Pumps – Motor driven – Relatively movable pumping members driven by relatively...
Patent
1991-11-27
1993-08-24
Bertsch, Richard A.
Pumps
Motor driven
Relatively movable pumping members driven by relatively...
417390, 417900, F04B 3500
Patent
active
052383717
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a control arrangement for a two-cylinder pump for thick materials with at least one hydropump whose delivery volume is adjustable by means of a setpoint signal, with two delivery cylinders which communicate with a material dispenser container and which can be actuated in push-pull operation by means of drive cylinders that are controlled by the hydropump, with a baffle arrangement for the material flow, which alternately connects the delivery cylinders to the material dispenser container and to a delivery line, and which is preferably designed as a shunt pipe and can be actuated by means of a reversing mechanism, and with one sampling device which responds to the end of each pressure stroke of the drive cylinder, and/or delivery cylinder and at whose output an end-position signal which initiates a reversal process for the baffle arrangement is adapted to be tapped off, and with a switching element, which is connected on the output side to a delivery-volume regulator of the hydropump and which features a control input that receives the end-position signals or the control signals derived from the end-position signals by means of signal conversion, as well as at least two switch positions which are adjustable by means of the signal level at the control input for the forced tripping of various setpoint signals to the delivery-volume regulator.
A known control arrangement of this type (DE-A-3 243 738) provides for a switching element that is connected on the output side to the delivery-volume regulator of the hydropump. After the stroke direction is reversed in the drive and delivery cylinders, this switching element trips the hydropump by force to the maximum delivery quantity. In this manner, the delivery gap that develops when the shunt pipe is reversed is supposedly filled in, and one supposedly attains a substantially uniform flow of delivered material at the end of the delivery line. In the case of the known arrangement, it is considered disadvantageous that the reversal of the tube switch is initiated simultaneously with the stroke reversal in the delivery cylinders by means of a reversing mechanism which is capable of being actuated independently by the hydropump. For this, an additional hydraulic pump is required. A similar arrangement had also already been proposed by the unpublished, older priority document WO 89/11037.
Starting from here, the object of the invention is to create a control arrangement for two-cylinder pumps for thick materials, with which the delivery volume of the hydropump can be optimally adapted in a one-way flow configuration to the prevailing requirements in the course of a delivery and reversal cycle.
The inventive solution begins with the realization that during the time the baffle arrangement is reversed, a quantity of oil is required that is dependent upon the quantity of oil for the delivery stroke. For one-way flow configurations, there is therefore a need to adjust the delivery volume of the hydropump to the specific operating condition. To achieve this, the invention proposes that the drive cylinders and the hydraulic reversing mechanism of the baffle arrangement be able to be actuated alternately by means of a servo control with pressure oil from the same hydropump, and that during the stroke phase of the drive cylinders and during the reversal process of the reversing mechanism, the delivery-volume regulator of the hydropump be able to receive setpoint signals, which are independent of one another. The stroke reversal in the drive cylinders is thereby advantageously initiated by means of a primary detector which can be actuated at the end of each reversal process of the baffle arrangement. A preferred refinement of the invention provides that in accordance with the switch position of the switching element, the setpoint values can show a selectable, functional dependence on the operating parameters of the two-cylinder pump for thick materials, in particular, of the hydropump. For example, the setpoint signals can be varied in dependence upon a
REFERENCES:
patent: 4666374 (1987-05-01), Nelson
patent: 4790728 (1988-12-01), Dwyer
patent: 5066203 (1991-11-01), Coja et al.
Bertsch Richard A.
Freay Charles G.
Putzmeister-Werk Maschinenfabrik GmbH
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