Automatic engine control for an excavator
US4838755A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 17, 1988 |
| Grant date | Jun 13, 1989 |
| Priority date | — |
| Expiry date | Aug 17, 2008 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H61/4061
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An excavator has a number of different hydraulically powered functions that are controlled by a closed center hydraulic system that features a pair of variable displacement, engine driven hydraulic pumps, the displacement of which is responsive to the demands of the system. The flow to the various hydraulic motors is controlled by pilot operated load sensing control valves that direct fluid pressure to a load sensing line when one of the hydraulic motors in the system is being operated. The load sensing line is connected to the control system of the pumps to place the pumps in stroke when a flow of pressurized fluid is required. The flow of the load sensing pressure to the controls for one of the pumps can be optionally disconnected to place said pump in a standby condition and thereby reduce the flow capacity of the hydraulic system at the option of the operator. The load sensing line is also connected to a pressure actuated switch that closes when pressure in the line falls below a predetermined point, which occurs when none of the hydraulic motors are being actuated. The closed switch provides electric power to a solenoid through a time delay circuit so that the solenoid shifts …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.