Pumps – Condition responsive control of drive transmission or pump... – Plural pumps with individual or relative control
Patent
1992-01-17
1993-01-05
Smith, Leonard E.
Pumps
Condition responsive control of drive transmission or pump...
Plural pumps with individual or relative control
60428, F04B 128
Patent
active
051765047
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus for controlling hydraulic pumps which are mounted on a construction machine.
BACKGROUND ART
For example, a construction machine for performing excavating operations is generally equipped with two variable capacity type hydraulic pumps adapted to be driven by an engine in order to feed a pressurized hydraulic oil to hydraulic actuators in the form of hydraulic cylinders, hydraulic motors or the like.
A technology for varying horse powers to be absorbed by variable capacity type hydraulic pumps corresponding to a magnitude of load while maintaining a sum of the absorptive horse powers of the hydraulic pumps at a level corresponding to a predetermined value has been heretofore proposed (e.g., refer to Japanese Patent Application NO. 60841/1984).
The foregoing predetermined value is practically set to a value which represents a rated horse power derived from the engine.
With the prior technology as described above, in a case where one of the hydraulic pumps has a smaller absorptive horse power, the absorptive horse power allowable relative to the other hydraulic pump is enhanced correspondingly. This enables the rated horse power of the engine to be utilized effectively.
However, it has been found that the prior technology has the following drawback.
Specifically, since the absorptive horse powers of the respective hydraulic pumps are not individually monitored, optimum distribution of the absorptive horse powers relative to the respective hydraulic pumps sometimes fails to be carried out.
Another drawback of the prior technology is that a controlling operation is performed with a low accuracy, because the prior technology is practiced by employing mechanical components.
The present invention has been made with the foregoing background in mind and its object resides in providing an apparatus for controlling hydraulic pumps for a construction machine wherein distribution of horse powers to be absorbed by the hydraulic pumps can adequately be carried out with an excellent accuracy.
DISCLOSURE OF THE INVENTION
To accomplish the above object, the present invention provides an apparatus for controlling hydraulic pumps for a construction machine wherein the construction machine includes first and second hydraulic pumps adapted to be driven by an engine and hydraulic actuators hydraulically connected to the first and second hydraulic pumps via first and second actuating valves, wherein the apparatus includes as essential components engine revolution number detecting means for detecting the number (N) of revolutions of the engine, pressure detecting means for detecting pressures (P.sub.1) and (P.sub.2) of hydraulic oils discharged from the first and second hydraulic pumps, horse power setting means for presetting reference absorptive horse powers relative to the first and second hydraulic pumps, target discharge capacity commanding means for commanding target discharge quantities (V.sub.1L) and (V.sub.2L) corresponding to quantities of actuations of the first and second actuating valves, absorptive horse power calculating means for calculating actual absorptive horse powers (HP.sub.01) and (HP.sub.02) derived from the first and second hydraulic pumps, extra horse power calculating means for calculating extra horse powers (.DELTA.HP.sub.1) and (.DELTA.HP.sub.2) based on the reference allowable absorptive horse powers and the actual absorptive horse powers (.DELTA.HP.sub.1) and (.DELTA.HP.sub.2), the extra horse powers (.DELTA.HP.sub.1) and (.DELTA.HP.sub.2) failing to be absorbed by the first and second hydraulic pumps, means for calculating allowable discharge capacities (V.sub.1P) and (V.sub.2P) based on the engine revolution number (N), the discharge pressures (P.sub.1) and (P.sub.2), the extra horse powers (.DELTA.HP.sub.1) and (.DELTA.HP.sub.2) and the reference allowable horse powers relative to the first and second hydraulic pumps, means for selecting a smaller one of the target discharge capacity (V.sub.1L) and the allowable discharge capacity
REFERENCES:
patent: 4395199 (1983-07-01), Izumi et al.
patent: 4773369 (1988-09-01), Kobayashi
patent: 4809504 (1989-03-01), Izumi et al.
patent: 5048293 (1991-09-01), Aoyagi
Kinoshita Shigeru
Moriya Yukio
Onoda Takumi
Yokoyama Toshio
Kabushiki Kaisha Komatsu Seisakusho
Smith Leonard E.
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