Shift control device for industrial vehicle

Abstract

A gearshift controller for an industrial vehicle, includes: a speed ratio detection unit that detects a speed ratio of speeds of an input axis and of an output axis of a torque converter; a gearshift control unit that shifts up a speed stage when the detected speed ratio is equal to or more than a first predetermined value and shifts down the speed stage when the detected speed ratio is equal to or less than a second predetermined value, which is smaller than the first predetermined value; and an operation member with which a downshift to the first speed is instructed by operation thereof by an operator. When the downshift is instructed by the operationmember, the gearshift control unit controls the speed stage to be kept at the first speed for a predetermined time period regardless of the speed ratio detected by the speed ratio detection unit.

Description

technical field [0001] The present invention relates to a speed change control device for industrial vehicles such as wheel loaders. Background technique [0002] Conventionally, there is known a device that transmits an output torque of an engine to a transmission via a torque converter (hereinafter referred to as a torque converter) (for example, refer to Patent Document 1). In the device described in this patent document 1, the ratio of the speed ratio between the input shaft side and the output shaft side of the hydraulic torque converter is calculated, and when the speed ratio reaches a predetermined value, it is automatically shifted up or down. files. [0003] Patent Document 1: Japanese Patent No. 3388594 [0004] However, a large driving force is required, for example, to perform excavation work by dashing a wheel loader into accumulated sand and soil. However, in the device described in the above-mentioned Patent Document 1, since the gear up is automatically pe...

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Problems solved by technology

[0004] However, for example, when driving a wheel loader into accumulated sand and digging, a large driving force is required

However, in the device described in the above-mentioned Patent Document 1, since the gear up is automatically performed when the speed of the torque converter is relatively high, for example, even if it rushes into the sand and soil in the 1st speed state, it may happen that the gear is shifted just before the speed. When the gear is shifted to 2nd speed, it may not be possible to obtain sufficient driving force during excavation work.

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