An internal gear fluidic machine, in particular a pump for the lubrication circuit of a motor vehicle engine, comprises an operating part including an external gear (2) and an internal gear (4), which is housed within an axial cavity (25) of the external gear (2) and meshes with the latter. The exte
An internal gear fluidic machine, in particular a pump for the lubrication circuit of a motor vehicle engine, comprises an operating part including an external gear (2) and an internal gear (4), which is housed within an axial cavity (25) of the external gear (2) and meshes with the latter. The external gear (2) is associated with a translating mechanism (8, 22), arranged to cause an axial sliding thereof relative to the internal gear (4) in order to vary the capacity and the fluid flow rate of the machine. The translating mechanism (8, 22) defines a first capacity, adjustment space (24) in communication with a high pressure chamber (48) of the machine, and a second capacity adjustment space (15) where pressure conditions exist that are dependent on the operating conditions of an element, different from the high pressure chamber (48), of a fluidic circuit in which the machine (1) is connected. The translating mechanism (8, 22) causes the sliding of the external gear (2) in response to the pressure conditions existing in the first or the second capacity adjustment spaces (24, 15), or in response to the combination of the pressure conditions existing in both spaces. The invention also concerns a method of varying the capacity of an internal gear fluidic machine.
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1. A fluidic machine with gears, comprising a supporting part where there are formed a low pressure chamber and a high pressure chamber communicating with low pressure and high pressure sections, respectively, of a fluidic circuit in which the machine is connected, and an operating part for transfer
1. A fluidic machine with gears, comprising a supporting part where there are formed a low pressure chamber and a high pressure chamber communicating with low pressure and high pressure sections, respectively, of a fluidic circuit in which the machine is connected, and an operating part for transferring a fluid between said low pressure and high pressure chambers, the operating part being mounted within the supporting part and including in turn: an external gear, arranged to rotate about a first axis and having an internal toothing with a first number of teeth; andan internal gear, which is housed within an axial cavity of the external gear, is arranged to rotate about a second axis different from the first axis and has an external toothing with a second number of teeth, arranged to mesh with the internal toothing of the external gear with only partial fluid seal, the teeth of both gears defining fluid chambers the volume of which changes during rotation and through which the fluid is transferred from a machine inlet connected to one of the low pressure and high pressure chambers to a machine outlet connected to the other one of the low pressure and high pressure chambers;wherein one of the internal and external gears is mounted in an axially fixed position and the other gear is associated with a translating mechanism, arranged to cause an axial sliding thereof relative to the gear mounted in the axially fixed position in order to vary the machine capacity by changing the axial extension of an area over which the teeth of both gears mesh, and wherein the translating mechanism defines a first capacity adjustment space in communication with the high pressure chamber and is arranged to slide in response to first pressure conditions existing in the first capacity adjustment space in order to make the axially slidable gear slide,wherein the translating mechanism further defines a second capacity adjustment space where second pressure conditions exist that are dependent on operating conditions of an element of the fluidic circuit different from the high pressure chamber of the machine, the translating mechanism being axially slidable in the supporting part either in response also to the pressure conditions existing in the second capacity adjustment space, or in response to a combination of the pressure conditions existing in the first and second capacity adjustment spaces;said external gear and said translating mechanism are arranged to define radial oriented openings for fluid inlet/outlet into/from said fluid chambers in order to obtain a radial feed of said fluidic machine; andwherein said translating mechanism comprises an external ring which is rigidly connected for the rotational and translational movements to said external gear. 2. The machine as claimed in claim 1, wherein at the coupling region of said external gear and said ring, the edge of said external gear being provided with cuts and the edge of said ring being provided with respective cuts; said cuts defining said radial oriented openings. 3. The machine as claimed in claim 2, wherein said external ring is connected to said external gear by means of an interference fit. 4. The machine as claimed in claim 3, wherein said external ring is connected on the bottom end of said external gear. 5. The machine as claimed in claim 4, wherein said external ring abuts against a step of the surface of said external gear. 6. The machine as claimed in claim 1, wherein the machine is a pump connected in the lubrication circuit of an engine of a motor vehicle, and the first capacity adjustment space is in communication with a delivery side of the pump. 7. The machine as claimed in claim 1, wherein the axially slidable gear is rigidly connected to or is formed as an integral body with the translating mechanism, and the first capacity adjustment space is a chamber formed internally of the translating mechanism. 8. The machine as claimed in claim 2, wherein the axially slidable gear is rigidly connected to or is formed as an integral body with the translating mechanism, and the first capacity adjustment space is a chamber formed internally of the translating mechanism. 9. The machine as claimed in claim 6, wherein the axially slidable gear is rigidly connected to or is formed as an integral body with the translating mechanism, and the first capacity adjustment space is a chamber formed internally of the translating mechanism. 10. The machine as claimed in claim 7, wherein the translating mechanism further includes a first closing body at a first axial end, and in that the chamber forming the first capacity adjustment space is defined between the first closing body, the walls of the axial cavity of the slidable gear and a body closing said cavity, which body is arranged in an axially fixed position in the same cavity and has, over part of a side surface, an external toothing complementary with the toothing of the slidable gear and arranged to sealingly mesh with such a toothing in order to separate the fluid chambers from the first capacity adjustment space while enabling the sliding of the slidable gear for the capacity adjustment. 11. The machine as claimed in claim 10, wherein the translating mechanism has, at an end opposite to the first closing body, an external ring where a second closing body is received in an axially fixed position, and in that the second capacity adjustment space is defined between an edge of the external ring, the second closing body and the walls of a cavity formed in the supporting part and receiving such an external ring and the second closing body. 12. The machine as claimed in claim 11, wherein the second closing body is arranged, in a rest position of the translating mechanism determining a maximum capacity of the machine, to abut against an adjacent end of the slidable gear and is arranged, in positions of the translating mechanism translated relative to the rest position, to define, together with such an end of the slidable gear and the external ring of the translating mechanism, a secondary chamber establishing a fluidic short-circuit between the low pressure chamber and the high pressure chamber. 13. The machine as claimed in claim 1, wherein the second capacity adjustment space is arranged to receive pressurised lubrication fluid sent back from an engine to the fluidic machine, and the translating mechanism is arranged to make the slidable gear slide when the pressure of the lubrication fluid in the first or the second capacity adjustment space exceeds a given threshold. 14. The machine as claimed in claim 2, wherein the second capacity adjustment space is arranged to receive pressurised lubrication fluid sent back from an engine to the fluidic machine, and the translating mechanism is arranged to make the slidable gear slide when the pressure of the lubrication fluid in the first or the second capacity adjustment space exceeds a given threshold. 15. The machine as claimed in claim 6, wherein the second capacity adjustment space is arranged to receive pressurised lubrication fluid sent back from the engine to the pump, and the translating mechanism is arranged to make the slidable gear slide when the pressure of the lubrication fluid in the first or the second capacity adjustment space exceeds a given threshold. 16. The machine as claimed in claim 1, wherein the machine is a pump and is associated with an external management logic establishing the capacity of the pump, and hence the flow rate of the lubrication fluid, depending on the operating conditions of an engine, and in that: the delivery side of the pump is connected to a pressurised fluid distribution valve associated with a control body which is controlled by the external management logic and is arranged to set the distribution valve in a first operating condition, when the pump is to operate at maximum capacity, or in a second operating condition, when the capacity of the pump is to be changed; andthe second capacity adjustment space is in communication, through the distribution valve, with either a low pressure point of the lubrication circuit, in the first condition of the distribution valve, or the delivery side of the pump, in the second condition of the distribution valve. 17. A method of varying the capacity of a fluidic machine with gears including an external gear, arranged to rotate about a first axis and having an internal toothing with a first number of teeth, and an internal gear, which is received in an axial cavity of the external gear, is made to rotate about a second axis different from the first axis and has an external toothing with a second number of teeth meshing with the internal toothing of the external gear with only partial fluid seal, the teeth of both gears defining fluid chambers the volumes of which change during rotation and through which a fluid is transferred from a machine inlet to a machine outlet, the method including the steps of: creating a first capacity adjustment space in communication with a high pressure chamber of the machine;making one of the gears slide relative to the other, in response to first pressure conditions existing in the first capacity adjustment space, in order to change the axial extension of an area over which the teeth of both gears mesh;creating a second capacity adjustment space;establishing in the second capacity adjustment space second pressure conditions that are dependent on operating conditions existing in an element, different from the high pressure chamber, of a fluidic circuit in which the machine is connected;making the axially slidable gear slide either in response also to the pressure conditions existing in the second capacity adjustment space, or in response to a combination of the pressure conditions existing in the first and second capacity adjustment spaces; andmaking said fluid transfer into/from said fluid chambers from said machine inlet/to said machine outlet through radial oriented openings defined by said external gear and said translating mechanism, so as to obtain a radial feed of said fluidic machine; andwherein said fluidic machine further comprises an external ring rigidly connected for the rotational and translational movements to said external gear. 18. The method as claimed in claim 17, wherein the step of making said fluid transfer into/from said fluid chambers is performed by making said fluid to pass through cuts provided at the edge of said external gear and respective cuts provided at the edge of said external ring, said cuts being provided at the coupling region of said external gear and said ring and defining said radial oriented openings. 19. The method as claimed in claim 17, wherein the fluidic machine is a pump connected in the lubrication circuit of an engine of a motor vehicle, and in that the step of establishing second pressure conditions in the second capacity adjustment space is performed either by sending back pressurised lubrication fluid from the engine to such a second space, or by connecting the second space to either a low pressure point of the lubrication circuit, if the operating conditions of the engine demand a maximum capacity of the pump, or a delivery side of the pump, if the operating conditions of the engine demand a capacity of the pump lower than the maximum capacity. 20. The method as claimed in claim 18, wherein the fluidic machine is a pump connected in the lubrication circuit of an engine of a motor vehicle, and in that the step of establishing second pressure conditions in the second capacity adjustment space is performed either by sending back pressurised lubrication fluid from the engine to such a second space, or by connecting the second space to either a low pressure point of the lubrication circuit, if the operating conditions of the engine demand a maximum capacity of the pump, or a delivery side of the pump, if the operating conditions of the engine demand a capacity of the pump lower than the maximum capacity.
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이 특허에 인용된 특허 (7)
Pfuhler Ulrich (Ulm DEX), Gear pump for feeding of fluids.
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