DE112015006483B4 - Electric evaporation pump for motor vehicles - Google Patents

Abstract

An automotive electric evaporation pump (10) having a gas suction port (50) and a gas discharge port (52), the pump comprising:an encapsulated electric motor (30) with a motor stator (32) comprising electromagnetic stator coils (33), and with a rotor device (16), which contains an impeller (18) with impeller blades (19), a rotatable rotor shaft (20) and a motor rotor (34), a separation encapsulation device (82) which in a gas-free Section arranged motor stator (32) fluidly separates from the motor rotor (34) arranged in a gas section, and a bearing device (36) which is arranged axially in the gas section between the motor rotor (34) and the pump wheel (18) and the motor rotor (34) rotatably mounted, wherein the separation encapsulation device (82) has an encapsulation body (60) with a cylinder section (84), the cylinder section (84) directly carrying the bearing device (36), and the encapsulation body (60) has an electronics chamber (83) which has an electronic motor control (40), separates from the gas section, and wherein the encapsulation body (60) is a sheet metal encapsulation body.

Description

The invention relates to an electric evaporation pump for motor vehicles, which has a gas inlet port and a gas outlet port.

Out of DE 698 04 745 T2 , US 2014/0017073 A1 and GB 2496014 A Electric motor vehicle liquid pumps are known in which a separating capsule device fluidically separates the motor stator from the motor rotor.

Electric evaporation pumps are used in motor vehicles having a fuel tank to pump fuel vapor from a fuel vapor source to a fuel vapor destination. The fuel vapor source can be the fuel tank itself or a vapor absorption unit that is filled, for example, with activated carbon as an absorption medium. Since the absorption unit has a limited total absorption capacity, the fuel vapor gas absorbed by the absorbent must be discharged from time to time. The extraction process is performed by the electric evaporation pump, which is arranged in fluid communication between the vapor absorption unit and the fuel vapor target, which may be, for example, the gas inlet manifold of an internal combustion engine. Alternatively, the evaporation pump is used to degas the cylinder cover or crankcase of the engine.

In gas pumps, the typical axial arrangement of the pump components electric motor, pump wheel and motor electronics is designed such that the electric motor is arranged axially in the middle and the electronics chamber, which has the motor control electronics, is arranged at one axial end and the pump wheel is arranged at the other axial end.

It is the object of the invention to create an electric evaporation pump for motor vehicles that has a compact design and is easy to assemble.

This task is achieved by an electric evaporation pump for motor vehicles with the features defined in claim 1.

The electric evaporation pump according to the invention is provided with a gas suction port and a gas discharge port. The gas intake port may be fluidly connected to a fuel vapor source, such as a fuel tank or a fuel vapor absorption unit. The gas exhaust port may be fluidly connected to a fuel vapor target such as a condenser unit or to a gas inlet manifold of an internal combustion engine.

The evaporation pump includes an encapsulated electric motor that includes a motor stator with at least two electromagnetic stator coils and a rotor device that includes an impeller with impeller vanes, a rotatable rotor shaft, and a motor rotor. The motor rotor is preferably designed as a permanently magnetized rotor body. The evaporation pump is provided with a separation encapsulation device which separates the motor stator provided in a gas-free section from the motor rotor provided in a gas section. The pumped gas is present in the gas section. The gas-free section is fluidically separated from the gas section by means of the separation encapsulation device, so that no pumped gas is present in the gas-free section. The gas-free section can be filled with air, but is fluidly isolated from the gas section in which the pumped gas is located.

The gas pump is provided with a bearing device which is arranged in the gas section and which rotatably supports the motor rotor. The bearing device can be a roller bearing, a friction bearing or a combination of both bearing types. The bearing device is preferably provided with roller bearings, due to the high rotational speed and the lack of bearing lubrication options with friction bearings.

The separation encapsulation device can have an encapsulation body with a cylindrical section. The cylinder section of the encapsulation body directly supports the storage device. The encapsulation body further separates a control electronics chamber, which has an electric motor control, from the gas section. In other words, the separation encapsulation has two functions, namely the direct holding of the bearing device and the fluidic isolation of the electronics chamber from the gas section of the pump. The encapsulation body is a sheet metal encapsulation body.

The bearing device, which contains the rotor device, can be pre-assembled on the cylinder section of the encapsulation body, and then the encapsulation body can be assembled together with the motor stator, so that the pump is realized as a simple assembly.

According to a preferred embodiment of the invention, the electronics chamber is arranged axially between the motor stator and the pump wheel. Since the evaporation pump only pumps gas that has a relatively low heat capacity, cooling the engine control electronics is somewhat problematic. By arranging the electronics chamber Finally, the motor control electronics near the pump wheel section, the cooling of the electronics chamber and the control electronics arranged therein can be significantly improved - compared to an arrangement of the motor control electronics at the axial end of the evaporation pump and away from the relatively strong gas flow in the area around the pump wheel.

Preferably, the electronics chamber is annular and surrounds the storage device. This results in a compact design of the evaporation pump in the axial direction.

According to a preferred embodiment of the invention, the electronic motor control is provided with at least one power semiconductor for supplying power to the stator coils. The power semiconductor is thermally connected to the encapsulation body by a separate thermal connecting element. The thermal connection element is made of a material that conducts thermal energy twice as well as air.

According to a preferred embodiment, the electronic motor control has a printed circuit board which is arranged essentially in a radial plane. The encapsulation body is provided with a substantially radial annular disk portion, so that the printed circuit board and the radial disk portion of the encapsulation body can be arranged parallel and close to one another.

Preferably, the printed circuit board can be designed as an annular disk. This configuration enables a very effective and compact arrangement of the electronic motor control in the axial direction of the evaporation pump.

Preferably, the thermal connection element is arranged essentially in the axial direction and connects the power semiconductor to the radial annular disk section of the encapsulation body.

Preferably, the stator coils are arranged in a solid plastic housing body which supports the axial end of a cylinder section of the encapsulation body. The separation encapsulation device has at least two elements, namely the solid plastic housing body that separates the stator coils from the motor rotor and the separation encapsulation device that additionally separates the gas section from the gas-free section of the pump.

The storage device can be provided with an axial gas passage. The axial gas passage of the bearing device can be realized through spaces and gaps between the adjacent roller elements of a roller bearing. Alternatively or additionally, the axial gas passage of the storage device can also be provided as an axial groove or channel in a fixed part of the storage device or in the static frame structure supporting the storage device.

The rotor shaft may also be provided with an axial gas passage, and the impeller is provided with an axial gas outlet passage upstream of the impeller blades, so that a drying gas path is realized through the bearing device, the shaft gas passage and the impeller gas outlet passage. The pumped gas flows axially through the bearing device gas passage to the distal end of the gas section and then flows axially back in the direction of the impeller through the rotor shaft gas passage and finally through the impeller outlet passage.

When the rotor device rotates, the gas pressure at the center of the impeller, where the gas outlet passage is located, is relatively low compared to the gas pressure radially outside the impeller vanes. This causes a drying path gas stream to flow from the area located radially outside the impeller blades to the impeller gas outlet passage in the middle.

The impeller is preferably provided as an impeller with an axial impeller inlet and a radial impeller outlet.

As long as the rotor device rotates, a continuous gas flow is caused in the drying path, so that the gas section is continuously ventilated. Consequently, no condensate, fuel or water can appear or remain in the gas section, especially not in the inaccessible areas of the gas section. Since moisture and condensate are continuously avoided, corrosion in the gas section is significantly reduced and mechanical resistance to rotation is also significantly reduced.

In general, the rotor shaft gas passage can be implemented in the form of one or more axial grooves in the rotor shaft. According to a preferred embodiment, the shaft gas passage is formed by an axial shaft bore which extends over the entire axial length of the rotor shaft.

Preferably, the impeller gas outlet passage is formed by an axial central opening in the impeller body. In the central area of the pump wheel, the gas pressure is relatively low, so that there is an outlet opening in this area, which is the fluidic end of the drying gas away, can be used to generate a continuous drying gas path stream.

According to a preferred embodiment of the invention, an inlet gas passage of the drying gas path is formed by a circular gap between the rotatable impeller and a non-rotating part of the pump frame, the pump housing or another static part of the pump. The impeller is preferably provided with a base disk from which the impeller blades protrude axially. The inlet gas passage of the drying path is preferably formed by a circular gap between the impeller base disk and another circular static part of the pump.

According to a preferred embodiment of the invention, the gas inlet passage formed by the impeller and a non-rotating part of the pump frame or pump housing may be provided with a circular labyrinth seal so that the total radial inlet flow is limited and moderated to a maximum dry gas path rate that is sufficient to avoid concentration and moisture in the gas section.

Preferably, a motor rotor gas passage is formed by a circular gap between the motor rotor and the separation encapsulation device. As an alternative or in addition to the circular gap, an axial groove provided in the separation encapsulation device and/or in the motor rotor body may serve as a motor rotor gas passage.

An electronic motor control is preferably provided, which is arranged axially between the motor stator and the pump wheel and which preferably surrounds the bearing device. The electronic engine control supplies electrical energy to the electromagnetic stator coils based on a commutation scheme. The arrangement of the motor control electronics axially between the motor stator and the pump wheel enables good mechanical protection of the electronics against environmental influences.

An embodiment of the invention is described below in connection with the accompanying drawing, in which the figure shows a longitudinal cross section through the electric evaporation pump.

The figure shows an electric evaporation pump 10 for pumping fuel vapor from a fuel vapor source to a fuel vapor destination, for example from a fuel vapor absorption unit to an inlet manifold of an internal combustion engine. The gas pump 10 is suitable for pumping gas, but unsuitable for pumping a liquid. The gas pump 10 is provided with a pump housing 11 which has an axial gas suction port 50 and a radial gas ejection port 52. The gas pump 10 is provided with a pump section that has an impeller impeller 18 and the ports 50, 52 and with a motor section that has an encapsulated electric motor 30 and a motor controller 40. The motor controller 40, which has a printed circuit board 41, is arranged in an annular electronics chamber 83 axially between the pump section and the electric motor 30.

The pump housing 11 essentially has two separate parts, namely the motor section housing 12 and the pump section housing 14. Both section housings 12, 14 are formed by solid plastic housing bodies 13, 15. The motor section housing 12 has and surrounds numerous stator coils 33 of a motor stator 32. The stator coils 33 are embedded in the plastic motor housing body 13. The motor housing body 13 further forms the annular motor control electronics chamber 83 in which the electronic motor control 40 is housed. The motor control 40 is formed by numerous electronic elements on the printed circuit board 41. The printed circuit board 41 has the shape of an annular disk and is provided with numerous power semiconductors 98 on the impeller side of the printed circuit board 41.

The gas pump 10 is provided with a rotary rotor device 16 having a plastic impeller 18, an elastic coupling member 21, a metal rotor shaft 20 and a motor rotor 34 with a motor rotor body 80 provided with permanent magnets defining numerous magnet rotor poles. The rotor shaft 20 carries the elastic coupling element 21, which directly carries the pump wheel 18, for joint rotation. The elastic coupling element 21 allows the pump wheel 18 to tilt within a limited range, so that blocking and tilting of the pump wheel 18 caused by solid particles can be avoided.

The plastic impeller 18 is provided with numerous impeller blades 19 which protrude axially from an impeller base disk body 54 which is arranged substantially in a radial plane. The impeller base disk body 54 is provided at its axial center with an axial center opening 57 which forms a drying gas outlet passage 55.

The rotor shaft 20 is formed by a metal rotor shaft body 22 which has an axial Shaft bore 25 is provided, which forms an axial drying gas passage 24. The distal end of the shaft bore 25 forms a drying gas inlet opening 28, and the proximal end of the shaft bore 25 forms a drying gas outlet opening 26.

The rotor device 16 is rotatably held by a bearing device 36 which has two roller bearings 37,38. The bearing device 36 is arranged axially between the motor rotor 34 and the pump wheel 18. The storage device 36 is provided with an axial gas passage 70, which enables the pumped drying gas to flow axially through the storage device 36. In the case of the roller bearings 37,38 described here, the axial gas passage is formed by the spaces between the roller elements of the roller bearing 37,38. In addition, the bearing device 36 is provided with a second axial gas passage formed by three axial grooves 106 provided in the cylindrical cylinder portion 84 of the encapsulation body 60. Even if the axial grooves 106 are not part of the roller bearings 37, 38, they also form axial bearing device gas passages in the sense of the patent claims. The axial gas passage grooves 106 transport 50% to 80% of the gas flowing through the drying path. This means that the grease from the roller bearings 37,38 is prevented from washing out.

The pump housing body 15 forms a pump spiral 56, which radially surrounds the pump wheel and leads fluidly into a radial pump outlet channel 53, which fluidly ends at the gas discharge port 52 of the pump.

The gas pump 10 is provided with a separation encapsulation device 82 which fluidly separates the motor stator 32, which is arranged in a gas-free section, from the motor rotor device 16, which is arranged in a gas section. The pumped gas is present in the gas section, while no pumped gas is present in the gas-free section. However, another gas such as air may be present in the gas-free section. In particular, the electronics chamber 83 is filled with air, but is not filled with pumped gas. The separation encapsulation device 82 has the cylindrical inner surface of the motor section housing body 13 and a separate sheet metal encapsulation body 60.

The sheet metal encapsulation body 60 has a substantially cylindrical cylinder section 84 and an annular disk section 85, which lies essentially in a radial plane. The circular edge 91 of the annular disk section 85 of the encapsulating body 60 is clamped between corresponding flanges of the pump housing body 15 and the motor housing body 13. Both flanges are provided with a respective circular groove 87,89. A respective sealing ring 88.90 is inserted into both circular grooves 87.89. The circular grooves 87, 89, the circular sealing rings 88, 90 and the circular edge 91 of the annular disk section 85 are axially aligned with one another, so that a reliable sealing arrangement is realized.

The outer cylindrical surfaces of the roller bearings 37, 38 are fixed to the inner cylindrical surface of the separating encapsulating cylinder portion 84 by clamping. The outer surface of the separating encapsulating cylinder portion 84 is also partially fixed to a cylindrical portion of the motor housing body 13 by clamping. The liquid seal is realized by a seal ring 92 disposed between the outer surface of the separating encapsulating cylinder portion 84 and the inner cylindrical surface of the motor housing body 13.

The circular gap between the base disk 54 of the impeller 18 and the annular disk portion 85 of the encapsulating body 60 forms a circular inlet drying gas passage 77 of a drying gas path that runs from the inlet drying gas passage 77 to the outlet drying gas passage 55. The circular gap is provided with a labyrinth seal 100, which is formed by a circular axial sealing land ring 102 on the rear of the disk portion 85 of the encapsulating body 60 and by a corresponding circular axial groove on the front of the annular disk portion 85 of the encapsulating body 60. The labyrinth seal 100 defines the maximum flow through the drying gas path so that the pneumatic shortcut formed by the drying gas path does not significantly affect the pneumatic efficiency of the gas pump 10.

The motor housing body 13 is provided on its cylindrical inner surface surrounding the motor rotor body 80 with one or more axial gas passage grooves 17, which allow an axial drying gas flow to pass through the motor rotor 34 in the axial direction.

The power semiconductors 98 are each thermally connected to the ring section 85 of the sheet metal encapsulation body 60 by separate thermal connecting elements 99. The connecting elements 99 connect the respective power semiconductors 98 axially to the annular disk section 85 of the sheet metal encapsulation body 60. Since this annular disk section of the sheet metal encapsulation body 60 is cooled by the gas that passes at a relatively high gas velocity flows and is pumped by means of the pump wheel, a considerable cooling capacity is realized so that the heat can be reliably dissipated from the power semiconductors 98.

When the gas pump 10 is active, the encapsulated electric motor 30 rotates, so that the impeller 18 also rotates. The impeller pumps the gas, which is fuel vapor, axially through the axial gas intake port 50 and radially outward into the pump scroll 56. From the pump scroll 56, the gas flows through the outlet channel 53 to the gas discharge port 52.

The gas pressure in front of the impeller 18 is lower than the gas pressure in the pump spiral 56. This causes a drying gas flow from the drying gas inlet passage 77 along the drying gas path to the drying gas outlet passage 55. The drying gas path has the circular drying gas inlet passage 77, the axial gas passages 70 , 106 of the bearing device 36, the axial gas passage grooves 17 on the motor housing body 13, the axial gas passage 24 of the rotor shaft 20 and the drying gas outlet passage 55 of the pump wheel 18.

As long as the impeller 18 rotates, the pressure difference between the gas suction port 50 and the gas discharge port 52 causes a flow of drying gas through the drying gas path, so that no relevant condensate of the pumped gas remains in the gas section of the gas pump 10.

Claims (7)

Electric evaporation pump (10) for motor vehicles, having a gas suction port (50) and a gas discharge port (52), the pump comprising: an encapsulated electric motor (30) with a motor stator (32), which has electromagnetic stator coils (33), and with a rotor device (16), which has an impeller (18) with impeller blades (19), a rotatable rotor shaft (20) and contains a motor rotor (34), a separation encapsulation device (82) which fluidly separates the motor stator (32) arranged in a gas-free section from the motor rotor (34) arranged in a gas section, and a bearing device (36) which is arranged in the gas section axially between the motor rotor (34) and the pump wheel (18) and rotatably supports the motor rotor (34), wherein the separation encapsulation device (82) has an encapsulation body (60) with a cylinder section (84), the cylinder section (84) directly carrying the bearing device (36), and the encapsulation body (60) separates an electronics chamber (83), which has an electronic motor control (40), from the gas section, and wherein the encapsulation body (60) is a sheet metal encapsulation body. Electric evaporation pump (10) for motor vehicles Claim 1 , in which the electronics chamber (83) is arranged axially between the motor stator (32) and the pump wheel (18). Electric evaporation pump (10) for motor vehicles Claim 2 , in which the electronics chamber (83) is annular and surrounds the bearing device (36). Electric evaporation pump (10) for motor vehicles according to one of the preceding claims, in which the electronic engine control (40) is provided with at least one power semiconductor (98) for supplying power to the stator coils (33), the power semiconductor (98) being provided by a thermal Connecting element (99) is thermally connected to the encapsulation body (60). Electric evaporation pump (10) for motor vehicles according to one of the preceding claims, in which the electronic engine control (40) has a printed circuit board (41) which is arranged substantially in a radial plane, and in which the encapsulation body (60) with is provided with a substantially radial annular disk section (85). Electric evaporation pump (10) for motor vehicles Claim 4 or 5 , in which the thermal connecting element (99) essentially axially connects the power semiconductor (98) to the encapsulation body (60). A motor vehicle electric evaporation pump (10) according to any one of the preceding claims, wherein the stator coils (33) are arranged in a solid plastic housing body (13) which supports the axial end of the cylinder portion (84) of the encapsulation body (60).

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