A steering system for steering front and rear wheels of an industrial vehicle has an upper frame rotatably coupled on an upper side of a lower frame, a steering system rotating the front and rear wheels in a predetermined direction as a steering wheel is rotated, a differential driving unit mounted
A steering system for steering front and rear wheels of an industrial vehicle has an upper frame rotatably coupled on an upper side of a lower frame, a steering system rotating the front and rear wheels in a predetermined direction as a steering wheel is rotated, a differential driving unit mounted to each of the wheels and differentially driving the left wheel and the right wheel according to a load applied to the wheels, a boom assembly having a boom length adjuster, and an upper frame pivoting unit provided between the lower and upper frames and rotating the upper frame in relation to the lower frame.
대표청구항▼
What is claimed is: 1. An industrial vehicle, comprising: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper p
What is claimed is: 1. An industrial vehicle, comprising: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper portion thereof and coupled upside the lower frame; steering cylinders, each provided with left and right input ports and a driving chain connected at opposite ends to opposite ends of a corresponding one of the steering cylinders for moving the driving chain left and right by means of a pressure oil supplied to the left and right input ports; left and right sprockets driven by the driving chain; front and rear wheel steering cases having left and right pivoting shafts, the left and right pivoting shafts being coupled to the left and right sprockets on upper portions thereof and to the left and right wheels on lower portions thereof to transmit driving force to the left and right wheels; a rotary valve connected to a steering pump and a hydraulic tank, provided with left and right output ports and discharging pressure oil from the steering pump to the left and right input ports based on rotation of the steering wheel; and a plurality of fluid channels connected between the left and right output ports of the rotary valve and the left and right input ports of the front and rear wheel steering cases or between the left and right input ports of the front and rear wheel steering cases, wherein the plurality of fluid channels include: when the steering cylinders are provided on inner sides in relation to the left and right pivoting shafts in the steering cases and when the front and rear wheel steering cases are symmetrically provided, a first fluid channel having a right fluid channel connecting the right input port of the front steering case and the left input port of the rear wheel steering case and a left fluid channel connecting a left input port of a hydraulic cylinder of the front wheel steering case and the right input port of the rear wheel steering case; a second fluid channel connecting the right output port of the rotary valve and the right fluid channel; and a third fluid channel connecting the left output port of the rotary valve and the left fluid channel. 2. The industrial vehicle as claimed in claim 1, further comprising at least one solenoid valve for opening/closing a flow of the pressure oil from the rotary valve to the front and rear wheel steering cases. 3. The industrial vehicle as claimed in claim 1, further comprising a differential driving unit which is mounted to each wheel and has a driving hydraulic motor which differentially drives the left wheel and right wheel according to a load applied to the wheels. 4. The industrial vehicle as claimed in claim 1, further comprising an upper frame pivoting unit provided between the upper frame and the lower frame and rotating the upper frame in relation to the lower frame. 5. An industrial vehicle, comprising: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper portion thereof and coupled upside the lower frame; steering cylinders, each provided with left and right input ports and a driving chain connected at opposite ends to opposite ends of a corresponding one of the steering cylinders for moving the driving chain left and right by means of a pressure oil supplied to the left and right input ports; left and right sprockets driven by the driving chain; front and rear wheel steering cases having left and right pivoting shafts, the left and right pivoting shafts being coupled to the left and right sprockets on upper portions thereof and to the left and right wheels on lower portions thereof to transmit driving force to the left and right wheels; a rotary valve connected to a steering pump and a hydraulic tank, provided with left and right output ports and discharging pressure oil from the steering pump to the left and right input ports based on rotation of the steering wheel; and a plurality of fluid channels connected between the left and right output ports of the rotary valve and the left and right input ports of the front and rear wheel steering cases or between the left and right input ports of the front and rear wheel steering cases, wherein the plurality of fluid channels include: when the steering cylinder is provided on inner sides in relation to the left and right pivoting shafts in the steering cases and when the front and rear wheel steering cases are symmetrically provided, a first fluid channel connecting one input port of the front steering case and one input port of the rear wheel steering case; a second fluid channel connecting one output port of the rotary valve and the other input port of the front wheel steering case; and a third fluid channel connecting the other output port of the rotary valve and the one input port of the rear wheel steering case. 6. The industrial vehicle as claimed in claim 5, further comprising a differential driving unit which is mounted to each wheel and has a driving hydraulic motor which differentially drives the left wheel and right wheel according to a load applied to the wheels. 7. An industrial vehicle, comprising: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper portion thereof and coupled upside the lower frame; steering cylinders, each provided with left and right input ports and a driving chain connected at opposite ends to opposite ends of a corresponding one of the steering cylinders for moving the driving chain left and right by means of a pressure oil supplied to the left and right input ports; left and right sprockets driven by the driving chain; front and rear wheel steering cases having left and right pivoting shafts, the left and right pivoting shafts being coupled to the left and right sprockets on upper portions thereof and to the left and right wheels on lower portions thereof to transmit driving force to the left and right wheels; a rotary valve connected to a steering pump and a hydraulic tank, provided with left and right output ports and discharging pressure oil from the steering pump to the left and right input ports based on rotation of the steering wheel; a plurality of fluid channels connected between the left and right output ports of the rotary valve and the left and right input ports of the front and rear wheel steering cases or between the left and right input ports of the front and rear wheel steering cases; and a differential driving unit which is mounted to each wheel and has a driving hydraulic motor which differentially drives the left wheel and right wheel according to a load applied to the wheels, wherein the differential driving unit includes: left and right wheels installed on left and right of the wheels; left and right driving hydraulic motors connected in parallel to the driving pump and driving the left and right wheels; and a gear case mounted a reduction gear train connecting the left and right wheels and the left and right driving hydraulic motors and coupled to the pivoting shafts, wherein a flow rate distributed from the driving pump to the left and right driving hydraulic motors according to a load applied to the left and right wheels to differentially drive the left and right wheels. 8. An industrial vehicle, comprising: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper portion thereof and coupled upside the lower frame; steering cylinders, each provided with left and right input ports and a driving chain connected at opposite ends to opposite ends of a corresponding one of the steering cylinders for moving the driving chain left and right by means of a pressure oil supplied to the left and right input ports; left and right sprockets driven by the driving chain; front and rear wheel steering cases having left and right pivoting shafts, the left and right pivoting shafts being coupled to the left and right sprockets on upper portions thereof and to the left and right wheels on lower portions thereof to transmit driving force to the left and right wheels; a rotary valve connected to a steering pump and a hydraulic tank, provided with left and right output ports and discharging pressure oil from the steering pump to the left and right input ports based on rotation of the steering wheel; a plurality of fluid channels connected between the left and right output ports of the rotary valve and the left and right input ports of the front and rear wheel steering cases or between the left and right input ports of the front and rear wheel steering cases; and an upper frame pivoting unit provided between the upper frame and the lower frame and rotating the upper frame in relation to the lower frame. 9. An industrial vehicle, comprising: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper portion thereof and coupled upside the lower frame; steering cylinders, each provided with left and right input ports and a driving chain connected at opposite ends to opposite ends of a corresponding one of the steering cylinders for moving the driving chain left and right by means of a pressure oil supplied to the left and right input ports; left and right sprockets driven by the driving chain; front and rear wheel steering cases having left and right pivoting shafts, the left and right pivoting shafts being coupled to the left and right sprockets on upper portions thereof and to the left and right wheels on lower portions thereof to transmit driving force to the left and right wheels; a rotary valve connected to a steering pump and a hydraulic tank, provided with left and right output ports and discharging pressure oil from the steering pump to the left and right input ports based on rotation of the steering wheel; a plurality of fluid channels connected between the left and right output ports of the rotary valve and the left and right input ports of the front and rear wheel steering cases or between the left and right input ports of the front and rear wheel steering cases; at least one solenoid valve for opening/closing a flow of the pressure oil from the rotary valve to the front and rear wheel steering cases; and a limit valve for switching the solenoid valve so as to supply the pressure oil from the front wheel steering case to the rear wheel steering case. 10. An industrial vehicle, comprising: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper portion thereof and coupled upside the lower frame; steering cylinders, each provided with left and right input ports and a driving chain connected at opposite ends to opposite ends of a corresponding one of the steering cylinders for moving the driving chain left and right by means of a pressure oil supplied to the left and right input ports; left and right sprockets driven by the driving chain; front and rear wheel steering cases having left and right pivoting shafts, the left and right pivoting shafts being coupled to the left and right sprockets on upper portions thereof and to the left and right wheels on lower portions thereof to transmit driving force to the left and right wheels; a rotary valve connected to a steering pump and a hydraulic tank, provided with left and right output ports and discharging pressure oil from the steering pump to the left and right input ports based on rotation of the steering wheel; a plurality of fluid channels connected between the left and right output ports of the rotary valve and the left and right input ports of the front and rear wheel steering cases or between the left and right input ports of the front and rear wheel steering cases; a solenoid valve for opening/closing a flow of the pressure oil from the rotary valve to the rear wheel steering case; an upper frame pivoting unit provided between the upper frame and the lower frame and rotating the upper frame in relation to the lower frame; and a direction switching valve provided between the rotary valve and the front wheel steering case so as to move the wheels in the same direction as a rotational direction of the steering wheel when the upper frame is pivoted about the pivoting unit in relation to the lower frame to be aligned in a direction opposite to the lower frame and then the steering wheel is rotated, and switching a direction of the pressure oil discharged from the left and right output ports of the rotary valve to the left and right input ports of the front wheel steering case. 11. The industrial vehicle as claimed in claim 10, wherein the plurality of fluid channels include: when the steering cylinders are provided on inner sides in relation to the left and right pivoting shafts in the steering cases and when the front and rear wheel steering cases are symmetrically provided, a first fluid channel having a right fluid channel connecting the right input port of the front steering case and the left input port of the rear wheel steering case and a left fluid channel connecting a left input port of a hydraulic cylinder of the front wheel steering case and the right input port of the rear wheel steering case; a second fluid channel connecting the right output port of the rotary valve and the right fluid channel; and a third fluid channel connecting the left output port of the rotary valve and the left fluid channel. 12. An industrial vehicle having: a lower frame on front and rear lower sides of which front and rear wheels are installed respectively, the front and rear wheels being composed of left and right wheels; an upper frame having a cab with a steering wheel located on an upper portion thereof and coupled upside the lower frame; steering cylinders, each provided with left and right input ports and a driving chain connected at opposite ends to opposite ends of a corresponding one of the steering cylinders for moving the driving chain left and right by means of a pressure oil supplied to the left and right input ports; left and right sprockets driven by the driving chain; front and rear wheel steering cases having left and right pivoting shafts, the left and right pivoting shafts being coupled to the left and right sprockets on upper portions thereof and to the left and right wheels on lower portions thereof to transmit driving force to the left and right wheels; a rotary valve connected to a steering pump and a hydraulic tank, provided with left and right output ports and discharging pressure oil from the steering pump to the left and right input ports based on rotation of the steering wheel; a plurality of fluid channels connected between the left and right output ports of the rotary valve and the left and right input ports of the front and rear wheel steering cases or between the left and right input ports of the front and rear wheel steering cases; a boom assembly connected to a rear arm having a rear end fixed pivotably in rear of the upper frame, said boom assembly comprising: a first main arm having a rear end fixed pivotably on a front end of the rear arm; a second main arm slidably coupled on a front end of the first main arm and having a working tool bracket and the working tool fixed rotatably on a front end thereof; a boom length adjuster provided between the first and second main arms and moving the second main arm in relation to the first main arm; a lifting actuator pivotably fixed to the upper frame in front of the rear arm on one end thereof and rotatably fixed in a middle portion of the first main arm on the other end thereof, to thus be telescoped to pivot the first main arm; a control link pivotably fixed in front of the upper frame on one end thereof and rotatably fixed to the first main arm on the other end thereof; and a working tool actuator fixed to the second main arm on one end thereof and pivotably fixed to the working tool bracket to rotate the working tool bracket. 13. The industrial vehicle as claimed in claim 12, wherein the boom length adjuster includes: a chamber provided on an inner side of the front end of the first main arm in a longitudinal direction; a first flange provided on an outer circumferential edge on the front end of the first main arm; a telescopic actuator having a rear end fixed in the chamber and the other end fixed on a rear end of said second main arm, and provided in the chamber to move the second main arm inserted into the chamber; and a second flange provided outside the second main arm so as to come into contact with the first flange with the telescopic actuator contracted.
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이 특허에 인용된 특허 (6)
Paul Lowell Allan,CAX ITX V3G 1K5 ; Cazes Lyle Cameron,CAX ITX V2T 5B3, Hydraulic drive and steering systems for a vehicle.
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