Power plants – Pressure fluid source and motor – Servo-motor having externally operated control valve sets...
Reexamination Certificate
2001-09-19
2003-06-03
Lopez, F. Daniel (Department: 3745)
Power plants
Pressure fluid source and motor
Servo-motor having externally operated control valve sets...
C254S361000, C242S390600
Reexamination Certificate
active
06571553
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention is based on a hydraulic control arrangement which is used to operate a winch in easing, hoisting and mooring modes and which has an adjustable hydraulic motor (
12
) to drive the winch (
10
), a proportionally adjustable directional control valve (
35
), spring-centered in a mid position, to control the flow paths of a pressure medium between a pressure medium source (
25
), the hydraulic motor (
12
) and a pressure medium supply container (
26
), a pilot controller (
65
) which is used to control the adjustment of the directional control valve (
35
) and of the hydraulic motor (
12
) and has a control lever (
81
) which can be actuated as desired and can be deflected from a neutral position in one direction over a specific easing angle range (
85
) for easing at different speeds and can be deflected in the opposite direction over a specific hoisting angle range (
86
) for hoisting at different speeds, during a deflection of the control lever (
81
) over the entire hoisting angle range (
86
), the directional control valve (
35
) being fully opened and the hydraulic motor (
12
) being adjusted to a minimum absorption volume.
A hydraulic control arrangement of this type is disclosed by the typesheet RD 65 050/03.96 from the applicant. In such a control arrangement, the winch is preferably driven by an adjustable hydraulic motor. Using a directional control valve which is pilot-controlled, proportionally adjustable and spring-centered in a mid position, the flow paths of a pressure medium are controlled between a pressure medium source, the hydraulic motor and a pressure medium storage container. To control the adjustment of the directional control valve and of the hydraulic motor, use is made of a pilot controller having a control lever which can be actuated as desired and can be deflected from a neutral position in one direction over a specific easing angle range for easing at different speeds, and can be deflected in the opposite direction over a specific hoisting angle range for hoisting at different speeds. In the process, two adjustments are involved in changing the speed of the winch. Firstly, during a deflection of the control lever, the directional control valve is opened further and further, so that the amount of pressure medium flowing to the hydraulic motor is increased further and further. Secondly, the absorption volume of the hydraulic motor is reduced. It is conceivable to change the opening cross section of the directional control valve and the absorption volume of the hydraulic motor in parallel with each other. In the prior art, however, provision is made that, up to a pilot control pressure of 18 bar, for example, only the hydraulically pilot-controlled directional control valve is adjusted and, in the range of a pilot control pressure from 20 to 30 bar, for example, only the adjustable hydraulic motor is adjusted.
In the mooring mode, the hawser is to be kept under a predefinable tension. This tension can be set by means of the absorption volume of the hydraulic motor. In the prior art, the control lever of the pilot controller is deflected from a neutral position counter to the force of a restoring spring in one direction for the hoisting mode of the winch and in the other direction for the easing mode of the winch. For the mooring mode, which is generally intended to be maintained over a relatively long time period without the control lever being held in a specific position by hand, a fixing brake is provided for the control lever in the known hydraulic control arrangement, said brake holding the control lever within the hoisting angle range, counter to the force of the restoring spring, in a position corresponding to a specific absorption volume of the hydraulic motor.
In the case of the known hydraulic control arrangement, in the hoisting mode, the variable to be set, namely the speed of the hawser, becomes greater as the deflection angle of the control lever increases. In the mooring mode, the variable to be set is the torque exerted by the hydraulic motor. This torque decreases with increasing deflection angle of the control lever, a behavior which contradicts the usual concepts of setting a variable via a control lever, and can therefore lead to wrong setting. Another drawback of the known hydraulic control is that the hoisting mode and mooring mode cannot be distinguished by using the position of the control lever.
SUMMARY OF THE INVENTION
The invention is based on the object of constructing a hydraulic control arrangement which has the introductory-mentioned features in such a way that a type of mooring mode corresponding to the usual concept is possible.
In a hydraulic control having the introductory-mentioned features, according to the invention, the intended object is achieved wherein, the control lever, as viewed from the neutral position, can be deflected over a mooring angle range on the other side of the hoisting angle range, wherein and, with increasing deflection of the control lever in the mooring angle range, the hydraulic motor is adjusted in the direction of a greater absorption volume. Therefore, with increasing deflection of the control lever, the torque that can be exerted by the hydraulic motor increases, which corresponds to the usual concept of a control system and reduces the probability of wrong control. In addition, the angle range in which the control lever is located for hoisting and the angle range for the mooring mode are separated from each other, so that a reference to a different mode of operation can already be taken from the position of the control lever.
Thus according to another feature of the invention, during an adjustment of the control lever from the hoisting angle range into the mooring angle range a considerable rise in torque is preferably detectable, so that it is clearly pointed out to the operator that he is leaving the hoisting angle range with the control lever and passing into the mooring angle range.
As already outlined, a winch is often operated in the mooring mode over a relatively long time period, for example during the period during which a ship is lying in a harbor. In order that a person does not have to hold the control lever fixed during this entire time, provision is expediently also made in a control arrangement according to the invention as in the known hydraulic control arrangement, for the control lever to be capable of being brought into a position for the mooring mode from which it does not automatically return into the neutral position. The possibility of leaving the control lever in a specific position provides a temptation to operate a winch contrary to the regulations. This is because a person can use the mooring mode to haul in the hawser by the person first moving the control lever into a specific position in the mooring angle range and then attempting to do something at the hawser or at the load. It is therefore beneficial if, in the mooring mode, the speed with which the hawser can be hauled in is limited to a small value. According to a feature of the invention, a hydraulic control arrangement according to the invention is equipped with a nozzle and a second directional control valve for such a speed limitation, it being possible for this second directional control valve, at the transition of the control lever from the hoisting angle range to the mooring angle range, to be changed over into a mooring position in which the nozzle is located in the flow path of the pressure medium leading via the hydraulic motor, with the effect of limiting the rotational speed of the hydraulic motor to small values. Such a limitation on the rotational speed of the hydraulic motor is primarily advantageous for the direction of rotation in which the hawser is wound up. If a hawser breaks, for example in the mooring mode, then winding up takes place only at the limited speed so that the loose cable does not thrash about wildly in the surrounding area and endanger personnel. In addition, in the case of the winch being operated contrary to the regul
Habermann Heinz
Kastel Wilhelm
Bosch Rexroth AG
Farber Martin A.
Lopez F. Daniel
LandOfFree
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