WO2012116676A1

WO2012116676A1 - Controllable coolant pump

Info

Publication number: WO2012116676A1
Application number: PCT/DE2012/000173
Authority: WO
Inventors: Andreas Schmidt; Franz Pawellek
Original assignee: Geräte- und Pumpenbau GmbH Dr. Eugen Schmidt
Priority date: 2011-03-02
Filing date: 2012-02-22
Publication date: 2012-09-07
Also published as: DE102011012826B3; EP2681452B1; EP2681452A1

Abstract

The invention relates to a controllable coolant pump for an internal combustion engine, which is driven by means of a belt pulley. The aim of the invention is to develop a driven controllable coolant pump which among other things ensures optimal heating of the engine by means of "zero leakage" and which enables reliable actuation of the valve slide with very little driving power even under unfavorable thermal boundary conditions, or even if the installation space for the coolant pump in the engine compartment is very limited, ensures continued functioning of the coolant pump (fail-safe) even if the controller fails, is characterized by a construction that is very simple in terms of production and assembly, cost-effective, "standardizable" for different pump sizes, and very short in the longitudinal extent of the construction, and also ensures high operational safety and reliability at high volumetric efficiency, does not require air-free filling at the factory, and also can be easily and cost-effectively integrated into the engine management system. According to the invention, said aim is achieved by means of a controllable coolant pump equipped with a control slide and driven by means of a belt pulley, said coolant pump being characterized among other things in that a spring plate (17) that forms a pressure chamber (16) together with the pump housing (1) is arranged on the pump housing (1) in the pump interior (14), on which spring plate the restoring spring (6) lies, and on the outer radius of which spring plate an inner slide seal (18) is arranged in such a way that the inner slide seal lies against the inside of the outer cylinder (8) of the control slide (7), at the same time an outer slide seal (19) that lies against the outside of the outer cylinder (8) of the control slide (7) being arranged in the pump housing (1) in such a way that the outer cylinder (8) of the control slide (7) can be variably moved against the spring force of the restoring spring (6) along the outflow region of the impeller (5).

Description

Adjustable coolant pump

The invention relates to a controlled via a pulley controllable coolant pump for internal combustion engines.

In the course of the continuous optimization of internal combustion engines in terms of emission and fuel consumption, it is important to bring the engine after the cold start as quickly as possible to the operating temperature.

This minimizes both the friction losses (as the oil temperature decreases, the viscosity of the engine oil and thus the friction on all oil-lubricated components) reduces the emission values (since the catalysts only become active after the so-called "light-off temperature" is the time until this temperature is reached significantly the exhaust emissions) and also significantly reduces fuel consumption.

A very effective measure for engine heating is the "standing water" or the "zero leakage" during the cold start phase, in which the cylinder head must not be flowed through by coolant, thereby bringing the exhaust gas temperature very quickly to the desired level.

In this context, vehicle manufacturers would like leakage flows of less than 0.5 l / h ("zero leakage"). The studies on the fuel consumption of internal combustion engines in motor vehicles have also shown that a consistent thermal management {ie those measures which lead to an energetically and thermomechanically optimal operation of an internal combustion engine) can be saved about 3% to 5% fuel.

In the prior art, therefore, the Applicant has described both in DE 10 2005 004 315 B4, in DE 10 2005 062 200 B3 as well as in WO 2009/143832 A2 from the crankshaft of the internal combustion engine via pulleys driven controllable coolant pumps, which a allow active control of the coolant flow rate, on the one hand by "zero leakage" to ensure optimum warming of the engine and on the other hand after the heating of the engine (ie in "continuous operation") to influence the engine temperature so that in the entire working range of the engine both the Pollutant emission, as well as the friction losses and also at the same time the fuel consumption can be significantly reduced.

In these solutions, a ring-shaped valve slide which is displaceably mounted in the pump housing in the direction of the shaft axis of the pump shaft is arranged with an outer cylinder which variably covers the outflow region of the impeller, which counter to the spring force of return springs either as in the solution according to DE 10 2005 004 315 B4 proposed electromagnetic, ie by means of a magnet coil arranged in the pump housing, which acts on a magnet armature rigidly connected to the valve slide, or, as proposed in DE 10 2005 062 200 B3, by means of a pneumatically or hydraulically actuated actuator (which is hydraulically mounted on the valve slide in the pump housing guided piston rods acts) can be moved linearly.

This arrangement of a guided, linearly displaceable, the outflow of the impeller variable overlapping valve spool is a very compact, simple and robust solution which ensures high reliability and high reliability.

The disadvantage, however, is that the production and assembly of the designs presented in DE 10 2005 004 315 B4 as well as the designs presented in DE 10 2005 062 200 B3 are very cost-intensive, since most of the functional assemblies of the above-mentioned US Pat. Solutions are not standardized, and therefore must be made separately for each pump size.

When installing an electromagnetically actuated coolant pump as well as the above-described in DE 10 2005 004 315 B4 design, for example in the vicinity of the turbocharger is necessarily cooling the solenoid (and thus a relatively large "space") required because otherwise already at temperatures from 120 ° C the magnetic coil would be destroyed.

For this necessarily required relatively large "space", either for the arranged according to DE 10 2005 004 315 B4 in the pump housing solenoid, or according to DE 10 2005 062 200 B3 arranged in the pump housing hydraulic or pneumatic actuators and their connecting lines results in another Disadvantage, which is diametrically opposed to the often very limited, available in the engine compartment "installation space" for the controllable coolant pump.

In order now even in unfavorable thermal boundary conditions, such as in the vicinity of the turbocharger, or even with very limited installation space a manufacturing and assembly technology simple, cost-effective, "standardizable" for different pump sizes, optimally exploiting the available space in the engine compartment space effective operation of the To ensure valve spool at high volumetric efficiency was presented by the applicant in the meantime also proven practice, disclosed in WO 2009/143832 A2 solution in which a hydraulic actuation of the valve spool via a equipped with a return spring in the form of a compression spring piston pump, the mechanical of In conjunction with a control according to the invention of the Piston pump "pumped volume flow" is this solution to a compact, very easy and inexpensive to be incorporated into the engine management, manufacturing and assembly technology simple and inexpensive to produce, robust and reliable solution.

A disadvantage of this solution, however, is that this design works too sluggish due to the return pump equipped with a return spring, and therefore is not suitable for high speed applications.

Also, the piston pump integrated in the pump housing from today's point of view requires too long a length expansion of the pump housing, with too many components and too high manufacturing and assembly costs.

The invention is therefore based on the object to develop a driven via a pulley variable coolant pump (with valve spool), which eliminates the aforementioned disadvantages of the prior art, on the one hand by "zero leakage" ensures optimum heating of the engine and also on the other hand the engine warming can influence the engine temperature in continuous operation so accurately that the pollutant emission as well as the friction losses and the fuel consumption can be significantly reduced in the entire working range of the engine and even in unfavorable thermal boundary conditions, such as in the vicinity of the turbocharger, or even with very limited installation space for the coolant pump in the engine compartment with very low drive power reliable actuation of the valve spool allows even in case of failure of the scheme further functioning of the coolant pump (fail-safe) ensures itself characterized by a manufacturing and assembly technology very simple, inexpensive, "standardizable" for different pump sizes, in their length very short design, optimally exploits the available space in the engine compartment, and also ensures high reliability and reliability at high volumetric efficiency, no factory air-free Filling requires and can also be easily and inexpensively integrated into the engine management.

According to the invention, this object is achieved by a driven via a pulley controllable coolant pump for internal combustion engines according to the features of the independent claim of the invention.

Advantageous embodiments, details and features of the invention will become apparent from the dependent claims and the following description of the in conjunction with seven representations of the inventive solution.

It show the following:

Figure 1: the controllable coolant pump according to the invention in section in the side view;

Figure 2: the controllable coolant pump according to the invention according to Figure 1 in partial section at A - A, at the end of the "inflow" just before the start of the compression phase through the eccentric bush 27;

FIG. 3 shows the controllable coolant pump according to the invention according to FIG. 1 in partial section at A-A, at the beginning of the "inflow phase";

Figure 4: the detail B of the invention controllable

Coolant pump according to Figure 1;

FIG. 5 shows a section at CC in the detail B with a possible design of the controllable coolant pump according to the invention according to FIG. 4; FIG. 6: the detail B of the controllable coolant pump according to the invention according to FIG. 1;

Figure 7: section at D-D in the detail B with another possible

Construction of the detail B of the controllable coolant pump according to the invention according to FIG. 6.

In these embodiments of the controllable coolant pump according to the invention shown in Figures 1 to 7 is in a pump housing 1, mounted in a / on the pump housing 1 in a pump bearing 2, driven by a pulley 3 pump shaft 4, one on a free, flow-side end of this pump shaft 4 rotatably mounted impeller 5, a pressure-operated, spring-loaded by a return spring 6, control slide 7 with a Ausströmbereich of the impeller 5 variably overlapping outer cylinder 8, a arranged in the pump housing 1 between the impeller 5 and the pump bearing 2 in a seal holder 9 shaft seal 10, a arranged on the pump housing 1 working housing 11 in which a solenoid valve 12 is arranged, wherein the inlet opening, a pressure channel 13 and to the outflow opening into the pump interior 14 recirculating passage 15 leads.

It is advantageous in this context that in the impeller 5, a vane bushing 42 is arranged, which reduces the manufacturing and assembly costs while increasing the reliability of the coolant pump.

Is essential to the invention that in the pump interior 14 on the pump housing 1 a together with the pump housing 1, a pressure chamber 16 forming spring plate 17 is arranged, on which the return spring 6 abuts, and on the outer radius of a slider inner seal 18 is arranged such that this inside of the outer cylinder 8 of Regulating slide 7 is applied, at the same time in the pump housing 1, an outside of the outer cylinder 8 of the Regulating slide 7 fitting slide outer seal 19 is arranged such that the outer cylinder 8 of the control slide 7 can be moved variable at pressure buildup in the pressure chamber 16 against the spring force of the return spring 6 along the Ausströmbereiches of the impeller 5.

It is characteristic that in the pump interior 14 between the impeller 5 and the contact area of the spring plate 17 on the pump housing 1 rotatably in the pump housing 1 through the spring plate 17 projecting through, with a closed pump hole 14 closed blind bore 20 provided pivot cylinder 21 is arranged, the open Bore end 22 opens into the pressure channel 13, and at the opposite end, a Kolbenanlagesteg 23 is arranged, wherein rotatably mounted on the pivot cylinder 21, a working piston 24 is arranged with a Kolbendurchlassbohrung 25, the Kolbendurchlassbohrung 25 arranged in the region of the Kolbendurchlassbohrung 25 in the pivot cylinder 21 Through hole 26 opens into the blind hole 20 of the swing cylinder 21.

According to the invention is further in this context that in the region of the working piston 24 rotatably on the pump shaft 4, an eccentric bushing 27 is arranged in the pump shaft side a circumferentially surrounding the impeller 5 adjacent arranged Ansaugringkanal 28 is arranged.

It is also essential to the invention that a crank disk ring 29 with a piston bore 30 for the working piston 24 is rotatably arranged on the outer jacket of the eccentric bushing 27, wherein a suction kidney 31 is arranged in the region of the piston bore 30 in the eccentric bushing 27 in such a way that when the eccentric bushing revolves with the pump shaft 4 27 located in Ansaugringkanal 28 medium is conveyed into the piston passage bore 25.

It is also advantageous if 24 piston rings 44 are arranged on the outer circumference of the slidably mounted in the piston bore 30 of the crank disk ring 29 region of the working piston, which at low Production and assembly costs ensure a high efficiency of the arrangement according to the invention.

Another feature of the invention is that the impeller 5 bears against both the eccentric bushing 27 and the crank disk ring 29 and has at least one, the Ansaugringkanal 28 adjacent arranged collecting ring channel 33, wherein the contact region of the impeller 5 on the eccentric bushing 27 as an annular gap filter 32 is formed, so that in this area a transfer of medium from the pump interior 14 into the collecting ring channel 33 / the Sammelringkanäie 33 and of this / these in the Ansaugringkanal 28 is possible.

It is essential that, as shown in Figure 5, the annular gap filter 32 at the same time fulfills the function of a centrifugal separator and consists of a arranged on the eccentric bushing 27 annular Filterplato 45, are introduced in the Filterkeilnuten 46 such that these from the outer radius the filter inlet 47 located at the inner radius of the slit filter 32 increase so that particles entrained by the coolant (such as chips or grains of sand) can not penetrate into the area of the slit filter 32 and even if the smallest particles are sucked in a good flow through the filter is ensured as a result of the filter wedge grooves 46, which widen inwardly to a great extent, wherein particles adhering to the filter are circulated at the same time as a result of the centrifugal forces acting on the filter.

In a further embodiment of the annular gap filter 32 shown in FIG. 7, this is formed by a filter disk 49, wherein in the region of the filter disk in the eccentric bushing 27, a scraper 50 projecting beyond the plane of the eccentric bushing 27 and projecting into the pump interior space 14 is oblique to the tangent is arranged on the filter disk 49 that in the region of the nip filter 32 "entrained" particles (such as chips or grains of sand) are discharged with the impeller 5 rotating towards the pump interior 14. Characteristic is also that between the bore outlet of the blind hole 20 and the pressure channel 13, a check valve 34, and in front of the solenoid valve 12 between the pressure channel 13 and the pressure chamber 16 a passage bore 35 is arranged, wherein the solenoid valve 12 causes a defined pressurization of the control slide 7 ,

If, in this arrangement according to the invention shown in FIG. 1, the impeller 5 is rotatably mounted on the pump shaft 4, the eccentric bushing 27, which is non-rotatably mounted on the pump shaft 4 and is provided with the suction ring channel 28 and the suction kidney 31, is simultaneously driven put a rotary motion. At the same time the rotatably arranged on the outer surface of the eccentric bushing 27 crank disk ring 29 is offset with its piston bore 30 in strokes.

The arranged in the piston bore 30 working piston 24 with its piston passage bore 25 easily oscillates in circumferential eccentric bushing 27 to the provided with the blind hole 20 swivel cylinder 21, in the blind bore 20 via the passage bore 26, the piston passage bore 25 opens.

The impeller 5 shown in section in Figure 1 is located both on the eccentric bushing 27 as well as the crank pulley ring 29 and has an outer the gap filter 32 adjacent collecting ring channel 33 and an inner, the Ansaugringkanal 28 adjacent collecting ring channel 33rd

Both collecting ring channels 33 are interconnected by means of overflow holes 43.

In the region of the annular gap filter 32, which may be formed as shown in Figures 5 and 7, is a transfer of cooling medium from the pump interior 14 behind the impeller 5 in the outer collecting ring channel 33 and the overflow holes 43 in the inner collecting ring channel 33 and ensured by this / these in the Ansaugringkanal 28.

The arrangement according to the invention with the intake kidney 31 arranged in the eccentric bush 27, the intake ring channel 28, now effects in, as shown in Figures 2 and 3, the rotating pump shaft 4, a defined according to the invention "conveying" the cooling medium from the Ansaugringkanal 28 via the Ansaugniere 31 into the piston bore 30 and from there via the Kolbendurchlassbohrung 25 and the passage bore 26 in the blind hole 20th the swing cylinder 21.

The stroke of the working piston 24 in the piston bore 30 of the crank disk ring 29 in the present embodiment game per revolution about 1 mm to 2 mm because due to the inventive arrangement already very low flow rates for accurate actuation / displacement of the control slide 7 sufficient.

The actuation of the control slide is now carried out by the conveyed into the blind hole 20 cooling medium via the (a backflow preventing) check valve 34 is pressed into the pressure channel 13.

This pressure kana! 13 opens on the one hand via the passage bore 35 in the pressure chamber 16 formed by the spring plate 17 and the pump housing 1 with the pressure-dependently slidably mounted in the pressure chamber 16 control slide 7, and on the other hand in the solenoid valve 12, wherein the solenoid valve 12 outlet openings are arranged in an in Pump housing 1 arranged Rückstömkanal 15 open, which is directly connected to the pump interior 14.

According to the invention, the solenoid valve 12 is normally open.

In the case of an "open" solenoid valve 12, the arrangement according to the invention conveys cooling medium "without pressure" via the outlet openings 36 of the solenoid valve 12 into an annular channel 37 arranged in the working housing 11, which opens into a return flow channel 15, via which the cooling medium flows back into the pump interior 1.

If necessary, the pressure in the pressure channel 13 by means of the solenoid valve 12 is increased continuously.

The subsidized by the inventive arrangement cooling medium is pressed into the pressure chamber 16. There, the thus injected cooling medium causes a defined (via the solenoid valve 12) adjustable pressurization of spring-loaded by the return spring 6 control slide. 7

The return spring 6 is located on the side facing away from the impeller 5 of the outer cylinder 8 of the control slide 7, to the spring systems 38 at.

It is advantageous in this context, if in the lateral surface of the pressure chamber 16 in the pump housing 1, one / more guide element e 39 is arranged / are, the / ensures optimal, low-friction and precise guidance of the control slide / ensure.

In this context, it is also advantageous that an outer scraper 40 and the slider inner seal 18 adjacent to the pump inner space 14 in the spring plate 17 are arranged in the pump housing 1 adjacent to an inner scraper 41 which prevents the entry of particles entrained by the coolant (such as, for example, FIG Chips, grains of sand, etc.) in the working area of the adjacent slide seals, thereby not only increasing the reliability and the life, but also significantly reducing the frictional losses and thereby the operating accuracy, ie improve the finely tunable nature.

This defined pressurization, the cross-sectional area of the control slide 7, now allows an exact translational displacement of the control slide 7 and thus a precisely adjustable overlap of the outflow of the impeller 5 through the outer cylinder 8 of the control slide. 7

Due to the arrangement according to the invention, an exact control of the delivered coolant volume flow is realized via the so effected, defined displacement of the control slide 7.

After the heating phase of the motor (with the closed control slide 7), the pressure in the pressure passage 13 can be precisely controlled by means of the solenoid valve 12 and thus a defined method of the control slide 7 along the outer edge of the impeller 5 realized, which in turn affects the engine temperature very accurately in continuous operation can be, so that Both the pollutant emissions as well as the friction losses and fuel consumption can be significantly reduced in the entire working range of the engine.

Even with unfavorable thermal boundary conditions, e.g. in the vicinity of the turbocharger and very limited installation space for the coolant pump in the engine compartment, the solution according to the invention ensures optimum cooling with minimal construction volume due to the arrangement of an integrated in the pump housing 1 and at the same time cooled by the coolant in the pump housing 1 solenoid valve 12.

In addition, the inventive solution allows a reliable operation of the control slide 7 with a very low drive power.

Even in case of failure of the scheme according to the invention, a further functioning of the coolant pump (fail-safe) is ensured because in the de-energized state, the solenoid valve 12 is open, so that the pressure in the pressure channel 13 and in the pressure chamber 16 drops, so that the return spring. 6 the control slide 7 moves in this case in the (rear) working position "OPEN".

When spring-loaded "retracting" of the control slide 7 in the "fail-safe position" the pumped from the inventive arrangement cooling medium from the pressure channel 13 via the open solenoid valve 12 in the return flow 15 and from there into the pump interior 14 of the coolant pump according to the invention.

Due to the inventive Zwanglaufes by the eccentric drive of the pump according to the invention, the present solution is suitable even for high speed applications.

The solution according to the invention is characterized in particular by their very short in their length design, which can take advantage of very small space available in the engine compartment space optimally.

The coolant pump according to the invention is manufacturing and assembly technology very easy and inexpensive to produce, is also in connection with the construction of different pump series and Sizes "standardizable" and requires no factory air-free filling.

In addition, the controllable coolant pump according to the invention can be easily and inexpensively integrated into the engine management. It ensures high volumetric efficiency, a very high reliability with very high reliability.

REFERENCE SYMBOL

1 pump housing

2 pump bearings

3 pulley

4 pump shaft

5 impeller

6 return spring

7 control slide

8 outer cylinders

9 gasket holder

10 shaft seal

11 working housing

12 solenoid valve

13 pressure channel

14 pump interior

15 return flow channel

16 pressure chamber

17 spring plate

18 slider inner seal

19 slide outer seal

20 blind hole Swivel cylinder bore end

Piston landing gear working piston

Piston port hole Through hole Excess bushing

Suction ring channel Crankshaft ring Piston hole

Ansaugniere

edge filter

Collector ring Check valve Through hole Outlet opening

annular channel

suspension system

Guide element outer wiper inner wiper

Vane bush Overflow holes Piston rings

filter Plato

Filterkeilnut

filter inlet

filter outlet

filter disc

scraper

Claims

claims

1. Controllable coolant pump with a pump housing (1), a in / on the pump housing (1) in a pump bearing (2) mounted by a pulley (3) driven pump shaft (4), one on a free, stromungsseitigen end of this pump shaft (4 ) rotatably arranged impeller (5), a pressure-actuated, by a return spring (6) spring-loaded, control slide (7) with a Ausströmbereich the impeller (5) variably overlapping outer cylinder (8), one in the pump housing (1), between the impeller ( 5) and the pump bearing (2) in a seal receptacle (9) arranged shaft sealing ring (10), with a on the pump housing (1) arranged working housing (11) in which a solenoid valve (12) is arranged, to whose inlet opening a pressure channel (13 ) and to whose outflow opening into the pump interior (14) emptying Rückströmkanal (15) leads, characterized

- That in the pump interior (14) on the pump housing (1) together with the pump housing (1) a pressure chamber (16) forming spring plate (17) is arranged on which the return spring (6) is applied, and at the outer radius of a slider inner seal (18 ) is arranged such that it rests on the inside of the outer cylinder (8) of the Regetschiebers (7), wherein at the same time in the pump housing (1) on the outside of the outer cylinder (8) of the control slide (7) fitting slide outer seal (19) is arranged such that the Outer cylinder (8) of the control slide (7) at pressure buildup in the pressure chamber (16) against the spring force of the return spring (6) along the Ausströmbereiches of the impeller (5) can be moved variably, and

- That in the pump interior (14) between the impeller (5) and the contact area of the spring plate (17) on the pump housing (1) rotatably in the pump housing (1) through the spring plate (17) projecting therethrough, with a pump interior (14) out closed blind hole (20) provided pivoting cylinder (21) is arranged, whose open bore end (22) in the pressure channel (13) opens, and at its opposite end, a piston abutment web (23) is arranged, wherein rotatably mounted on the pivot cylinder (21) has a working piston (24 ) is arranged with a piston passage bore (25), wherein the piston passage bore (25) via a in the region of Kolbendurchlassbohrung (25) in the pivot cylinder (21) arranged through hole (26) in the blind hole (20) of the pivot cylinder

(21) opens, and

- That in the region of the working piston (24) rotatably on the pump shaft (4) an eccentric bushing (27) is arranged in the pump shaft side over the entire circumference revolving, the impeller (5) arranged adjacent Ansaugringkanal (28) is arranged, and

- That on the outer surface of the eccentric bushing (27) rotatably a crank disk ring (29) having a piston bore (30) for the working piston

(24) is arranged, wherein in the region of the piston bore (30) in the eccentric bushing (27) a suction kidney (31) is arranged such that at with the pump shaft (4) circumferential eccentric bushing (27) located in Ansaugringkanal (28) medium into the piston bore

(25), and

- That the impeller (5) on both the eccentric bushing (27) and on the crank disk ring (29) and at least one, the Ansaugringkanal (28) adjacent arranged collecting ring channel (33), wherein the contact area of the impeller (5) on the Exzenterbuchse (27) is designed as an annular gap filter (32), so that in this area a passage of medium from the pump interior (14) in the collecting ring channel (33) / the collecting ring channels (33) and of this / these in the Ansaugringkanal (28 ) is possible, and

- That between the bore outlet of the blind hole (20) and the pressure channel (13) a check valve (34), and in front of the solenoid valve (12) between the pressure channel (13) and the pressure chamber (16) Through hole (35) is arranged, wherein the solenoid valve (12) causes a defined pressurization of the control slide (7).

2. Controllable coolant pump according to claim 1, characterized in that on the impeller (5) facing away from the outer cylinder (8) of the control slide (7) one / more spring system / s (38) is arranged / are.

3. Controllable coolant pump according to claim 1, characterized in that in the lateral surface of the pressure chamber (16) in the pump housing (1) one / more guide element / s (39) is arranged / are.

4. Controllable coolant pump according to claim 1, characterized in that the outer slide seal (19) in the pump housing (1) adjacent to a Außenabstreifer (40) and / or the slider inner seal (18) in the direction of the pump interior (14) in the spring plate (17) adjacent Inner scraper (41) is arranged.

5. Controllable coolant pump according to claim 1, characterized in that in the impeller (5) a Flügelradbuchse (42) is arranged.

6. Controllable coolant pump according to claim 1, characterized in that in the arrangement of a plurality of collecting ring channels (33) in the impeller (5) and / or in the impeller bushing (42) they are interconnected by means of overflow holes (43).

7. Controllable coolant pump according to claim 1, characterized in that on the outer circumference of the in the piston bore (30) of the crank disk ring (29) slidably mounted portion of the working piston (24) piston rings (44) are arranged.

8. Controllable coolant pump according to claim 1, characterized in that the annular gap filter (32) at the same time fulfills the function of a centrifugal separator and consists of a on the eccentric bush (27) arranged annular Filterplato (45) in the Filterkeilnuten (46) are introduced such in that they increase from the filter inlet (47) located at the outer radius of the gap filter (32) to the filter outlet (48) located at the inner radius of the gap filter (32).

9. Controllable coolant pump according to claim 1, characterized in that the annular gap filter (32) by a filter disc (49) is formed in the eccentric bushing (27), in the region of the filter disc (49), one or more of the plane of the eccentric bushing (49). 27) outstanding, in the pump interior (14) projecting scraper (50) are arranged obliquely to the tangent to the filter disc (49) that from the rotating impeller (5) in the filter gap entrained particles to the pump interior (14) are discharged out.