Variable displacement pump and control therefor

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the control of the output of a variable displacement pump. More specifically, the present invention relates to control of an oil pump for oil pressure control in an internal combustion engine.

BACKGROUND OF THE INVENTION

[0002] It is desirable to properly lubricate the moving components in an internal combustion engine and provide hydraulic power. Typically, oil pumps used in engines are directly connected to the crankshaft of the engine. While this configuration is generally adequate, there are some disadvantages. First, there is not much control of the actual discharge pressure relative to the pressure needed by the engine under certain/given operating conditions. For instance, during start-up conditions it may be desirable to have higher initial pressure to get engine oil into the engine. At crucial start-up, this cannot be facilitated with the direct drive pumps. Additionally, with the pump shaft RPM directly tied to the engine RPM, in many areas over the RPM range the engine oil pressure is higher or lower than that which is desirable. This results in inefficient use of engine power and/or inefficient engine oil lubrication.

[0003] In commonly assigned co-pending application U.S. Serial No. 10/021,566 (US 2002/0114708), a mechanical hydraulic arrangement is shown for providing control of a variable displacement vane pump. This provides for a more optimized control of engine oil pressure. However, it is yet desirable to provide some further control depending on engine needs or variables. Thus, in the present invention there is provided a method of control and system for control of a variable displacement vane pump by the use of an engine control unit which actuates a solenoid for directly or indirectly controlling the stroke of a variable displacement vane pump.

[0004] In EP-A-0945619 there is described a control system for controlling hydraulic pumps in hydraulic construction machines, such as excavators in which a diesel engine serves as prime mover and drives the hydraulic pumps to deliver hydraulic fluid to hydraulic actuators. The pumps are swash plate pumps and are equipped with regulators for controlling the tilting positions of the swash plates, the regulators comprising tilting actuators and servo valves. Solenoid control valves control the pressure for controlling the tilting positions of the pumps.

SUMMARY OF THE INVENTION

[0005] In accordance with the present invention there is provided a control system for controlling a variable displacement pump for controlling oil flow and oil pressure in a circuit in an engine, comprising: a pump; a de-stroke actuating member capable of acting against an on-stroke actuating member for controlling the displacement of the pump; an engine fluid pressure circuit for receiving oil flow and oil pressure from the pump; a solenoid being operably associated with the de-stroke actuating member for selectively controlling the displacement of the pump, wherein forces act on said on-stroke actuating member and said de-stroke actuating member acts against both said on-stroke actuating member and said forces; an electronic control unit connected to and providing an input control signal to the solenoid for controlling oil flow and oil pressure; and wherein the de-stroke actuating member is hydraulically actuated and the solenoid is used to control oil flow and oil pressure from the pump.

[0006] With a control system embodying the invention input from an engine control unit can actuate the solenoid for controlling the engine oil pressure to the desired level under any operating conditions.
The present invention also provides a variable displacement pump for an engine having an engine control unit comprising: a pump having a de-stroke actuator that acts against an on-stroke actuator and controls the pressure and flow of oil to a pressure lubricating circuit of the engine; a pilot pressure line that has oil flow and oil pressure supplied by the engine; a flow control valve for hydraulically varying the pump displacement by facilitating movement of said de-stroke actuator, wherein forces act on said on-stroke actuator and said de-stroke actuator acts against both said on-stroke actuator and said forces; a solenoid controlled by said engine control unit, said solenoid being operably associated with said flow control valve for providing control of oil flow through said flow control valve.

[0007] A further understanding of the present invention will be had in view of the description of the drawings and detailed description of the invention, when viewed in conjunction with the subjoined claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0009] Figure 1 is a hydraulic schematic showing a first embodiment of the present invention;

[0010] Figure 2 is a hydraulic schematic showing a second embodiment of the present invention

[0011] Figure 2a is a variation of the second embodiment of the present invention;

[0012] Figure 3 is a hydraulic schematic showing a third embodiment of the present invention;

[0013] Figure 4 is a hydraulic schematic showing a forth embodiment of the present invention;

[0014] Figure 5 is a hydraulic schematic showing a fifth embodiment of the present invention;

[0015] Figure 6 is a hydraulic schematic showing a sixth embodiment of the present invention;

[0016] Figure 7 is a hydraulic schematic showing a seventh embodiment of the present invention; and

[0017] Figure 8 is a hydraulic schematic showing an eighth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0019] In the present invention, a method of controlling a variable displacement pump 10 for an engine is provided. In a preferred embodiment of the invention that incorporates a solenoid 26, unless stated otherwise, it should be understood that the solenoid 26 is normally, or is defaulted to, the closed position when no power is supplied to the solenoid 26. When the solenoid 26 is in the closed position there will be high fluid displacement by the pump 10. Thus, in an emergency event, such as when there is an electrical failure, the solenoid 26 will move to its default position so the engine oil pressure will remain high and that the vehicle can continue operating until it can serviced. However, it is to be understood that with the solenoid in a closed position the system could also be configured so that there is fluid displacement with the pump 10.

[0020] In accordance with Figure 1, the pump is a vane-type variable displacement pump, as set forth in co-pending application Serial No. 10/021,566, filed December 12, 2000 (Publication No US 2002/0114708), the specification of which is incorporated by reference herein. Specifically, the pump is designed for an engine lubrication circuit. The pump is generally shown at 10. The pump 10 may be a vane pump which has the displacement varied by movement of an eccentric ring 11. It is also possible to incorporate other types of pumps, in which the stroke or displacement may be adjusted during operation.

[0021] A flow control valve 12 is used to mechanically vary the displacement of a pump 10, by moving the eccentric ring 11, based on an engine pilot pressure 14 acting on the flow control valve 12 which controls the volume of oil in each control chamber on each side of the eccentric ring 11. A compression spring 16 acts against a pilot pressure 14 for maintaining some pressure on the flow control valve 12 and to provide a return pressure in absence of the pilot pressure 14. The flow control valve 12 in this particular embodiment is a spool valve such as a three-way spool valve. However, it should be understood that the flow control valve 12 can be a spool valve of any type of configuration. Also, the flow control valve 12 does not necessarily need to be a spool valve at all, as will be seen in Figure 6. The compression spring 16 gives the spool portion of the valve 12 travel distance that is proportional to the differential between the actual pressure of the system and the desired or target system pressure. The differential pressure is variable by way of a valve 18, which controls the amount of pressure acting on the variable target piston 20 against spring 22 for varying the amount of spring 16 pressure on valve 12. An engine control unit (ECU) 24 monitors the engine conditions and parameters such as temperature, speed and engine load. In this embodiment, the engine control unit 24 monitors the engine conditions pressure, speed, and engine load and then selects a desired oil pressure, and sends the appropriate current to the solenoid 26 acting on valve 18. This varies the pressure acting on the piston 20, changing its position and thereby reducing or increasing target pressure, depending upon the desired engine oil pressure target. The flow control valve 12 then regulates the pump's 10 eccentric ring 11 to maintain target pressure.

[0022] With respect to Figure 2, like items referenced in Figure 1 are similarly designated with reference numerals differing by 100. The operation of this embodiment is similar to the embodiment shown in Figure 1. The valve 112a includes a closed center valve portion 112b. However, the main operating difference is the use of a pressure reducing and regulating valve 128. The regulating valve 128 creates a fixed input pressure for the solenoid valve 118 in that the pressure, which in Figure 1 was taken from the discharge port of the pump 10 into the solenoid control valve 18, is now at a constant pressure and, therefore, provides better control of the variable target pressure acting on piston 120. This ultimately provides improved control over the desired movement of the eccentric ring 111 of the pump 110.

[0023] Fig. 2a operates in a similar manner as Fig. 2. The main difference between Fig. 2 and Fig. 2a is that the pressure reducing and regulating valve 128 of Fig. 2a creates a fixed target pressure that acts directly on the piston 120. The solenoid 126 opens or closes to further adjust the pressure of fluid acting on the piston 120. When the solenoid 126 moves the valve 118a to the closed position there is an increase in variable target pressure. When the solenoid 126 moves the valve 118a to the open position the variable target pressure will decrease as the fluid moves to the sump with less resistance. Additionally, unreduced pressure is fed to the spool valve 112A before the pressure reducing and regulating valve 128 after the filter. Just as in Fig. 2, this embodiment is also a passive system for controlling oil flow and oil pressure since an engine control unit 124 controls the solenoid 126 for positioning the piston 120, however, the engine control unit 124 does not directly sense oil pressure.

[0024] With respect to Figure 3, like items referenced in Figure 2 are similarly designated with reference numerals differing by 100. In Figure 3, the source for the pressure which is regulated by the valve 218 is taken from the pilot line instead of the discharge line. Otherwise, the control operation is similar to that shown in Figures 1 and 2.

[0025] With respect to Figure 4, like items referenced in Figure 3 are similarly designated with reference numerals differing by 100. In this particular embodiment the solenoid 326 directly controls the movement of the variable target piston 320. The engine control unit 324 is connected to the solenoid 326 and controls the actuation of the solenoid. The configuration of this embodiment (i.e., the solenoid acting directly on the variable target piston 320) allows the variable target piston to be adjusted in accordance with the engine control unit's 324 commands directly, rather than using additional hydraulics.

[0026] With respect to Figure 5, like items referenced in Figure 4 are similarly designated with reference numerals differing by 100. With respect to Figure 5, this embodiment includes a solenoid 426 attached to the flow control spool valve 412 directly, to regulate the stroke or de-stroke conditions of the pump 410. The solenoid 426 is connected directly to the engine control unit 424. The engine control unit 424 samples the pilot pressure from a pressure transducer in the engine circuit in order to make the proper calculations as to the best spool position based on the current actual and target pressures. Return spring 416 provides the return pressure for adjusting the flow control spool valve 412 in absence of solenoid 426 input, and allows for predetermined functions of spool position versus current.

[0027] With respect to Figure 6, like items referenced in Figure 5 are similarly designated with reference numerals differing by 100. With respect to Figure 6, a very simple control mechanism is used by the control solenoid 526 moving a valve 512A for controlling the de-stroke actuator of the pump 510. The solenoid 526 adjusts the pressure acting on the large piston which pushes against the discharge pressure acting on the small piston on the opposite side. An on-stroke return spring is provided for balancing the eccentric control ring against control inputs which can also work alone (as shown). In this embodiment, the engine control unit 524 samples the pilot pressure from a pressure transducer in the engine circuit in order to make the proper calculations as to the best valve 512A position.

[0028] With respect to Figure 7, like items referenced in Figure 6 are similarly designated with reference numerals differing by 100. Figure 7 is another embodiment wherein engine control unit 624 directly controls a solenoid 626 which acts directly on either the actuating piston for the eccentric ring or directly on the eccentric ring. This allows direct control of the displacement of the pump 610 based on ECU 624 monitoring of the pilot pressure of the oil pressure circuit, although this arrangement is not in accordance with the invention as defined in the claims which follows..

[0029] Figure 8 illustrates a further embodiment wherein the solenoid 726 directly actuates the spool flow control valve 712. Again, the ECU 724 is monitoring the engine oil circuit pressure and adjusting the solenoid in accordance with the necessary engine oil pressure, as calculated by the ECU. In this embodiment, pressure from the discharge is reduced by the solenoid valve and used to bias the position of the flow control spool valve 712 against the spring for varying the displacement of the pump. Flow across the solenoid can be directed to the inlet port, as shown of the vane pump 710, but can also be drained to the sump.

[0030] As can be seen by the drawings, the methods shown in Figures 1 through 4 are passive systems which allow the ECU to monitor engine conditions and provide a pressure target to the pump system, but the pump system is self-regulated to the pressure target by mechanical and hydraulic controls. Figures 5 through 8 provide active control of the oil pressure by the ECU. In these embodiments, the ECU monitors the oil pressure and actively adjusts the system on a real time basis to control oil pressure in the engine.

[0031] Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited, since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.

[0032] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the scope of the claims are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the scope of the invention.

Claims

1. A control system for controlling a variable displacement pump for controlling oil flow and oil pressure in a circuit in an engine, comprising:

a pump (10);

a de-stroke actuating member capable of acting against an on-stroke actuating member for controlling the displacement of the pump (10);

an engine fluid pressure circuit for receiving oil flow and oil pressure from the pump (10);

a solenoid (26) being operably associated with the de-stroke actuating member for selectively controlling the displacement of the pump, wherein forces act on said on-stroke actuating member and said de-stroke actuating member acts against both said on-stroke actuating member and said forces;

an electronic control unit (24) connected to and providing an input control signal to the solenoid (26) for controlling oil flow and oil pressure; and

wherein the de-stroke actuating member is hydraulically actuated and the solenoid (26) is used to control oil flow and oil pressure from the pump.

2. The control system of claim 1, wherein the electronic control unit (24) is connected to and monitors the pressure in a pilot line (14) that is connected to the engine fluid pressure circuit, wherein the electronic control unit (24) generates input signals to the solenoid (26) in response to pressure conditions in the pilot line (14) for controlling displacement of the pump (10).

3. The control system of claim 1 or 2, wherein the electronic control unit (24) monitors the oil pressure and actively adjusts the system on a real time basis to control oil pressure in the engine oil pressure circuit.

4. The control system of claim 1, 2 or 3, wherein a valve member (12) is functionally connected between the solenoid (26) and the de-stroke actuating member and controls an amount of hydraulic pressure inputted to the de-stroke actuating member in response to the movement of the solenoid (26).

5. The control system of claim 4, wherein the solenoid (426; 526) is directly connected to the valve member (412; 512A) and controls the opening and closing of the valve member.

6. The control system of claim 5, wherein the valve member (512A) is connected to a sump, so that when the solenoid (526) opens the valve member, an input pressure to the actuating member increases.

7. The control system of claim 5 or 6, wherein the input pressure to the de-stroke actuating member decreases when the solenoid (526) closes the valve member.

8. The control system of any one of the preceding claims further comprising monitoring engine conditions selected from the group comprising engine temperature, engine speed, engine load, and combinations thereof.

9. The control system of any one of claims 1 to 8, further comprising a piston forming part of said de-stroke actuating member and a piston on an on-stroke side of the pump, wherein the piston on said de-stroke side is larger than the piston on the on-stroke side of the pump.

10. The control system of anyone of claims 1 to 9, wherein said forces comprise discharge pressures.

11. The control system of any one of claims 1 to 10, wherein said forces comprise spring forces caused by a spring member operably connected to said on-stroke actuating member.

12. A variable displacement pump for an engine having an engine control unit comprising:

a pump (10) having a de-stroke actuator that acts against an on-stroke actuator and controls the pressure and flow of oil to a pressure lubricating circuit of the engine;

a pilot pressure line (14) that has oil flow and oil pressure supplied by the engine;

a flow control valve (12) for hydraulically varying the pump displacement by facilitating movement of said de-stroke actuator, wherein forces act on said on-stroke actuator and said de-stroke actuator acts against both said on-stroke actuator and said forces;

a solenoid (26) controlled by said engine control unit (24), said solenoid being operably associated with said flow control valve (12) for providing control of oil flow through said flow control valve.

13. The variable displacement pump of claim 12, further comprising a piston forming part of the de-stroke actuator and a piston on an on-stroke side of the pump, wherein the piston on said de-stroke said is larger than the piston on the on-stroke side of the pump.

14. The variable displacement pump of claim 12 or 13, wherein said forces comprise discharge pressures.

15. The variable displacement pump of claim 12, 13 or 14, wherein said forces comprise spring forces caused by a spring member operably connected to said on-stroke actuating member.

Ansprüche

1. Steuerungssystem zur Steuerung einer Pumpe mit variabler Förderleistung zur Steuerung von Ölfluss und Öldruck in einem Kreislauf in einem Motor, umfassend:

eine Pumpe (10);

ein Destroke-Betätigungsglied, das imstande ist, gegen ein Onstroke-Betätigungsglied zu wirken, zur Steuerung der Förderleistung der Pumpe (10);

einen Motorflüssigkeits-Druckkreislauf zum Empfangen von Ölfluss und Öldruck von der Pumpe (10);

einen Schaltmagnet (26), der operativ mit dem Destroke-Betätigungsglied assoziiert ist, zur selektiven Steuerung der Förderleistung der Pumpe, wobei Kräfte auf das Onstroke-Betätigungsglied wirken und das Destroke-Betätigungsglied gegen sowohl des Onstroke-Betätigungsglied als auch die Kräfte wirkt;

eine elektronische Steuereinheit (24), die mit dem Schaltmagnet (26) verbunden ist und dafür ein Eingangssteuerungssignal bereitstellt, zur Steuerung von Ölfluss und Öldruck; und

wobei das Destroke-Betätigungsglied hydraulisch betätigt wird und der Schaltmagnet (26) zur Steuerung von Ölfluss und Öldruck von der Pumpe verwendet wird.

2. Steuerungssystem nach Anspruch 1, wobei die elektronische Steuereinheit (24) mit einer Vorsteuerleitung (14), die mit dem Motorflüssigkeits-Druckkreislauf verbunden ist, verbunden ist und den Druck darin überwacht, wobei die elektronische Steuereinheit (24) Eingangssignale für den Schaltmagnet (26) als Reaktion auf Druckbedingungen in der Vorsteuerleitung (14) zur Steuerung der Förderleistung der Pumpe (10) erzeugt.

3. Steuerungssystem nach Anspruch 1 oder 2, wobei die elektronische Steuereinheit (24) den Öldruck überwacht und das System zur Steuerung des Öldrucks in dem Motoröl-Druckkreislauf auf einer Echtzeitbasis aktiv anpasst.

4. Steuerungssystem nach Anspruch 1, 2 oder 3, wobei ein Ventilglied (12) funktional zwischen dem Schaltmagnet (26) und dem Destroke-Betätigungsglied verbunden ist und einen Betrag von Hydraulikdruck steuert, der als Reaktion auf die Bewegung des Schaltmagnets (26) in das Destroke-Betätigungsglied eingegeben wird.

5. Steuerungssystem nach Anspruch 4, wobei der Schaltmagnet (426; 526) direkt mit dem Ventilglied (412; 512A) verbunden ist und das Öffnen und Schließen des Ventilglieds steuert.

6. Steuerungssystem nach Anspruch 5, wobei das Ventilglied (512A) mit einem Sumpf verbunden ist, so dass, wenn der Schaltmagnet (526) das Ventilglied öffnet, ein Eingangsdruck zu dem Betätigungsglied zunimmt.

7. Steuerungssystem nach Anspruch 5 oder 6, wobei der Eingangsdruck zu dem Destroke-Betätigungsglied abnimmt, wenn der Schaltmagnet (526) das Ventilglied schließt.

8. Steuerungssystem nach einem der vorstehenden Ansprüche, weiter Überwachen von Motorbedingungen umfassend, die aus der Gruppe ausgewählt werden, die Motortemperatur, Motordrehzahl, Motorlast und Kombinationen davon umfasst.

9. Steuerungssystem nach einem der Ansprüche 1 bis 8, weiter einen Kolbenbildungsteil des Destroke-Betätigungsglieds und einen Kolben an einer Onstroke-Seite der Pumpe umfassend, wobei der Kolben an der Destroke-Seite größer als der Kolben an der Onstroke-Seite der Pumpe ist.

10. Steuerungssystem nach einem der Ansprüche 1 bis 9, wobei die Kräfte Austrittsdrücke umfassen.

11. Steuerungssystem nach einem der Ansprüche 1 bis 10, wobei die Kräfte Federkräfte umfassen, die von einem Federglied verursacht werden, das operativ mit dem Onstroke-Betätigungsglied verbunden ist.

12. Pumpe mit variabler Förderleistung für einen Motor mit einer Motorsteuerungseinheit, umfassend:

eine Pumpe (10) mit einem Destroke-Betätigungsglied, das gegen ein Onstroke-Betätigungsglied wirkt und den Druck und Fluss von Öl zu einem Druckschmierkreis des Motors steuert;

ein Vorsteuerleitung (14), die den Ölfluss und Öldruck, die von dem Motor zugeführt werden, aufweist;

ein Flusssteuerventil (12) zum hydraulischen Verändern der Pumpenförderleistung durch Erleichterung der Bewegung des Destroke-Betätigungsglieds, wobei Kräfte auf das Onstroke-Betätigungsglied wirken und das Destroke-Betätigungsglied sowohl gegen das Onstroke-Betätigungsglied als auch die Kräfte wirkt;

einen Schaltmagnet (26), der von der Motorsteuerungseinheit (24) gesteuert wird, wobei der Schaltmagnet operativ mit dem Flusssteuerventil (12) assoziiert ist, um Steuerung des Ölflusses durch das Flusssteuerventil bereitzustellen.

13. Pumpe mit variabler Förderleistung nach Anspruch 12, weiter einen Kolbenbildungsteil des Destroke-Betätigungsglieds und einen Kolben an einer Onstroke-Seite der Pumpe umfassend, wobei der Kolben an der Destroke-Seite größer als der Kolben an der Onstroke-Seite der Pumpe ist.

14. Pumpe mit variabler Förderleistung nach Anspruch 12 oder 13, wobei die Kräfte Austrittsdrücke umfassen.

15. Pumpe mit variabler Förderleistung nach Anspruch 12, 13 oder 14, wobei die Kräfte Federkräfte umfassen, die von einem Federglied verursacht werden, das operativ mit dem Onstroke-Betätigungsglied verbunden ist.

Revendications

1. Système de commande destiné à commander une pompe à cylindrée variable pour piloter le débit d'huile et la pression d'huile dans un circuit monté dans un moteur, comprenant :

une pompe (10) ;

un élément d'actionnement de course retour capable d'agir contre un élément d'actionnement de course aller afin de commander la cylindrée de la pompe (10) ;

un circuit de pression de fluide moteur servant à recevoir le débit d'huile et la pression d'huile en provenance de la pompe (10) ;

un solénoïde (26) lequel est associé de façon opérationnelle à l'élément d'actionnement de course retour afin de commander sélectivement la cylindrée de la pompe, cas dans lequel des forces s'exercent sur ledit élément d'actionnement de course aller et ledit élément d'actionnement de course retour agit à la fois contre ledit élément d'actionnement de course aller et contre lesdites forces ;

une unité de commande électronique (24) laquelle est connectée au solénoïde (26), et fournit un signal de commande d'entrée à ce solénoïde, afin de piloter le débit d'huile et la pression d'huile ; et

cas dans lequel l'élément d'actionnement de course retour est actionné hydrauliquement et le solénoïde (26) est utilisé pour piloter le débit d'huile et la pression d'huile en provenance de la pompe.

2. Système de commande selon la revendication 1, l'unité de commande électronique (24) étant connectée à une ligne pilote (14) et surveillant la pression de cette ligne pilote qui est raccordée au circuit de pression de fluide moteur, cas dans lequel l'unité de commande électronique (24) génère des signaux d'entrée se rendant au solénoïde (26) en réaction à des conditions de pression dans la ligne pilote (14) afin de commander la cylindrée de la pompe (10).

3. Système de commande selon la revendication 1 ou 2, l'unité de commande électronique (24) surveillant la pression d'huile et réglant de façon active le système suivant une base en temps réel afin de piloter la pression d'huile dans le circuit de pression d'huile-moteur.

4. Système de commande selon la revendication 1, 2 ou 3, un élément de soupape (12) étant raccordé de façon fonctionnelle entre le solénoïde (26) et l'élément d'actionnement de course retour et gérant une quantité de pression hydraulique injectée à l'élément d'actionnement de course retour en réaction au mouvement du solénoïde (26).

5. Système de commande selon la revendication 4, le solénoïde (426 ; 526) étant directement raccordé à l'élément de soupape (412 ; 512A) et pilotant l'ouverture et la fermeture de l'élément de soupape.

6. Système de commande selon la revendication 5, l'élément de soupape (512A) étant raccordé à un carter inférieur, de sorte qu'une pression d'admission vers l'élément d'actionnement va augmenter lorsque le solénoïde (526) ouvre l'élément de soupape.

7. Système de commande selon la revendication 5 ou 6, la pression d'admission vers l'élément d'actionnement de course retour diminuant lorsque le solénoïde (526) ferme l'élément de soupape.

8. Système de commande selon l'une quelconque des revendications précédentes, comprenant en outre la surveillance des conditions de moteur sélectionnées à partir du groupe composé des facteurs suivants, à savoir température du moteur, régime du moteur, charge du moteur et des combinaisons de ceux-ci.

9. Système de commande selon l'une quelconque des revendications 1 à 8, comprenant en outre un piston lequel fait partie dudit élément d'actionnement de course retour et un piston monté sur un côté course aller de la pompe, cas dans lequel le piston situé sur ledit côté course retour est plus grand que le piston situé sur le côté course aller de la pompe.

10. Système de commande selon l'une quelconque des revendications 1 à 9, lesdites forces englobant des pressions de refoulement.

11. Système de commande selon l'une quelconque des revendications 1 à 10, lesdites forces englobant des forces de ressort provoquées par un élément à ressort raccordé de façon opérationnelle audit élément d'actionnement de course aller.

12. Pompe à cylindrée variable pour un moteur comportant une unité de commande de moteur, comprenant :

une pompe (10) dotée d'un actionneur de course retour qui agit contre un actionneur de course aller et pilote la pression et le débit d'huile se rendant à un circuit de lubrification à pression du moteur ;

une ligne de pression pilote (14) dont l'alimentation en débit d'huile et en pression d'huile est assurée par le moteur ;

une soupape de commande de débit (12) pour faire varier hydrauliquement la cylindrée de la pompe du fait qu'elle facilite le mouvement dudit actionneur de course retour, cas dans lequel des forces s'exercent sur ledit actionneur de course aller et ledit actionneur de course retour agit à la fois contre ledit actionneur de course aller et contre lesdites forces ;

un solénoïde (26) géré par ladite unité de commande de moteur (24), ledit solénoïde étant associé de façon opérationnelle à ladite soupape de commande de débit (12) afin d'assurer le pilotage du débit d'huile à travers ladite soupape de commande de débit.

13. Pompe à cylindrée variable selon la revendication 12, comprenant en outre un piston lequel fait partie de l'actionneur de course retour et un piston monté sur un côté course aller de la pompe, cas dans lequel le piston situé sur ladite course retour est plus grand que le piston situé sur le côté course aller de la pompe.

14. Pompe à cylindrée variable selon la revendication 12 ou 13, lesdites forces englobant des pressions de refoulement.

15. Pompe à cylindrée variable selon la revendication 12, 13 ou 14, lesdites forces englobant des forces de ressort provoquées par un élément à ressort raccordé de façon opérationnelle audit élément d'actionnement de course aller.

Drawing