[0001] The present invention concerns a concrete pump comprising means to modulate the speed
of the piston stroke into the pumping cylinders, said means being electronically controlled
according to the maximum concrete capacity allowed by the pump.
[0002] The object of the invention is to improve the characteristic of the concrete capacity
fed into the concrete transport and delivery duct, at the different working speeds
of the pumping unit.
[0003] There are known to be concrete pumps which comprise a pumping unit, fed from a hopper,
and a transport and delivery duct to distribute the concrete on the working site.
Generally, the pumping unit consists of a pair of concrete pumping cylinders, alternatively
operated by a pair of hydraulic cylinders, and of a special rocking valve (S-valve)
which connects the concrete transport and delivery duct to one of the two pumping
cylinders, while the other cylinder draws concrete from the hopper. The rocking S-valve
is alternatively moved by a second pair of hydraulic cylinders. By combining the movement
of the S-valve with the movement of the pumping cylinders, the concrete flow is generated
through the transport and delivery duct. Said concrete flow is apt to move through
the duct in the two directions; the concrete is actually pumped when the flow is directed
from the pumping unit towards the outlet end of the duct, so as to be delivered, while
it is drawn when the flow is directed in the opposite sense. The two types of operations
are obtained by suitably combining the movement of the pumping cylinders with the
position of the S-valve.
[0004] This type of known pumps leads to cracks in the material drawn from the hopper, in
the filling step of the pumping cylinders, thus involving discontinuities in the capacity
of the concrete subsequently pumped into the transport and delivery duct.
[0005] The present invention proposes to overcome this drawback - highly unpleasant, for
obvious reasons - by providing to modulate the speed at which the pistons of the pumping
cylinders move into said cylinders by way of electronic control means.
[0006] More precisely, the present invention concerns a concrete pump - of the type comprising
a pair of pumping cylinders alternatively operating under the control of a backflow
hydraulic pump, to draw concrete from a hopper and feed it by way of a rocking valve
(S-valve) into the transport and delivery duct, and wherein said cylinders are provided
with stops to control the starting movement of the S-valve - characterized in that
the speed of the piston stroke of said cylinders is modulated by being increased in
the initial length of said stroke, and in that electronic means are provided to control
said speed according to the maximum concrete capacity allowed by the pump.
[0007] In this pump, said electronic means preferably comprise a microprocessor unit, which
receives the signals issued by said stops, detects and reckons the number of pumping
cycles per minute, reckons the pump operating time with maximum capacity, and controls
the movement of the S-valve and the reversal of the backflow hydraulic pump.
[0008] The invention is now described in further detail, with reference to the accompanying
drawings, which illustrate a preferred embodiment thereof and in which:
Fig. 1 is a general diagram of a concrete pump comprising the means according to the
invention; and
Fig. 2 diagrammatically illustrates how the means according to the invention are applied
onto a pump as shown in fig. 1.
[0009] As shown on the drawings, a concrete pumping plant essentially comprises a pumping
unit 1 fed from a hopper 2, and a transport and delivery duct (not shown) to distribute
the concrete on the working site. The pumping unit 1 consists of a pair of concrete
pumping cylinders 3 alternatively operated by a pair of hydraulic cylinders 4 controlled
in the two directions by a backflow hydraulic pump 5 operated by a prime mover 6,
and of a rocking S-valve 7 which connects the concrete transport and delivery duct
to one of the two pumping cylinders 3, while the other cylinder draws concrete from
the hopper 2. The S-valve 7 is alternatively moved by a second pair of hydraulic cylinders
8, fed by a hydraulic circuit with accumulator 9 and controlled by a set of solenoid
valves 10. By combining the movement of the S-valve 7 with the movement of the pumping
cylinders 3, a concrete flow is generated (the concrete being either pumped, or drawn)
and moves, in a practically continuous but irregular manner, through the concrete
transport and delivery duct.
[0010] According to the invention, the backflow hydraulic pump 5 - which controls the hydraulic
cylinders 4 - and the S-valve 7 are operated by a microprocessor unit 11, into which
are set the working cycles by a panel 12 and which receives signals issued by stops
13 of the pumping cylinders 3, and by a sensor 14 detecting the number of cycles of
the pump 5. The microprocessor unit 11 controls the speed of the piston strokes of
the pumping cylinders 3 according to the maximum concrete capacity allowed by the
pump 5, increasing said speed in the initial length of the stroke, so as to promptly
remove the cracks produced in the concrete drawn from the hopper 2, when filling said
cylinders 3, to the full advantage of a homogeneous and continuous concrete delivery
from the respective duct.
[0011] This allows to obtain curves to modulate the speed of the piston strokes, apt to
improve the pumping performances according to the operating conditions and to the
concrete characteristics, particularly its consistency.
[0012] The concrete pumping plant is controlled by the microprocessor unit 11 according
to the following flow diagram:
which perfectly synthesizes the sequence of the operating steps.
[0013] It is anyhow understood that the invention is not limited to the embodiment described
heretofore, but other practical embodiments may fall within the protection scope thereof.
1. Concrete pump, of the type comprising a pair of pumping cylinders alternatively operating
under the control of a backflow hydraulic pump - to draw concrete from a hopper and
feed it, by way of a rocking valve (S-valve), into the transport and delivery duct
- wherein said cylinders are provided with stops to control the starting movement
of the S-valve, characterized in that the speed of the piston stroke of said cylinders
is modulated by being increased in the initial length of said stroke, and in that
electronic means are provided to control said speed according to the maximum concrete
capacity allowed by the pump.
2. Concrete pump as in claim 1), wherein said electronic means comprise a microprocessor
unit, which receives the signals issued by said stops, detects and reckons the number
of pumping cycles per minute, reckons the pump operating time with maximum capacity,
and controls the movement of the S-valve and the reversal of the backflow hydraulic
pump.
