Motors: expansible chamber type – With signal – indicator or inspection means
Patent
1992-06-30
1994-04-26
Bertsch, Richard A.
Motors: expansible chamber type
With signal, indicator or inspection means
60426, 60452, 91517, 91518, 417 34, F01B 2526, F16D 3102
Patent
active
053056809
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a control device for hydraulic actuating cylinders of a loading tailgate of a vehicle.
BACKGROUND
A known control device, see for example German U 70 24 806, comprises a motor-driven hydraulic medium pump which can be connected via associated control valves to a medium reservoir and via pump branch lines to a chamber of a lifting cylinder and a locking cylinder of the loading tailgate. A pressure intensifier piston cylinder is connected in parallel to the pump branch lines.
According to an earlier proposal, see U.S. application Ser. No. 07/838,406, filed Mar. 3, 1992, by the inventor hereof, now U.S. Pat. No. 5,255,517, to which Austrian Patent No. 392,447 corresponds, an electric manometric or pressure switch by means of which the pump motor drive can be stopped when a predetermined pressure is exceeded, or an adjustable hydraulic valve by means of which the pump branch lines can be blocked or the pump line can be connected to a return line to the medium reservoir and possibly the pump motor drive can be stopped, is connected to the chamber of the smaller head end of the pressure intensifier piston cylinder connected to the locking cylinder.
By virtue of this device, the pump motor is stopped and/or the hydraulic medium supply line is blocked or unloaded in a constructionally simple manner before overload of the closing cylinder of the loading tailgate can occur.
According to an advantageous embodiment as disclosed in the earlier proposal, a counter for the number of cases where the pressure is exceeded can be activated by the electric manometric or pressure switch or by the adjustable hydraulic valve.
THE INVENTION
The object of this invention is an improvement of the system of the prior application, now U.S. Pat. No. 5,255,517, by means of which not only the number of cases of loading leading to stoppage or interruption can be determined, but also the level of the maximum overload of the closing cylinder which can occur when the loading tailgate is unduly further loaded after stoppage of the pump motor or interruption of the hydraulic medium line, possibly then leading to breakdown of the closing cylinder.
Briefly, in a control device of the type described above, an electric manometric switch connected to a meter and an interrupter switch for the connection to the electric pump motor and by means of which the pump motor can be stopped when a predetermined pressure is exceeded, is connected to the closing cylinder, and a manometer or pressure gauge having a maximum indicator which is not accessible from the outside and indicates a possible maximum overload of the loading tailgate after stoppage of the pump motor being connected to this manometric switch.
The invention allows for accurate indication of an inadmissable overload of the loading tailgate without the possibility of intervention on the part of the operator.
An alternative control device according to the invention has the features that an adjustable hydraulic shuttle or shut-off valve by means of which the pump branch lines can be blocked or the pump line can be connected to a return line to the medium reservoir and possibly the pump motor can be stopped, is connected to the chamber of the smaller head end of the pressure intensifier piston cylinder connected to the closing cylinder; in accordance with a feature of the invention, a manometer having a maximum indicator which is not accessible from the outside, indicating a possible maximum overload of the loading tailgate after activation of the adjustable hydraulic valve, is connected to the closing cylinder.
DRAWINGS
Embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which:
FIG. 1 is a hydraulic circuit diagram of a control device according to the invention, and
FIG. 2 is a hydraulic circuit diagram of an alternative embodiment.
DETAILED DESCRIPTION
According to FIG. 1, a hydraulic medium pump 1 is driven by an electric motor 2 and is connected to a hydraulic system via a
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Bertsch Richard A.
Nguyen Hoang
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