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Title:
MOTOR VEHICLE AUXILIARY POWER UNIT VACUUM PUMP
Document Type and Number:
WIPO Patent Application WO/2018/033194
Kind Code:
A1
Abstract:
Vapor pump (12) for automotive applications, in particular a purge pump for venting a fuel vapor accumulator (16) comprising a housing group (13) including at least a pump housing (21) with a pump chamber (24) and a motor housing (22) with a motor chamber (25), wherein the pump housing (21) has an inlet opening (30) and an outlet opening (44), wherein a pumping wheel (34) is provided in the pump chamber (24) for pumping fuel vapor from the inlet opening (30) to the outlet opening (44), wherein the pump wheel (34) is mounted on a rotor shaft (36) for rotation therewith, wherein a drive motor (50) with a motor stator (51), a motor rotor (52) and a motor control unit (53) is provided in the motor chamber (25), wherein the motor rotor (52) is connected with the rotor shaft (36) for rotation therewith, and wherein a contact plug (60) is provided for electric connection of the motor control unit (53), whereby the pumping wheel (34) is made at least in part from an electrically conductive plastic material and the rotor shaft (36) is made from an electrically conductive material, wherein the rotor shaft (36) is rotatably supported in an electrically conductive bearing arrangement (26) which is electrically connected either indirectly or directly with the contact plug (60) via conducting means (27).

Inventors:
MALVASI, Alessandro (Mauerstrasse 18, Düsseldorf, 40476, DE)
Application Number:
EP2016/069326
Publication Date:
February 22, 2018
Filing Date:
August 15, 2016
Export Citation:
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Assignee:
PIERBURG PUMP TECHNOLOGY GMBH (Alfred-Pierburg-Strasse 1, Neuss, 41460, DE)
International Classes:
F04D9/00; B60K15/035; F02M25/08; F04D13/06; F04D25/06; F04D29/02
Foreign References:
US20060219231A12006-10-05
EP2060773A22009-05-20
US6014958A2000-01-18
DE10324800A12004-01-08
DE19843022C12000-03-09
US20150285170A12015-10-08
Attorney, Agent or Firm:
PATENTANWÄLTE TER SMITTEN EBERLEIN RÜTTEN (Burgunderstr.29, Düsseldorf, 40549, DE)
Download PDF:
Claims:
Claims

1. Vapor pump (12) for automotive applications, in particular a purge pump for venting a fuel vapor accumulator (16) comprising a housing group (13) including at least a pump housing (21) with a pump chamber (24) and a motor housing (22) with a motor chamber (25), wherein the pump housing (21) has an inlet opening (30) and an outlet opening (44), wherein a pumping wheel (34) is provided in the pump chamber (48) for pumping fuel vapor from the inlet opening (30) to the outlet opening (44), wherein the pump wheel (34) is mounted on a rotor shaft (36) for rotation therewith, wherein a drive motor (50) with a motor stator (51), a motor rotor (52) and a motor control unit (53) is provided in the motor chamber (25), wherein the motor rotor (52) is connected with the rotor shaft (36) for rotation therewith, and wherein a contact plug (60) is provided for electric connection of the motor control unit (53), characterized in that the pumping wheel (34) is made at least in part from an electrically conductive plastic material and the rotor shaft (36) is made from an electrically conductive material, wherein the rotor shaft (36) is rotatably supported in an electrically conductive bearing arrangement (26) which is electrically connected either indirectly or directly with the contact plug (60) via conducting means (28).

2. Vapor pump for automotive applications of claim 1, characterized in that the pumping wheel (34) includes electrically conductive fillers such as graphite.

3. Vapor pump for automotive applications of claim 1 or 2, characterized in that the rotor shaft (36) is made of metal.

4. Vapor pump for automotive applications of one of the preceding claims, characterized in that the motor housing (22) is a solid plastic material housing with an overmolded motor stator (51).

5. Vapor pump for automotive applications of claim 4, characterized in that the pump chamber (24) of the pump housing (21) is enclosed by a pump housing part (47) and an end face (46) of the plastic housing (22).

6. Vapor pump for automotive applications of one of the preceding claims, characterized in that the drive motor (50) is a permanently excited drive motor, wherein the motor rotor (52) comprises permanent magnets potted in plastic material.

7. Vapor pump for automotive applications of claim 5, characterized in that the drive motor (50) is an asymmetrically permanently excited drive motor.

8. Vapor pump for automotive applications of one of the preceding claims, characterized in that the pumping wheel (34) is a centrifugal wheel.

9. Vapor pump for automotive applications of one of the preceding claims, characterized in that the conducting means (28) are formed at least by a conductive wire connection to the contact plug (60).

10. Vapor pump for automotive applications of one of claims 1 - 9, characterized in that the conductive wire connection is guided via a circuit board (35) of the motor control unit (53).

Description:
Motor vehicle auxiliary power unit vacuum pump

The invention relates to a vapor pump for automotive applications, in particular to a purge pump for venting a fuel vapor accumulator comprising a housing group including at least a pump housing with a pump chamber and a motor housing with a motor chamber, wherein the pump housing has an inlet opening and an outlet opening, wherein a pumping wheel is provided in the pump chamber for pumping fuel vapor from the inlet opening to the outlet opening, wherein the pump wheel is mounted on a rotor shaft for rotation therewith, wherein a drive motor with a motor stator, a motor rotor and a motor control unit is provided in the motor chamber, wherein the motor rotor is connected with the rotor shaft for rotation therewith.

In an automotive application, an electric vapor pump is used, among others, as a part of an automotive vapor pump arrangement for pumping gas comprising fuel vapor from a vapor absorption unit to a vapor target, for example to the intake section of an internal combustion engine. An example of a typical automotive fuel vapor pump arrangement is disclosed in US 2015/0285170 Al . A typical purge pump is also described in this publication.

A great disadvantage of these pumps is the electrostatic charging of the pumping wheel and the accompanying danger of sparking and of the fuel vapor being ignited. Further, the water proportion in the fuel vapor may cause substantial corrosion damages to the vapor pump.

Therefore, it is an object of the invention to develop a vapor pump such that the above disadvantages are avoided in a simple and economic manner. This object is achieved according to the invention by making the pumping wheel at least in part from an electrically conductive plastic material and by making the rotor shaft from an electrically conductive material, wherein the rotor shaft is rotatably supported in an electrically conductive bearing arrangement which is electrically connected either indirectly or directly with the contact plug via conducting means and is grounded in this manner. Thereby, an ignition of the fuel vapor is prevented in a simple and economic manner. Moreover, at least corrosion damages to the pumping wheel are prevented.

According to a preferred embodiment the pumping wheel includes electrically conductive fillers such as graphite, for example. As an alternative, however, intrinsically conductive polymers may also be used to manufacture the pumping wheel.

To guarantee a simple and economic electric connection from the pumping wheel to the contact plug it is advantageous if the rotor shaft is made of metal.

In a particularly advantageous manner the motor housing is a solid plastic housing with a motor stator potted therein. In this manner, the motor stator and, possibly, electronic components are sealed off completely from the pump chamber. Thus, it is possible to exclude corrosion damage to metal components caused by fuel vapor. As an alternative it would of course also be possible to provide a can known per se. In this regard it is particularly advantageous if the pump chamber of the pump housing is enclosed by a pump housing part and an end face of the plastic housing.

In a particularly advantageous manner the drive motor is a permanently excited motor, the motor rotor comprising permanent magnets overmolded with plastic material. In this manner a very effective protection against corrosion is guaranteed. In this regard it is particularly advantageous if the drive motor is an asymmetrically permanently excited drive motor. This allows for a very compact motor housing. Due to the fact that the motor stator is provided only one side of the motor rotor, the manufacture of the molded pump housing is considerably simplified.

In an advantageous embodiment the pumping wheel is designed as a centrifugal wheel. The centrifugal wheel may preferably be formed by a vane portion of plastic material and a pot portion connected with the same, the centrifugal wheel being fixedly mounted to the rotor shaft via the pot portion.

Advantageously, the conducting means may be formed by a conductive wire connection with the contact plug or, as an alternative, the conductive wire connection is guided via a circuit board of the motor control unit in order to avoid electric charging of the pumping wheel.

One embodiment of the invention is described with reference to the enclosed drawing, which shows schematically an automotive vapor pump arrangement comprising a vapor pump in longitudinal cross section.

The drawing schematically shows an automotive vapor pump arrangement 10 with a vapor pump 12 for pumping a pump gas comprising fuel vapor. The vapor pump arrangement 10 comprises an automotive fuel tank 14 which is fluidically connected to a vapor absorption unit 16. The vapor absorption unit 16 can comprise charcoal. The vapor absorption unit 16 is fluidically connected with a pump inlet 30 of the automotive vapor pump 12. A pump outlet 44 of the vapor pump 12 is fluidically connected to a vapor target 18 which is an intake section of an internal combustion engine (not shown). The vapor pump 12 is also known as a so-called purge pump. The vapor pump 12 is designed as a flow pump comprising a housing arrangement 13 which comprises two separate housing parts, namely a pumping housing part 21 defining a pumping room 24 and having the pump inlet opening 30 and the pump outlet duct 40, and a separate motor housing part 22 defining a motor room 25 and comprising an electric motor 50, a bearing arrangement 26 with a steel bush 27 and two roller bearings 38, 39, an electric connector plug 60, an impeller-like pumping wheel 34, which is configures as centrifugal wheel with an axial gas inlet. The rotating pumping wheel 34 rotates with high rotational speed of between 10000 to 45000 rpm. The pump gas is thereby accelerated and radially flows into an outlet volute 32 from where the pump gas flows into a tangential outlet duct 40 with the pump outlet 44 at its distal end. The pressure rise caused by the rotating pumping wheel 34 is in the range 50 and 100 mbar.

The rotor assembly comprises the pump wheel 34 supported by a rotor shaft 36 which is rotatably supported by the two roller bearings 38, 39 at the motor housing part 22. The rotor shaft 36 also is provided with a permanently magnetized motor rotor 52 which is surrounded by a motor stator 51 whereby the motor 50 is build up as a so called asymmetrical motor. The rotor assembly is rotating around a rotation axis 31, whereby permanent magnets 55 of the rotor 52 are plastic molded.

The motor housing part 22 also defines a motor electronics chamber 54 which comprises a motor control unit 53 for driving the rotor 52. The electronics chamber 54 is closed by a separate electronics chamber cover 23.

The pumping housing part 21 defines an axial inlet duct 33 which is axially aligned with the pumping wheel 34 and the rotation axis and also defines a tangential outlet duct 40 which is defined by a tube-like and straight outlet duct wall 42. The outlet duct 40 defines a general outlet duct axis 41.

The motor housing part 22 defines an electric connector plug 60 with a couple of contact pins 62. The electric connector plug 60 has a general plugging axis 61 which is the general direction for connecting or disconnecting a corresponding plug with/from to the electric connector plug 60. The electric connector plug 60 is electrically connected to an external control unit 19 for controlling the vapor pump 12.

To guarantee that an electrostatic charging of the pumping wheel does not cause an ignition of the fuel vapor, the invention provides that the pumping wheel 34 is made at least in part from an electrically conductive plastic material and the rotor shaft 36 is made from an electrically conductive material. The rotor shaft 36 is rotatably supported in an electrically conductive bearing arrangement 26. In the present embodiment the bearing arrangement 26, and thus the steel bush 27, are electrically connected with the contact plug 60 via conductive means 28 which, in the present instance, are designed as an electric wire connection, so as to effect a connection to ground. However, it is also conceivable to guide the conductive wire connection via a circuit board 35 which, in a manner known per se, is a part of the motor control unit 53. An electrical path from the pumping wheel 34 to the contact pins 62 of the contact plug 60 is indicated by the reference sign 48.

In the present embodiment the pumping wheel 34 includes fillers of graphite in order to achieve electric conductivity. In the present embodiment the motor housing 22, and thus a motor chamber 25 enclosed thereby, is formed substantially as a solid plastic material housing in which the motor stator 51 is potted. Together with a pump housing part 47, an end face 46 of this plastic material housing 22, directed to the pumping wheel 34, encloses a pump chamber 24 in which, substantially, the pumping wheel is supported on the metal rotor shaft 36 for rotation therewith. On the side of the plastic material housing opposite the end face, the circuit board 35 is provided which is closed by means of the cover 23. This embodiment provides protection against corrosion damages in a simple and economic manner.