EP2002123B1 - Fluid pump - Google Patents

Abstract

There is proposed an embodiment of an electric fluid pump of a semi-axial design wherein support ribs (31) are arranged between a radially outer pump housing portion (32) and a first, radially inner motor housing portion (8) that radially surrounds the electric motor (1), wherein the radially outer pump housing portion (32) is formed integrally with the first motor housing portion (8) and the support ribs (31). In this manner, as compared to previously known embodiments, small wall thicknesses of the pump housing can be realized because the support ribs will offer sufficient strength. Thus, the number of component parts and the weight can be reduced.

Description

The invention relates to a fluid pump for internal combustion engines with an electric motor having a rotor disposed in a motor housing and a stator, wherein the rotor is at least rotationally fixed on a drive shaft, an impeller which is mounted on the drive shaft; at least one stator, which is arranged in the flow direction of the fluid to be conveyed behind the impeller, and a pump housing, which surrounds the motor housing, the impeller and the stator and at the opposite ends at the axial ends of a discharge nozzle and a suction nozzle, support ribs between a are arranged radially outer pump housing part and a first radially inner motor housing part, which surrounds the electric motor radially, wherein the radially outer pump housing part is formed integrally with the motor housing part and the support ribs.

Fluid pumps for internal combustion engines are used in particular as coolant pumps in the cooling circuit. Whereas in the past there was a direct coupling to the engine speed and the pumps were driven by belt drives or chain drives, in newer engines variable speed electric coolant pumps with split tubes are increasingly used to realize a modern heat management. An abundance in the flow rate can thus be prevented, so that, for example, a faster heating of the internal combustion engine after the cold start is possible. The flow rate can be regulated according to the actually required cooling capacity.

Such a pump is known for example from MTZ no.11 Jg.2005 (S. 872-877). This electric coolant pump comprises an EC motor as a drive unit and has a pump head with axial inlet and tangential outlet on. However, the components used here and in particular housing parts are relatively large for the power consumption of the pump, since a relatively large drive motor must be used.

In the US 2002/0106290 A1 Therefore, an electric fluid pump is disclosed in Halbaxialbauweise, with the same power consumption of the electric motor, this can be made smaller to achieve higher speeds, so that with smaller size equal flow rates can be achieved. It has a completely encapsulated electric motor, on whose outer side a stator is formed. In the flow direction behind the stator, however, obstacles to carry out the electrical contact with the electronics unit arise.
On the impeller side, the entire motor is sealed by seals against the environment. To what extent such a seal on the rotating tables is sufficient at least questionable.

The pump housing is made in two parts and has different gradations and through holes for the electrical contact. Depending on the desired maximum flow rate different electric motors and housings have to be designed. Complete twist freedom is probably not achieved due to the relatively short vanes. Also, the pressure loss through the feedthroughs of the electrical contact is relatively high, so that the gain in terms of power consumption of the electric motor is partially counteracted by the pressure losses occurring.

From the FR 2.222.885 a Halbaxialpumpe is known, which has a multi-part housing, the central part surrounds the electric motor and serves as a one-piece motor and pump housing, wherein the pump housing are connected to the motor housing via support ribs. In the flow direction behind these housing parts, the electrical contact is guided via additional pipes to the outside.

From the DE 202 01 183 U1 is known an axial pump, which also has such a one-piece engine and pump housing part. An electrical contact with the outside is not disclosed.

In both pumps, the support ribs are straight and therefore do not serve as a stator to reduce the existing twist. Rather, high pressure losses occur because the energy of the tangential component of the flow is almost completely converted into friction losses.

It is therefore an object of the invention to reduce the size of the pump and thus the electric motor and to avoid pressure losses so the efficiency of the pump while maintaining the same capacity. Furthermore, the weight of the pump and the number of parts should be reduced.

This object is achieved in that the support ribs are shaped such that they serve as a stator of the fluid pump and have a width such that an electrical contact element of an electronic unit to a stator winding through a hole in one or more of the support ribs can be guided. As a result, the support ribs take on the additional function of converting the tangential flow component into an axial flow component without higher pressure drops. The efficiency is increased and components saved. Performing the electrical contacting by the ribs reduces the flow resistance and increases the efficiency of the pump, since internal internals are omitted in the flow. In comparison to known embodiments, small wall thicknesses of the pump housing can be realized, as is given by the support ribs sufficient strength. The number of parts and the weight are reduced.

In a further embodiment, the radially outer pump housing part is cylindrical, whereby the connection to a suction-side and a pressure-side pump housing part is easy to manufacture and low losses occur.

In a particular embodiment, a suction-side pump housing part which widens in the flow direction is formed integrally with a housing part of an upstream valve. It can thus be a modular design with upstream Bypass or thermostatic valves are achieved, which in turn reduces parts and costs are saved.

Preferably, the first motor housing part limits the electric motor on the suction side. The production remains cost-effective, for example, in Alumidiumdruckguss possible, again the number of parts is low, the sensitivity to corrosion is low and assembly errors are avoided.

It is thus provided a fluid pump which has a low number of parts and a low weight, is easy to assemble, reduces flow losses and thus increases the efficiency compared to known pumps.

An embodiment of the invention is illustrated in the drawing and will be described below.

The figure shows a side view of a fluid pump according to the invention in a sectional view.

The fluid pump shown in the figure, which is particularly suitable as a coolant pump in internal combustion engines, is driven by an electronically commutated electric motor 1, which consists of a stator 2 and a arranged on a drive shaft 3 rotor 4. At the axial end of the drive shaft 3, an impeller 5 is arranged, which is designed in a semi-axial design and by the rotation of the fluid to be delivered, in particular a coolant from a suction nozzle 6 is conveyed substantially axially through the fluid pump to a discharge nozzle 7.

The electric motor 1 is arranged in a motor housing which consists of a first suction-side motor housing part 8 and a second pressure-side motor housing part 9. Through the suction-side motor housing part 8, the drive shaft 3 is guided, on which the impeller 5 is arranged. For this purpose, the suction-side motor housing part 8 has a bore 10, in which a first bearing 11 for supporting the drive shaft 3 is arranged. Viewed from the suction side behind the first bearing 11 is a ceramic Axialgleitlager 12 and a rubber boot 13 and a spacer 14. By this assembly a sufficiently vibration damped mounting of the impeller side of the drive shaft 3 of the electric motor 1 is achieved. The spacer serves to extend the distance of the first bearing 11 to a second bearing 15, whereby an angular error in the manufacture of the bore 10 for receiving the bearing can be better compensated. Again behind the spacer 14, a rotor laminated core 16 is arranged on the shaft, which has slits extending in the axial direction for receiving magnets 17, which correspond in a known manner with a stator winding 18. The rotor 4 is bounded axially and radially by a capsule 19. The stator winding 18 is wound on an insulating body 20 and delimits axially in a known manner a laminated stator core 21. This laminated stator core 21 is connected in a form-fitting manner with a return plate 22 for closing the magnetic circuit. This return plate 22 abuts against a stop 23, which is formed on an inner surface of the first suction-side motor housing part 8.

The rotor 4 is separated from the stator 2 by a split tube 24, which rests on the suction side of the pump in a corresponding receiving opening 25 of the suction-side motor housing part 8 and the opposite axial end is in turn arranged in a corresponding receiving opening 26 of the pressure-side motor housing part 9. The stator 2 with its sensitive winding 18 thus lies in a separated by the two motor housing parts 8 and 9 and the can 24 dry space.

At the pressure-side end of the can 24, a closure member 27 is arranged, in which the second bearing 15 is arranged for mounting the drive shaft 3. Axially, this closure member 27 is secured by the pressure-side motor housing part 9, which is arranged with the interposition of a seal 28 in a receiving opening 29 of the suction-side motor housing part 8.

The contacting of the stator winding 18 via a bore 30, in the radial direction through the pressure-side motor housing part 9. In order to prevent flow losses through such additional internals, as is the case from the prior art is known, this bore is guided by support ribs 31, which are necessary for sufficient strength and attachment of a pump housing. For this purpose, the support ribs 31 have a sufficient width and are designed in a kind of airfoil shape, so that no cross-sectional constriction arises. Through the bore 30 so now not shown electrical contact element can be passed through the bore 30 to a likewise not shown electronic unit for controlling the motor 1.

In the illustrated embodiment, the support ribs 31 are shaped such that they also serve as a stator, so that no additional stator immediately behind the impeller 5 is necessary. This allows a simple one-piece production of the suction-side motor housing 8 with the support ribs and a cylindrical radially outer pump housing part 32. This pump housing part 32 surrounds the radially inner motor housing part 8 and the entire electric motor. 1

At the downstream and the upstream side of the housing part 8, 31, 32, two identical pump housing parts 33, 34 are fastened by means of a screw connection with the interposition of a seal 50. The suction side in the flow direction expanding pump housing part 33 comprises the suction nozzle 6 which is designed as a cylindrical portion 35 and an adjoining widening portion 36. In the transition region 37 between the first portion 35 and the second portion 36, the semi-axial impeller 5 of the fluid pump is arranged. In the present embodiment, the expanding section 36 is followed by another short cylindrical section 38 of larger diameter, in order to achieve a clean transition to the cylindrical pump housing part 32.

Corresponding narrowing in the flow direction sections and cylindrical portions also has the pressure-side pump housing part 34, wherein due to the identity of the parts like reference numerals are used.

Furthermore, grooves 39 are formed in the identical pump housing parts 33, 34, into which radial ends 40 of return vanes 41 engage. These return blades 41 serve as Nachleitapparat 42 by means of which behind the discharge nozzle 7 a completely twist-free flow is achieved. This Nachleitapparat 42 is formed on a surface 43 of the pressure-side motor housing part 9 and is therefore necessary that the serving as a stator support ribs 31 are made relatively short and in this area of the fluid pump complete swirl reduction is not achieved in the rule. Furthermore, the pressure-side motor housing part 9 can be produced in plastic, while the suction-side motor housing part is made as far as possible in aluminum and is therefore more expensive. An embodiment of the stator in this area would require a relatively expensive manufacturing process, while the Nachleitapparat the plastic housing part 9 is simple and inexpensive to manufacture.

By the grooves 39, the position of the pressure-side pump housing part 34 is set to the pressure-side motor housing part 9 at the same time. When assembling the pump presses when tightening the screws for fixing the pressure-side pump housing part 34 on the cylindrical pump housing part 32, the pressure-side pump housing part 34 via the return vanes 40, the motor housing part 9 against the motor housing part 8 and into the receiving openings 29 of the motor housing part 8. Furthermore, this is the motor housing part pressed against the closure member 27 and the can 24, so that an additional attachment of the two motor housing parts 8, 9 is not necessary.

When the pump is running, the fluid to be delivered, in particular the coolant, is conveyed through the space between the pump housings 32, 33, 34 and motor housings 8 and 9 by the rotation of the impeller 5 which consists of a plurality of impeller blades 44, flows past the support ribs 31, where already a part of the twist is removed from the flow by its function as a stator and further on the Nachleitapparat 42, in which the flow is completely freed from the existing twist, so that the energy used can be converted as completely as possible in pressure energy and thus axial flow without losing much friction.

A part of the fluid flows behind the impeller 5 through holes 45 which are formed in the suction-side motor housing part 8. Another part of the fluid flows also behind the impeller 5 to the drive shaft 3 and here between the first bearing 11 and the drive shaft 3 through, so that the existing sliding bearing is sufficiently lubricated. Thus, coolant is in the rotor chamber, which in turn is continued between the drive shaft 3 and the second bearing 15 and by non-visible holes in the closure member 27 in a space 46 behind it. This space 46 is connected via a further bore 47, which extends axially through the pressure-side motor housing part 9, with the space behind it. Thus, both a lubrication of the bearings 11, 15 as well as a possibility for cooling and removal of any existing amounts of air in the rotor chamber.

This semi-axial pump is characterized in particular by the fact that it is particularly small to build, since the same power consumption an equal capacity with a smaller motor size and increased speed compared to known pumps can be achieved. This is achieved in particular by the extremely reduced pressure losses in such a design, but also by the semi-axial design.

Furthermore, such a pump can be produced very inexpensively, since there are fewer differently designed components. This simultaneously reduces possible errors during assembly. By eliminating the additional stator and the integration of the electrical contact in the support ribs additional components are avoided and reduces pressure losses. It is thus achieved a total of higher efficiency.

Of course, it is also possible due to the simplicity of the pump housing parts 33, 34 to equip them with a arranged on the pressure or suction nozzle flange. This makes it possible to produce a connection directly to a motor housing as well as to connect several pumps in series to increase the delivered fluid volume flow. This is possible in particular in that a spin-free flow is generated by the Nachleitapparat 42, so that directly the impeller 5 of a downstream pump could be flown without energy losses. Thus, it is not necessary when required twice the power to build a larger pump with in turn larger engine, but by the part equality simply the corresponding required number of pumps in a row to switch.

It is also conceivable, by the simplicity, in particular of the suction-side pump housing part 33, to carry this integrally with valve housing parts, so that the pump housing part 33 has, for example, a receptacle for a bypass or an integrated thermostatic valve. Also, parts of the housing of a sliding ring valve could be made in one piece with the suction-side pump housing part 33.

It should be noted that the illustrated embodiment is merely a possible embodiment of the invention, the construction of which is subject to change without departing from the scope of the claims.

Claims (4)

1. A fluid pump for internal combustion engines, comprising
   an electric motor (1) with a rotor (4) arranged in a motor housing (8) and a stator (2), the rotor being arranged on a drive shaft (3) at least in a manner secured against rotation,
   an impeller (5) fastened on the drive shaft,
   at least one set of guide vanes arranged behind the impeller in the flow direction of the fluid to be conveyed,
   and a pump housing (32, 33, 34) enclosing the motor housing, the impeller and the guide vanes and at which a pressure port (7) and an intake port (6) are formed opposite the axial ends,
   supporting ribs (31) arranged between a radially outer pump housing part (32) and a first radially inner motor housing part (8) that surrounds the electric motor (1) radially,
   wherein the radially outer pump housing part (32) is formed integrally with the motor housing part (8) and the supporting ribs (31),
   characterized in that
   the supporting ribs (31) are formed such that they serve as the set of guide vanes of the fluid pump, and have such a width that an electric contact element may be passed from an electronic unit to a stator winding (18) through a bore (30) in one or a plurality of said supporting ribs (31).
2. The fluid pump for internal combustion engines of claim 1, characterized in that the radially outer pump housing part (32) is cylindrical in shape.
3. The fluid pump of one of the preceding claims, characterized in that an intake-side pump housing part (33), flaring in the direction of flow, is formed integrally with a housing part of an upstream valve.
4. The fluid pump of one of the preceding claims, characterized in that the first motor housing part (8) delimits the electric motor (1) on the intake side.

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