FR2820458A1 - AUTOMATIC DEVICE FOR REGULATING THE OIL LEVEL IN A 4-STROKE ENGINE - Google Patents

Abstract

The invention relates to an automatic device for adding oil in the oil sump (2) of the internal combustion engine of a vehicle which comprises an oil reserve (5) connected by a first pipe (6) to a point of addition (3) of oil in said crankcase and by a second pipe (10) at an outlet point (4) of any oil overflow in said crankcase, characterized in that it comprises, furthermore: means (8, 12, 14) for both transferring oil from said reserve to said point of adding oil and, simultaneously, removing any overflow of oil optionally via said discharge point in the direction of said reserve, the oil flow capacity that can be removed by said means being greater than the added oil flow; and control means of said transfer and discharge means ensuring that the latter are started up when certain conditions are met.

Description

The invention relates to an automatic level control device.

  oil in a 4-stroke thermal engine.

  Reducing the cost of maintaining vehicles and limiting their downtime for maintenance are desirable objectives, the achievement of which involves extending the oil change intervals (beyond 000 km and if possible to 100,000 km ). From this perspective, the problem arises of loading the vehicle with the quantity of oil necessary to compensate for its consumption between two oil changes. Indeed, the space available in the oil pan is not sufficient, especially since the latter tends to be reduced in useful volume in order to increase the compactness of the engine. In addition, the manual production of multiple oil additions is not realistic at a time when we seek to provide customers with a "worry-free" vehicle. There is therefore a need for a system that automatically compensates for the consumption of engine oil, without

  risk to the product and people and at an acceptable cost.

  Various automatic oil make-up systems have already been proposed; see in particular JP-A-80 21225, JP-A-83 26519, JP-A-91 00711, FR-A - 2 729 714, and FR-A-2 735 814. All these systems, most of which use to a measurement of the oil level in the engine, suffer, however, from a lack of security, nothing is foreseen in case of system failure. There is therefore a need for a safe oil make-up system, making it possible in particular to avoid the risk of overfilling, which could lead, in the case of a diesel engine, to runaway of the latter,

or even its destruction.

  The invention aims to satisfy this need.

  More specifically, the invention relates to an automatic device for adding oil to the oil pan of the combustion engine of a vehicle which comprises a reserve of oil connected by a first tube to a point of addition of oil in said casing and by a second tube at a point of evacuation of the possible overflow of oil in said casing, characterized in that it further comprises: means making it possible both to transfer oil from said reserve to said point of adding oil and, simultaneously, to evacuate any possible oil overflow by said discharge point in the direction of said reserve, the oil flow capacity which can be evacuated by said means being greater than the added oil flow; and means for controlling said transfer and evacuation means ensuring that the latter are started after a predetermined period since the engine has stopped and provided that (a) the temperature of the oil in the crankcase or the temperature of the engine cooling water is within a predetermined temperature range and (b) a predetermined minimum mileage has been traveled by the vehicle since the vehicle was put into service or the make-up operation

previous oil.

  Preferably, the oil discharge point is located approximately at the barycentric point of the positions of the level of regulation of the oil contained in the sump. The barycentric point is the point of intersection of the planes occupied by the surface of the oil contained in the crankcase for different plates of the parked vehicle. The oil regulation level is the oil level fixed by the point

in the housing.

  Also preferably, the oil transfer and evacuation means comprise a double pump, that is to say a pumping device combining two pumps mechanically mounted on a shaft

common training.

  The control means may consist, at least in part, of the electronic engine control unit usually mounted

  on most current motor vehicles.

  At each top-up operation, the device of the invention introduces into the engine an amount of oil whose value is limited. In fact, by construction, the level that the oil in the engine can reach cannot exceed the level of the discharge point provided in the crankcase. As soon as the oil level reaches this point of evacuation, the oil overflow is evacuated and returned to the reserve. In the preferred case where the discharge point is located at the barycentric point, the quantity of oil introduced will be insensitive to

  the attitude of the vehicle at the time of the operation.

  The device of the invention therefore makes it possible to guard against the risk of

overfilling with engine oil.

  The frequency and the duration of the topping-up operations can be easily determined and programmed in the control means as a function of the normal consumption of engine oil and by ensuring that the energy consumed (proportional to the duration of the by each operation is compatible with the energy reserves available on the stationary vehicle, that is to say, usually with the capacity of the battery. Relative to a booster device controlled from a measurement of the oil level, the device of the invention allows: - the elimination of the risk of overfilling with engine oil either by inadvertent triggering of the booster device from incorrect oil level information, i.e. in the event of a system failure with non-stopping of the means supplying the make-up oil to the engine, risk affecting product and personal safety (runaway of diesel engine with the possibility of loss of control of the vehicle), - easier installation in the engine oil sump: the overflow discharge pipe being less bulky than an oil level gauge, - a steering strategy simplified, not requiring software locks intended to limit the effects of failures in the oil gauging chain and no longer requiring specific, long and costly validation, - simplified development thanks to the possibility of operating only with the usual electronic engine control unit without the need for information from other electronic vehicle control units (for example passenger compartment, dashboard), - simplified maintenance in the agent network thanks to a lesser

complexity of the system.

  The following description made with reference to the accompanying drawing will do well

understand the invention.

  In the drawing, Figure 1 is a schematic view of a device according to the invention, while Figures 2 to 5 illustrate an alternative embodiment of this device. Figure 1 shows the engine 1 of a vehicle (not shown) conventionally comprising an oil pan 2 at its lower part. This

  crankcase shelters a point 3 of oil refill and a point 4 of evacuation of a too-

  full of oil if necessary. Preferably, as illustrated, the evacuation point 4 is located at the barycentric point of the planes (shown in phantom) occupied by the oil surface at the oil regulation level and for plates different from the vehicle (three plates only have been

shown in the figure).

  The make-up point 3 is connected to the lower part of an oil reserve 5 by a pipe 6 through a non-return valve 7 and the first pump 8 of a double pump 9. On its side , the discharge point 4 is connected to the upper part of the reserve 5 by a pipe 10 through a non-return valve 11 and the second pump 12 of the double pump 9. The two pumps 8 and 12 are mounted on a common shaft which is rotated by an electric geared motor 13. The two pumps, which therefore rotate in the same direction at an identical speed, have, by construction, different flow capacities, the flow capacity of the second pump 12 being greater than that of the first pump 8, regardless of the viscosity difference between the oil from the reserve 5 and the oil from the crankcase 2. The pump 12, if it does not is not self-priming, must be located at a level lower than that of the evacuation point ation 4 so as to guarantee its priming whatever the attitude of the vehicle. This condition disappears if the pump 12 is self-priming. The

  pipes 6 and 10 pass through the wall of the casing by sealed passages.

  The two non-return valves 7 and 11 can be of the ball and spring type as illustrated. It should be noted that the valve 7 has the role of preventing the oil contained in the reserve 5 from flowing, under the effect of gravity, into the casing 2 through the pump 8 when stopped. when all or part of this oil is at a level higher than the maximum level of the oil contained in the sump, which is usually the case when, as illustrated, the reserve 5 is located at a level higher than said maximum oil level in the housing. To this end, the setting of the valve spring 7 must be sufficient to withstand the pressure difference generated by the maximum possible difference in the oil levels in the reserve 5, on the one hand, and in the crankcase 2, on the other. go. For its part, the valve 11 has the function of avoiding an air intake by the engine in operation under the effect

  reduced pressure in the housing.

  The reserve 5 may have any oil capacity sufficient to provide the top-up for a desired mileage. A capacity of two or three liters is usually sufficient for a mileage of 40,000 to 60,000 kilometers based on an average oil consumption of 0.05 liter / 1000 kilometers. The reserve 5 is provided at its upper part with an air intake 15 preventing its internal volume from being depressed when oil therein

is taken up by pump 8.

  The device also includes a control unit 14 of the moto-

  electric reducer 13, which consists of the electronic engine control unit usually mounted on most current vehicles after

  proper programming of it.

  The device of the invention is triggered when the engine, after an operating period, has been stopped for a time t (for example of the order of 15 to 20 minutes) sufficient to ensure the return of the oil contained in the engine at the bottom of the engine crankcase and provided that, moreover, the vehicle has traveled a certain mileage (for example between 1000 and 2000 km) since it was put into service or the previous oil topping-up operation and that the temperature engine water is greater than, say, 70 C to be sure that at least 95% of the oil is returned to the sump at the bottom of the engine. A water temperature of C usually corresponds to an oil temperature of 40 to 80 C. Alternatively, one could, of course, substitute the oil temperature, when available, for the water temperature, as a trigger parameter. When the triggering conditions are satisfied the control unit 14 triggers the operation of the reduction motor 13 and, therefore, of the double pump 9, and this for a predetermined duration, by

1 minute example.

  We give below some quantified examples in the case of a Renault F9Q turbo-diesel engine with a displacement of 1.9 liters having a maximum functional oil volume at 20 C of 3.3 liters and a volume of minimum functional oil at 20 C of 2.5 liters, and consuming on average 0.05

liter of oil per 1000 kilometers.

  The double pump used had the following flow rates, depending on the temperature, for a 5W30 oil: Oil temperature Pump flow rate Booster pump flow rate 8 (l / min) * discharge 12 (I / min)

-250C 0.228 1.27

0 C 0.244 1.37

+20 C 0.228 1.27

+40 C 0.204 1.15

+50 C 0.156 0.88

+80 C 0.044 0.25

  (*) measured values (o) estimated values Note that in all cases the flow capacity of the evacuation pump exceeds the flow capacity of the booster pump 8, which is a guarantee against overfilling the engine in oil, even in

  failure situation with a double pump that keeps turning.

  It will also be noted that the flow rate of the make-up pump 8 is sufficient to ensure in I minute, or even less, a make-up of oil sufficient to compensate for a normal oil consumption (0.05 liter / 1000 km) or even

increased.

  Figures 2 to 5 illustrate an alternative embodiment of the device

Figure 1.

  According to this variant, the assembly constituted by the gear motor 13, the double pump 9 and the valves 7 and 11 is replaced by a piston pump 20 and with double chamber 21, 22, four ball valves 23-26 and a electric motor 27 driving a flywheel 28 associated with a connecting rod 29 driving the

  rod 30 of the piston 20 of the pump in a reciprocating movement.

  Figures 2 to 5 illustrate various phases of the operation of

  this variant during an oil top-up operation.

  In FIG. 2, the piston 20 is at the end of its travel, the volume of the chamber 21 being at its minimum and the chamber 22 being completely

  filled with oil previously aspirated from reserve 5 via valve 23.

  Figure 3 illustrates the retraction phase of the piston. During this phase, the oil contained in the chamber 22 is injected into the oil sump 2 of the engine, while, simultaneously, any overflow of oil arriving at point 4 of evacuation is sucked into the chamber 21 via line 10 and

valve 25.

  Figure 4 shows the piston in the fully retracted position. Chamber 22 is reduced to its minimum volume and chamber 21 contains an amount of oil corresponding to the overflow reached at point 4

  during the oil injection.

  FIG. 5 illustrates the advance phase of the piston. During this phase the oil contained in the chamber 21 is discharged into the reserve 5 via the valve 26, while the chamber 22 is filled with oil sucked from the

reserve 5.

  Because the maximum volume of the chamber 21 is greater than that of the chamber 22 taking into account the volume occupied by the rod 30 of the piston, the pump 19 has the capacity to evacuate from the oil pan, via point 4 and line 10, a maximum oil flow rate higher than the makeup oil flow rate

  injected into the casing 2 via the conduit 6, thus avoiding any risk of over-

  filling. The use of a piston pump has, moreover, the advantage of not causing any priming problem, the oil suction being guaranteed whatever the position of the pump relative to the point level.

evacuation 4.

  It goes without saying that the embodiments described are only examples and that they could be modified, in particular by substitution of technical equivalents, without departing from the present invention.

Claims (6)

  1. An automatic device for adding oil to the oil pan (2) of the internal combustion engine of a vehicle which comprises a reserve (5) of oil connected by a first tube (6) to a point d addition (3) of oil in said casing and by a second tube (10) at a discharge point (4) of any overflow of oil in said casing, characterized in that it further comprises : means (8, 12, 14) making it possible both to transfer oil from said reserve to said point of adding oil and, simultaneously, to evacuate any possible oil overflow by said discharge point towards said reserve, the capacity of oil flow evacuatable by said means being greater than the added oil flow; and means for controlling said transfer and evacuation means ensuring that the latter are started after a predetermined period since the engine has stopped and provided that (a) the temperature of the oil in the crankcase or the temperature of the engine cooling water is within a predetermined temperature range and (b) a predetermined minimum mileage has been traveled by the vehicle since the commissioning of the   vehicle or the previous oil topping up operation.   2. A device according to claim 1, characterized in that the discharge point (4) of oil is located approximately at the barycentric point   positions of the level of regulation of the oil contained in the crankcase.   3. A device according to claim 1, characterized in that the oil transfer and discharge means comprise a rotary pump double (9).   4. A device according to claim 1, characterized in that the oil transfer and evacuation means comprise a pump (19) to   piston (20) and double chamber (21, 22).   5. A device according to claim 3 or 4, characterized in that the   pump is associated with valves (7, 11, 23-26).   6. A device according to claim 1, characterized in that the control means consist, at least in part, of the   electronic control (14) of the vehicle engine.