WO2019042530A1

WO2019042530A1 - Coolant pump for an internal combustion engine

Info

Publication number: WO2019042530A1
Application number: PCT/EP2017/071628
Authority: WO
Inventors: Stefan Rothgang; Michael-Thomas Benra; Andreas Burger; Stephan Zielberg
Original assignee: Pierburg Pump Technology Gmbh
Priority date: 2017-08-29
Filing date: 2017-08-29
Publication date: 2019-03-07
Also published as: CN111108271B; CN111108271A; DE112017007961A5

Abstract

Coolant pumps for internal combustion engines having a drive shaft (18), a coolant pump impeller (20), which is arranged at least for conjoint rotation on the drive shaft (18) and via which coolant can be conveyed, a pump housing (10) and an adjustable control slide (58), via which a flow cross-section of an annular gap (62) between an outlet (64) of the coolant pump impeller (20) and the surrounding feed channel (12) can be regulated, wherein the control slide (58) can be moved by means of a wall surface (73; 85; 92) axially along a radially directly opposite wall surface (78; 89; 94) of the pump housing (10), are known. In order to reduce wear during adjustment of the control slide (58), according to the invention, directly opposite wall surfaces (73, 78; 85, 89; 92 , 94) of the control slide (58) and of the pump housing (10) are each provided with a coating, wherein the coating of the wall surface (78; 89; 94) of the pump housing (10) is harder than the coating of the opposite wall surface (73; 85; 92) of the control slide (58).

Description

DESCRIPTION

Coolant pump for an internal combustion engine

The invention relates to a coolant pump for an internal combustion engine having a drive shaft, a coolant pump impeller which is at least rotationally fixed on the drive shaft and via which coolant is conveyed, a pump housing, an adjustable control slide, via which a flow cross-section of an annular gap between an outlet of the coolant pump impeller and the surrounding conveyor channel is controllable, wherein the control slide with a wall surface axially along a radially immediately opposite wall surface of the pump housing is displaceable.

Such coolant pumps are used in internal combustion engines to control the amount of coolant necessary for cooling in order to prevent overheating of the internal combustion engine. The drive of these pumps is usually via a belt or chain drive, so that the Kühlmittelpumpenrad is driven by the speed of the crankshaft or a fixed ratio to the speed of the crankshaft.

In modern internal combustion engines, the pumped coolant quantity is to be adapted to the coolant requirement of the internal combustion engine or of the motor vehicle. To avoid increased pollutant emissions and to reduce fuel consumption, it is particularly desirable to be able to shorten the cold-running phase of the engine. This is done, inter alia, by throttling or completely shutting off the coolant flow during this phase. Pump designs have become known. In addition to electrically driven pumps pumps are known, which can be coupled via couplings, in particular hydrodynamic couplings to their drive or separated from this. However, a particularly cost-effective and simply constructed possibility for controlling the conveyed coolant flow is the use of an axially displaceable hollow cylindrical control slide, which is pushed over the coolant pump impeller, so that to reduce the coolant flow of the flow cross-section of the annular gap through which the pump impeller, the coolant in the surrounding conveyor channel pumped, reduced or completely closed.

The regulation of these slides also takes place in different ways. In addition to a purely electrical adjustment, especially a hydraulic adjustment of the slide has proven. For this purpose, located on the side facing away from the pump impeller of the slide, a pressure chamber which is filled with a pressurized hydraulic fluid to produce a pressure difference across the slide, which leads to a displacement of the control slide. A provision of the slide is carried out either by acting on a second, opposite pressure chamber with liquid under pressure or by means of spring elements and releasing the pressure from the first pressure chamber. The hydraulic pressure can be generated for example by a secondary pump arranged on the drive shaft, so that the coolant is also used for adjusting the control slide.

Such a coolant pump is described for example in DE 10 2015 119 093 AI. An integral with the Kühlmittelpumpenlaufrad Regelpumpenlaufrad generated in a delivery channel, which is formed in a first pump housing part, a pressure which selectively separated by the control slide is pushed over the coolant pump impeller or releases its outlet cross section accordingly. The sealing of these two pressure chambers to each other via arranged on the wall surfaces between the control slide and the pump housing piston rings.

A problem with these coolant pumps with control slide is that there are contact surfaces between the pump housing parts and the control slide over which slides the control slide on the pump housing parts along. On the one hand, these wall surfaces, which are directly opposite one another, must have as tight a tightness as possible in order to reliably prevent a transfer of coolant from one space to the other; on the other hand, the actuating forces of the control slide must be kept as low as possible. It is also difficult to obtain an exactly linear guidance of the control slide, since pressure fluctuations and inaccuracies in the production can lead to a slight tilting of the control slide. All this leads to increased wear on the opposite wall surfaces, which can eventually lead to jamming and thus endanger the functionality of the pump.

It is therefore an object to provide a coolant pump for an internal combustion engine, in which a leakage current between the control slide and the pump housing over the longest possible life can be minimized. For this purpose, the wear on the pump housing and the control slide should be minimized as possible and so a terminal can be prevented. Thus, the most accurate and low-friction adjustment of the control slide is to be guaranteed in all positions, in which only small actuating forces are required. Main claim 1 solved.

Characterized in that the immediately opposite wall surfaces of the control slide and the pump housing are each provided with a coating, wherein the coating of the wall surface of the pump housing is harder than the coating of the wall surface of the control slide, the surface strengths of the two wall surfaces are improved and reduces the roughness, which a significantly lower wear also leads to tilting of the sliding sleeve to the pump housing. It has been shown that it is cheaper to provide the moving and tilting partner with the less hard surface, as this damage to the housing are kept significantly lower. By reducing the roughness and a better frictionless sliding is guaranteed and also largely prevented the formation of small grooves.

Preferably, the coating of the wall surface of the pump housing is a chemical coating. Such a coating is applied particularly uniformly, so that tolerances can be maintained. These coatings are also suitable for complex shaped components and for coating aluminum alloys.

In particular, it is advantageous if the coating of the wall surface of the pump housing is a chemical nickel coating. This is also known by the term chemical hard nickel plating. Such a coating has a high surface strength and hardness and provides excellent corrosion protection, as required in the field of use of liquid coolants.

Preferably, the coating of the wall surface of the pump housing has a layer thickness of 5 to 15 μιτι, so that the the lifetime can already be increased considerably.

In a further advantageous embodiment of the invention, the coating of the wall surface of the control slide is an oxide coating on the control slide made of aluminum, which is applied by electrolytic oxidation, so that an aluminum oxide layer is formed. This method has become known by the term eloxal method. In this case, an oxide of aluminum is formed in the upper metal layer. This surface has a significantly increased degree of hardness and very good corrosion protection and is insensitive to scratches.

In this case, the coating of the wall surface of the control slide preferably has a layer thickness of 10 to 25 μιτι on. Such a thin layer can be applied with high dimensional accuracy, so that the necessary tolerances can be maintained to the pump housing.

The control slide advantageously has a bottom which separates two spaces from one another and from which a hollow cylindrical peripheral wall extends axially in the direction of the coolant pump impeller. Such a floor separates either two pressure chambers from each other or a pressure chamber and a space in which a spring element is effective for adjustment. Such a control slide is simple and accurate to run, so that the pump can be designed with small gaps.

Preferably, the pump housing has a first housing part with a radially outer wall surface, along which a radially inner wall surface of the hollow cylindrical peripheral wall of the control slide is displaceable. Accordingly, the control slide with this tilting can be largely avoided.

Furthermore, it is advantageous if the pump housing has a second housing part with an axially extending to the coolant pump impeller annular projection on the inner wall surface along a radially outer wall surface of the hollow cylindrical peripheral wall of the control slide is displaceable. This is in particular formed at the other axial end of the peripheral wall, so that a guide over both axial ends of the peripheral wall takes place, which also prevents tilting.

Another guide is preferably produced by the bottom has a central opening through which a radially inner wall surface is formed, which is displaceable upon movement of the control slide along a radially opposite second radially outer wall surface of the first housing part of the pump housing, so that on the first Housing part a two-sided leadership is achieved. So you can work with tighter tolerances.

Preferably, a delivery channel is formed in the first housing part, which cooperates with a Regelpumpenlaufrad to build up pressure, wherein the Regelpumpenlaufrad is integrally formed with the Kühlmittelpumpenlaufrad and wherein the bottom of the control slide two pressure chambers axially separated from each other. Such a pump can reliably promote the required amount of coolant without additional spring or additional impeller.

Thus, a coolant pump for an internal combustion engine is created in which wear and scoring on the control slide is largely avoided and with narrow gaps to increase the tightness in the design of the coolant pump is avoided as far as possible and the surfaces, if there is a tilting, are designed so that only minimal damage to the slide or the leading housing parts arise. This is achieved by a corrosion-free and durable coating, which simultaneously has a high strength and acts as a sliding partner to each other. Thus, over a long life a consistent function of the coolant pump can be ensured. At the same time an exact guidance of the control slide is achieved, so that all columns can be minimized.

An embodiment of a coolant pump according to the invention for an internal combustion engine is shown in the figure and will be described below.

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

The coolant pump according to the invention consists of a pump housing 10 with an outer housing part 11 in which a spiral conveying channel 12 is formed, in which a coolant is sucked in via an axial housing 14 also formed in the outer housing part 11, which is formed via the conveying channel 12 to a formed in the outer housing part 11 tangential pump outlet 16 and is conveyed into a cooling circuit of the internal combustion engine. This outer housing part 11 may for example be formed integrally with the crankcase or the cylinder head of an internal combustion engine.

For this purpose, a coolant pump impeller 20 is mounted radially inside the conveying channel 12 on a drive shaft 18, which is designed as Radialpumpenrad, by the rotation of the promotion of the coolant in the Axial side of the coolant pump impeller 20 is a Regelpumpenlaufrad 22 is formed, which is rotated in accordance with the coolant pump impeller 20. This control pump impeller 22 has blades 23, which are arranged axially opposite to a flow channel designed as a side channel 24, which is formed in a first inner housing part 26 of the pump housing 10. In this first housing part 26, an unillustrated inlet and a likewise not shown outlet are formed, so that the control pump impeller 22 forms a control pump 28 with the flow channel 24, via which the pressure of the coolant from the inlet of the control pump 28 is increased to the outlet.

The drive of the coolant pump impeller 20 and the control pump impeller 22 via a belt which engages in a pulley 30 which is secured to the coolant pump impeller 20 opposite axial end of the drive shaft 18. The pulley 30 is mounted on a double-row ball bearing 32, the outer ring 34 is pressed on the pulley 30 and the inner ring 36 on a second stationary housing part 38 of the pump housing 10.

The second housing part 38 has an inner axial passage opening 40, through which the drive shaft 18 projects with the interposition of a shaft seal 42 and into which an inner annular projection 44 of the first housing part 26 projects, via which the first housing part 26 is centered to the second housing part 38. The first housing part 26 is fastened to the second housing part 38 via screws 46, which axially penetrate the first housing part 26. The second housing part 38 is secured to the outer housing part 11 with the interposition of a seal 48. For this purpose, the outer housing part 11 at its pump inlet 14 opposite axial end a receiving opening 50 constant Housing part 38 projects, on whose limiting flange-shaped wall 54, which rests axially against the outer housing part 11, a groove 56 is formed, in which the seal 48 is arranged.

This projection 52 also serves as a rear stop for a control slide 58, the radially outer hollow cylindrical peripheral wall 60 can be pushed over the coolant pump impeller 20 that a free cross section of an annular gap 62 between an outlet 64 of the coolant pump impeller 20 and the delivery channel 12 is controlled. In accordance with the position of this control slide 58, the coolant flow conveyed through the coolant circuit is thus regulated. This peripheral wall 60 has correspondingly a shoulder 66, from which the peripheral wall 60 with an enlarged diameter extends further axially in the direction of the annular gap 62. The outer diameter of this portion 68 corresponds approximately to the outer diameter of the annular projection 52, so that the annular projection 52 and this portion 68 of the peripheral wall 60 are formed directly opposite to an inner wall 70 of the receiving opening 50 of the outer housing part 11, whereby gaps in this area are minimized ,

At the section 72 of the outer peripheral wall 60 extending from the shoulder 66 in the opposite direction to the coolant pump impeller 20, a radial groove 74 is formed on a radially outer wall surface 73 of the control slide 58, in which a sealing ring 76 is arranged. The sealing ring 76 is arranged such that it rests in any position of the control slide 58 on a radially inner wall surface 78 of the annular projection 52 of the second housing part 38.

The control slide 58 has, in addition to the peripheral wall 60 has a bottom 80 with an inner opening 82, from the outer periphery of which the peripheral wall 60 extends axially and from the inner circumference of a Coolant pump impeller 20 extends. On a radially inner wall surface 85 of this peripheral wall 84, a radial groove 86 is formed, in which also a sealing ring 88 is arranged. The radially inner wall surface 85 of the peripheral wall 84 slides on a radially outer wall surface 89 of an axially extending cylindrical portion 90 of the first housing part 26, which is formed between the annular projection 44 and the flow channel 24 forming portion of the first housing part 26. The section 90 serves to support the control slide 58.

Furthermore, there is only a slight gap between a radially inner wall surface 92 of a region of the circumferential wall 60 of the control slide 58 projecting toward the coolant pump impeller 20 and an opposing radially outer wall surface 94 of the first housing part 26 of the pump housing 10.

According to the invention, the three wall surfaces 73, 85, 92 of the control slide 58 made of aluminum or an aluminum alloy to ensure a low-friction guidance and low wear an oxide coating of about 25 μιτι layer thickness. This is applied by electrolytic oxidation, so that an aluminum oxide layer is formed. This method is known by the term anodizing. In particular, a hartanodische oxidation can be used, in which a layer is formed, as offered for example under the name Hart-Coat ^® or HC-GL, the HC-GL coating additionally has improved sliding properties. Such a coating has an average roughness of only about 0, 1 to 0.2 μιτι at a hardness of about 500 HV. Pump housing 10 are also provided with a coating which is harder than the coating of the wall surfaces 73, 85, 92 of the control slide 58. In particular, here chemical nickel coatings are provided with a layer thickness of about 15 μιτι. A suitable coating is known, for example, the term Durni- Coat ^® DNC 520th This coating has a hardness of 550 to 1000HV, depending on the heat treatment carried out. The abrasion resistance is correspondingly high. Also, as with the coating of the control slide 58, a very high corrosion resistance.

As a result of these sliding combinations, only slight actuating forces are required when the control slide 58 moves, and a high degree of tightness is achieved between the front side and the rear side of the control slide 58. Furthermore, these remain due to the high wear resistance over a long period of time.

This is important because on the side facing away from the coolant pump impeller 20 side of the control slide 58, a first pressure chamber 96 is formed axially through the second housing part 38 and the bottom 80 of the control slide 58 and radially outwardly through the annular projection 52 of the second housing part 38 and is bounded radially inwardly by the first housing part 26 and on the side facing the Kühlmittelpumpenlaufrad 20 of the bottom 80, a second pressure chamber 98 is formed axially through the bottom plate 80 and the first housing part 26, radially outwardly through the peripheral wall 60 of the control slide 58th and is bounded radially inwardly by the portion 90 of the first housing part 26. Depending on the bottom 80 of the control slide 58 in the two pressure chambers 96, 98 adjacent pressure difference, the outer peripheral wall 60 of the control slide 58 in accordance with the annular gap 62 in or out of the annular gap 62nd between the two pressure chambers 96, 98, a high tightness of the pressure chambers 96, 98 to each other is required, which by the sealing rings 76, 88 and the manufacturable small tolerances of the selected coatings of the opposite wall surfaces 73, 78, 85, 89, 92, 94 and their good sliding properties is achieved.

The necessary to adjust the control slide 58 pressure difference is generated by the control pump 28 by means of two pressure chambers 96, 98 with different pressure levels. For this purpose, correspondingly arranged and not visible in the figures channels are formed in the two housing parts 26, 38. The pressurized space 98 is supplied with pressurized coolant from a first outlet of the control pump 28, which leads from behind the inlet from the flow channel 24 of the control pump 28, while the pressure chamber 96 is supplied under still higher pressure coolant, which from a in the direction of Regelpumpenlaufrades 22 further away from the inlet remote second outlet of the control pump 28 and is supplied via a solenoid valve 100 either the pressure chamber 96 or discharged therefrom. As a result of the pressure difference of the pressure chambers 96, 98 of the control slide 58 is pushed to reduce the amount of coolant delivered in the annular gap 62 or pushed out to maximize the funded in the cooling circuit coolant amount from this.

The coolant pump described has a very precise inner guide, so that only small actuating forces are required despite small gaps, which is further enhanced by the good sliding properties of the sealing rings and the opposite wall surfaces. By the coatings used, which can be applied with high accuracy with respect to their layer thickness, the pressure chambers are reliably sealed against each other, so that an adjustment of the control slide with low actuating forces is possible and a Above all, this is maintained over a long period of time, since the choice of coatings grooves and other roughness, which could occur in particular on the housing parts by tilting the movable control slide reliably avoided because the coatings of the wall surfaces of the pump housing particularly hard and are wear-resistant. Both the coatings of the pump housing and the control slide have a low roughness, so that the sliding properties are maintained over a long period of time.

It should be clear that the scope of the main claim is not limited to the embodiment described. In particular, other housing divisions or another type of actuation of the control slide are conceivable. In addition to a purely hydraulic adjustment and electrical adjustments or a bias by means of compression springs are conceivable. The coatings can be applied to individual opposing wall surfaces as well as on all sliding wall surfaces. It is also conceivable to coat the entire control slide or the entire to the control slide facing pump housing. Also, other coatings are selectable, which, however, must be suitable both for use in the coolant sector as well as their hardness according to the main claim match each other.

Claims

P A T E N T A N S P R E C H E

Coolant pump for an internal combustion engine with

a drive shaft (18),

a coolant pump impeller (20) which is arranged at least rotationally fixed on the drive shaft (18) and via which coolant can be conveyed,

a pump housing (10),

an adjustable control slide (58), via which a flow cross-section of an annular gap (62) between an outlet (64) of the coolant pump impeller (20) and the surrounding conveyor channel (12) is adjustable,

wherein the control slide (58) with a wall surface (73; 85; 92) axially along a radially immediately opposite wall surface (78; 89; 94) of the pump housing (10) is displaceable,

characterized in that

92, 94) of the control slide (58) and the pump housing (10) are each provided with a coating, the coating of the wall surface (78; 89; 94) of the pump housing (10 ) is harder than the coating of the opposite wall surface (73; 85; 92) of the control slide (58).

Coolant pump for an internal combustion engine according to claim 1,

characterized in that

the coating of the wall surface (78; 89; 94) of the pump housing (10) is a chemical coating. claim 2,

characterized in that

the coating of the wall surface (78; 89; 94) of the pump housing (10) is a chemical nickel coating.

Coolant pump for an internal combustion engine according to claim 3,

characterized in that

the coating of the wall surface (78; 89; 94) of the pump housing (10) has a layer thickness of 5 to 15 μm.

Coolant pump for an internal combustion engine according to one of the preceding claims,

characterized in that

the coating of the wall surface (73; 85; 92) of the control slide (58) is an oxidic coating on the aluminum control slide (58) which is applied by electrolytic oxidation to form an aluminum oxide layer.

Coolant pump for an internal combustion engine according to claim 5,

characterized in that

the coating of the wall surface (73; 85; 92) of the control slide (58) has a layer thickness of 10 to 25 μιτι.

characterized in that

the control slide (58) has a bottom (80) which separates two spaces (96, 98) from each other and from which a Coolant pump impeller (20) extends.

8. coolant pump for an internal combustion engine according to claim 7,

characterized in that

the pump housing (10) has a first housing part (26) with a radially outer wall surface (94) along which an inner wall surface (92) of the hollow cylindrical peripheral wall (60) of the control slide (58) is displaceable.

9. Coolant pump for an internal combustion engine according to claim 7 or 8,

characterized in that

the pump housing (10) has a second housing part (38) with an annular projection (52) on the inner wall surface (78) along a radially outer wall surface (73) of the hollow cylindrical peripheral wall (60) of the control slide (58) is displaceable.

10. A coolant pump for an internal combustion engine according to any one of claims 7 to 9,

characterized in that

the bottom (80) has a central opening (82) through which a radially inner wall surface (85) is formed which, when the control slide (58) moves along a radially opposite second radially outer wall surface (89) of the first housing part (26). of the pump housing (10) is displaceable.

11. Coolant pump for an internal combustion engine according to one of the preceding claims,

characterized in that cooperates with a control pump impeller (22) for pressure build-up, wherein the control pump impeller (22) is formed integrally with the Kühlmittelpumpenlaufrad (20) and wherein the bottom (80) of the control slide (58) two pressure chambers (96, 98) axially separated from each other.