EP0779414B1

EP0779414B1 - Device for automatically topping-up a container with liquid

Info

Publication number: EP0779414B1
Application number: EP96119798A
Authority: EP
Inventors: Mauro Chicarella; Antonio Lucco
Original assignee: Irisbus Italia SpA
Current assignee: Irisbus Italia SpA
Priority date: 1995-12-12
Filing date: 1996-12-10
Publication date: 2001-05-16
Anticipated expiration: 2016-12-10
Also published as: DE69612821T2; ITTO950993A0; ES2157391T3; DE69612821D1; ITTO950993A1; IT1281064B1; EP0779414A1

Description

The present invention relates to a device for automatically topping-up a container with liquid, in particular for topping-up with lubricating oil the sump of a heat engine of a commercial vehicle. The following description will refer explicitly to this application without resorting to unnecessary generalities.
The known devices (see, for example EP-A-0 538 660) essentially comprise a pump provided with a pneumatically operated piston having an inlet orifice connected via an intake duct to an oil reservoir and an outlet orifice connected via a delivery duct to the sump. Devices of this type also comprise a cylindrical sensor connected to the pump and disposed inside the sump with its axis parallel to the surface of the oil and so as to be fully submerged in the oil itself when the latter reaches a predetermined level. In particular, the sensor comprises a blind cylinder defining a cylindrical chamber and having a plurality of openings communicating with the interior of the sump, and a piston sliding in a sealed manner in the chamber itself. Moreover, the pistons of the pump and of the sensor are securely connected by a single actuating rod mounted to slide in a sealed manner in a through-hole provided in the side wall of the sump.
The sensor piston is prevented from sliding if the chamber defined by the blind cylinder is completely filled with oil (which cannot be compressed), whereas sliding is permitted if a certain amount of air (which can be compressed) is present in said chamber. Therefore, the pump can control the topping-up of the sump with oil only when the oil level in the sump itself is such that the blind cylinder is not completely submerged.
However, devices of the type briefly described above have a number of drawbacks.
In commercial vehicles the oil reservoir and the sump are usually disposed rather far apart. Owing to its design the above-described topping-up device necessarily has to positioned adjacent the sump and, therefore, a long connecting duct has to be provided from the reservoir to the inlet orifice of the pump, with substantial pressure losses, particularly in cold weather as a result of the high viscosity of the oil; the variability in viscosity with temperature also leads to differing behaviour of the system as the climatic conditions vary. Finally, it is necessary to provide two through-holes, provided with respective sealing elements, in the side wall of the sump, one hole for the duct connecting the outlet orifice of the actuator cylinder to the sump itself and another hole for the insertion of an actuating rod.
The object of the present invention is to devise a a device for automatically topping-up a container with liquid, which does not have the drawbacks associated with the known devices described above.
This object is achieved by the present invention in that it relates to a device for automatically topping-up a container with liquid, comprising:

a piston-type pump adapted to be actuated pneumatically and having an intake orifice connected to a liquid reservoir and a delivery orifice for the liquid itself;
means for hydraulically connecting said delivery orifice to said container, and
cylindrical sensor means disposed substantially in alignment with a desired level of the liquid in said container and comprising a first chamber having at least one opening communicating with the interior of the container itself and a first piston sliding in a sealed manner in said first chamber, the presence or absence of liquid in said first chamber precluding or allowing the sliding of said first piston;

With a view to a better understanding of the present invention a preferred embodiment will be described non-restrictively by way of example below, with reference to the accompanying drawings, in which:
Figure 1 illustrates schematically a device for automatically topping up a container with liquid, designed in accordance with the present invention.
Figure 2 is an axial section, on an enlarged scale, of a detail of the device in Figure 1;
Figure 3 is an axial section, on an enlarged scale, of another detail of the device in Figure 1;
Figure 4 is a section along the line IV-IV in Figure 3.
Referring now to Figure 1, the reference numeral 1 generally designates a device for automatically topping-up a container with liquid, in particular for topping-up with lubricating oil a sump 2 of a heat engine (not shown) of a commercial vehicle (not shown).
The device 1 comprises a pneumatically operated injector 3 adapted to feed a predetermined quantity lubricating oil to the sump 2, and a pneumatically operated pump 4 connected to an oil reservoir 5 and to the injector 3 respectively by means of an intake duct 6 and a delivery duct 7. The device 1 also comprises a compressed air supply 8 connected via a pipe 9 to the injector 3 and to the pump 4, and a two-way, two-position solenoid valve 10 which is normally closed and arranged in series with the pipe 9.
Referring now to Figures 1 and 2, the injector 3 comprises a casing 13 fixed externally to and projecting through a side wall 14 of the sump 2 and having an axis A substantially parallel to the free surface of the oil in the sump 2 itself, and an internally hollow blind cylinder 15 which has an axis A and is arranged inside the sump 2 between the minimum and maximum oil levels, respectively L1 and L2 in Figure 1, and which is securely connected with the casing 13.
In particular, the casing 13 comprises a first sleeve 16 partly inserted inside the sump 2 through a hole 17 coaxial to the axis A provided in the wall 14, a second sleeve 18 disposed outside the sump 2 and securely connected with the sleeve 16, a cylindrical body 20 which is securely connected with the sleeve 18 on the other side of the sleeve 16 and which has a passage 21 on the axis A. The casing 13 also comprises a flange 22 which is fitted on to the sleeve 16 and is securely connected therewith, and which is adapted to be fixed to the wall 14 of the sump 2 with the interposition of sealing means 24.
The sleeves 16 and 18 define internally a cylindrical chamber 23 on the axis A and communicating at one end with the internal volume of the cylinder 15 and at the opposite end with the passage 21.
The cylindrical body 20 also comprises a blind radial threaded hole 26 adapted to be engaged by an end connector of the pip 9, and an opening 27 parallel to the axis A and connecting the hole 26 with the chamber 23.
The cylinder 15 has a blind end 28 disposed in a substantially central position inside the sump 2 and an opposite end 29 accommodated in the sleeve 16. In particular, the cylinder 15 is provided with a plurality of radial through-holes 30 which are provided in its side wall and are disposed in the vicinity of its blind end 28, and which are adapted to communicate the interior of the sump 2 with the cylinder 15 itself. Moreover, in alignment with its end 29 the cylinder 15 has an annular projection 31 arranged to abut against an associated inner annular shoulder 32 provided in the sleeve 16.
The injector 3 also comprises a piston 33 mounted to slide axially and in a sealed manner inside the cylinder 15 and defining with the walls of the blind end 28 of the cylinder 15 itself a substantially cylindrical chamber 34. The piston 33 acts as a level sensor for the oil in the sump 2 and is adapted to slide inside the cylinder 15 only when the oil level in the sump 2 is below a level L3 at which the cylinder 15 is completely submerged and, therefore, a given amount of compressible air is present in the chamber 34.
According to the present invention, the injector 3 also comprises a pneumatic actuator member 35 adapted to actuate the piston 33, and a tubular shaft 36, which is coaxial to the A, securely connected to the piston 33 and to the actuator member 35 and defining an axial duct 37 communicating with the oil-delivery duct 7 through an end connector 43. In particular, the shaft 36 extends through the cylinder 15 and the casing 13 and engages in a sliding manner the passage 21 of the cylindrical body 20.
The piston 33 also comprises an intermediate section 38 of reduced diameter defining with the wall of the cylinder 15 itself an annular duct 39 and a substantially T-shaped duct 40 which is provided in the body of the piston 33 itself and has an axial hole 41 on the axis A communicating with the duct 37 and a diametral hole 42 which communicates with the annular duct 39.
The actuator member 35 is adapted to displace the piston 33 between a retracted fluidtight separating position between the duct 40 and the holes 30 in the cylinder 15 and an advanced opening position, in which the duct 40 communicates with the holes 30.
The actuator member 35 is formed by a further annular piston which is coaxial to the axis A and is mounted to slide in a sealed manner inside the sleeve 18, and which is securely connected outwardly to the side wall of the shaft 36 by means of a resilient abutment ring 46 secured to the shaft 36 and compressed between the piston 33 and a bush 44 screwed therein. The piston 35 is held adjacent the body 20 by a helical spring 47 accommodated in the chamber 23 around the shaft 36 and compressed axially between the piston 35 and the annular projection 31 of the cylinder 15. The piston 35 is actuated pneumatically by the compressed air supplied by the supply 8 to the opening 27 and acting on the piston 35 itself in the opposite direction to the force of the spring 47.
Referring now to Figures 3 and 4, the pump 4 comprises a substantially parallelepipedal body 48 defining internally a substantially cylindrical chamber 49, and a piston 50 mounted to slide in a sealed manner inside the chamber 49 itself.
The pump 4 also has an inlet orifice 51 provided in a head 52 of the body 48 and connected with the oil-intake duct 6 and with the chamber 49, an outlet orifice 53 also provided in the head 52 and connected with the delivery duct 7 and with the chamber 49 on the same side as the orifice 51, and a compressed-air supply orifice 54 provided in a head 55 opposite the body 48 and connected with the pipe 9 and with the chamber 49 on the opposite side to the orifices 51 and 53. Respective non-return valves 56 are also provided in the orifices 51 and 53 and they are adapted to allow flow only to and from the chamber 49, as indicated by the arrows in Figure 4.
The piston 50 is held pressed against the head 55 by a helical torsion spring 57 accommodated in the chamber 49 and compressed between the piston 50 and the head 55 itself.
Finally, the device 1 also comprises an electronic control unit 58 connected to the solenoid valve 10, the injector 3, the pump 4 and a proximity sensor 60 which is accommodated in a radial seat 61 provided in the sleeve 16 and which is adapted to detect any displacement of the piston 35 relative to the casing 13.
The control unit 58 is programmed to actuate the device 1 automatically after a preset period of time (several minutes) has elapsed from the stopping of the vehicle and the switching-off of the engine; alternatively, it is possible for the device 1 to be actuated manually.
The operation of the device 1 has been described starting from an initial condition, in which the vehicle engine is inoperative, the solenoid valve 10 is closed and the ignition key for the engine is removed from the control panel (not shown) of the vehicle itself. Moreover, in this initial condition, the piston 50 of the pump 4 is held by the spring 57 in abutment against the head 55, the piston 35 of the injector 3 is held by the spring 47 in abutment against the body 20 and the duct 37 is filled with oil.
The signal sent by the control unit 58 induces the opening of the solenoid valve 10, thus allowing compressed air to flow towards the orifice 54 and the opening 27. The pressure applied by the air originating from the orifice 54 induces the piston 50 to be displaced towards the head 52 of the body 48, whereby the oil present in the chamber 49 is fed to the injector 3.
If the oil level in the sump 2 is equal to or higher than the level L3, the oil in the sump 2 completely fills the chamber 34 and, owing to its inability to be compressed, prevents the full travel of the piston 33 towards the advanced opening position and, therefore, also of the piston 35 secured thereto. No topping up takes place since the duct 40 remains isolated from the injector holes 30. The piston 35, which is prevented from completing its travel, does not induce the tripping of the proximity sensor 60 and, therefore, the control unit 58 operates the stopping of the operation.
In the event that the oil level in the sump 2 is below the level L3, the presence of compressible air inside the chamber 34 allows the full travel of the pistons 33 and 35. However, the piston 33 is displaced towards the blind end 28 of the cylinder 15 in the connecting position of the annular duct 39 with the holes 30 and allows the injection of oil into the sump 2. The displacement of the piston 35 towards the sleeve 16 induces the tripping of the proximity sensor 60 which sends an enabling signal to the control unit 58. After a preset time has elapsed, which is sufficient for the flow of all the oil from the chamber 49 to the sump 2, the solenoid valve 10 is switched over and the topping-up cycle is terminated.
If said enabling signal is present, this cycle is repeated automatically until the oil level L3 in the sump 2 is fully restored; when this level is reached, the pistons 33 and 35 do not complete their travel and the lack of a signal from the proximity sensor 60 induces the stopping of the operation.
The advantages which can be achieved with the present invention are apparent from a study of the features of the device 1 designed in accordance therewith.
In particular, the hydraulic connection between the injector 3 and the pump 4 is particularly versatile; in fact, in this case the pump 4 may, for example, being situated in remote position with respect to the sump 2 and in the vicinity of the reservoir 5, thereby limiting the pressure losses in the oil in the duct connecting the pump 4 to the reservoir 5 itself.
Moreover, the design of the sump is simplified in that it is sufficient to provide only one through-hole, provided with its respective sealing element, in the side wall of the sump 2 for the insertion of the casing 13.
Finally, it is evident that the device 1 can be subject to modifications and variants which do not depart from the scope of protection of the claims.

Claims

A device (1) for automatically topping-up a container (2) with liquid, comprising:

a piston-type pump (4) adapted to be actuated pneumatically and having an intake orifice (51) connected to a liquid reservoir (5) and a delivery orifice (53) for the liquid itself;

means (37, 40) for hydraulically connecting said delivery orifice (53) to said container (2), and

cylindrical sensor means (15, 33) disposed substantially in alignment with a desired level (L3) of the liquid in said container (2) and comprising a first chamber (34) having at least one opening (30) communicating with the interior of the container (2) itself and a first piston (33) sliding in a sealed manner in said first chamber (34), the presence or absence of liquid in said first chamber (34) precluding or allowing the sliding of said first piston (33);

characterised in that said hydraulic connecting means comprise at least a first duct (40) through said first piston (33), said device (1) also comprising actuator means (13, 35) connected with said first piston (33) and adapted to be actuated pneumatically to displace the first piston (33) itself between a fluidtight separating position between said first duct (40) and said opening (30) and an opening position connecting between said first duct (40) and said opening (30), and means (8 10) for actuating pneumatically and simultaneously said pump (4) and said actuator means (35).
A device according to claim 1, characterised in that said cylindrical sensor means comprise an internally hollow blind cylinder (15) disposed between the minimum and maximum levels (L1) and (L2) of the liquid in said container (2) and having an axis (A) substantially parallel to the surface of the liquid in the container (2) itself.
A device according to claim 1 or 2, characterised in that said actuating means comprise a casing (13) which can be secured to a side wall (14) of said container (2) and defining internally a second chamber (23), and a second piston (35) sliding in a sealed manner in said second chamber (23).
A device according to claim 3, characterised in that said casing (13) is coaxial to the axis (A) of said blind cylinder (15), is disposed at least partly inside said container (2) and is securely connected to the blind cylinder (15) itself.
A device according to claim 4, characterised in that said first and second pistons (33, 35) are securely connected to one another by a tubular shaft (36) which is coaxial to the axis (A) of said blind cylinder (15) and which extends through the blind cylinder (15) itself and the casing (13), said hydraulic connecting means comprising a second duct (37) provided inside said shaft (36) and communicating with said delivery orifice (53) and with said first duct (40).
A device according to claim 5, characterised in that said first piston (33) has an intermediate section (38) defining with the wall of the blind cylinder (15) a third annular duct (39) communicating with the first duct (40), said first duct (40) having a branch (41) connected with said second duct (37) and a branch (42) communicating with said third duct (39).
A device according to any one of the preceding claims, characterised in that said actuating means comprise a compressed air supply (8) connected via a pipe (9) to said pump (4) and to said actuator means (13, 35), and a solenoid valve (10) disposed in series with said pipe (9).
A device according to any one of the preceding claims, characterised by comprising an electronic control unit (58) adapted to control said actuating means (8, 10), said pump (4) and said actuator means (13, 35), and a proximity sensor (60) connected to said control unit (58) and adapted to detect any displacement of said actuator means (35).
A device according to any one of the preceding claims, characterised in that said container (2) is the sump of a heat engine of a commercial vehicle, and said liquid is lubricating oil.