Damping Force Control Shock Absorber Air Bleeding
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Solution Overview
Problem
Conventional damping force control type shock absorbers face challenges in achieving both air bleeding performance and damping force responsiveness due to complex structures and increased manufacturing costs, particularly in semi-active suspension systems.
Innovation Solution
A damping force control type shock absorber with a damping valve mechanism that includes a damping force generating valve, a control valve, and a solenoid, which uses a communicating passage with an orifice to control hydraulic fluid flow between the cylinder's upper and lower chambers, preventing air from escaping and allowing for adjustable damping force generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sectional area of the passage for expelling air is reduced, then the delay in rising of damping force is minimized, but the manufacturing cost increases due to tighter tolerances
Solution Approach 1:
The invention extracts the air venting function from the main hydraulic circuit by providing a dedicated air vent passage that is separate from the damping force control passage. This allows air to be expelled efficiently without requiring tight tolerances in the main damping passage, thus maintaining fast damping force response while avoiding increased manufacturing costs.
2Reliability
If a check valve is provided in the passage to block hydraulic fluid flow, then air bleeding performance is improved, but the structure becomes complicated and manufacturing cost increases
Solution Approach 1:
The invention segments the hydraulic circuit into separate functional passages: one dedicated to air venting and another to damping force control. This segmentation eliminates the need for check valves to manage air bleeding, as air can escape through the dedicated air vent passage without interfering with the damping fluid flow path, thereby simplifying the overall structure.
Solution Approach 2:
The invention introduces a dedicated air vent passage as an intermediary pathway that allows air to be expelled from the hydraulic system without requiring complex valve mechanisms. This intermediary passage provides a simple, effective solution for air bleeding that does not complicate the main damping control system.
3Reliability
If the passage for expelling air is always open, then air bleeding performance is maintained, but the damping force adjustable range is limited
Solution Approach 1:
The invention divides the hydraulic circuit into separate passages for air venting and damping control. The air vent passage remains open to maintain air bleeding performance, while the damping control passage can be independently regulated by the damping valve mechanism, thus preserving the full adjustable damping force range without compromise.
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 design effectively prevents delay in damping force rise and expands the adjustable range while reducing manufacturing costs by simplifying the structure and maintaining air bleeding performance, thus enhancing the shock absorber's responsiveness and efficiency.
Implementation Method 1
a solenoid (54) driving the movable element (53) in the axial direction
Implementation Method 2
The communicating passage in the shaft portion is communicated at one end thereof with the pilot chamber and at the other end thereof with an upstream one of the two chambers in the cylinder through an orifice
Implementation Method 3
a damping valve mechanism provided in the cylinder to generate damping force by controlling a flow of hydraulic fluid between the two chambers in the cylinder that is caused by movement of the piston rod
Data Source
AI summary
A damping force control type shock absorber capable of achieving both air bleeding performance and damping force responsiveness at reduced cost. When a pilot valve (47) is closed during the extension stroke of a piston rod (6), a cylinder upper chamber (2A) is communicated with a back-pressure chamber (46) through a passage (73) including an orifice (76), a communicating passage (70), a pilot chamber (33), and a communicating passage (50). At this time, the cylinder upper chamber (2A) is not communicated with a cylinder lower chamber (2B); therefore, damping force responsiveness is ensured. Further, because there is no need to provide a check valve in the passage, it is possible to suppress an increase in manufacturing cost. Further, air entering the pilot chamber (33) moves upward through the communicating passage (70). Therefore, the air can be discharged into the cylinder upper chamber (2A) through the passage (73).