Travel control device for hydraulic traveling vehicle

Abstract

A rotational speed pickup 71 (traveling speed detection means), a hydraulic pressure sensor 72 (traveling operation detection means), a hydraulic pressure sensor 73 (drive status detection means), and a voltage sensor 74 (transmission shift position detection means) detect parameters regarding the traveling state of a hydraulic traveling vehicle. A control unit 80, a solenoid proportional valve 81, an engine control system 82, and a motor regulator 33 determine the operating state of the hydraulic traveling vehicle based on the parameters regarding the traveling state, and control the equivalent displacement of the traveling system including a hydraulic traveling motor 14 and the maximum flow rate supplied to the hydraulic traveling motor 14 according to the result of determination. The pump flow rate and motor displacement are controlled according to the traveling state in this way, thereby ensuring favorable traveling performance without degrading the fuel efficiency.

Description

technical field [0001] The present invention relates to a travel control device for a hydraulic traveling vehicle, and more particularly to a traveling control device for a hydraulic traveling vehicle such as a wheeled hydraulic excavator. A variable capacity type hydraulic travel motor driven by the supplied hydraulic oil controls the travel torque by changing the capacity of the hydraulic travel motor. Background technique [0002] The travel control device of a hydraulic traveling vehicle such as a wheeled hydraulic excavator usually uses a hydraulically driven traveling motor of variable capacity type, and the load pressure (traveling load pressure) of the traveling motor increases during acceleration, uphill travel, etc. In the case of , increase the capacity of the travel motor to generate the required torque. In addition, when decelerating, the circuit pressure (brake pressure) is adjusted through the overload relief valve in the hydraulic drive circuit for travel, a...

AI Technical Summary

Problems solved by technology

However, since the control system is complicated as described in Patent Document 1, the capacity control of the hydraulic pump tends to cause a problem of cost increase.

In addition, when the control to increase the maximum engine speed is performed in conjunction with the capacity switching of the travel motor by self-pressure, since the control of the maximum engine speed and the travel motor are performed using the preset pump discharge pressure as a threshold Therefore, the setting deviation and the response delay of the control are unavoidable. When the discharge pressure of the hydraulic pump is reduced so that it is out of the absorption torque control, and the discharge flow rate of the hydraulic pump increases, the vehicle speed may be Temporary increase, in order to improve this, there are still many things to be confirmed in development

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