Fail-Safe Valve for Damping Force Control in Shock Absorbers
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Solution Overview
Problem
The stroke of the valving element in a shock absorber's solenoid valve needs to be increased, which restricts the available space and makes it difficult to maintain appropriate damping force in the event of a failure.
Innovation Solution
A damping force control type shock absorber with a normally-open solenoid valve and a fail-safe valve that includes a valving element, a seat part, a guide part, an urging member, and a magnetic attraction part, allowing the valving element to move between normal and fail-safe positions to control hydraulic fluid flow, independent of the solenoid valve's stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the stroke of the valving element in the solenoid valve is increased to control damping force, then the degree of freedom for adjusting damping force characteristics is improved, but the available space in the shock absorber is restricted
Solution Approach 1:
The invention divides the damping force control function into two separate components: a solenoid valve for normal operation and a fail-safe valve for failure conditions. This segmentation allows each valve to have optimized stroke lengths, with the fail-safe valve having a shorter stroke that does not restrict space, while the solenoid valve handles the main adjustment capability.
Solution Approach 2:
The fail-safe valve acts as an intermediary mechanism that takes over damping force control when the solenoid valve fails. It includes a valving element, seat part, guide part, urging member, and magnetic attraction part that work together to provide fail-safe operation with a compact structure that doesn't compromise available space.
2Device complexity
If the solenoid valve is used alone for damping force control, then the structure is simplified, but the shock absorber cannot maintain appropriate damping force in the event of a failure
Solution Approach 1:
The fail-safe valve is pre-configured with an urging member (spring) and magnetic attraction part that are ready to activate immediately upon solenoid valve failure. The valving element is positioned to automatically assume control of the damping force generation, providing beforehand cushioning against the harmful effect of complete control loss.
Solution Approach 2:
The fail-safe valve changes the operational parameters by using a magnetic attraction part made of magnetic material that interacts with the coil's magnetic field to move the valving element, rather than relying solely on electromagnetic force in the solenoid valve. This allows different failure modes to be handled with appropriate physical principles.
3Force
If the valving element is made of magnetic material and positioned near the coil, then the magnetic attraction force is improved for fail-safe operation, but the stroke length requirement increases
Solution Approach 1:
The invention replaces the purely electromagnetic actuation of the solenoid valve with a hybrid system in the fail-safe valve that combines magnetic attraction (for positioning) with mechanical spring urging (for actuation). The magnetic attraction part serves as a positioning element rather than the primary actuator, reducing the required stroke length while maintaining sufficient magnetic force for reliable operation.
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 the generation of appropriate damping force even in the event of a failure, with the fail-safe valve ensuring smooth operation and maintaining damping force characteristics.
Implementation Method 1
a magnetic attraction part magnetically attracting the valving element through the magnetic field of the coil to move the valving element to the normal position
Implementation Method 2
The valving element and the magnetic attraction part are made of a magnetic material forming a magnetic path through the magnetic field of the coil
Implementation Method 3
an urging member urging the valving element toward the fail-safe position
Implementation Method 4
a damping force generating mechanism generating a damping force by controlling a flow of hydraulic fluid induced by sliding movement of the piston in the cylinder
Data Source
AI summary
PROBLEMProvided is a damping force control type shock absorber capable of obtaining an appropriate damping force even in the event of a failure independently of the stoke of a valving element of a solenoid valve.MEANS FOR SOLVINGA piston 5 having a piston rod 6 connected thereto is fitted in a cylinder 2 having hydraulic oil sealed therein, and a flow of hydraulic oil induced by movement of the piston 5 is controlled by a damping force generating mechanism 26 to generate a damping force. In the damping force generating mechanism 26, damping force is generated by a pilot-type main valve 27 and a normally-open pilot valve 28 which is a solenoid valve, and the damping force is adjusted by energization of a coil 37. A fail-safe valve 100 is provided downstream of the pilot valve 28. During normal operations, the fail-safe valve 100 opens the flow path through excitation of the coil 37 of the pilot valve 28. In the event of a failure, due to loss of excitation, the fail-safe valve 100 restricts the flow path to generate an appropriate damping force in place of the pilot valve 28, which has become inoperable.