulic pressure path for the reverse clutch is not filled with hydraulic oil, preventing rapid engagement.
Innovation Solution
A hydraulic control device and method that includes a switching valve capable of selectively switching hydraulic pressure between the forward and reverse clutches, with a rotational speed increase control of the electric oil pump when switching to the R range during idling stop, and a predetermined waiting time before switching to the P range to ensure immediate hydraulic pressure supply to the reverse clutch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric oil pump operates at normal rotational speed during idling stop, then energy consumption is reduced, but hydraulic pressure supply to the reverse clutch is insufficient and responsiveness is low
Solution Approach 1:
The electric oil pump's rotational speed is made dynamically adjustable based on operating conditions. During idling stop with R range selection, the pump operates at high rotational speed to rapidly supply hydraulic pressure. During normal idling stop without R range selection, the pump operates at low rotational speed to conserve energy. This dynamic speed adjustment resolves the contradiction between responsiveness and energy consumption.
Solution Approach 2:
The rotational speed parameter of the electric oil pump is changed based on the selected range and idling stop state. When the range selector is in R range during idling stop, the pump rotational speed is increased to a higher level to ensure rapid hydraulic pressure supply for reverse clutch engagement. This parameter change allows the system to achieve high responsiveness only when needed, rather than continuously consuming high energy.
2Loss of time
If the switching valve directly switches from D range position to P range position, then the switching operation is completed quickly, but the hydraulic pressure path for the reverse clutch may not be properly filled and engagement reliability is compromised
Solution Approach 1:
The system performs preliminary action by selecting the R range as an intermediate state before final P range engagement. When switching from D to P range during idling stop, the range selector first moves to R range position, which pre-fills the hydraulic pressure path for the reverse clutch. This preliminary action ensures that when the reverse clutch is subsequently engaged, hydraulic pressure is already available, improving engagement reliability without significantly increasing total switching time.
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
Enables rapid transmission of driving force to the driving wheels even when switching from the D range to the R range during idling stop by increasing the electric oil pump's rotational speed, ensuring immediate hydraulic pressure supply to the reverse clutch and enhancing responsiveness.
Implementation Method 1
a hydraulic pressure path for a reverse clutch is not filled with a hydraulic oil. Therefore, it is not possible to rapidly engage the reverse clutch
Data Source
AI summary
A hydraulic control device and hydraulic control method of a transmission are provided. The hydraulic control device of a transmission, which includes a forward clutch engaged in a Drive range, a reverse brake engaged in a Reverse range, and a switching valve that is able to selectively switch supply of a hydraulic pressure to the forward clutch and the reverse brake, wherein the hydraulic control device receives a shift position of a vehicle on which the transmission is mounted and idling stop information. When the range is switched to the Reverse range from the Drive range during idling stop, and the switching valve is positioned at a position at which a hydraulic pressure is able to be supplied to the reverse brake, rotational speed increase control with a rotational speed of an electric oil pump higher than a normal rotational speed is performed.