FR3038016A1 - ELECTRICAL COMPRESSOR WITH IMPROVED WHEEL - Google Patents

Abstract

The present invention relates to an electric compressor 1 comprising a shaft 2 driven in rotation by an electric motor by means of bearings 4, the shaft driving in rotation a compressor wheel 14, the compressor comprising a ring 210 door sealing segment mounted around the shaft 2 between the bearings 4 and the compressor wheel 3, the wheel being plastic overmolded on an overmolding support ring.

Description

The present invention relates to the field of electric compressors, and more particularly to an electric supercharging compressor. BACKGROUND OF THE INVENTION

In the context of the invention, an electric compressor is a device used to supercharge a heat engine, operating with an electric motor. More specifically, the compressor comprises a compressor wheel driven by an electric motor. The electric compressor is placed on the air intake line of an internal combustion engine, in addition to a turbocharger. The electric compressor plays the same role as the turbocharger, namely increase the intake pressure of the fresh gases in the engine, but is used in particular during transient phases to overcome turbocharger response time problems. Currently, the compressor wheel is aluminum alloy, and is either molded or machined in the mass. The wheel is disposed at one end of the electric compressor shaft and held in place by a nut. A disadvantage of this type of aluminum alloy wheel is that its inertia is not optimized. Indeed, the response time of the electric compressor must be as short as possible, and a significant inertia increases this response time and also the energy required for the acceleration of the electric compressor. To solve this problem, it is possible to use a plastic wheel. However, the molding constraints of the plastic parts impose quasi-constant thicknesses, which makes the clamping area by a nut too fragile with a plastic wheel. In addition, the plastic tends to flow over time and the tightening can then be lost. It is therefore not possible to directly replace the aluminum wheel with a plastic model while maintaining the method of assembly with a nut. The present invention therefore aims to overcome one or more of the disadvantages of the prior art devices by providing an electric compressor 3038016 2 with an improved compressor wheel, thus reducing the inertia and consequently the response time of the compressor. For this, the present invention provides an electric compressor comprising a shaft driven in rotation by an electric motor by means of bearings, the shaft driving in rotation a compressor wheel, the compressor comprising a ring mounted sealing ring ring around the shaft between the bearings 4 and the compressor wheel, the wheel being plastic overmolded on an overmolding support ring. The use of plastic reduces the inertia of the wheel, which increases the efficiency of the compressor. According to one embodiment of the invention, the support ring is made of steel. According to one embodiment of the invention, the overmolding support ring is an additional ring of the ring bearing segment. According to another embodiment of the invention, the support ring is formed by the ring bearing segment. According to one embodiment of the invention, the shaft comprises a thread, at its end opposite to that where is positioned an electric motor. According to one embodiment of the invention, the wheel is held in place with a nut screwed onto the end of the shaft provided with a thread.

According to one embodiment of the invention, the support ring comprises a tapping, at its end opposite to that where is positioned at least one sealing segment, for screwing on the shaft. According to one embodiment of the invention, the ring segment holder has a length adapted so as to carry at least one sealing segment and the overmolded wheel 25. According to one embodiment of the invention, the motor is a variable reluctance or permanent magnet motor. According to one embodiment of the invention, the compressor is an electric supercharging compressor of a heat engine.

Other objects, features and advantages of the invention will be better understood and will appear more clearly on reading the description given hereinafter with reference to the appended figures given by way of example and in which: FIG. 1 is a diagrammatic representation in section showing an electric compressor; FIG. 2 is a diagrammatic representation in section showing part of an electric compressor according to one embodiment of the invention; FIG. schematic representation in section showing a part of an electric compressor according to another embodiment of the invention, - Figure 4 is a schematic sectional view showing a portion of an electric compressor according to another embodiment of the invention. 'invention. The present invention relates to an electric compressor. In the context of the invention, the term "electric compressor" means an air compressor, whether volumetric or not and for example centrifugal or radial, driven by an electric motor, for the purpose of supercharging a heat engine. According to one embodiment of the invention, the electric motor is an asynchronous DC or AC motor, or any type of electric motor of the same type. More specifically, according to one embodiment of the invention, the electric motor 20 is a variable reluctance motor (also called SRM machine for Switched Reluctance Motor according to the English terminology). According to another embodiment of the invention, the motor is a permanent magnet motor. Figure 1 illustrates an example of an electric compressor 1. The electric compressor 1 comprises at least one electric motor 8, bearings 4 and a compressor wheel 3. The electric motor allows the rotation of a shaft 2 of the electric compressor via the bearings 4. The shaft 2 thus rotates the wheel 3 of the compressor 1. More precisely one end of the shaft 2 is rotated by the electric motor, and another end of the shaft 2 rotates the wheel 3 of the compressor.

According to one embodiment of the invention, the compressor 1 conventionally comprises a volute 5 allowing the passage of air from the compressor 1. According to one embodiment of the invention, the compressor 1 comprises a set of electronics 6 for controlling the electric compressor 1.

The assembly is disposed in a compressor housing 7. The intermediate portion of the shaft is protected by the compressor body. This intermediate portion of the shaft 2 comprises a sealing member, and more specifically a dynamic sealing member disposed between the wheel and the electric machine.

According to one embodiment of the invention, this member is formed of at least a first sealing segment 22 positioned on the side of the compressor wheel. According to one embodiment of the invention, the sealing member comprises a second sealing segment 23 positioned on the side of the bearings 4. This or these segments have the role of protecting the bearings from pollution that may come from the wheel of the compressor.

In the context of the invention, at least one sealing segment is carried by a segment-carrying ring 21, 210. According to one embodiment of the invention, the ring is made of steel. Preferably, the ring is made of treated steel to increase the hardness. According to another embodiment of the invention, the segments are arranged in two recesses 220, 230 formed in the ring.

The ring is disposed against a flat wall of the shaft 2 or in another recess dug in the shaft 2. This other recess is configured to allow easy insertion of the ring on the shaft 2. According to a embodiment of the invention, the wheel of the compressor 1 is a paddle wheel illustrated in detail in FIGS. 2, 3 and 4.

In the context of the invention this wheel is made of plastic and overmolded. According to one embodiment of the invention, the plastic is a plastic resistant to at least 150 ° C, preferably resistant to 200 ° C. According to one embodiment of the invention, the plastic is polyetheretherketone or PEEK (for PolyEtherEtherKetone according to the English terminology).

3038016 5 The use of plastic reduces the inertia of the wheel, which increases the efficiency of the compressor. In the context of the invention, the wheel 3 is overmolded on a support ring 211, 210 overmolding.

The support ring is metallic. More specifically, the support ring 210, 211 is made of steel, preferably treated steel. This support ring 211, 210 passes through the wheel 3 longitudinally. One end of the support ring is in contact with a shoulder 214 of the shaft, so that the clamping force passes through the support ring.

According to one embodiment of the invention, the overmolding support ring is an additional ring 211 illustrated in FIG. 2. This ring is added on one end of the shaft following the segment-carrying ring 210. The wheel is overmolded on this additional ring. According to another embodiment of the invention, the support ring is formed by the ring bearing segment. The wheel 3 is overmolded on the ring 210 door segment. The wheel 3 is overmolded at the end of the ring not including the segment or segments. The length of the ring 210 is then adapted so as to be able to bear the sealing segment or segments and the overmoulded wheel illustrated in FIGS. 3 and 4. The overmoulding on the ring 210 does not require any additional piece with respect to the wheel version. aluminum of the prior art. Overmolding directly on the ring also reduces the size of the compressor. According to a first variant of the invention, the overmolded wheel 3 is held in place with a nut 9 disposed at the end of the shaft. The nut 9 is supported on the end of the ring 210, 211 support. The thread for tightening the nut 9 is made directly at the end of the shaft 2. The tightening by the nut 9 is improved by the support on the treated steel ring. Indeed, a first end of the support ring is in contact with the nut, while the second end is in contact with a shoulder of the shaft, so that the clamping force passes through the ring. According to a second variant embodiment of the invention, illustrated in FIG. 4, the wheel 3 is held in place by a thread formed directly at the end of the support ring, illustrated in FIG. is the support ring which is screwed directly on the shaft 2. In this variant, the nut is removed, since its function 5 is integrated into the ring. The hardness of the ring makes the tapping mechanically strong, allowing effective tightening. The scope of the present invention is not limited to the details given above and allows embodiments in many other specific forms without departing from the scope of the invention. Therefore, the present embodiments are intended to be illustrative, and may be modified without departing from the scope defined by the claims.

Claims (10)

REVENDICATIONS1. Electric compressor 1 comprising a shaft 2 driven in rotation by an electric motor through bearings 4, the shaft driving in rotation a compressor wheel 3, the compressor comprising a ring 210 bearing sealing ring mounted around the shaft 2 between the bearings 4 and the compressor wheel 3, characterized in that the wheel is made of plastic overmolded on a ring 210, 211 overmoulding support. 2. Compressor 1 according to claim 1, wherein the support ring 210, 211 is made of steel. 3. Compressor 1 according to one of claims 1 or 2, wherein the overmolding support ring is an additional ring 211 of the ring 210 segment door. 4. Compressor 1 according to one of claims 1 or 2, wherein the support ring is formed by the ring 210 segment door. 5. Compressor 1 according to one of claims 1 to 4, wherein the shaft 2 comprises a thread 212 at its end opposite to that where is positioned an electric motor. 6. Compressor 1 according to one of claims 1 to 5, wherein the wheel 3 is held in place with a nut 9 screwed onto one end of the shaft 2 provided with a thread 212. 7. Compressor 1 according to one of claims 1 to 5, wherein the ring 210, 211 support comprises a thread, for screwing on the shaft 2. 8. Compressor 1 according to one of claims 1 to 2 and 4 to 6, wherein the ring 210 segment door has a length adapted to be able to carry at least one sealing segment and the overmolded wheel. 9. Compressor 1 according to one of claims 1 to 8, wherein the motor is a variable reluctance motor or permanent magnet. 10. Compressor 1 according to one of claims 1 to 9, wherein the compressor is an electric supercharger compressor engine.