WO2016041682A1

WO2016041682A1 - Flow-cooled coolant pump having a wet rotor

Info

Publication number: WO2016041682A1
Application number: PCT/EP2015/067735
Authority: WO
Inventors: Jens Hoffmann; Christian BÄTZ; Franz Pawellek
Original assignee: Nidec Gpm Gmbh
Priority date: 2014-09-17
Filing date: 2015-07-31
Publication date: 2016-03-24
Also published as: DE102014113412B3

Abstract

The invention relates to a coolant pump (1) for a coolant circuit of an internal combustion engine. A motor chamber (20) having a pump motor (40) and having an axially oriented pump shaft (50) is arranged in a region of a pump housing through which flow passes axially. A flow channel (30) between an inlet chamber (11) and a pump chamber (12) surrounds the outer surface of the motor chamber (20) and is tapered toward the motor shaft (50) in the direction of the pump chamber (12), such that the coolant is guided around the motor chamber (20) as a jacket flow and, upon entering the pump chamber (12), axially flows against a pump impeller (55) arranged in the pump chamber. In the motor chamber, a can (60) is arranged between a rotor (45) and a stator (41) coaxially to the motor shaft (50), such that a part of the coolant is branched off into the can (60) as a bypass flow and, after flowing through the motor chamber (20), is fed back to the jacket flow, whereupon the merged coolant is circulated by the pump impeller (55) in the pump chamber (12).

Description

description

Flow-cooled coolant pump with wet rotor

The present invention relates to a coolant pump for a coolant circuit of an internal combustion engine.

State of the art

For a long time electrically driven coolant pumps have been used in coolant circuits of internal combustion engines. In an increasing number of applications, electric coolant pumps are preferably used over mechanical, for example belt driven, coolant pumps because they are driven independently of engine speed and greater flexibility in controlling a coolant loop in response to various engine operating parameters or environmental conditions enable. A problem in the prior art is the sufficient cooling of the electric motor and the control electronics within the coolant pump, which represents a significant factor for the life of the coolant pump and also for the reliability of the internal combustion engine and possibly the driven vehicle. The coolant temperature may, in critical circumstances, approach very close to the maximum allowable temperature of the electronic and electrical components required for the construction of an electrical coolant pump, such that overheating failure may result from additional waste heat from the electric pump motor. When using an electric motor as a pump motor this is usually encapsulated installed in order to protect selbige from impairment of reliability by penetrating coolant or other corrosive influences and contamination during operation. Due to the encapsulation, the own waste heat of the electric motor, which is associated with its power loss, not be dissipated as in other applications by an air flow.

In a suitable electric pump motor, the power loss is about 20% of the electrical power, so that in a pump motor with 500 W, as used for example in a coolant pump of a coolant circuit in a car, at full load operation, a heat input of 100 W is produced by the Coolant pump is additionally recorded on the waste heat of the coolant addition.

In addition, the coolant pump is usually installed to save space in the immediate vicinity of the internal combustion engine. Consequently, the coolant pump is exposed to a considerably heated by the waste heat of the internal combustion engine ambient temperature.

To maintain the permissible operating temperature of the coolant pump, a heat exchange with the coolant of the internal combustion engine can be used. The coolant has a much higher coefficient of thermal conductivity of about 0.441 W / ra compared to 0.0262 W / mK air. In addition, during operation of the coolant circuit, it maintains a defined temperature range, whereas the temperature of the air varies greatly depending on the environment, in particular of the internal combustion engine, and possibly on a speed of movement. However, during operation of the internal combustion engine, the coolant assumes a high temperature and, apart from the power loss of the coolant pump, itself already introduces a high heat input into the coolant pump. After passing through the radiator or a heat exchanger with the environment, the coolant should still have a maximum temperature of up to 1 13 ° C according to standards of the automotive industry. However, in heavy duty applications, extreme ambient temperatures, or in adverse circumstances, for example, the coolant in a coolant circuit of an internal combustion engine in a vehicle may reach a temperature of 120 ° C or even 130 ° C. Here, a small temperature difference of only a few degrees between the coolant temperature and the permissible operating temperature of the coolant pump is available to dissipate the heat of the power loss of the electric motor. In order to ensure reliable operation of the electric motor and the electronic components in the coolant pump even under critical conditions with respect to the operating state of the engine or the outside temperature, there is a technical requirement, despite the low usable Temperaturdi fference to produce an efficient heat transfer between the coolant pump and the coolant. With the German patent application DE 103 14 526 AI, the applicant has disclosed a flow-cooled, electric coolant pump, in which a motor housing is flowed around by the coolant. In this case, a suction nozzle in the region of the pump impeller facing away from the end of the pump motor is arranged. The coolant, which is sucked in through the suction port, is guided past the pump motor by a flow channel bounded by the outer wall of the pump housing and the facing inner wall of the pump housing.

European Patent Application EP 2 573 401 A2 describes a coolant pump with a housing, a drive arranged therein and an impeller. A shaft seal is a vacuum area on the The outlet side of the assigned, whereby the seal is not directly exposed to a load by the flow.

The patent application US 2002/0106290 A1 relates to a fluid pump comprising an encapsulated stator assembly which seals a pump motor and facilitates heat transfer from the motor and electronics to the working fluid.

By this construction, an effective cooling of the pump motor and the control electronics could already be achieved by a large heat exchange surface to the sheath flow. However, this pump structure requires a particularly reliable and complex sealing of the motor housing with respect to the coolant flow, which is associated with increased costs. In addition, each seal has a limited life, which also represents a decisive factor for the maximum achievable operating life of the coolant pump.

The patent application DE 10 2008 055 614 AI discloses a centrifugal motor pump in Naßläuferbauart, in which an electric motor rotor is surrounded by a potting material having the stator, the windings, the stator and a canned or a split pot. The stator is in turn surrounded by a motor housing.

EP 0 657 653 A1 describes a canned motor pump with an enclosed motor of relatively small size and low power output, for example for use in circulating warm water. In such canned pumps with a wet-rotor motor, the entire flow is passed through a split tube which houses the shaft and the rotor and separates the stator from the flow. However, this type of pump brings high churning losses, since the entire flow of the rotating rotor must happen, so that the desired efficiency is no longer achieved at higher flow rates.

European Patent Application EP 1 045 149 A2 and German Patent DE 10 2011 009 192 B3 describe radial pump-type coolant pumps with a wet rotor in which the coolant flows axially onto a radial pump impeller arranged between the pump inlet and the pump motor. In this case, a small portion of the coolant from the pump chamber passes as a leakage current through a gap between the pump impeller and shaft (as in the pump from EP 1 045 149 A2), or between pump impeller and pump housing (as in the pump from DE 10 201 1 009 192 B3) or, as is also known from the prior art, through a hollow shaft of the pump motor, into a wet running region of the pump motor, circulation being generated by the circulation on rotating components of the pump motor with a return flow into the pump chamber.

A wet runner as a pump motor eliminates the use of a seal in these coolant pumps and the small circulating leakage current causes little churning losses. However, this also contributes an insignificantly small portion of the coolant at the heat transfer to dissipate the waste heat of the pump motor in the coolant circuit. Thus, the substantial replacement of the waste heat from the power loss of the pump motor between the outer surface of the pump housing and the air takes place in an environment heated by the internal combustion engine.

task

It is therefore an object of the present invention to provide a coolant pump for a coolant circuit of an internal combustion engine, which allows effective cooling of the pump motor and none Sealing between rotating and static elements of the coolant pump compared to the coolant requires.

The underlying object is, starting from the described in DE 103 14 526 AI coolant pump with a jacket flow and the use of a wet rotor with canned motor as a pump motor, according to the invention solved in that a motor chamber at the axial ends of the split tube one from an inlet chamber to the canned has an opened inlet portion and an outlet portion opened from the split tube to a radially tapered portion of the flow channel so that a portion of the refrigerant flowing from the inlet chamber to the engine chamber is branched into the gap tube at the inlet portion of the engine chamber in the split tube as a bypass flow is axially passed along the motor shaft through the motor chamber, while passing the rotor, and at the outlet region of the motor chamber coaxial with the motor shaft, the bypass flow in the tapered portion of the flow channel is fed back, after which the thus merged coolant the pump louse Frad axially flows close to the motor shaft, is circulated by the pump impeller in the pump chamber, and flows through the outlet port of the pump chamber.

In the case of the pump construction according to the invention, an axial throughflow of the wet-rotor pump motor is provided for the first time despite the correspondingly high delivery rate of a coolant pump. In contrast to known coolant pumps with wet rotors, in which a leakage circuit circulates through an annular gap or a hollow shaft, in this case flows a significantly higher volume flow within the stator, which is favored by a pressure difference on both sides of the motor chamber or the can.

In addition, an axial flow around the outside of the stator is provided by a sheath flow, which leads to a large part of the delivered volume flow. The initial combination of the two streams and a set ratio between these two, it is possible to minimize the churning losses of the flow-through rotor over the conventional design of canned pumps and to achieve a medium pump suitable as conveying efficiency.

With the coaxially guided flow and flow through the pump motor, forced convection water cooling is realized, which is superior, especially under critical ambient and operating conditions, to free convection air cooling between an outer surface of the pump housing and an environment heated by the internal combustion engine. By means of two annular heat exchange surfaces between pump motor and coolant as well as a turbulent coolant flow, a particularly effective heat transfer is achieved. As a result, even at high power dissipation under full load operation of the pump motor and high coolant temperature sufficient heat dissipation is achieved on the pump motor, so that a small temperature difference between the coolant and the pump components is ensured, and exceeding the allowable B etri ebstemperatur the coolant pump is reliably prevented.

Thus, a coolant pump with a previously unattainable temperature compatibility could be created that reliably withstood limit values of 150 ° C maximum ambient temperature and 135 ° C maximum coolant temperature. Thus, among other things, a special reliability in critical applications, such as in motor vehicles in hot areas, such as a four-wheel drive vehicle for use in the desert, guaranteed.

The coolant pump according to the invention is due to the efficient heat dissipation especially for high-performance electric motors of eg 1000 W. suitable, which produce a correspondingly higher waste heat at a power loss of 200 W. As a result, with conventional dimensioning of the coolant pump, additional power reserves can be provided for the increased circulation speed of the coolant circuit in critical operating states. Otherwise, by using a particularly powerful electric motor, a smaller-sized coolant pump in relation to the internal combustion engine or its coolant circuit can be used at a lower production cost. In addition, omitted in the inventive coolant pump of

Use of a reliable and correspondingly complex sealing between rotating and static components, in particular between the motor shaft and a housing of the pump motor. As a result, manufacturing and assembly costs are saved. Above all, however, a component with a limited service life is eliminated in the pump structure according to the invention, whereby the maximum achievable operating life of the coolant pump is increased.

Furthermore, the coolant pump according to the invention has no volumetric loss, since the two coolant streams are reunited before the pump impeller.

In addition, due to the configuration of the pump housing and the flow guide, a sufficiently dimensioned motor chamber for different stator diameters can be provided, and design freedom can be created for the use of different types of pump impellers, in particular radially or axially accelerating types of pump impellers.

Advantageous developments of the invention will become apparent from the features of the dependent claims. In a preferred embodiment of the coolant pump, it is provided that the coolant pump has a radially accelerating pump impeller, wherein the pump chamber comprises a spiral housing and a tangentially discharging outlet stub. Thus, the pump structure according to the invention can be realized with the advantages mentioned above as a Halbaxialpumpe. In this embodiment, the coolant pump has a short axial length.

In a further embodiment of the coolant pump, the coolant pump may have an axially accelerating pump impeller, wherein the pump chamber opens into an axially aligned outlet port. Thus, the pump structure according to the invention with the advantages mentioned above can be realized as an axial pump. According to a further preferred embodiment of the coolant pump, the motor chamber is closed on the side facing the inlet chamber by a cover with a spherical surface, in which an open inlet region and an intake of the axial end of the can is arranged. Through the lid, the components of the pump motor can be inserted into the motor chamber in the axial direction during assembly of the coolant pump. The spherical shape provides a favorable flow characteristic in the radial distribution of the jacket current and the bypass current to the motor chamber. In a further preferred embodiment of the coolant pump is the

Motor shaft mounted on the motor chamber, wherein a receptacle for a shaft bearing is formed in the lid and a receptacle for a shaft bearing on the axially opposite end portion of the motor chamber is formed, at which the motor shaft exiting the motor chamber. By this arrangement, compared to a bearing receiver on the can, a good Flow characteristic of the bypass flow through the split tube are produced. Furthermore, a maximum axial distance over the extension of the motor chamber can be used for the arrangement of the two shaft bearings, so that a distance between the pump impeller at the free end of the motor shaft and the nearest shaft bearing and a dynamic load on the same is minimized.

In a further preferred embodiment of the coolant pump, the motor chamber covers an axial end of the can in the inlet region, and is opened within the radius of the can through filter bores or through a filter element through which the bypass flow flows into the can. As a result, foreign matter can be kept away from the bypass current and a deposition of the same can be prevented at the shaft bearings. Further, the rotor, which temporarily moves at high speed in the bypass current, is protected from contact with foreign matter. In the case of filter bores, the permissible large particle size can be accurately determined.

According to a preferred embodiment of the coolant pump according to the filter bores extend conically, with a diameter increasing in the flow direction, preferably with a diameter of 0.05 mm to 0.3 mm, more preferably from 0.1 mm to 0.15 mm. With a particle size of less than 0.1 mm, a defective effect of the foreign matter on the rotating components of the pump motor can be excluded. Due to the conical cone shape of the filter bores a self-cleaning effect is achieved, which counteracts clogging thereof. In addition, a spherical shape at the inlet region promotes drift of foreign bodies along the spherical surface into the sheath flow, thereby effectively preventing deposition and clogging by foreign particles of critical particle size at the entrance of the filter bores. In a further preferred embodiment of the coolant pump, the motor chamber covers an axial end of the can in the outlet region, and is open within the radius of the can through concentric with the motor shaft outlet holes through which the bypass flow flows into the flow channel of the bypass flow. By means of a flow cross-section, which results from the number and diameter of the outlet bores, a pressure difference in the can is set in relation to the flow cross-section of the filter bores or of the filter element. Furthermore, a ratio of the volume flow between the bypass flow and the bypass flow can be adjusted through the entire flow cross section through the filter bores or the filter element and the outlet holes.

In a particularly preferred embodiment of the coolant pump, the volume flows of sheath flow and bypass flow have a ratio a) preferably from about 90% to 10% to 95% to 5%,

b) more preferably from about 93% to 7% to 97% to 3%,

c) most preferably from about 95% to 5% of the total pumped coolant flow. In this determined volume flow ratio, the design of the coolant pump according to the invention is characterized by a particularly advantageous ratio between an effective heat dissipation of the bypass flow and at the same time low churning losses of the rotor in the bypass flow.

According to a further preferred embodiment of the coolant pump, the shaft bearings of the bearing of the motor shaft have a bearing gap, so that a part of the coolant flowing through the motor chamber within the radius of the gap tube flows through the bearing gap of the shaft bearings. the Coolants are additives such as glycerol or the like attached. These additives can also be used simultaneously for the lubrication of correspondingly suitable shaft bearings, in combination with the previously described filtering to keep contaminants, the lubricity of the bypass current can be ensured at the bearing of the shaft and a deterioration of low friction values by deposits on selbiger be suppressed.

In a preferred embodiment of the coolant pump are, in the vertical cross section to the axial direction, between the pump housing and the motor chamber a plurality of radially extending retaining webs, or even axially extending fins, arranged, and the flow channel of the jacket stream is arranged in a plurality around the motor chamber around divided arcuate segments. This structure allows the design with a plurality of, preferably symmetrically arranged, holding webs between the pump housing and the motor chamber, in which the electrical supply line of the pump motor is guided. This creates a torsionally rigid construction for integrating the motor chamber in the pump housing. According to a further preferred embodiment of the coolant pump, the electronic components, such as a control device of the coolant pump, in the vertical cross section to the axial direction, adjacent to the flow channel of the sheath flow in the pump housing are arranged. As a result, the control electronics arranged outside the pump housing can also be effectively flow-cooled.

In a preferred embodiment of the coolant pump, an inner wall of the inlet chamber, into which the at least one inlet port opens, is spherical, and is formed by a bell, which is fixed to the inlet-side axial end of the pump housing. This will in particular in combination with the opposite spherical surface of the motor chamber, created a radially outwardly leading flow cross section with a favorable flow characteristic of the sheath flow around the motor chamber. By replacing the bell-shaped component, the coolant pump can be easily configured with inlet chambers in different variants with regard to the number and orientation of inlet sockets.

According to a particular embodiment of the coolant pump for this purpose, the coolant pump has only one inlet port, which opens at an angle to the axis of the motor shaft in the spherically shaped inner wall of the inlet chamber. By the one inclined suction nozzle, the axial length of the coolant pump continues to decrease. The more compact design and the choice of the angle allows greater freedom in the integration into a coolant circuit of an internal combustion engine, such as in the arrangement in confined spaces in the engine compartment of a vehicle.

Embodiment described above will be explained in more detail below embodiments with reference to the figures of the drawing. It shows:

1 is a perspective view of an exemplary embodiment of the

Coolant pump;

Fig. 2 is a longitudinal sectional view through an exemplary embodiment of

Coolant pump;

Fig. 3 is a cross-sectional view through an exemplary embodiment of

Coolant pump; 4 shows a longitudinal sectional view through an exemplary embodiment of the coolant pump with an illustrated flow path of the coolant;

The structure of an exemplary embodiment of the coolant pump 1 according to the invention will be described below.

The electric coolant pump 1 conveys the coolant circulating in the coolant circuit between the engine and the heat exchanger or radiator. For this purpose, the coolant pump 1 sucks the coolant from the engine via the radiator and pushes it back to the engine. Thus, the coming from the radiator, cooled coolant is used to absorb the waste heat of the power loss of the electric motor and to cool it to the allowable operating temperature.

As shown in the external representation of the coolant pump 1 in Fig. 1, the pump housing 10 in primary subdivision, an inlet chamber 1 1 with one or more inlet port 13 on the one hand, a pump chamber 12 with an outlet 14 on the other hand, and an intermediate interior.

The sectional view in Fig. 2 shows that in the interior of the pump housing, a motor chamber 20 is located in which an electric pump motor 40 is received with a motor shaft 50, via which a pump impeller 55 is driven in the pump chamber 12.

Depending on the application, the coolant pump 1 may have one, two or more inlet ports 13 for conveying different circuits to different heat exchangers. In the applications in a vehicle, in addition to the Kühlmittelkrei slauf of the internal combustion engine, for example, another Circuit operated for a separate heat exchanger of a heater fan for the passenger compartment or the like. In the embodiment depicted in FIG. 2, the coolant circuit coming from the radiator of the combustion engine is connected to the larger volume flow at the axially oriented inlet port 13, and the circulation at lower volume flow to an inlet port 13 which extends differently from the axial direction. The inlet chamber 1 1 of the illustrated embodiment has a spherical inner wall, which provides a favorable flow path for entry into the pump housing 10 for any desired orientation angle and / or multiple inlet ports 13. In the illustrated embodiment, the inlet chamber 11 is formed by a domed bell 15 fixed to the inlet-side axial end of the pump housing.

As shown in FIG. 3, the motor chamber 20 has a cylindrical shape when viewed in cross-section with respect to the axial direction, and is arranged concentrically in an inner space of the pump housing having a cylindrical cross section. In this case, the motor chamber 20 occupies a large part of the interior of the pump housing, so that in cross-section only an annular gap between the motor chamber 20 and the pump housing 10 remains as a free space. Viewed in the axial direction, the outer contour of the motor chamber 20 follows the inner contour of the pump housing, so that within the annular gap in cross-section over an axial extent of the motor chamber 20 and the pump housing away a jacket-shaped flow channel 30 is formed between the two.

The motor chamber 20 is held by holding webs 21 and fins, which extend in the radial direction between the motor chamber 20 and the pump housing 10 and extending in the axial direction of the motor chamber 20, centrally in the pump housing 10. The four radial retaining webs 21 shown in FIG. 3 divide the annular sheath flow in four flow channels with a curved segment-shaped flow cross-section.

The control electronics 43 of the coolant pump 1 is arranged in an outer region of the pump housing close to the outer contour of the jacket-shaped flow channel s 30. A holding web 21 receives the electrical leads 42 from the control electronics 43 to the pump motor 40 in itself and leads them radially through the shell-shaped flow channel 30 into the motor chamber 20th

In the motor chamber 20, the pump motor 40 is arranged with the motor shaft 50 coaxial with the cylindrical structure of the motor chamber 20 described above in cross section to the axial direction. The radially outer stator 41 of the pump motor 40 is enclosed in an annular space of the motor chamber 20, which is formed outwardly through the wall of the motor chamber 20, and is closed inwardly by a split tube 60, which is coaxial with the motor shaft 50 through the motor chamber 20th extends through. The annular space, which comprises the wiring of the pump motor 40, in particular the coils of the stator 41, receives the leads 42 from the control electronics 43 from the holding web 21 and is sealed by the non-rotating can 60 with respect to the coolant.

The radially inner rotor 45 of the pump motor 40 is arranged together with the motor shaft 50 concentrically in the cylindrical space within the can 60. The split tube 60 has in the illustrated embodiment in an axial region for receiving the rotor 45 has an enlarged cross-section. The split tube 60 forms a concentric flow channel 30, which runs coaxially with the motor shaft 50 and the jacket-shaped flow channel 30. The motor shaft 50 extends from the inlet-side axial end of the motor chamber 20 through the split tube 60, exits at the axially opposite end of the motor chamber 20 and extends into the pump chamber 12, in which the pump impeller 55 rotatably on the circumference of the motor shaft 50 is arranged. On the motor chamber 20, shaft bearings 51, 52 are provided for the rotatable mounting of the motor shaft 50 in the region of the axial ends of the split tube 60, within the same radius. The shaft bearings 51, 52 have a bearing gap, which can be flowed through by the coolant, and thereby lubricated by additives such as glycerol or the like in the coolant.

On the side facing the inlet chamber 11, the motor chamber 20 has a spherical surface which provides a flow-favorable supply of the inflowing coolant into the sheath flow. The spherical surface is formed in the embodiment shown in Fig. 2 by a curved lid 22 which closes the motor chamber 20 to the outside. The cover 22 also has in the center an inlet region with filter bores 26 through which coolant can enter the can 60. In addition, the cover 22 has a receptacle for the axial end of the split tube 60, which seals tightly with respect to the outer annular space of the motor chamber 20, and a receptacle for a shaft bearing 51 of the motor shaft 50. The filter bores 26 have a conically increasing from the outside to the inside of the lid 22 diameter of 0.1 mm to 0.15 mm.

On the pump chamber 12 side facing the motor chamber 20 tapers in the axial direction of the pump chamber 12, both the cylindrical cross section of the inner contour of the pump housing and the outer contour of the motor chamber 20 equally, so that also extending therebetween coat-shaped flow channel 30 in Outlet region of the motor shaft 50 from the motor chamber 20 tapers to near the radius of the motor shaft 50 radially inwardly. In the exit region of the motor shaft 50 is another Mount for a shaft bearing 52 is provided. At the axial end of the can 60, an outlet region of the engine chamber 20 is formed within the radius thereof, in which outlet bores 23 distributed concentrically with the motor shaft 50 are arranged, through which the coolant which has entered the can 60 in the inlet region of the engine chamber 20 emerges again can. The outlet holes 23 lead directly into the tapered region of the shell-shaped flow channel 30th

The tapered shell-shaped flow channel 30 leads the coolant axially close along the motor shaft 50 to the pump impeller 55, which defines an entrance into the pump chamber 12. The pump chamber 12 and a portion of the pump housing which forms the outer contour of the radially inwardly tapered portion of the shell-shaped flow passage 30 are integrally formed as a member which is inserted and fixed in the axial end of the pump housing. In FIGS. 2 and 4, the coolant pump 1 is designed as a semi-axial pump and has a radial pump impeller 55 and a pump chamber 12 with a spiral housing 16 and a tangential outlet connection 14.

Hereinafter, an operation of the above-described exemplary embodiment of the coolant pump 1 according to the present invention will be described with reference to FIG. 4.

The sucked by the coolant pump 1 from the radiator and possibly other heat exchangers coolant flows through the inlet port 13 into the inlet chamber 1 1 of the pump housing. The refrigerant drawn from the one or more coolant circuits that has entered the inlet chamber 11 then flows toward the engine chamber 20 and is concentrically divided at the spherical shaped cover 22 of the engine chamber 20 into two coolant streams. In this case, a large part of the coolant, in the present example 95%, flows along the surface of the cover 22 along radially outside in the shell-shaped flow channel 30 and forms a sheath flow in the pump housing 10. A small portion of the coolant, in the present example 5%, flows through the filter bores 26 at the inlet region of the cover 22 and is thereby branched off as a bypass flow into the can 60 of the motor chamber 20.

The bypass flow surrounds the motor chamber 20, wherein a temperature exchange between the passing coolant and the outer surface of the motor chamber 20 takes place. Insofar as the engine chamber 20 has a higher temperature than the coolant due to the waste heat of the power loss of the pump motor 40, the waste heat is dissipated by the volume flow of the coolant. The sheath flow may similarly receive at the opposite surface of the pump housing, a waste heat of the control electronics 43, which is arranged close to the outer periphery of the shell-shaped flow channel 30 in the pump housing. The bypass flow is directed radially inwardly near the motor shaft 50 toward the end of the axial flow around the motor chamber 20 in the tapered portion of the jacket-shaped channel.

The branched bypass stream, after passing through the filter bores 26, partially flows through an annular gap formed between the inner surface of the can 60 and that of the cover 22 within the can 60

Then, the bypass flow flows into the enlarged diameter portion of the can 60 in which the rotor 45 is received, and passes through an annular gap between the inner surface of the can 60 and the outer circumference of the rotor 45. In turn, as described above, a temperature exchange between the surfaces of the rotor 45 and the split tube 60 takes place with the coolant. By the rotating rotor 45, there is a turbulence of the bypass flow or to a turbulent flow, so that when the waste heat of the pump motor 40 exceeds the coolant temperature, despite lower flow in comparison to the sheath flow, an effective heat dissipation within the motor chamber 20 is achieved with still low churning losses of the rotor 45. At the axial end of the can 60, the bypass flow flows partly through the outlet bores 23 at the outlet region of the motor chamber 20 and partly through the bearing gap of the shaft bearing 52 received in the exit region of the shaft from the motor chamber 20 and enters the tapered section of the bypass flow.

The sucked reunited coolant stream then flows axially into the pump impeller 55 in the pump chamber 12 and is circulated through radially accelerating vanes in the pump impeller 55. The accelerated coolant leaves the pump impeller 55 radially outward, flows into a tangentially discharging volute 16 of the pump chamber 12, and exits the coolant pump 1 through the outlet port 14. Other Embodiments and Modifications

In one embodiment, not shown, of the coolant pump 1 is followed by the pump housing 10 on the one hand a bell 15 of the inlet chamber 1 1 with a single angled exiting intake manifold, and on the other hand, a radially acting pump chamber 12 at. This embodiment thus has a particularly short axial dimension.

In an embodiment, not shown, of the coolant pump 1, however, instead of the radially acting pump chamber 12, an axially acting pump chamber 12 with a substantially cylindrical shape can be connected to the pump housing 10, in which an axial impeller 55 and an impeller is arranged Coolant is ejected after circulating through an axially extending outlet 14. Furthermore, in a modification of the described embodiment of the coolant pump 1, only one retaining web 21 can be provided as a connection between the motor chamber 20 and the pump housing 10, which holds the motor chamber 20 in position within the pump housing and leads the supply lines 42 to the pump motor 40, so that the sheath flow is formed in cross-section as a one-piece or simply slotted annular gap between the motor chamber 20 and the pump housing 10. Likewise, any number of retaining webs 21 between the motor chamber 20 and the pump housing 10 may be formed. In addition, the retaining webs 21 may be configured in a different orientation than a radial course and / or extend over the entire length of the motor chamber 20 or only over a part thereof.

In a further modification of the described embodiment of the coolant pump 1, instead of the filter bores 26, a suitable filter element can be inserted into the cover 22 of the motor chamber 20 within the radius of the can 60. Furthermore, the motor chamber 20 may also be open over the entire radius of the can 60 and have no filtering of the bypass current.

In particular, in this case, the shaft bearings 51, 52 of the motor shaft 50 can be supported against the can 60 instead of against the motor chamber 20. In this case, a sufficient flow cross section between the outer diameter of the shaft bearing 51, 52 and the inner diameter of the split tube 60 may be provided, for example by a radially braced bearing support in the can 60.

Claims

speech

A coolant pump (1) adapted for a coolant circuit of an internal combustion engine, comprising: a pump housing (10) having an inlet chamber (11) with at least one inlet port (13) and a pump chamber (12) with an outlet port (14), the pump housing ( 10) in an axial direction between the inlet chamber (11) and the pump chamber (12) is flowed through by the coolant of the coolant circuit, a motor chamber (20) which is arranged in the axially flow-through region in the pump housing (10) and an electric pump motor (40 ) with a motor shaft (50), wherein the motor shaft (50) axially between the inlet chamber (1 1) and the pump chamber (12) is aligned on the side facing away from the inlet chamber (1 1) side of the motor chamber (20) emerges , extends into the pump chamber (12), and in the pump chamber (12) a pump impeller (55) on the motor shaft (50) is arranged; a flow passage (30) leading from the inlet chamber (11) to the pump chamber (12), formed in a vertical cross section to the axial direction between the pump housing (10) and the motor chamber (20) and surrounding an outer surface of the motor chamber (20) in that the flow channel (30) tapers in an axial section between the motor chamber (20) and the pump chamber (12) radially inwardly towards the motor shaft (50), so that the coolant, which flows through the at least one inlet port (13) via the inlet chamber (11) in the pump housing (10) over a coaxial to the motor shaft (50) extending portion of the flow channel (30) away, as a substantially cylindrical sheath flow around the Motor chamber (20) is guided, and, after flowing through a radially tapered portion of the flow channel (30), in the region of entry into the pump chamber (12), axially near the motor shaft (50) flows, a split tube (60) extending coaxially with the motor shaft (50) between a rotor (45) of the pump motor (40) and a stator (41) of the pump motor (40) through the motor chamber (20) extends, so that within the radius of the can (60) lying portion of Motor chamber (20), in which the motor shaft (50) and the rotor (45) are rotatably mounted, from the outside of the radius of the split tube (60) lying portion of the motor chamber (20) in which the stator (41) is included, is delimited; characterized in that the motor chamber (20) at the axial ends of the can (60) has an inlet region opened from the inlet chamber (11) to the can (60) and an outlet region opened from the can (60) to the radially tapered portion of the flow channel (30) such that a portion of the refrigerant flowing into the engine chamber (20) from the inlet chamber (11) is branched into the can (60) at the inlet portion of the engine chamber (20) in the can (60) as a bypass flow axially passing along the motor shaft (50) through the motor chamber (20) passing the rotor (45) and at the outlet area of the motor chamber (20) coaxial with the motor shaft (50) the sheath flow in the tapered portion of the flow channel (30) is fed again, according to which the thus merged refrigerant the pump impeller (55) flows axially close to the motor shaft (50), is circulated by the pump impeller (55) in the pump chamber (12), and through the outlet port (14) flows out of the pump chamber (12).

Coolant pump (1) according to claim 1, comprising a radially accelerating pump impeller (55), wherein the pump chamber (12) comprises a volute (16) and a tangentially discharging outlet (14).

Coolant pump (1) according to claim 1, comprising an axially accelerating pump impeller (55), wherein the pump chamber (12) opens into an axially aligned outlet port (14).

The coolant pump (1) according to any one of claims 1 to 3, wherein the motor chamber (20) is closed on the side facing the inlet chamber (11) by a lid (22) having a spherical surface in which an opened inlet area and one to the motor chamber (20) is formed inside receiving the axial end of the can (60).

Coolant pump (1) according to claim 4, wherein the motor shaft (50) is mounted on the motor chamber (20), wherein a receptacle for a shaft bearing (51) in the cover (22) is formed and a receptacle for a shaft bearing (52) the axially opposite end portion of the motor chamber (20) is formed at which the motor shaft (50) from the motor chamber (20) emerges. Coolant pump (1) according to one of claims 1 to 5, wherein the

Motor chamber (20) an axial end of the can (60) covered in the inlet region, and within the radius of the can (60) through filter bores (26) or through a filter element is opened, through which the bypass flow flows into the can (60) ,

Coolant pump (1) according to claim 6, wherein the filter bores (26) are conical, with a diameter which increases in the flow direction, particularly preferably with a diameter of 0.1 mm to 0.15 mm.

Coolant pump (1) according to one of claims 1 to 7, wherein the motor chamber (20) covers an axial end of the can (60) in the outlet region, and within the radius of the can (60) via concentrically arranged to the motor shaft (50) outlet bores (23 ) is opened, through which the bypass current flows into the flow channel (30) of the sheath current.

Coolant pump (1) according to one of claims 1 to 8, wherein flow rates of sheath flow and bypass flow a ratio a) preferably from about 90% to 10% to 95% to 5%,

b) more preferably from about 93% to 7% to 97% to 3%,

c) most preferably from about 95% to 5%,

of the entire conveyed coolant flow.

Coolant pump (1) according to one of claims 5 to 9, wherein the shaft bearings (51, 52) of the motor shaft (50) have a bearing gap, so that a portion of the coolant, the motor chamber (20) within the radius of the can (60) flows through, through the bearing gap of the shaft bearing (51, 52) flows. Coolant pump (1) according to one of claims 1 to 10, wherein in the vertical cross section to the axial direction, between the pump housing (10) and the motor chamber (20) a plurality of radially extending retaining webs (21), or even in the axial direction extending fins arranged are divided, and the flow channel (30) of the sheath current into a plurality of around the motor chamber (20) arranged around arcuate segments.

Coolant pump (1) according to one of claims 1 to 1 1, wherein electronic components (43), such as a control device of the coolant pump (1), in the vertical cross section to the axial direction, adjacent to the flow channel (30) of the sheath flow in the pump housing (10). are arranged.

The coolant pump (1) according to any one of claims 1 to 12, wherein an inner wall of the inlet chamber (11) into which the at least one inlet port (13) opens is spherical, and is constituted by a bell (15) located at the inlet side axial end of the pump housing (10) is fixed.

Coolant pump (1) according to one of claims 1 to 13, comprising only an inlet port (13) which opens at an angle to the axis of the motor shaft (50) in the spherically shaped inner wall of the inlet chamber (1 1).