Electrically driven coolant pump

The invention relates to an electrically operated coolant pump with a stator of a the electric motor enclosed rotor with a hollow design rotor shaft, through which the liquid is supplied to the pump impeller, said stator in a stator disposed of the motor housing and the rotor shaft is rotatably supported in the motor housing, wherein the bearing of the rotor shaft via rolling bearings.

The US 5,288,215 A shows an electric motor operated pump whose hollow design rotor shaft is mounted via roller bearings. The roller bearings are separate from the mechanical seals separated by the filled liquid to be pumped spaces. For cooling the electric motor the pump is an internal oil circulation, said oil production own, with the Rotor shaft connected conveyor blades are arranged at both ends of the stator space.

There are known coolant pumps, in which the rotor shaft on sliding bearings in the motor housing the electric motor is mounted. Between the stator and the rotor is a rotor with the arranged connected canned, which rests on the O-rings on the motor housing. This Canned serves to separate the space between the stator and the rotor as the stator must remain dry, but the rotor chamber is filled with the liquid. Around the magnetic not to hinder the river, the canned plastic is performed. This arrangement however, has the disadvantage that due to their construction, a relatively large gap between rotor and stator produces, and thus comparatively large gap losses. If the wall thickness running of the can on the other hand too thin, it comes as a result of increased wear, especially under high thermal loads to leaks between the canned and the O-ring seals.

Further is known from FR 2608228 A a coolant pump with a hollow, sliding bearings in the motor housing mounted rotor shaft is known which is surrounded by a stator. Measures for sealing the rotor space from the stator are not provided. at However, a flooded stator chamber must be provided additional measures to isolate the stator windings from the coolant which, however, the efficiency of adversely affect.

The storage over plain bearings further has the disadvantage that in case of slow pump speed the sliding bearings the mixed friction occurs and therefore exposed to this increased wear are.

The US 5,407,331 A shows a motor-driven pump for rocket fuel, in particular for liquid oxygen, wherein the rotor shaft is mounted by roller bearings. The font is not refer suggestion to use liquid-tight bearings.

The US 3,719,436 A shows an electric motor-driven axial pump with a hollow executed rotor shaft which is mounted on rolling bearings in a housing. sealing the Rolling via separate sealing rings. Furthermore, it is between the rotor chamber and the stator a canned provided.

The US 5,273,404 A shows electrically operated coolant pump with axial impellers, wherein the liquid is transported through the hollow design rotor shaft, wel che is mounted on rolling bearings in a housing. Measures for sealing the bearings compared with the pumped liquid are of this document to refer to none.

The US 4,413,958 A shows an electrically driven pump assembly, wherein the hollow design The rotor shaft is mounted on rolling bearings in a housing. This publication also is no evidence shows that the rolling bearings are liquid-tight.

The object of the invention is to avoid these disadvantages and at a coolant pump of the aforementioned type to improve the efficiency and low-wear to enable operation at any operating speed.

According to the invention this is achieved in that at least one roller bearing as a liquid-tight Rolling is formed and sealing elements are integrated in the roller bearing cage, carried out and that the liquid-tight separated from the liquid being pumped dry stator is. The Rolling allow low-wear operation at any pump speed and enable a very compact design of the electric motor-pump unit. The function the seal between the end regions of the rotor shaft and the stator is adopted by the fluid-tight bearings. This eliminates additional sealing, as a can or the like, and the gap between stator and rotor can be as small be executed as possible, which is beneficial to the efficiency.

Self sealing running bearings, for example with sealing disks, have long been known. Such bearings arranged on both sides sealing discs are usually provided by the manufacturer with a grease filling and are considered maintenance-free bearings. The Sealing washers are used here, both to avoid the leakage of grease and on the other hand penetration of foreign matter, water spray or the. like. to prevent. So far it was assumed that especially in pumps own sealing devices necessary are to provide a reliable seal the stator space opposite with pressurized To ensure delivery fluid filled gap spaces.

Surprisingly, it has been shown that dispense with further sealing measures can be when the bearings themselves are designed to be liquid-tight. By eliminating additional sealing measures are available to the designer greater freedom in Design and construction of the pump is available, so the size opposite known comparable pumps can be substantially reduced. simultaneously saving components, whereby an extremely cost-effective production is possible. The in an extremely simple manner dry running stator has opposite pumps flooded stator chamber also has the advantage that much lower loss in purchasing must be taken.

Especially at coolant pump at high speed, it is advantageous if at least one Rolling is designed as angular contact ball bearings. Optionally, two angular contact ball bearings be provided in tandem in order to increase the rigidity in the axial direction. It is also conceivable one or two angular contact ball bearings in combination with single- or multi-row use cylindrical roller bearings.

Furthermore, it is advantageous if the electric motor is a synchronously running motor. this makes possible a very good control of the speed by a power electronics, which in particular in the start-up phase, a relatively high torque can be applied. Thereby , a fixed uneaten due longer downtime of the pump impeller without back major effort be made consistently.

The invention will be explained in more detail with reference to FIGS. Show it:<sl><li>Fig. 1 shows a longitudinal section through the coolant pump according to the invention,</li><li>Figs. 2 and 3 Bearing variants in detail.</li></sl>

Fig. 1 shows a longitudinal section through the coolant pump 1 with a rotor 2 and a motor housing 3. The rotor 2 is made of hollow structural rotor shaft 4, which with the rotor shaft 4 fixed to the impeller 5 and mounted on the rotor shaft 4 rotor laminations 6. The rotor shaft 4 is over designed as a ball bearing roller bearing 7, 8 at both Ends mounted in the motor housing. 3 The bearing cages 7a, 8a of the roller bearings 7, 8 are liquid-tight executed and have sealing elements 9, 10 on which the stator 11, in which the stator 12 of the electric motor 13 is arranged, of the liquid-filled, in the roller bearings 7, 8 adjoining rooms separate. This is one part of the contact of the rolling elements the bearings 7 and 8 with the liquid being pumped and prevents other hand ensures that the stator 11 remains dry. The roller bearing 7, 8 allow a very compact design of the coolant pump 1 and make optimal storage at each Speed ​​in the pump characteristics map possible. Characterized in that the rolling bearing 7, 8 liquid-tight are performed, no need for additional sealing elements, so that expensive sealing measures can be eliminated between the rotor 2 and the stator 12th Thus, the air gap 14 between be carried to the rotor plate 6 and the stator plate 15 as small as possible, thereby the air gap losses can be minimized.

The feed liquid passes through the pipe 16 into the hollow rotor shaft 4 to the pump impeller 5, and after passing through the impeller blades and the pump 5a of the scroll 18 Coolant outlet 17, respectively.

. Apart from the embodiment shown in Figure 1, the rolling bearing can also - as shown in FIG. 2 - a liquid tight angular contact ball bearings, optionally also as tandem angular contact ball bearings be carried out, whereby a high speed is possible. Furthermore, it is conceivable one or two angular contact ball bearings in combination with single- or multi-row cylindrical roller bearings use.

As an alternative to rolling bearings 7, 8 whose bearing cages 7a, 7b provided with sealing elements 9, 10 are able to seal the bearings 7, 8 relative to the fluid-filled spaces other known shaft seals, eg axial face seals 10a used be illustrated as FIG. 3.

Since the rotor shaft 4 is practically inaccessible from the outside, the electric motor 13 is advantageously designed as a synchronously running motor, which has a relatively high starting torque having. This makes it possible that a left unattended fixed gefressener Rotor 2 can again be made accessible without external intervention.