Straight Travel Valve Control for Intended Curved Machine Motion
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Solution Overview
Problem
Existing construction machines fail to ensure safe curved travel when working devices are operated, leading to potential safety accidents as they tend to move straight against the driver's intention during intended curved travel.
Innovation Solution
A control method and system that includes an electrical control valve with a solenoid or proportional pressure reducing valve, shuttle valves, and pressure sensors to detect and manage pilot pressures, blocking the straight travel mode when the pressure difference exceeds a set value to enable curved travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the straight travel valve is switched to enable straight travel when working devices are operated, then the machine can maintain straight travel stability, but the machine cannot perform curved travel as intended by the driver
Solution Approach 1:
The patent applies dynamics by making the straight travel valve switchable between two states: enabled and disabled. The control system dynamically adjusts the valve state based on detected travel conditions (straight vs. curved). When curved travel is detected through pressure difference sensing, the system automatically disables the straight travel valve, allowing the machine to perform curved travel as intended. This dynamic switching resolves the contradiction between maintaining straight travel stability and enabling curved travel capability.
2Ease of operation
If the straight travel valve is always enabled to prevent single travel, then the machine moves straight against driver's intention during intended curved travel, but if disabled, then straight travel cannot be maintained when working devices are operated
Solution Approach 1:
The patent implements feedback control by using pressure sensors to detect the pressure difference between left and right travel motors. This pressure difference serves as feedback information about the driver's intended travel direction. When the pressure difference exceeds a predetermined threshold, the control system interprets this as an intention for curved travel and automatically disables the straight travel valve. This feedback mechanism ensures that the machine responds accurately to the driver's intentions while maintaining reliable travel control.
3Adaptability or versatility
If pressure difference detection is used to control straight travel valve, then curved travel can be enabled when intended, but the system complexity increases with additional sensors and control logic
Solution Approach 1:
The patent applies self-service by utilizing the existing hydraulic system's pressure differences as the detection mechanism. The pressure sensors measure the natural pressure differences that already exist in the hydraulic circuit during operation, without requiring additional complex detection equipment. The control system leverages these self-generated pressure signals to automatically control the straight travel valve, enabling the system to detect travel intentions and adjust accordingly using readily available information from the hydraulic circuit itself.
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
The system effectively prevents straight travel during curved operations, ensuring the machine follows the driver's intention and enhancing safety by allowing controlled curved movement.
Implementation Method 1
the straight travel valve (14) which is switched by a pilot pressure applied from the electrical control valve (13)
Implementation Method 2
pressure sensors (17, 18, 21, 22) for detecting pilot pressures applied to the left and right travel motor control valves (5, 10) and the first and second working device switch valves (6, 7, 11, 12)
Implementation Method 3
The electrical control valve includes a solenoid valve, in which the solenoid valve is adjusted between an initial state position and an on-state position by a control signal
Implementation Method 4
The electrical control valve includes a proportional pressure reducing valve, the proportional pressure reducing valve being adjusted to allow the pilot pressure from the pilot pump to the straight travel valve, in response to an electrical signal
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
Disclosed are a straight traveling apparatus for a construction machine and a control method thereof, which can allow a curved travel when the working device is operated during the curved travel. The straight traveling apparatus comprises a first and a second variable displacement hydraulic pump and a pilot pump; a left travel motor and a first working device that are operated by the first hydraulic pump; a plurality of switch valve that are installed in the path of the first hydraulic pump and control the hydraulic oil supplied to the left travel motor or the first working device; a right travel motor and a second working device that are operated by the second hydraulic pump; a plurality of switch valve that are installed in the path of the second hydraulic pump and control the hydraulic oil supplied to the right travel motor or the second working device; a straight travel valve that is switched by the pilot pressure applied from an electrical control valve, and supplies the hydraulic oil of one of the first and second hydraulic pumps to the left and right travel motors while supplying the hydraulic oil of the other of the first and second hydraulic pumps to the left and right working devices; a pressure detection sensor for detecting the pilot pressure applied to the left and right travel motor switch valves and the pilot pressure applied to the first and second working device switch valves; and a controller that outputs the control signal to the electrical control valve so that the pilot pressure applied to the straight travel valve is blocked in case that the difference between the pilot pressures applied to the left and right travel motor switch valves is larger than the pre-set pressure value, when the first and second working devices are operated during the travel.