Hydropneumatic monitoring device

A hydropneumatic monitoring device in which a hydraulic fluid passageway is controlled by a piston and plunger spring biased in one direction and shiftable by air pressure in opposition to the bias for aligning a passageway-connecting bypass in the plunger with the passageway which is intersected by the plunger. Air pressure metered through the piston passes to an air passage. Air pressure failure or blockage in the air passage cause deviation of the piston and plunger from a state of open passageway equilibrium, for blocking the passageway.

BACKGROUND OF THE INVENTION 
In systems, such as for lubrication which in their operation utilize 
hydraulic fluid as well as air pressure, undesirable variations in air 
pressure are disruptive of proper functioning. The detection and control 
of disruptive air pressure or air flow rate has been difficult of 
attainment. 
By way of example lubrication systems where it is necessary at more or at 
less regular intervals to apply air pressure impulsed lubricant, 
especially lubricant in the form of an air spray, must avoid any prolonged 
malfunction which will starve the associated mechanism of relatively 
moving parts such as journals, bearings, gear boxes, and the like, in 
order to avoid overheating and breakdown. 
Numerous and varied detection ad signalling devices have been employed with 
more or less success, but there has been need for a compact, simple, 
reliable device for monitoring air pressure or air flow rate deviations 
from a predetermined or preset level, and especially in connection with 
lubrication systems, and which device will be readily adaptable to 
convenient location in the system, even though the system may have fault 
or malfunction signalling means elsewhere therein. 
SUMMARY OF THE PRESENT INVENTION 
An important object of the present invention is to provide a new and 
improved hydropneumatic monitoring device in which a hydraulic fluid 
supply line is effectively controlled by combination of air pressure flow 
rate differential and biasing means. 
Another object of the invention is to provide a new and improved monitoring 
device by which the flow rate of a gas can be monitored, with the 
occurrence of hydraulic blockage in a hydraulic flow line. 
Still another object of the invention is to provide a new and improved 
device especially useful in monitoring hydropneumatic lubricating systems. 
Pursuant to the principles of the present invention, there is provided in a 
hydropneumatic monitoring device means providing a body having therein an 
air passage leading therefrom, a hydraulic fluid passageway extending 
through the body and adapted to be connected at one end to a hydraulic 
fluid supply means and adapted to be connected at its opposite end to a 
point of use, an elongate plunger bore in the body traversing the 
passageway and having at one end a piston cylinder which communicates at 
its inner end with said air passage and is adapted to receive air under 
pressure at its outer end, a control plunger shiftably reciprocatable in 
the bore and having an outer end in the cylinder and having 
passageway-connecting means intermediate its length, a reciprocatable 
piston in the cylinder shorter than the cylinder and operatively 
associated with the outer end of the plunger, means for biasing the 
plunger with predetermined force longitudinally toward the outer ends and 
for thereby locating the passageway-connecting means out of alignment with 
the passageway, and means for metering the air under pressure through the 
piston to the passage and for effecting a predetermined air flow rate 
differential on opposite sides of the piston for limited driving of the 
piston in opposition to said biasing means and for thereby shifting the 
plunger for opening the passageway by aligning the passageway-connecting 
means with the passageway, the biasing means being set to cooperate with 
the air flow rate differential to maintain the piston and plunger in 
substantially a state of open passageway equilibrium.

DETAILED DESCRIPTION 
A hydropneumatic monitoring device 10 (FIG. 1) is especially adapted for 
monitoring increase or decrease from a preset or predetermined level in 
air flow rate, i.e. air pressure in a dynamic system. Although the device 
10 may be utilized in various hydropneumatic systems where the flow rate 
of a gas may be monitored, an important utility is found in lubricating 
systems wherein the lubricant is sprayed from air nozzles and where 
monitoring of the air flow rate through the nozzles is desired. Although 
the device 10 may be mounted at different locations in a system, it is 
well suited for close association with a spray nozzle assembly 11 which 
may, for example, be mounted on or in connection with a point of lubricant 
use such as a gear box 12 into which an air generated spray 13 is adapted 
to be directed for lubrication of moving parts therein. The gear box may 
have pressure relief valve means 14 and also pressure switch means 14a for 
signalling in any well known manner loss of air pressure within the 
environment in the gear box 12. 
Means for supplying air under predetermined pressure to the device 10 
includes a duct 15. While the term "air" is used herein because most 
usages of the device may involve air, any preferred gas may be utilized 
and should be considered equivalent, i.e. air in a generic sense. 
Means for delivering hydraulic fluid, i.e. lubricant, to the device 10 
includes a delivery line 17 leading from a hydraulic fluid pressure 
responsive device 18 through which the hydraulic fluid is directed from 
source by way of a main line 19. In this instance the pressure sensitive 
device 18 controls a reciprocatable indicator pin 20 which is adapted to 
be projected for actuating a switch 21 connected with any preferred form 
of signal means. 
In a simple and efficient construction, the device 10 comprises means such 
as a block providing a body 22 (FIGS. 1-4). As shown, the body 22 has an 
air passage 23 leading therefrom. A hydraulic fluid passageway 24 extends 
through the body 22. In this instance, the air spray nozzle means or 
assembly 11 is attached to the body 22 and has both the air passage 23 and 
the hydraulic fluid or lubricant passageway 24 appropriately connected 
thereto. 
By way of example, the spray nozzle assembly 11 may be of a more or less 
conventional form having a member 25 provided with a stem 27 threaded into 
the body 22 for communication of the lubricant passageway with a chamber 
28 from which a duct 29 controlled by a spring biased check valve 30 leads 
to an orifice 31 having a terminal nozzle discharging into a spray head or 
tip 32. The air passage 23 communicates by way of an annular distributor 
groove 33 into a plurality of air ducts 34 which lead to an annularly 
eductor orifice 35 cooperating with the lubricant orifice 31 for 
generation of lubricant spray through spray orifice 37 in the nozzle tip 
32. 
An elongate plunger bore 38 in the body 22 traverses the lubricant 
passageway 24 and has at one end a piston chamber or cylinder 39 from 
which the air passage 23 extends. In this instance the cylinder 39 is of 
substantially greater diameter than the bore 38 and the air passage 23 
extends tangentially from the inner end of the cylinder. A control plunger 
40 shorter than the bore 38 is shiftably reciprocatable in the bore and 
has its outer end in the cylinder 39. A piston 41 in the cylinder 39 is 
shorter than the cylinder and is operatively associated with the adjacent 
end of the plunger which extends from the bore 38 into the cylinder 39. In 
a preferred form the piston 40 comprises an annulus fixedly secured to the 
associated end of the plunger and having an annular peripheral groove 42 
carrying a ring lip seal 43 for assuring efficient, substantially leak 
free retention of air pressure at the head or outer end of the piston 40 
which is exposed to air pressure supply means delivering through an inlet 
port 44 into the outer end of the cylinder. In a desirable form, the port 
44 extends through a nipple 45 removably threaded into the body 22 at the 
outer end of the cylinder 39 and of a large diameter to provide an access 
opening large enough for assembling the piston 40 into the cylinder. The 
air supply line 15 is secured in connection with the port 44 and nipple 45 
in usual fashion. 
Means are provided comprising an expansion spring 45 for biasing the 
plunger 40 in one longitudinal direction toward closing the passageway 24, 
wherein a cylindrical area of the plunger 40 extends in blocking relation 
across the passageway as best seen in FIGS. 2 and 3. In a preferred form, 
the spring 45 comprises an elongated coiled cylindrical expansion spring 
seated at one end on shoulder means comprising a washer disk seat 47 
thrusting against a threaded internal adjusting nut 48 which is received 
in an outer end threaded section 49 of the bore 38 and is accessible for 
adjusting the tension of the spring 45 as desired. A threaded, removable 
closure plug 50 normally protectively closes the adjacent threaded 
terminal end of the bore. In the passive condition of the assembly, the 
piston is biased against the stop shoulder provided by the inner end of 
the nipple 45. 
From its adjustable abutment seat end, the spring 45 extends into and 
through a hollow bore 51 in the hollow tubular plunger 40. Within the 
plunger 40, and adjacent to the piston 41, the biasing spring 45 thrusts 
against a shoulder 52 provided by means of a nipple or orifice plug 53 
secured into the outer end of the bore 51 in the plunger 40. 
Air pressure supplied through the port 44 is delivered to the outer end of 
the cylinder 39 and acts on the piston 41 in opposition to the biasing 
spring 45 for shifting the plunger 40 into a position wherein 
passageway-connecting means comprising an annular external control of 
bypass groove 54 intermediate the length of the plunger 40 registers with 
the passageway 24 for connecting the chamber 28 at one end of the 
passageway 24 with inlet port 55 at the opposite end of the passageway and 
to which the supply line 17 is connected. 
In order to assure that the passageway 24 will only be opened by 
registration of the control groove 54 in the plunger 40 with the 
passageway 24 when air pressure conditions are as desired in the system 
with which the device 10 is associated, means are provided for metering 
the air under pressure through the piston 41 to the air passage 23 and for 
effecting a predetermined air flow rate differential on opposite sides of 
the piston for driving the piston in opposition to the biasing means 
spring 45 for shifting the plunger into the passageway opening position. 
To this end, the nipple 53 at the head or outer end of the piston 41 has a 
metering orifice 57 of predetermined size through which air under pressure 
from the outer side or end of the piston is metered to the inner or back 
side or end of piston and more particularly the rear portion of the 
cylinder chamber 39 to which the metered air passes by way of ports 58 
opening through the wall of the hollow plunger tube adjacent to the 
piston. Thence, the metered air flows to and through the air passage 23. 
The arrangement is such that when the air flow rate through the metering 
orifice 57 is corelated with the compression imparted to the biasing 
spring 45 by the adjusting nut 48, and the location of the plunger control 
groove 54, having regard to the air pressure supplied, an equilibrium 
condition can be attained wherein the control groove 54 registers with the 
passageway 24. Small changes in inlet air pressure and consequent flow 
rates can be attained by adjusting the spring compression by means of the 
nut 48. Larger changes can be attained by changing the size of the orifice 
57. 
Any significant deviation from the equilibrium condition such as may be 
caused by a malfunction or failure in the air supply or air passage, will 
cause the plunger 40 to be shifted from or fail to attain the passageway 
connecting or opening position. That is, if the air pressure is too great 
at the entry port end of the cylinder 39, or there is a leak or break or 
other undesirable drop in pressure in or related to the air passage 23, 
the piston 41 and the plunger 40 will be caused to override the biasing 
spring 45 to the extent of causing the control groove 54 of the plunger to 
override the passageway 24 and the plunger blocks the passageway. Should 
there be an air pressure failure in the supply line or a blockage in 
respect to the air passage 23, the piston 41 will not be moved from its 
fully spring biased position and the passageway 24 will remain blocked. 
In the slightly modified form of the invention as depicted in FIGS. 5-8, 
the hydrodynamic monitoring device 10' is much the same as the device 10 
except that the body 22', the bore 38', the plunger 40' and the biasing 
spring 45' may be somewhat longer to accommodate a more spaced apart 
orientation of the air passage 23' and the hydraulic fluid passageway 24'. 
As shown in FIG. 6 the chamber 28' to which the passageway 24' leads is 
adapted to communicate with a duct 59 instead of directly with a spray 
nozzle. Also the air passage 23' instead of communicating directly with a 
spray nozzle communicates with a duct 60 connected by way of a nipple 61 
in an outlet 62 with the air passage 23' leading off from the inner end of 
the piston chamber 39'. In other respect the device 10' is substantially 
the same as the device 10, and the description of structure by way of 
primed reference characters and function will be understood to be the same 
and should be so understood. 
For illustrative purposes the device 10' has been selected for 
demonstration in greater particular of certain performance characteristics 
common to both of the devices 10 and 10' and it should be understood that 
the following description of a typical example applies with equal effect 
to both forms of the device. Air from the pressure regulated source may be 
supplied to the inlet air port 44' at 30 psi. This pressure acts on the 
head area of the pneumatic piston 41' which may be 0.625 inch in diameter 
so that about 9.2 lbs of force are developed on the head end of the 
piston. The air travels from the piston head side of the piston chamber 
39' and is metered through the orifice 57', which may of 0.030 inch 
diameter, at the rate of 0.9 scfm and arrives at the inner or back side of 
the piston chamber 39' at 15 psig, which is common to the normal operating 
pressure in the passage 23'. This pressure acting on the back side of the 
pneumatic piston develops at 4.6 lb force in an opposite direction from 
the initial 9.2 lbs force. the net force of 4.6 lbs acting on the 
pneumatic piston 41' is transmitted along the longitudinal axis of the 
piston and the plunger 40' and compresses the spring 45'. The force of the 
spring 45' is adjustable by means of the adjustment screw 48' which serves 
to further compress or to relax the spring from a given setting. The rate 
of the spring 45' may be selected such that when the piston 41' has 
travelled 0.178 inch the spring develops 4.6 lbs opposing force and holds 
the piston in equilibrium. The equilibrium position of the piston is where 
the connecting channel or groove 54' is aligned with the passageway 24', 
allowing hydraulic fluid to flow through the passageway. 
The central bore 51' vents the chamber area at the inner end of the plunger 
40' to the 15 psi prevailing under normal operating conditions in the 
piston chamber 39' back of the piston 41'. This aids in balancing the 
differential areas with respect to the front and back sides of the piston 
41' and allows lubricating hydraulic fluid to leak through the sliding 
tolerance between the bore 38' and the plunger 40' and to be carried out 
in the air stream through the air passage 23'. This arrangement is also 
advantageous in that any need for sealing means along the plunger 40' is 
avoided, and eliminates frictional forces whereby operation of the 
monitoring device is more reliable and consistent. 
The various adjustments may be made to provide for a reasonable operating 
tolerance range such, for example, as about 10% from the equilibrium 
position involving either increase or decrease in air pressure without 
blocking the hydraulic fluid passageway. Should there be a greater than 
the 10% deviation caused, for example by loss in pressure in the passage 
23' or blockage of the air outlet line, the pressure differential at the 
piston 41' is disrupted. For example, if there is a blockage in or 
affecting the air passage 23', the biasing force of the spring 45' will 
override the air source pressure and cause shifting of the plunger 41' 
toward the right as veiwed in FIG. 5, whereby the passageway-connecting 
groove 54' will be shifted from the dashed position to the full line 
position and the passageway 24' will be blocked. This same situation will 
occur, of course, should the air source pressure drop to an undesirable 
level. 
On the other hand, should a break or serious leak occur in respect to the 
air passage 23', the pressure on the backside of the piston 41' may drop 
sufficiently or altogether below the equilibrium force so that the 
pressure on the outer side of the piston 41' will overcome resistance of 
the spring 45' and cause shifting of the plunger 40' from the flow-through 
alignment position of the bypass groove 54' as shown in FIG. 7 to the 
passageway blocking position shown in FIG. 8. 
In setting up or adjusting the device 10 or 10' for operation, and more 
particularly effecting adjustments for desired operation of the air 
pressure actuated hydraulic fluid passageway controlling plunger 40, 40' 
inspection access enabling direct visual observation of the plunger and 
more particularly the passageway-connecting groove 54, 54' is adapted to 
be effected through the hydraulic fluid inlet 55, 55'. The arrangement, as 
best observed in FIGS. 3 and 6, is such that the hydraulic fluid inlet may 
be exposed for inspection by removing a connector nipple 65, 65' from the 
inlet. At its inner end, the inlet 55' is located relatively close to the 
bore 38, 38' so that visualization of the plunger 40, 40' may be readily 
seen through the short adjacent section of the passageway 24, 24'. 
Operation of the plunger 40, 40', and more particularly with respect to 
the connecting groove 54, 54', is readily observable through the open 
inlet 55, 55' while air pressure is applied to the piston 41, 41', and 
various adjustments are effected such as in the air pressure applied, and 
the compression loading of the spring 45, 45' by means of the adjustment 
screw 48, 48', and the like. This greatly facilitates attaining optimum 
operating results from the device 10, 10'. 
It will be understood that variations and modifications may be effected 
without departing from the spirit and scope of the novel concepts of this 
invention.