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Multiple cylinder cycle
In previous sections, we analyzed EM devices and possible circuit solutions.
In the following paragraphs, we address the required safety conditions for the cycle below:
A + / B +C – / A – / B – / C +
1
2
3
4
5
The letters correspond to the cylinders and their movement through the various Phases.
Figure 23
Phase 1:
stroke
A +
The safety condition required to execute this stroke; the piston rod/piston of cylinder
C
must have completed the
positive stroke.
Line 1:
in order to energize solenoid
B1
of the solenoid valve, the contact of limit switch
c1
must be closed,
contact
x
must be closed and at least one of the two buttons
P1
or
P2
must be activated.
By energizing
B1
, the solenoid valve changes over and the piston rod/piston of cylinder
A
completes the positive
stroke.
An eventual activation of the manual device on solenoid
B3
(solenoid valve of cylinder
B
), modifying the condition
required of contact
x
, does not allow, even with the activation of buttons
P1
or
P2
, to start the cycle.
The equation for this motion is:
(P1+P2) * c1 * b1 =
A +
Phase 2:
stroke
B + C –
As the piston rod/piston of cylinder
A
initiates its movement, buttons
P1
and
P2
can be released.
Line 2:
when the positive end position has been reached and limit switch
a1
activated, solenoids
B3
and
B6
are
energized, their respective solenoid valves change over permitting the
B +
and
C –
strokes.
The equation for this motion is:
a1 =
B + C –
The safety condition required to proceed to the next step; the piston rod/piston of cylinders
B
and
C
must have
completed the stroke.
Phase 3:
stroke
A –
Line 3:
the closing of contacts
x1
and
y
, connected in series and both
NO
, ensures that the piston rod/piston of
cylinders
B
and
C
reached their positions in the previous phase.
Solenoid
B2
is energized to effectuate the return of the piston rod/piston of cylinder
A
.
The energizing of solenoid
B1
, opposite to
B2
is interrupted as both limit switch
c1
and contact
x
have inverted
their state.
The equation for this motion is:
b1 * c0 =
A –
The safety condition required to proceed to the next step; the piston rod/piston of cylinder
A
must have completed
the stroke.
Phase 4:
stroke
B –
Line 4:
the closing of contact
a0
ensures that cylinder
A
reached its position in the previous phase. Solenoid
B4
of the solenoid valve is energized, it changes over and the piston rod/piston of cylinder
B
returns. This operation is
possible due to the absence of a signal to solenoid
B3
, as limit switch
a1
is interrupted. The relevant equation is:
a0 =
B –
The safety condition required to proceed to the next step; the piston rod/piston of cylinder
B
must have completed
the stroke.
Phase 5:
stroke
C +
Line 5:
the closing of contact
b0
ensures that the piston rod/piston of cylinder
B
reached its position in the previous
phase. Solenoid
B5
of the valve is energized, with the changing over of the solenoid valve, the piston rod/piston of
cylinder
C
completes the positive stroke. This operation is possible due to the absence of a signal to solenoid
B6
,
as limit switch
a1
is interrupted.
6
210
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