Pumping Engine
In “Reciprocating Pumps” one could
find a general schema and a few variants of a particular type of pumps based on
it. For convenience, a few passages from “Reciprocating Pumps” are repeated
here.
Here, a special variant of a pump
of this type is presented, the pump, which is driven by a built-in internal
combustion engine.
Following is a general schema of a Pump:
PL RL PB RR PR
AL CL B CR AR
It is a large tube divided by 4 walls into 5 compartments, from
left to right:
AL,
CL, B, CR and AR
It contains one movable part – a piston-rod assembly, consisting
of 3 pistons
PL,
PB and PR
connected with two “rods”:
RL
and RR
“Rods” could be implemented as
tubes to better resist bending forces on them, when they are under pressure.
Walls between chambers have tight
openings for “rods”. They also help resisting bending forces, when “rods” are
under compression.
A chamber B operates as a double
acting pump.
Chambers AL and AR
are a part of the engine. Only a part of these chambers without a “rod” in it
is used to burn fuel, as it is in other internal combustion engines.
Note that when valves of the
chamber B are closed, the piston-rod assembly cannot move. This is used to
control working of the engine.
Chambers CL and CR
have opening, trough which a “hand” connected to the “rod” is extended outside
the main tube. These two “hands” reach to a Valve Control Box and this allows
synchronization between opening/closing of valves and position of the movable
piston-rod assembly.
In the pump driven by internal
combustion, the same Valve Control Box contains controls for injection of fuel,
controls allowing exit of exhaust, and controls for injection of compressed
air.
Note that one joint Valve Control Box
could synchronize operations of two or even more such pumps. For example, piston-rod
assemblies of different pumps could move in opposite directions and this should
minimize vibration caused by pumps operations.
We prevent hydraulic
shocks in the system through smooth and slow opening and closing of valves
controlled in the Valve Control Box.
Most likely, we would want chambers
of different diameters. This could be done because pistons are confined to
their respective chambers. The shape of chambers CL and CR
should be defined only by demands of structural soundness of the pump during
operations.
Obviously, in such case,
we would not be able to use one tube to house all assembly, but would need to
combine the pump from a few components of different diameters. They could be
welded or joined some other way.
To minimize leaks of gasses and
facilitate lubrication of “rods”, additional narrow chambers should be “carved
out” from chambers CL and CR next to walls of adjacent
chambers AL and AR. These chambers should be filled with
lubricant.
An unusual feature of
this design of the internal combustion engine is addition of a compressor.
Usually, air is compressed by the pistons of the engine itself. Here, a
separate air compressor is used. Compressed air is injected into the chamber of
the engine twice, first to facilitate fuller evacuation of contents of the
chamber after burning and after that second time to fill the chamber with
compressed air for burning on the next step of operations.
Hence, three tanks need to be used
together with the compressor. A large tank simply accumulates compressed air
and facilitates maintaining the same level of air pressure. Two small tanks
hold exact amount of compressed air needed on each cycle of the engine’s
operation. They are filled from the large tank before exhaust has to be expelled;
air from the first tank is used to facilitate evacuation of products of
combustion and the second one to fill the chamber with fresh air for burning.
Note that a most likely use of such
engine is to pump fluid of hydraulic transmission. In such case, it is natural
to have a compressor driven by the same hydraulic transmission. It could be a
compressor for general use, as long it provides air compressed to required
level, or it could be a dedicated compressor.
We start with the state, where
burning of fuel in the left chamber AL pushed piston-rod assembly
right to its limit. The limit is defined by the Valve Control, which is aware
of the position of piston-rod assembly via “hands” extending from the CL
and CR chambers. Exhaust valve in the chamber AR is still
open, as it has been during this movement from left to right, and products of
the combustion in the chamber were mostly expelled.
From this point, the system goes
through following steps preparing chamber AR
1.
Movement of piston-rod assembly is blocked; it is
held still by closed valves controlling movement in the chamber B
2.
Air from the first small tank is used to expel
remnants of products of combustion; after that first small tank is refilled
with compressed air
3.
Exhaust valve is closed and compressed air from the
second small tank fills the chamber; after that second small tank is refilled
with air
4.
Piston-rod released and measured amount of fuel is
injected in the chamber; it is ignited spontaneously or via a spark
This starts movement of piston-rod
assembly from right to left, which expels exhaust from the chamber AL
and pumps fluid in the chamber B. When this movement is complete, the system in
the situation described above, only chambers AL and AR
are flipped. The system goes through similar steps.
It is natural to use a
special pump to inject fuel into the chamber. When the engine is pumping fluid
of a hydraulic transmission, this pump could be driven by the same hydraulic
transmission. Measures should be taken though, that amount of injected fuel is
controllable.
Compressed air could be used to
cool entire Engine. After that, it could be mixed with exhaust and burn in
Afterburner. Gasses after Afterburner should exchange heat with going into the
combustion chamber air and fuel.
Alexander Liss 7/24/2019