Forklift

Patent metadata

Field	Value
Publication number	US-2016297657-A1
Application number	US-201415100664-A
Country	US
Kind code	A1
Filing date	Oct 16, 2014
Priority date	Dec 2, 2013
Publication date	Oct 13, 2016
Grant date	—

Abstract

The present disclosure relates to a forklift. The forklift according to the present disclosure is controlled such that when a traveling speed reaches or becomes higher than a predetermined traveling speed, pressure of hydraulic oil to be provided to a steering unit is reduced. Therefore, in order to implement a desired direction change, a steering wheel needs to be rotated to a relatively larger degree than when the forklift travels at a low speed. That is, straight traveling performance may be improved by reducing sensitivity of a direction change of the forklift to an operation of the steering wheel.

First claim

1 . A forklift comprising:
a transmission 11 which outputs power of which the speed is changed to a first speed or a second speed; a pump 10 which is operated by the power and discharges pressurized hydraulic oil; a traveling priority valve 12 which is controlled to provide the hydraulic oil preferentially to a traveling motor when a control unit selects a traveling mode; a steering unit 20 which is supplied with hydraulic oil from the traveling priority valve 12 and provided with a steering wheel 21 which is rotated to discharge hydraulic oil for a direction change; a steering actuator 30 which is operated by the hydraulic oil for the direction change so as to change a traveling direction of a rear wheel tire 31 ; a controller 100 which stores a predetermined traveling speed, and outputs a control command when a current traveling speed reaches or becomes higher than the predetermined traveling speed; and a control valve 200 which is installed in a hydraulic line through which hydraulic oil is provided from the traveling priority valve 12 to the steering unit 20 , and controlled such that when the control command is outputted, an opening degree of the valve is increased and pressure of hydraulic oil is decreased.

2 . The forklift of claim 1 , wherein the current traveling speed is computed based on a value of an engine rotational speed (rpm) provided from an engine control unit.

3 . The forklift of claim 1 , wherein the current traveling speed is computed based on a value of a driving speed provided from the transmission 11 .

4 . The forklift of claim 1 , wherein the current traveling speed is computed based on a value of an engine rotational speed (rpm) provided from an engine control unit or a value of a driving speed provided from the transmission 11 .

5 . The forklift of claim 1 , wherein an opening degree of the control valve 200 is controlled in proportion to the current traveling speed.

Assignees

• Doosan Corp

Inventors

• Han Dong Ho

Classifications

• B60T8/341

  Systems characterised by their valves (B60T8/36, B60T8/38 take precedence) · CPC title

• B66F9/22 Primary

  Hydraulic devices or systems · CPC title

• B62D5/06 Primary

  fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle · CPC title

• B62D6/02 Primary

  responsive only to vehicle speed · CPC title

• B66F9/07568

  Steering arrangements · CPC title