Power plants – Pressure fluid source and motor – Condition responsive control of or by input to input pump...
Patent
1992-03-03
1993-10-26
Look, Edward K.
Power plants
Pressure fluid source and motor
Condition responsive control of or by input to input pump...
60426, 91515, 91532, F16D 3102
Patent
active
052555178
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a control device for hydraulic operating cylinders of a platform to be used with vehicles which can be raised and lowered, to place loads on the platform and, by then rotating the platform about an axis close to one end of the platform, forming a closing wall, and more particularly to such a device which operates reliably even if the load on the platform is located off center, or is excessive.
BACKGROUND
It is known to provide a motor-driven hydraulic fluid pump which can be made to communicate with the fluid supply and, via pump branch lines beginning at a pump line, with a chamber of at least one lifting cylinder and of at least one closing cylinder, which rotates the lifting platform and closing wall combination, respectively, via associated control valves. A pressure transformer and piston cylinder unit is connected across the pump branch lines.
In previously known control devices of this type, a problem has arisen in practice that, if the load is not positioned on the combination lifting platform and closing wall in accordance with regulations, or directions of use, for example being off-center or an overload, tilting torques may arise which translate into increased tensile and compressive forces in the lifting arms and in the closing cylinders of the combination platform and closing wall. For example, the allowable forces may be exceeded by up to a factor of 5, which can damage or destroy the lifting arms and/or the closing cylinders.
THE INVENTION
It is an object of the invention to provide a device which, in case of unbalanced placement of loads, averts the dangers discussed above.
Briefly, a pressure-responsive element, such as an electrical switch, is provided which shuts down the pump drive motor in case an overload is sensed. The pressure-responsive device is coupled to the smaller one of the cylinder-piston chambers of the pressure transducer, which provides for a simple connection. Alternatively, the pressure sensing device may be a hydraulic pressure sensor, sensing the pressure in the smaller one of the piston-cylinder chambers of the pressure transducer. The action of this pressure sensor is such that the branch lines can be blocked off, or the pump line, providing a main hydraulic supply, is hydraulically coupled to a return line to the fluid supply; optionally, the pump motor can also be shut down, under hydraulic over-pressure.
As a result, in a structurally simple manner, the pump motor is shut down and/or the hydraulic fluid feed line is blocked before an overload or unbalance may cause damage, for example to the components to the lifting platform and closing wall such as the lifting arms and closing cylinders.
In accordance with a preferred feature of the invention, a counter mechanism for counting the number of times that pressure is exceeded can be activated by the pressure sensor, either by the electric pressure switch, or by the adjustable hydraulic pressure sensor which, in a simple form, is an adjustable hydraulic valve.
DRAWINGS
The invention is described in further detail below in terms of exemplary embodiments, referring to the drawings, in which:
FIG. 1 shows a hydraulic circuit diagram of a control device according to the invention; and
FIG. 2 is a circuit diagram of an alternative embodiment.
DETAILED DESCRIPTION
According to FIG. 1, a hydraulic fluid pump 1 is driven by an electric motor 2 and communicates via a line 3 with a hydraulic fluid supply 4. The pump 1 also communicates to a hydraulic system via a pump line 5, which includes a check valve 6, with a fluid return line 7 and with a line 8 that branches into branch lines 8', 8". The left-hand branch 8' in FIG. 1, via a controllable lifting valve 9 and two controllable lifting cylinder valves 10, feeds two lifting cylinders 11 of the lifting platform and closing wall, which is not shown.
Analogously, the right-hand branch line 8" in FIG. 1, via a controllable closing valve 12 and two controllable closing cylinder valves 13, feeds two closing cylind
REFERENCES:
patent: 2229561 (1941-01-01), Galanot
patent: 2326594 (1943-08-01), Wood
patent: 2611246 (1952-09-01), Ackerman
patent: 2892312 (1959-06-01), Allen et al.
patent: 3727520 (1973-04-01), McKown et al.
patent: 3811458 (1974-05-01), Kuhnelt
patent: 3868062 (1975-02-01), Cunningham et al.
patent: 4192337 (1980-03-01), Alderson et al.
patent: 4505111 (1985-03-01), Okamoto et al.
patent: 4617854 (1986-10-01), Kropp
Look Edward K.
Nguyen Hoang
LandOfFree
Control device for hydraulic operating cylinders of a combined l does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control device for hydraulic operating cylinders of a combined l, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control device for hydraulic operating cylinders of a combined l will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-951023