TRANSPORTER VEHICLE

• US 20120274121A1
• Filed: 12/09/2010
• Published: 11/01/2012
• Est. Priority Date: 01/20/2010
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Minoshima, Toshikazu, Fushiki, Michio, Tamura, Katsumi, Kurosawa, Takao
• Granted Patent: US 8,840,189 B2
• Time in Patent Office: Days
• US Class Current: 298/22.R
• CPC Class Codes: B60P 1/162 the hydraulic system itself

Abstract

In case a burden is discharged from a vessel (3), the vessel (3) is raised obliquely backward with respect to a vehicle body (2) by a hoist cylinder (10). However, when discharging work is stopped on the way, the vessel (3) is temporarily lowered to a position at which this sits on the vehicle body (2). When the vessel (3) lowers, a weight of the burden left loaded thereon acts on the hoist cylinder (10) as a load in addition to the weight of the vessel (3). A controller (35) determines whether the vessel (3) lowers in a burden loading state based on various detection signals. When the vessel (3) lowers in the burden loading state, switching of directional control valves (20) and (21) is controlled so as to decrease a contracting speed of the hoist cylinder (10), thereby prevent the vessel (3) from colliding against the vehicle body (2).

Claims

1. A transporter vehicle comprising:

an automotive vehicle body, which travels by a wheel;

a loading platform tiltably provided on said vehicle body on which a burden being a transporting target is loaded;

a hoist cylinder provided between said loading platform and said vehicle body so as to be extendable for extending to obliquely tilt said loading platform when said burden is discharged from said loading platform;

a hydraulic source for generating pressure oil to be supplied to said hoist cylinder;

a control valve unit provided between said hydraulic source and said hoist cylinder for controlling supply and discharge of said pressure oil to and from said hoist cylinder; and

an operation device for performing switching operation of said control valve unit,

wherein said transporter vehicle comprises;

a tilting state detector for detecting a tilting state of said loading platform with respect to said vehicle body;

a burden loading detector for detecting whether said burden is loaded on said loading platform; and

a controller for controlling switching of said control valve unit based on signals from said operation device, said tilting state detector, and said burden loading detector,

wherein said controller includes;

a burden lowering determining means for determining whether it is operated such that said loading platform is lowered in the burden loading state based on said signals from said operation device, said tilting state detector, and said burden loading detector, and

flow amount throttling means for throttling a flow amount of oil liquid returned from said hoist cylinder to a hydraulic source side through said control valve unit by controlling the switching of said control valve unit so as to decrease a contracting speed of said hoist cylinder when it is determined that said loading platform lowers in the burden loading state by said burden lowering determining means.

2. A transporter vehicle according to claim 1, wherein said burden lowering determining means is configured to judge that said loading platform is in the burden loading state by said detection signal from said burden loading detector when a weight of said loading platform side is larger than a predetermined weight value compared with the weight in an unladen state in which said burden is not loaded on said loading platform.

3. A transporter vehicle according to claim 1, wherein said control valve unit has a plurality of switching positions, which are a neutral position to stop the supply and discharge of said pressure oil to stop motion of said hoist cylinder, a raising position to extend said hoist cylinder by the supply and discharge of said pressure oil to raise said loading platform, a floating position to allow falling of said loading platform by a self-weight by contracting said hoist cylinder by the self-weight of said loading platform side, and a lowering position to lower said loading platform by contracting said hoist cylinder by the supply and discharge of said pressure oil,

said control valve unit has a variable throttling portion for throttling the flow amount of the oil liquid in accordance with a control signal from said controller when being switched to said floating position or said lowering position, and

said flow amount throttling means is configured to throttle the flow amount of the oil liquid returned from said hoist cylinder to said hydraulic source side by using said variable throttling portion.

4. A transporter vehicle according to claim 1, wherein said control valve unit is constituted by combining;

a first directional control valve switched to any one position of a neutral position to stop the supply and discharge of said pressure oil to and from said hoist cylinder, a raising position to raise said loading platform by extending said hoist cylinder by the supply and discharge of said pressure oil, and a floating position to allow falling of said loading platform by a self-weight by contracting said hoist cylinder by the self-weight of said loading platform side in accordance with a control signal from said controller, and

a second directional control valve switched to any one position of said neutral position, said raising position, and a lowering position to rotate said loading platform downward by contracting said hoist cylinder by the supply and discharge of said pressure oil in accordance with said control signal from said controller,

said first directional control valve has one variable throttling portion for throttling the flow amount of the oil liquid in accordance with said control signal from said controller when being switched to said floating position,

said second directional control valve has another variable throttling portion for throttling the flow amount of the oil liquid in accordance with said control signal from said controller when being switched to said lowering position, and

said flow amount throttling means is configured to throttle the flow amount of the oil liquid returned from said hoist cylinder to said hydraulic source side by using said one variable throttling portion or said another variable throttling portion.

5. A transporter vehicle according to claim 1, comprising a suspension for suspending said vehicle body relative to said wheel, wherein said burden loading detector is constituted by a pressure sensor for detecting an inner pressure of said suspension.

6. A transporter vehicle according to claim 1, wherein said tilting state detector is constituted by a sit-down sensor for detecting whether said loading platform sits on said vehicle body.

7. A transporter vehicle according to claim 1, wherein said tilting state detector is constituted by an angle sensor for detecting a tilting angle of said loading platform with respect to said vehicle body.