EP1945955B1 - Fluid pump - Google Patents

Abstract

The invention relates to an electric fluid pump with a semi-axial construction, in which a motor housing part (9), situated at the pressure end, has a conduction device (42). The conduction device (42) allows an almost completely irrotational flow to be achieved so that the kinetic energy of the tangential component of the flow velocity is converted into pressure energy with negligible friction losses. This feature of the invention increases the efficiency of the fluid pump. The dimensions of the electric motor can therefore be reduced while maintaining the same delivery quantity.

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 in Flow direction of the fluid to be conveyed is arranged behind the impeller, and a pump housing, which surrounds the motor housing, the impeller and the stator and on which opposite to the axial ends of a discharge nozzle and a suction nozzle are formed.

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. 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 parts 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.

The DE 202 01 183 U1 , which is considered to be the closest prior art, discloses an axial pump with an electric motor, which is surrounded by a housing part with straight support ribs, which are to serve as a stator. Due to its straight design, the pressure loss is very high. In addition, a swirl freedom is unlikely to be achieved by such an embodiment.

It is therefore an object of the invention to achieve a swirl-free outflow with the lowest possible pressure losses and thus to increase the efficiency in reducing the installation space. Furthermore, when using the same housing parts different maximum delivery rates can be realized.

This object is achieved in that a pressure-side motor housing part has a Nachleitapparat, which is formed by return vanes. Through this Nachleitapparat almost complete freedom from twist can be achieved, so that the kinetic energy of the tangential component of the flow velocity is converted with little friction losses in pressure energy. This increases the efficiency of the fluid pump. To achieve an equal flow rate, the size of the electric motor can thus be reduced.

In a further embodiment, the return vanes are made in one piece with the pressure-side motor housing part and formed on its surface, whereby no additional components are needed and the freedom from twist is ensured with low energy losses. The return vanes serve to convert the tangential flow component into an axial flow component without higher pressure drops. The efficiency is increased and components saved.

Preferably, the pressure-side motor housing part is narrowing in the flow direction and surrounded by a correspondingly shaped pressure-side pump housing part. As a result, the return vanes are limited at their radial ends by the pump housing, so that an overflow of the blades is reliably prevented.

It is advantageous if grooves are formed in the pressure-side pump housing part into which the radial ends of the return vanes extend. This in turn reduces the flow resistance by preventing overflow of the blades and fixes the position of the motor housing part to the pump housing part, so again mounting errors are avoided, since the grooves serve as guide grooves during assembly.

In a further embodiment, the pressure-side motor housing part by sliding the pressure-side pump housing part on the pressure-side motor housing part with the interposition of a seal in a receiving opening of an axially adjacent motor housing part displaceable, wherein fastening the pressure-side pump housing part to a axially adjacent motor housing part radially outboard pump housing part, the pressure-side motor housing part is fixed. Fasteners must not be used accordingly for the attachment of the pressure-side motor housing part. Alone by the attachment of the pump housing, a tight attachment of the motor housing is guaranteed, so that the assembly cost decreases.

Preferably, the pressure-side pump housing part has a flange, via which the fluid pump can be fastened to an internal combustion engine. It is produced by the simplicity of the pump housing parts of the discharge nozzle in one piece with the flange, so that the fluid pump can be flanged without additional intermediate lines idrekt, for example, to a motor housing.

It when several fluid pumps are connected in series via a flange connection, wherein the flanges are formed on the pressure-side pump housing part of the first and on a suction-side pump housing part of a downstream pump is particularly advantageous. There is the possibility of a series connection without additional components to achieve a higher required maximum volume flow. This is possible in particular by the swirl freedom in the outlet through the Nachleitapparat. So can be created in a small space without re-design and without changing the components, a different flow at different engine sizes. This can reduce costs.

It is thus created a fluid pump, which provides a swirl-free flow in the outlet and works with low pressure losses due to friction and the like. This increases the efficiency since a large part of the kinetic energy is actually converted into pressure energy. Through a series connection different delivery rates can be achieved with the same components in a small space.

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 8 has a hole 10 in which a first bearing 11 is arranged for supporting the drive shaft 3. Viewed from the suction side behind the first bearing 11 is a ceramic thrust bearing 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 known in the prior art, this bore is guided by support ribs 31, which is sufficient Strength and attachment of a pump housing are necessary. 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 expanding in the flow direction 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, the same 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 a 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 to attach 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, thereby the motor housing part 9 is pressed against the closure member 27 and the can 24, so that a 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 also flows behind the impeller 5 to the drive shaft 3 and here between the first bearing 11 and the drive shaft 3, 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 Halbaxialpumpe is characterized in particular by the fact that it is very small to build, since the same power consumption an equal capacity with a smaller motor size and increased speed compared to known To reach pumps. 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 to build a larger pump with again required larger engine with required double power, but simply switch through the part equality the corresponding required number of pumps in a row.

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 it is in the illustrated embodiment, only a possible embodiment of the invention, the construction in various points without departing from the scope of the claims.

Claims (7)

1. A fluid pump for internal combustion engines, comprising
   an electric motor having a rotor and a stator disposed in a motor housing, the rotor at least being arranged on a drive shaft for rotation therewith,
   an impeller mounted on the drive shaft,
   at least one guide wheel arranged downstream of the impeller in the flow direction of the fluid to be conveyed,
   and a pump housing enclosing the motor housing, the impeller and the guide wheel, and which is formed with a pressure port and a suction port on opposing axial ends thereof,
   characterized in that
   a pressure-side motor housing part (9) comprises a set of downstream guide vanes (42) formed by recirculation vanes.
2. The fluid pump for internal combustion engines of claim 1, characterized in that the recirculation vanes (41) are manufactured integrally with the pressure-side motor housing part (9) and are formed on the surface (43) thereof.
3. The fluid pump for internal combustion engines of claim 1 or 2, characterized in that the pressure-side motor housing part (9) is formed so as to narrow in the flow direction, and that it is enclosed by a correspondingly shaped pressure-side pump housing part (34).
4. The fluid pump for internal combustion engines of one of the preceding claims, characterized in that the pressure-side pump housing part (34) is formed with grooves (39) into which the radial ends (40) of the recirculation vanes (41) extend.
5. The fluid pump for internal combustion engines of claim 4, characterized in that the pressure-side motor housing part (9) is adapted to be displaced into a receiving opening (29) of an axially adjoining motor housing part (8) by pushing the pressure-side pump housing part (34) onto the pressure-side motor housing part (9), with the interposition of a seal (28), wherein the pressure-side motor housing part (9) is fixed by mounting the pressure-side pump housing part (34) to a pump housing part (8) situated radially outward with respect to the axially adjoining motor housing part (8).
6. The fluid pump for internal combustion engines of one of the preceding claims, characterized in that the pressure-side pump housing part (34) has a flange by which the fluid pump can be mounted to an internal combustion engine.
7. The fluid pump for internal combustion engines of one of claims 1 to 5, characterized in that a plurality of fluid pumps are connected in series via a flange connection, the flanges being formed at the pressure-side pump housing part (34) of the first pump and to a suction-side pump housing part (33) of a downstream pump.

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