Internal-combustion engines – Engine speed regulator – Having condition responsive means with engine being part of...
Patent
1992-04-16
1993-11-30
Miller, Carl S.
Internal-combustion engines
Engine speed regulator
Having condition responsive means with engine being part of...
123373, F02D 3100
Patent
active
052655695
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a system for controlling rotational speed of a prime mover particularly suitable for use on a construction machine such as hydraulic power shovel or the like for controlling rotational speed of the prime mover.
BACKGROUND OF THE INVENTION
Generally, a Diesel engine is mounted on construction machines to serve as a prime mover for driving hydraulic pumps.
In this regard, it has been the general practice for conventional construction machines of this to provide a control lever in an operator's cabin and to link the control lever with a governor mechanism of the engine through a controlling cable, link rod and so forth for control the rotational speed of the engine. However, the mechanical linkage of the control lever with the governor mechanism through the control cable and link rod has a drawback that it requires large operating forces.
With a view to eliminating such a drawback, there has been proposed an electric remote control system for governor mechanism, including an electric motor provided in the vicinity of an engine for governor adjustment, a rotational angle sensor adapted to detect the rotational angle of the governor mechanism indicative of the rotational speed of the engine, and a command means in the form of operating switches or the like provided in the operator's cabin in association with a controller such as microcomputer. The controller is adapted to control the electric motor through feedback control in such a manner so as to make the difference between a signal value specified by the command means and a signal value detected by the rotational angle sensor zero, thereby turning the governor lever of the governor mechanism to a position corresponding to the specified value.
In this connection, FIGS. 11 to 13 show, by way of example a construction machine employing a prior art prime mover rotational speed control system with a governor mechanism of the type mentioned above.
In FIGS. 11-13, a Diesel engine 1 is mounted on a construction machine as a prime mover with governor 2 being provided on the engine 1. The governor 2 includes an elongated governor lever 3 and stoppers 4 and 5 for limiting the rotational range of the governor lever 3 by abutting engagement therewith. The governor 2 functions to adjust the rotational speed of the engine 1 according to the rotational angle of the governor lever 3 in an accelerating direction H or decelerating direction L, and, as shown in FIG. 12, to hold the engine at the lowest speed N.sub.L (idling speed) when the governor lever 3 abuts against the stopper 4 where the value of lever rotation is 0%, while holding the engine at the maximum speed N.sub.H (full speed) when the governor lever 3 abuts against the stopper 5 where the value of lever rotation is 100%.
A reversible stepping motor is mounted in the vicinity of the engine 1. A lever 6A is mounted on the output shaft of the stepping motor 6 and is connected to the governor lever 3 through a link 7. The stepping motor 6 is rotatable in a forward direction F or in a reverse direction R in dependence upon a control pulse signal from a controller 10, which will be described hereinbelow to thereby rotate the governor lever 3 in the accelerating direction H or in the decelerating direction L through the link 7. Even when the rotation of the governor level is stopped by a stop signal received from the controller 10, the governor lever 3 is retained in the current angular position to operate the engine 1 at the current rotational speed.
A potentiometer 8 is provided in the vicinity of the engine 1 to serve as a rotational angle sensor. A lever 8A is mounted on a rotational shaft of the potentiometer 8 and is connected to the link 7. The potentiometer 8 is preadjusted such that its detection range (output range) is held in a predetermined relationship with the rotational range of the governor lever 3 as indicated by solid line in FIG. 12. The potentiometer 8 is adapted to detect the rotational angle of the governor lever 3 through the lever 8A and link 7
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Egashira Masaki
Haga Masakazu
Hirata Touichi
Tomikawa Osamu
Hitachi Construction Machinery Co. Ltd.
Miller Carl S.
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