Hydraulic Control Assembly Pre-filling via Throttled Valve
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Solution Overview
Problem
Existing hydraulic control arrangements for power-split transmissions face issues with unreliable pre-filling and inefficient energy usage due to gravity-dependent venting solutions, leading to undefined switching times and energy losses.
Innovation Solution
A hydraulic control arrangement that connects two working lines via a valve arrangement, allowing for throttled pressure medium pre-filling of actuating devices independently of gravity, ensuring reliable and precise actuation of clutches across different driving ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gravity-based venting solutions are used to prevent air in the working line, then air can be vented from the actuating device, but the directional control valve must be arranged above the actuating device counter to the direction of gravity, representing a geometric boundary condition that makes it difficult to utilize available installation space and generally requires a large amount of installation space
Solution Approach 1:
The patent replaces the gravity-based mechanical venting system with a pressure-based hydraulic system. A check valve allows pressure medium to flow from the pressure medium source through the directional control valve to the actuating device, forcing air out through the venting line regardless of orientation. This substitution of the venting mechanism eliminates the geometric constraint of needing to position the valve above the actuating device.
Solution Approach 2:
The invention uses hydraulic pressure to achieve venting functionality. By connecting the actuating device to a pressure medium source through a check valve and directional control valve, pressurized fluid flows through the system to expel air bubbles through the venting line. This hydraulic approach replaces gravity-dependent air removal with pressure-driven air expulsion, enabling flexible installation orientations.
2Reliability
If gravity-based venting solutions are used to prevent air in the working line, then air can be vented from the actuating device, but this represents a geometric boundary condition that must be complied with, which makes it difficult to utilize the available installation space
Solution Approach 1:
The patent replaces the gravity-based mechanical venting system with a pressure-based hydraulic system. A check valve allows pressure medium to flow from the pressure medium source through the directional control valve to the actuating device, forcing air out through the venting line regardless of orientation. This substitution of the venting mechanism eliminates the geometric constraint of needing to position the valve above the actuating device.
Solution Approach 2:
Instead of relying on gravity to pull air out (which requires specific orientation), the system inverts the approach by using pressurized fluid to push air out. The check valve and pressure medium source create a pressure differential that forces air expulsion in the opposite direction of gravity's influence, allowing the system to function in any orientation.
3Reliability
If venting solutions are used to prevent air in the working line, then air can be vented from the actuating device, but when the clutch is open, there is an additional leakage flow from the working line via the actuating device to the tank or sump, which must be replaced, representing an additional loss of energy
Solution Approach 1:
The patent extracts the venting function from the main working line by providing a separate venting line that branches off. The check valve allows air to be removed through this separate path without creating continuous leakage. The venting line is only active when needed to remove air, while the main working line maintains its pressure seal, eliminating continuous energy loss.
Solution Approach 2:
The system performs preliminary air venting through the dedicated venting line before normal operation begins. Once air is removed and the system is sealed, the venting line remains closed by the check valve, preventing continuous leakage. This preliminary action separates the air removal function from the pressure maintenance function, eliminating ongoing energy loss.
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 provides a more reliable and space-efficient pre-filling mechanism, enabling defined and reproducible actuation of clutches, reducing energy losses and improving shifting quality in power-split transmissions.
Implementation Method 1
a valve arrangement (62), via which the first working line (42) can be brought into a throttled pressure medium connection with the second working line (44)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The hydraulic control arrangement (3) has a hydraulic actuating device (50,52) for each of the clutches (C1,C2), which is fluidically connected with a pressure medium sink. The two actuating devices are connected with a pressure medium source through a working line (42,44) in each case for actuating the associated clutch. A valve assembly (62) is provided, through which the two working lines are brought together in a throttled pressure medium connection. An independent claim is included for a method for pre-filling the working line of a control arrangement of a transmission.