Automatic transmission mechanism of hydraulic motor

Abstract

To smoothly perform the turning with a good riding quality in an automatic transmission mechanism of a construction machine.A variable capacity type hydraulic motor 1 is shiftable to a second speed and a first speed. A capacity control cylinder 18 shifts the hydraulic motor 1 to the second speed when the pressure oil is supplied to a cylinder chamber 20, and to the first speed when the pressure oil is discharged. A capacity switching valve 21 is switchable between a supply position f for connecting the capacity control cylinder 18 with a hydraulic source and a discharge position d for connecting the capacity control cylinder 18 with a tank 45. A driving pressure passage 23 is formed to introduce a driving pressure of the hydraulic motor 1 to achieve the oil pressure for moving a valve element 22 of the capacity switch valve 21 to one side. When the construction machine is turned, a flow rate in supplying the pressure oil to the cylinder chamber 20 of the capacity control cylinder 18 is restricted by a first throttle 31, and a flow rate in discharging the pressure oil from the cylinder chamber 20 is restricted by the first throttle 31 and a second throttle 32.

Description

technical field [0001] The present invention relates to the technology of an automatic transmission mechanism of a hydraulic motor driving a traveling axle of a construction machine. Background technique [0002] As a transmission device of a hydraulically driven vehicle (for example, a construction machine such as a hydraulic excavator) whose axle is driven by a hydraulic motor, there is a device disclosed in Patent Document 1, for example. [0003] The constitution of aforementioned device is as patent document 1 figure 1 As shown, there are variable capacity hydraulic motors 4·5 on the left and right, and each hydraulic motor 4·5 has a capacity control pressure cylinder 12 for changing and controlling its capacity (specifically, the inclination angle of the swash plate 11). The pressure chamber 14 of each displacement control cylinder 12 is connected to the control hydraulic pump 15 through a second switching valve (displacement switching valve) 21 . When the driving pr...

AI Technical Summary

Problems solved by technology

However, just by reducing the throttle valve, it is not possible to quickly shift from 1st speed to 2nd speed, and the acceleration feeling is poor, and the handling feeling is not good.

In addition, the gear shifting timings of the left and right hydraulic motors 4 and 5 are greatly deviated, and the linearity of the construction machine is poor.

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