CONSTRUCTION VEHICLE

• US 20110308878A1
• Filed: 03/12/2010
• Published: 12/22/2011
• Est. Priority Date: 04/09/2009
• Status: Active Grant

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Shirao, Atsushi
• Granted Patent: US 8,316,983 B2
• Time in Patent Office: Days
• US Class Current: 180/305
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/103 of fluid type
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2710/0605 Throttle position
• CPC Class Codes: B60W 2720/10 Longitudinal speed
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: B60Y 2200/41 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: B60Y 2200/415 Wheel loaders
• CPC Class Codes: E02F 9/2253 Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission
• CPC Class Codes: E02F 9/2289 Closed circuit
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F16H 61/47 for achieving a target output speed

Abstract

A construction vehicle includes a hydraulic pump for travelling driven by an engine and a hydraulic motor for travelling driven by a pressurized oil discharged from the hydraulic pump. A control unit is configured to set an upper limit of a command value of an acceleration opening degree in accordance with a magnitude of a travelling load and a magnitude of a vehicle speed, and to set a lower limit of a displacement of the hydraulic motor for travelling in order to maximize the vehicle speed at the acceleration opening degree limited to a predetermined amount.

Claims

1. A construction vehicle comprising:

an engine;

a hydraulic pump for travelling configured to be driven by the engine;

an accelerator pedal configured to adjust an acceleration opening degree in accordance with a pressed amount thereof;

a hydraulic motor for travelling configured to be driven by a pressurized oil discharged from the hydraulic pump for travelling;

a travelling load detecting section configured to detect a magnitude of a travelling load applied in travelling;

a vehicle speed detecting section configured to detect a vehicle speed; and

a control unit configured to set an upper limit of a command value of the acceleration opening degree in accordance with the magnitude of the travelling load and a magnitude of the vehicle speed, the control unit being further configured to set a lower limit of a displacement of the hydraulic motor for travelling in order to maximize the vehicle speed at the acceleration opening degree limited to a predetermined amount.

4. The construction vehicle recited in claim 1, wherein

the travelling load is a hydraulic pressure of the pressurized oil to be supplied to the hydraulic motor for travelling.

5. The construction vehicle recited in claim 1, wherein

the travelling load is an output torque of the engine.

6. The construction vehicle recited in claim 1, wherein

the travelling load is a product of a hydraulic pressure of the pressurized oil to be supplied to the hydraulic motor for travelling and the displacement of the hydraulic motor for travelling.

2. A construction vehicle comprising:

an engine;

a hydraulic pump for travelling configured to be driven by the engine;

an accelerator pedal configured to adjust an acceleration opening degree in accordance with a pressed amount thereof;

a hydraulic motor for travelling configured to be driven by a pressurized oil discharged from the hydraulic pump for travelling;

a vehicle speed detecting section configured to detect a vehicle speed;

a storage section configured to store engine torque curve data having a characteristic that an engine speed is reduced in proportion to increase in the vehicle speed towards a maximum vehicle speed; and

a control unit configured to control the engine based on the engine torque curve data in accordance with a magnitude of the vehicle speed, the control unit being further configured to set a lower limit of a displacement of the hydraulic motor for travelling in order to maximize the vehicle speed at the acceleration opening degree limited to a predetermined amount.

3. The construction vehicle recited in claim 2, further comprising:

a travelling load detecting section configured to detect a magnitude of a travelling load to be applied in travelling,

wherein the engine torque curve data further has a characteristic that the engine speed is reduced in proportion to reduction in the travelling load, and

the control unit is configured to control the engine based on the engine torque curve data in accordance with the magnitude of the travelling load, the control unit being further configured to set the lower limit of the displacement of the hydraulic motor for travelling in order to maximize the vehicle speed at the acceleration opening degree limited to the predetermined amount.

7. The construction vehicle recited in claim 3, wherein

the travelling load is a hydraulic pressure of the pressurized oil to be supplied to the hydraulic motor for travelling.

8. The construction vehicle recited in claim 3, wherein

the travelling load is an output torque of the engine.

9. The construction vehicle recited in claim 3, wherein

the travelling load is a product of a hydraulic pressure of the pressurized oil to be supplied to the hydraulic motor for travelling and the displacement of the hydraulic motor for travelling.