Pressure Reducing Valve Unit Suppressing Self-Excited Vibrations
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Solution Overview
Problem
Conventional solenoid type pressure reducing valve units in construction machines, such as hydraulic excavators, face issues with self-excited vibrations in the main spool due to delayed pressure response in the output port when components with large load volumes or low wall surface rigidity are connected, leading to unstable pressure output.
Innovation Solution
The pressure reducing valve unit design sets a first distance smaller than a second and third distance, ensuring the pilot pressure chamber communicates with the tank port before the output port is blocked, gradually increasing pressure in the pilot pressure chamber, thereby maintaining balance between pilot pressure, output port pressure, and spring urging force, suppressing self-excited vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If components with large load volumes or low wall surface rigidity are connected to the output port, then the system can accommodate various mounting configurations, but the pressure response at the output port is delayed
Solution Approach 1:
The patent introduces a pilot pressure chamber as an intermediary between the solenoid valve and the output port. The pilot pressure chamber receives controlled primary pressure from the solenoid valve and uses it to control the main spool, which in turn controls the output port. This intermediary mechanism allows gradual pressure buildup and spool movement, solving the response delay issue caused by large volume or low rigidity components connected to the output port.
2Device complexity
If the pilot pressure chamber communicates directly with the primary pressure port, then pressure control is simplified, but self-excited vibrations occur in the main spool
Solution Approach 1:
The patent implements preliminary action by establishing communication between the pilot pressure chamber and the tank port before the main spool moves to block the output port. This sequence ensures that the pilot pressure chamber pressure increases gradually in advance, creating a balanced pressure distribution that prevents sudden spool movements and self-excited vibrations.
Solution Approach 2:
The patent applies beforehand cushioning by using the tank port communication to gradually increase pilot pressure before the main spool reaches positions that would cause abrupt pressure changes. This cushioning effect absorbs pressure fluctuations and prevents the conditions necessary for self-excited vibrations.
3Speed
If the main spool moves quickly to respond to pressure changes, then control responsiveness is improved, but self-excited vibrations are generated
Solution Approach 1:
The patent applies dynamics by making the pilot pressure chamber pressure buildup a dynamic process controlled by the spool position. As the main spool moves, the communication between the pilot pressure chamber and tank port changes dynamically, creating a progressive pressure increase that matches the spool movement speed, thereby preventing vibrations while maintaining responsiveness.
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 stabilizes the pressure output at the output port even when large volume or low rigidity components are connected, effectively suppressing self-excited vibrations and ensuring a stable pressure response.
Implementation Method 1
a solenoid actuator (32) configured to drive a pilot spool (36) in response to a control signal
Implementation Method 2
the pilot spool (36) moves to establish communication between the controlled primary pressure flow passage (19) and the pilot pressure chamber (25)
Implementation Method 3
a main spool (24) movable in an axial direction in response to the pilot pressure
Implementation Method 4
a first return spring (27) disposed in the feedback pressure chamber (26) to urge the main spool (24) in the axial direction
Implementation Method 5
a throttle passage (30) configured to limit a flow amount of hydraulic oil to be discharged to the tank port (15) from the pilot pressure chamber (25)
Implementation Method 6
balance between a load (for example, a force that pushes the spool in one direction) by the controlled primary pressure (pilot pressure), and a load (for example a force that pushes the spool in the other direction) by the pressure of the output port and an urging force of a spring
Data Source
Figure 1
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AI summary
A main spool (24) has a throttle passage (30) that, when the main spool (24) moves to an axial other side against a first return spring (27) in a main spool insertion hole (13), communicates a pilot pressure chamber (25) with a first tank port (15) and limits a flow amount of hydraulic oil to be discharged to the first tank port (15) from the pilot pressure chamber (25). When the main spool (24) moves to the axial other side along the main spool insertion hole (13), the throttle passage (30) communicates the pilot pressure chamber (25) with the first tank port (15) before a state where a first pump port (17) is communicated with an output port (16) and a state where the output port (16) is blocked from the first tank port (15).