Rotary pump with a variable flow rate, particularly for oil

Description

[0001] The present invention relates to a rotary pump with a variable flow rate, and in particular to a gear pump as specified in the preamble of claim 1. Such a pump is for oil, known eg from any of GB-A-1152188 or BE-A-443167. As is known, a gear pump comprises a support body, which delimits a suction mouth, which, in use, is connected to an oil tank, and a delivery mouth, which, in use, is connected to a delivery circuit, and accommodates two toothed rotors which engage with one another, and delimit a plurality of apertures, in order to convey oil from the suction mouth to the delivery mouth.

[0002] The known gear pumps of the above-described type are used for example in motor vehicles, in order to convey the oil to the lubrication circuit of a corresponding internal combustion engine, the drive shaft of which actuates one of the rotors of the pump, and thus sets the speed of rotation of the rotors themselves.

[0003] In use, it is necessary to meet the requirements both of guaranteeing a sufficient flow rate of oil to the lubrication circuit, in minimum conditions of rotation, and of limiting the flow rate, and thus the oil pressure at high speeds of rotation.

[0004] For this purpose, the known pumps of the above-described type are provided with a corresponding by-pass valve, which can recirculate the excess oil from the delivery mouth to the tank, according to the pressure present in the delivery circuit.

[0005] Although they are widely used, the known pumps of the above-described type are unsatisfactory, since the oil which is recirculated through the by-pass valve is compressed by the pump, which thus absorbs corresponding mechanical compression energy from the engine shaft, without this energy then being actually used.

[0006] GB-A-1152188 discloses a rotary positive-displacement pump, which has externally-meshing gears. A piston is provided to move a gear relative to another meshing gear, thereby varying the output of the pump in response to the actual oil pressure at the pressure side of the gears. BE-A-443167 discloses a hydraulic circuit having a similar pump. According to a variation, BE-A-443167 also discloses a pump and a motor provided in a single hydraulic device having a drive shaft and an output shaft, which are coaxial and engage respective groups of gears forming part of a row of axially fixed gears. The input and output shafts are axially slidable to engage a greater or a lower number of gears, in order to vary the angular speed of the output shaft.

[0007] The object of the present invention is to provide a rotary pump with a variable flow rate, particularly for oil, which makes it possible to solve the above-described problems simply and economically.

[0008] According to the present invention, a rotary pump with a variable capacity, particularly for oil, is provided, as defined in claim 1.

[0009] The invention will now be described with reference to the attached drawings, which illustrate a non-limiting embodiment of it, in which:

• Figure 1 illustrates in perspective, and with parts removed for the sake of clarity, a preferred embodiment of the pump with a variable flow rate, particularly for oil, produced according to the present invention;
• Figure 2 is a perspective view of a detail of the pump in Figure 1; and
• Figure 3 is a further perspective view of the pump in Figure 1, with parts illustrated in cross-section, according to the line III-III in Figure 2.

[0010] In Figure 1, 1 illustrates a pump with a variable flow rate, in particular a pump which can be fitted in a motor vehicle (not illustrated), in order to convey oil to a lubrication circuit of an internal combustion engine (not illustrated) of the motor vehicle itself.

[0011] With reference to the attached Figures, the pump 1 is of the gear type, and comprises a support body 2, which can be connected integrally, in a manner which is known and is not described in detail, to a portion of the engine, and has a suction mouth 3 (Figure 2) which can be connected to an oil tank (not illustrated), and a delivery mouth 4, which can be connected to the lubrication or delivery circuit. The body 2 delimits a cavity 5, which communicates with the exterior by means of the mouths 3 and 4, and accommodates two sets 6 and 7 of wheels respectively 10 and 11, which are toothed on the exterior.

[0012] The wheels 10, 11 of each set 6, 7 are superimposed on one another along respective axes 12 and 13, which are parallel to one another, and each engage with a corresponding wheel 11, 10 of the other set. The wheels 10, 11 all have the same axial thickness, they are disposed in fixed axial positions, and can rotate around the corresponding axes 12 and 13, in order to convey oil from the mouth 3 to the mouth 4 by means of a plurality of compartments 14, which are delimited by the body 2 and by the wheels 10, 11 themselves. The wheels 11 are keyed in an idle manner onto a cylindrical pin 15 (Figure 2) which is connected to the body 2, whereas at least some of the wheels 10 are rotated by a coaxial shaft 16, which is connected to the body 2, in a fixed axial position and in a rotary manner.

[0013] The shaft 16 comprises an external end section 17, onto which there is keyed, in a fixed position, a gear 18 which is actuated by a drive shaft (not illustrated) of the motor vehicle, by means of a chain (not illustrated) which is wound around the gear 18 itself.

[0014] The shaft 16 additionally comprises a grooved end section (not visible), onto which there is keyed a coaxial body 20, which is in the shape of a cup, and is connected to the grooved section itself in a manner which is axially sliding and angularly fixed. The body 20 is delimited externally by a lateral surface 21, which has two flattened parts 22, it is complementary to through axial seats 23 provided in the wheels 10, and engages the seats 23 themselves in a manner which is axially sliding and angularly fixed.

[0015] The body 20 constitutes part of a regulation unit 25, in order to vary the flow rate of the pump 1 according to the delivery pressure of the oil.

[0016] The unit 25 also comprises a pin 26 which is coaxial relative to the body 20, disposed on the side opposite the shaft 16, and comprises an axial end 27, which abuts the body 20, has in transverse cross-section the same outer profile as the body 20, and comprises two integral projections 28, which are opposite the body 20 itself.

[0017] The pin 26 defines the mobile unit of a single-effect hydraulic actuator 29, which constitutes part of the unit 25, and comprises a pre-loaded spring 30, which is interposed axially between the body 20 and an axial shoulder 31 of the shaft 16. The actuator 29 additionally comprises a control chamber 32, which is provided in a hollow portion 33, which, in its interior, has a transverse cross-section which is complementary to that of the end 27, is delimited by the end 27 itself, and communicates with the mouth 4 via a duct 34. Thus, in relation to the portion 33, the pin 26 is angularly fixed, and slides axially in a manner sealed against fluids, under the action of the pressure in the chamber 32, in order to thrust the body 20 against the resilient action of the spring 30.

[0018] With reference to Figure 1, the pump 1 additionally comprises a hydraulic accumulator device 35, which in turn comprises a cylindrical cavity 36 provided in the body 2 along an axis 38. The cavity 36 is engaged in a manner which is axially sliding and sealed against fluids, by a plate 39, which, on opposite axial sides, delimits two chambers 40 and 41, of which the chamber 40 has a variable volume, and communicates with the mouth 4 via a passage not illustrated, whereas the chamber 41 is preferably put into communication with the tank, and accommodates a pre-loaded spring 42, which is interposed axially between the plate 39 itself and a fixed stop ring 43. The plate 39 is subject to the opposing thrusts of the pressure in the chamber 40 and the resilient action of the spring 42, in order to transfer oil between the chamber 40 and the mouth 4, according to the delivery pressure, and to compensate for any variations in the delivery pressure itself.

[0019] Starting from an outer edge, on part of the lateral surface which delimits the chamber 41, there is provided a groove 45, which also imparts to the device 35 the function of a safety by-pass valve. In use, as the delivery pressure increases, the spring 42 is compressed progressively by the plate 39, and the volume of the chamber 40 increases to a limit value which corresponds to a maximum delivery pressure level, when the chamber 40 enters into communication with the groove 45, and the oil flows from the chamber 40 towards the exterior.

[0020] Starting from an initial condition, in which the engine runs in conditions of minimum rotation, the resilient action of the spring 30 maintains the body 20 and the pin 26 in a position of end of travel, in which the projections 28 are supported against a base wall of the chamber 32, and the pin 26 is disconnected from the wheels 10, whereas the body 20 is connected to all the wheels 10, and rotates fully the sets 6 and 7, which thus define respectively the drive and driven rotors of the pump 1.

[0021] As the speed of rotation of the engine, and thus of the shaft 16 increases, the flow rate of the pump 1 increases, such that the delivery pressure also increases. When the pressure in the chamber 32 reaches a threshold value which is dependent on the pre-loading by the spring 30, the pin 26 and the body 20 move axially against the action of the spring 30 itself. During this displacement, the body 20 becomes detached from some wheels 10, whereas simultaneously, the pin 26 engages the seats 23 of the wheels 10, which are left free by the body 20. When a position of equilibrium has been reached (indicated schematically by the broken line in Figure 3), only a part A of the sets 6, 7 is rotated by the body 20, and defines the drive and driven rotors of the pump 1, whereas a remaining part B of the sets 6, 7 themselves is maintained in a fixed position by the pin 26, such that the volume of each compartment 14 which conveys oil decreases in relation to the above-described initial condition.

[0022] If the pressure in the chamber 32 decreases, for example owing to an increase of oil used by the delivery circuit, or to a decrease in the speed of the shaft 16, the pin 26 and the body 20 withdraw under the thrust of the spring 30, such that the body 20 engages with other wheels 10, so that the number of wheels of the part A and the volume of the compartments 14 increase, whereas the number of wheels of the part B decreases.

[0023] It is apparent from the foregoing that the cylinder capacity of the pump 1 is variable, owing to the unit 25, which thus makes it possible to regulate the flow rate output from the mouth 4 simply and efficiently, according to the delivery pressure, without wasting energy, which is not then actually used, in compressing flow rates of oil, which on the other hand is the situation in the known solutions which are provided with by-pass valves.

[0024] In fact, the unit 25 regulates the number of wheels 10 and 11 which belong to the parts A and B of the sets 6 and 7, and thus, the axial thickness of the drive and driven rotors, which are actually defined by the rotary part A of the sets 6 and 7 themselves. Thus, the unit 25 varies the axial dimension of the mobile compartments 14, the volume of which is proportional to the flow rate of oil distributed by the pump 1. By blocking angularly the part B of the sets 6 and 7, the pin 26 prevents this part B from being driven by friction by the part A.

[0025] In addition, the flow rate is regulated accurately, since the sets 6, 7 comprise a relatively large number of wheels 10, 11, which have the same axial thickness, and, simultaneously, the unit 25 is very simple and compact.

[0026] Finally, the device 35 makes it possible to compensate for any temporary and relatively sudden drops and peaks of pressure in the delivery circuit, and, simultaneously, to allow oil to be vented when the delivery pressure reaches a maximum safety level.

[0027] Finally, it is apparent from the foregoing description that modifications and variants which do not depart from the field of protection of the present invention as defined in the appended claims can be made to the pump 1 described and illustrated.

[0028] In particular, the pump 1 could be of the lobe type instead of of the gear type, and/or it could be used for applications other than that indicated.

[0029] In addition, the number and dimensions of the wheels 10 and 11, and the shape of the pin 26 and of the body 20 could be different from those illustrated, and/or a drive other than of the chain type could be provided.

Claims

1. Rotary pump (1) with a variable flow rate, particularly for oil, comprising:

- a support body (2), with a suction mouth (3), which can be connected to a tank for a fluid, and a delivery mouth (4), which can be connected to a circuit for delivery of the fluid itself;

- a toothed drive rotor (6) and a driven rotor (7), which engage with one another and are accommodated in said support body (2) such as to rotate around their own axes (12, 13), in order, in use, to convey said fluid from said suction mouth (3) to said delivery mouth (4);

- automatic regulating means (25) to vary the axial dimension of said rotors (6, 7) according to the actual delivery pressure of said fluid;

- a drive shaft (16), which is connected to said support body (2) in a fixed axial position and in a rotary manner and is coaxial with said toothed drive rotor (6);

characterised by comprising two sets (6, 7) of toothed wheels (10, 11), each wheel being superimposed coaxially on the wheels (10, 11) of the same set (6, 7), being located in axially fixed position, and engaging with a corresponding wheel (11, 10) of the other set (7, 6); said automatic regulating means (25) comprising:

- first angular means (20) for constraint, in order to render angularly integral, in each said set (6, 7), a first plurality of wheels (A), which defines a corresponding said rotor moved by said drive shaft (16),

- second angular means (26) for constraint, which are supported by said support body (2), in order to lock angularly, with respect to said support body (2), remaining second plurality of wheels (B),

- actuating means (29) to vary the quantity of wheels (10, 11) which belong to said first and second plurality of wheels (A, B), according to the actual delivery pressure.

2. Pump according to claim 1, characterised in that said first angular means for constraint comprise a first body (20), which is connected to said drive shaft (16) in axially sliding and angularly fixed manner and engages the first plurality of wheels (A) defining said toothed drive rotor, in axially sliding and angularly fixed manner.

3. Pump according to claim 1 or 2, characterised in that said first and second means (20, 26) for angular constraint are associated with a single said set (6) of wheels (10); and in that said actuating means comprise a single actuator (29) to regulate both said first and second means (20, 26) for angular constraint.

4. Pump according to claim 3, characterised in that said single actuator (29) is a single-effect hydraulic actuator, and comprises pre-loaded resilient means (30), in order to keep said second means (26) for angular constraint disconnected from the corresponding said set (6) of wheels (10).

5. Pump according to claims 4 and 2, characterised in that said resilient means (30) comprise a pre-loaded spring axially interposed between said first body (20) and an axial shoulder (31) of said drive shaft (16).

6. Pump according to claim 4 or 5, characterised in that said first and second means (20, 26) for angular constraint respectively comprise a first (20) and a second (26) body, which engage through axial seats made in the wheels of the corresponding said set (6), in a manner which is angularly fixed and axially sliding; said second body (26) constituting part of said single actuator (29), and defining an axial thrust unit of said first body (20).

7. Pump according to Claim 6, characterised in that said second body (26) is connected such as to be sealed against fluids, in a manner which is axially sliding and angularly fixed, to a hollow portion (33) of said support body (2), which communicates with said delivery mouth (4).

8. Pump according to claim 6 or 7, characterised in that said second body (26) comprises an end portion (27) which, in transverse cross-section, has the same outer profile as said first body (20), and at least one end projection (28) opposite the first body (20) itself.

9. Pump according to any one of the preceding claims, characterised in that said wheels (10, 11) have the same axial dimension.

10. Pump according to any one of the preceding claims, characterised in that it additionally comprises hydraulic accumulator means (35), comprising a chamber (40) with a variable volume, which communicates with said delivery mouth (4).

11. Pump according to claim 10, characterised in that said chamber (40) with a variable volume is provided in said support body (2), and is delimited by a plate (39) which slides in a manner which is sealed against fluids, in a seat (36) provided in the support body (2) itself.

12. Pump according to claim 10 or 11, characterised by additionally comprising means (45) for venting said fluid, which constitute part of said hydraulic accumulator means (35).

13. Pump according to claim 12, characterised in that said means (45) for venting comprise a channel (45) which communicates with said chamber (40) with a variable volume, when the volume itself reaches a maximum limit value.

14. Pump according to claims 12 and 13, characterised in that said channel (45) is provided in part of the surface of lateral delimitation of said seat (36).

Ansprüche

1. Rotationspumpe (1) mit variablem Durchfluss, insbesondere für Öl, welche aufweist:

- einen Trägerkörper (2) mit einer Ansaugöffnung (3), die mit einem Tank für ein Fluid verbunden werden kann, und einer Abgabeöffnung (4), die mit einem Kreis zur Abgabe des Fluids selbst verbunden werden kann;

- einen gezahnten Antriebsrotor (6) und einen angetriebenen Rotor (7), die ineinander eingreifen und in dem Trägerkörper (2) derart aufgenommen sind, dass sie um ihre eigenen Achsen (12, 13) drehen, damit im Betrieb das Fluid von der Ansaugöffnung (3) zu der Abgabeöffnung (4) transportiert wird;

- automatische Reguliermittel (25) zur Änderung der axialen Abmessung der Rotoren (6, 7) gemäß dem tatsächlichen Förderdruck des Fluids;

- eine Antriebswelle (16), die mit dem Trägerkörper (2) in einer festen axialen Position und drehbar verbunden ist, und die mit dem gezahnten Antriebsrotor (6) koaxial ist;

dadurch gekennzeichnet, dass sie zwei Sätze (6, 7) aus Zahnrädern (10, 11) umfasst; wobei jedes Rad koaxial auf die Räder (10, 11) des gleichen Satzes (6, 7) aufgesetzt ist, in einer axial festen Position angeordnet ist und mit einem entsprechenden Rad (10, 11) des anderen Satzes (7, 6) ineinander greift; wobei die automatischen Reguliermittel Mittel (25) umfassen:

- erste eckige Mittel (20) zur Beschränkung, zur winkelmäßigen Integrierung, einer ersten Anzahl von Rädern (A) in jedem Satz (6, 7), die einen durch die Antriebswelle (16) bewegten entsprechenden Rotor definiert,

- zweite eckige Mittel (26) zur Beschränkung, die durch den Trägerkörper (2) gehaltert werden, zur winkelmäßigen Feststellung, in Bezug auf den Trägerkörper (2), der verbleibenden zweiten Anzahl von Rädern (B),

- Betätigungsmittel (29) zur Veränderung der Anzahl der Räder (10, 11), die zu der ersten und zweiten Anzahl von Rädern (A, B) gehören, gemäß dem tatsächlichen Förderdruck.

2. Pumpe gemäß Anspruch 1, dadurch gekennzeichnet, dass die ersten Winkelmittel zur Beschränkung einen ersten Körper (20) umfassen, der mit der Antriebswelle (16) in einer axial gleitenden und in einer winkelmäßig festen Art und Weise verbunden ist und in die erste Anzahl von Rädern (A), die den gezahnten Antriebsrotor festlegen, in einer axial gleitenden und winkelmäßig festen Art und Weise eingreift.

3. Pumpe gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass die ersten und zweiten Mittel (20, 26) zur Winkelbeschränkung einem einzigen Satz (6) von Rädern (10) zugeordnet ist; und dadurch dass die Betätigungsmittel ein einziges Stellglied (29) zur Regulierung sowohl der ersten und zweiten Mittel (20, 26) zur Winkelbeschränkung umfassen.

4. Pumpe gemäß Anspruch 3, dadurch gekennzeichnet, dass das einzige Stellglied (29) ein einfachwirkendes hydraulisches Stellglied ist und vorgespannte Federmittel (30) umfasst, damit die zweiten Mittel (26) zur Winkelbeschränkung getrennt von dem entsprechenden Satz (6) von Rädern (10) gehalten werden.

5. Pumpe gemäß Anspruch 4 und 2, dadurch gekennzeichnet, dass die Federmittel (30) eine vorgespannte Feder umfassen, die axial zwischen den ersten Körper (20) und einen axialen Ansatz (31) der Antriebswelle (16) eingefügt ist.

6. Pumpe gemäß Anspruch 4 oder 5, dadurch gekennzeichnet, dass die ersten und zweiten Mittel (20, 26) zur Winkelbeschränkung entsprechend einen ersten (20) und zweiten (26) Körper umfassen, die durch die in den Rädern des entsprechenden Satzes (6) gebildeten axialen Sitze eingreifen, in einer Art und Weise, die winkelmäßig fest und axial gleitend ist; wobei der zweite Körper (26) einen Teil des einzigen Stellgliedes (29) bildet und eine Axialdruckeinheit des ersten Körpers (20) definiert.

7. Pumpe gemäß Anspruch 6, dadurch gekennzeichnet, dass der zweite Körper (26) fluiddicht, axial gleitend und winkelmäßig fest, mit einem Hohlabschnitt (33) des Trägerkörpers (2), der mit der Abgabeöffnung (4) in Verbindung steht, verbunden ist.

8. Pumpe gemäß Anspruch 6 oder 7, dadurch gekennzeichnet, dass der zweite Körper (26) einen Endabschnitt (27), der im Querschnitt das gleiche Außenprofil wie der erste Körper (20) aufweist, und wenigstens einen dem ersten Körper (20) selbst gegenüberliegenden Endfortsatz (28) aufweist.

9. Pumpe gemäß einem der vorherigen Ansprüche, dadurch gekennzeichnet, dass die Räder (10, 11) die gleiche axiale Abmessung aufweisen.

10. Pumpe gemäß einem der vorherigen Ansprüche, dadurch gekennzeichnet, dass die Pumpe zusätzlich Hydraulikspeichermittel (35) umfasst, die eine Kammer (40) mit einem variablen Volumen, die mit der Abgabeöffnung (4) verbunden ist, aufweisen.

11. Pumpe gemäß Anspruch 10, dadurch gekennzeichnet, dass die Kammer (40) mit einem variablen Volumen in dem Trägerkörper (2) vorgesehen ist und durch eine Platte (39), die fluiddicht in einem in dem Trägerkörper (2) selbst vorgesehen Sitz (36) gleitet, abgegrenzt ist.

12. Pumpe gemäß Anspruch 10 oder 11, dadurch gekennzeichnet, dass die Pumpe zusätzlich Mittel (45) zur Entlüftung des Fluids umfasst, die einen Teil der Hydraulikspeichermittel (35) bilden.

13. Pumpe gemäß Anspruch 12, dadurch gekennzeichnet, dass die Mittel (45) zur Entlüftung einen Kanal (45) umfassen, der mit der Kammer (40) mit einem variablen Volumen in Verbindung steht, wenn das Volumen selbst einen Maximalgrenzwert erreicht.

14. Pumpe gemäß Anspruch 12 und 13, dadurch gekennzeichnet, dass der Kanal (45) in einem Teil der Oberfläche der seitlichen Abgrenzung des Sitzes (36) vorgesehen ist.

Revendications

1. Pompe rotative (1) avec un débit variable, en particulier pour l'huile, comprenant:

- un corps de support (2) avec une embouchure d'aspiration (3) qui peut être connectée à un réservoir pour un fluide et une embouchure de distribution (4), qui peut être connectée à un circuit pour distribuer le fluide lui-même ;

- un rotor d'entraînement denté (6) et un rotor entraîné (7), qui s'engagent l'un l'autre et qui sont logés dans ledit corps de support (2) de telle manière à tourner autour de leurs propres axes (12, 13) afin, en utilisant, de transporter ledit fluide depuis ladite embouchure d'aspiration (3) vers ladite embouchure de distribution (4) ;

- des moyens de régulation automatique (25) pour modifier la dimension axiale desdits rotors (6, 7) selon la pression de distribution réelle dudit fluide ;

- un arbre d'entraînement (16) qui est connecté audit corps de support (2) dans une position axiale fixe et d'une manière rotative et qui est coaxial avec ledit rotor d'entraînement denté (6) ;

caractérisée en ce qu'elle comprend deux ensembles (6, 7) de roues dentées (10, 11), chaque roue étant superposée de manière coaxiale sur les roues (10, 11) du même ensemble (6, 7) étant situés dans une position fixe axialement et s'engageant avec une roue correspondante (11, 10) de l'autre ensemble (7, 6) ; lesdits moyens de régulation automatique (25) comprenant:

- des premiers moyens angulaires (20) pour contraindre, afin de rendre intégral de manière angulaire, dans chaque dit ensemble (6, 7), une première pluralité de roues (A), qui définit un dit rotor correspondant déplacé par ledit arbre d'entraînement (16),

- des deuxièmes moyens angulaires (26) pour contraindre, qui sont supportés par ledit corps de support (2), afin de verrouiller de manière angulaire, par rapport audit corps de support (2), la deuxième pluralité restante de roues (B),

- des moyens d'actionnement (29) pour modifier la quantité de roues (10, 11) qui appartiennent à ladite première et deuxième pluralité de roues (A, B) selon la pression de distribution réelle.

2. Pompe selon la revendication 1, caractérisée en ce que lesdits premiers moyens angulaires pour la contrainte comprennent un premier corps (20), qui est connecté audit arbre d'entraînement (16) d'une manière pouvant coulisser dans le sens axial et fixe de manière angulaire et engage la première pluralité de roues (A) définissant ledit rotor d'entraînement denté, d'une manière axialement coulissante et fixe de manière angulaire.

3. Pompe selon la revendication 1 ou 2, caractérisée en ce que lesdits premiers et deuxièmes moyens (20, 26) pour la contrainte angulaire, sont associés avec un seul dit ensemble (6) de roues (10) ; et en ce que lesdits moyens d'actionnement comprennent un seul actionneur (29) pour réguler lesdits premiers et deuxièmes moyens (20, 26) pour la contrainte angulaire.

4. Pompe selon la revendication 3, caractérisée en ce que ledit actionneur unique (29) est un actionneur hydraulique à effet unique et comprend des moyens résilients pré chargés (30), afin de maintenir lesdits deuxièmes moyens (26) pour la contrainte angulaire déconnectés dudit ensemble correspondant (6) de roues (10).

5. Pompe selon les revendications 4 et 2, caractérisée en ce que lesdits moyens résilients (30) comprennent un ressort pré chargé interposé de manière axiale entre ledit premier corps (20) et un épaulement axial (31) dudit arbre d'entraînement (16).

6. Pompe selon la revendication 4 ou 5, caractérisée en ce que lesdits premiers et deuxièmes moyens (20, 26) pour la contrainte angulaire comprennent respectivement un premier (20) et un deuxième (26) corps, qui s'engagent par l'intermédiaire de sièges axiaux réalisés dans les roues dudit ensemble correspondant (6), d'une manière qui est fixe dans le sens angulaire et coulissante dans le sens axial ; ledit deuxième corps (26) constituant une partie dudit actionneur unique (29) et définissant une unité de poussée axiale dudit premier corps (20).

7. Pompe selon la revendication 6, caractérisée en ce que ledit deuxième corps (26) est connecté de telle manière à être étanche contre les fluides, d'une manière qui est coulissante dans le sens axial et fixe dans le sens angulaire, à une partie creuse (33) dudit corps de support (2), qui communique avec ladite embouchure de distribution (4).

8. Pompe selon la revendication 6 ou 7, caractérisée en ce que ledit deuxième corps (26) comprend une partie d'extrémité (27) qui, dans la section transversale, a le même profil externe que ledit premier corps (20) et au moins une saillie d'extrémité (28) opposée au premier corps (20) lui-même.

9. Pompe selon l'une quelconque des revendications précédentes, caractérisée en ce que lesdites roues (10, 11) ont la même dimension axiale.

10. Pompe selon l'une quelconque des revendications précédentes, caractérisée en ce qu'elle comprend en outre des moyens formant accumulateur hydraulique (35), comprenant une chambre (40) avec un volume variable, qui communique avec ladite embouchure de distribution (4).

11. Pompe selon la revendication 10, caractérisée en ce que ladite chambre (40) avec un volume variable est prévue dans ledit corps de support (2) et est délimitée par une plaque (39) qui coulisse d'une manière qui est étanche contre les fluides, dans un siège (36) prévu dans le corps de support (2) lui-même.

12. Pompe selon la revendication 10 ou 11, caractérisée en ce qu'elle comprend en outre des moyens (45) pour ventiler ledit fluide, qui constituent une partie desdits moyens formant accumulateur hydraulique (35).

13. Pompe selon la revendication 12, caractérisée en ce que lesdits moyens (45) pour ventiler comprennent un canal (45) qui communique avec ladite chambre (40) avec un volume variable, lorsque le volume lui-même atteint une valeur limite maximale.

14. Pompe selon les revendications 12 et 13, caractérisée en ce que ledit canal (45) est prévue dans une partie de la surface de délimitation latérale dudit siège (36).

Drawing