WO2013056855A1

WO2013056855A1 - Adjustable coolant pump

Info

Publication number: WO2013056855A1
Application number: PCT/EP2012/054512
Authority: WO
Inventors: Michael Weiss; Klaus Hahn
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2011-10-20
Filing date: 2012-03-15
Publication date: 2013-04-25
Also published as: US20140241864A1; DE102011084853A1; CN103874858A

Abstract

Disclosed is an adjustable coolant pump for a cooling circuit in an internal combustion engine, comprising a hollow bearing shaft which is accommodated in a bearing sleeve, supports a drive gear at one end, and is permanently connected to an impeller at the opposite end thereof, the impeller having a stop surface on the face thereof. The space between the stop surface and the impeller forms the pumping cross-section for a cooling medium. A piston that can be axially displaced by an adjusting unit is arranged in the hollow bearing shaft. At its outer end, the piston has a guide disk that includes a projection which points in the direction of the impeller and which is used to entirely or partially close the pumping cross-section in accordance with the position of the piston. The adjusting unit has a disengagement lever (16, 32, 35) which can pivot about a fulcrum (17, 31, 36) by means of an electromechanical adjusting element and which, when pivoted, allows the piston (13) to be positioned in the axial direction.

Description

Name of the invention

Adjustable coolant pump Description

FIELD OF THE INVENTION The invention relates to a controllable coolant pump for a cooling circuit of an internal combustion engine, having a hollow bearing shaft received in a bearing sleeve, which carries a drive wheel at one end and is connected at its opposite end to an impeller having an abutment face at the end, wherein the space between stop surface and vane wheel is designed as a conveying cross section for a cooling medium and in the hollow bearing shaft a piston axially displaceable by an adjusting unit is arranged, which has at its outer end a guide plate, which has a projection for complete or partial closing of the conveyor cross section has depending on the position of the piston.

Background of the invention

In the field of internal combustion engines predominantly water-cooled engines have prevailed. In this case, cooling water is pumped by means of a coolant pump in a closed circuit through cooling channels in the region of the cylinder for cooling the brake motor and then conveyed to an air-water cooler, where the heated water is cooled down again by means of the airstream. The necessary for circulating the cooling water pump is usually connected via a belt with a pulley of the crankshaft of the internal combustion engine.

This direct coupling of the coolant pump and the crankshaft causes the speed of the pump depending on the speed of the internal combustion engine is. This has the consequence that in the high speed range of the internal combustion engine, a correspondingly large volume flow is provided by the pump, which is not needed to this extent for cooling. When cold starting the engine, however, the problem occurs that immediately coolant circulates through the cooling channels, whereby the heating of the combustion chambers obstructed and thus the achievement of an optimal operating temperature is delayed.

From DE 10 2008 046 424 A1 a generic controllable coolant pump is known. In this coolant pump, a guide disk with a contour corresponding to the impeller is arranged between impeller and a stop surface, which is guided over the impeller and the stop surface connecting axial webs and axially displaceable by means of a piston placed within the hollow shaft by an actuator.

The guide disc has at its outer edge on a projection with which it covers a ring channel of a pump housing in dependence on the position between the impeller and stop surface. Thus, the annular channel can be completely or partially covered, so that no cooling liquid is pumped through cooling channels. The axial positioning of the piston takes place by means of a magnet. Although this conventional coolant pump has basically proven itself, a coolant pump is required whose controllability is improved.

The invention is therefore based on the object of specifying a controllable coolant pump whose controllability is improved, in particular during a cold start.

Summary of the invention

To achieve this object, the invention provides, in the case of a controllable coolant pump of the type mentioned in the introduction, that the actuating unit has a release lever, which can be pivoted about an axis of rotation by means of an electromechanical actuating element, by means of which the piston can be axially positioned. According to the invention, the controllability of the coolant pump can be substantially improved by providing a release lever which is coupled or connected or connectable on the one hand to the electromechanical actuator as drive and on the other hand to the piston. The release lever may have a first lever arm and a second lever arm and is pivotable about an axis of rotation. Thus, an operation, ie an adjustment of the piston and thus a control of the delivery rate in a simple manner by the fact that the actuator acts on a lever arm of the release lever, whereby the release lever is pivoted about the axis of rotation. The other lever arm adjusts the piston during pivoting, whereby the delivery cross section for the cooling medium is adjusted or changed. Alternatively, the lever may have a single lever arm and be pivotable about a lever end.

In the coolant pump according to the invention, it is preferred that the release lever is pivotally mounted on the bearing sleeve. The release lever may preferably be arranged fixedly on the bearing sleeve, so that it is pivotable about its attachment point. The attachment point is preferably designed as a bearing point. With regard to the attachment of the release lever are basically two positions on the bearing sleeve in question. The disengagement lever can either be fastened to the bearing sleeve in the vicinity of the actuating unit; alternatively, the disengagement lever can be fastened to a position of the bearing sleeve remote from the actuating unit at the opposite end of the bearing sleeve.

A particularly reliable function results in the coolant pump according to the invention, when between the second lever arm of the release lever and the piston, a thrust bearing is arranged. The thrust bearing serves to decouple the rotational speed of the release lever and the piston. Preferably, the thrust bearing comprises two discs between which rolling elements are arranged. In the simplest case, the rolling elements can be replaced by another disc or the like. A disc of the thrust bearing touches the second lever arm of the release lever, the other disc of the rolling bearing touches the piston, which may have a transverse pin or the like. If the piston rotates, the rotational movement is absorbed by the disc of the thrust bearing connected to the piston, as this disc is also rotated. The rolling elements between the two discs of the thrust bearing are rotated, but the disc associated with the release lever disc of the thrust bearing is not set in rotation, whereby the desired speed decoupling is realized. As part of a development of the invention, it may be provided that the second lever arm of the release lever has two spaced-apart end portions, which abut against the thrust bearing, in particular on a disc of the thrust bearing. It can be provided that the second lever arm of the release lever is fork-shaped and has an enlarged area between end portions of the fork, wherein the drive shaft and the piston are arranged in the interior of the bearing shaft.

It is also within the scope of the invention that the electromechanical actuator has an axially displaceable spindle acting on the release lever. By means of a spindle, a particularly precise adjustment of the piston is possible, so that the delivery cross section for the cooling medium can be precisely controlled or regulated.

It is particularly preferred that the spindle is coupled to a driven by an electric motor spindle nut. The electric motor and the spindle nut are arranged stationary, upon rotation of the output shaft of the electric motor, the spindle nut is rotated, whereby the spindle is axially displaced. The electric motor of the coolant pump according to the invention may have a meshing with the spindle nut pinion, in this way, a translation of the rotational speeds of the electric motor and the spindle can be realized. A particularly failsafe variant of the controllable coolant pump results when it comprises a second, independent of the first electromechanical actuator electromechanical actuator for pivoting the release lever. The second electromechanical actuating element can be actuated either as an alternative to the first electromechanical actuating element, on the other hand it can be used when the first electromechanical actuating element has a defect.

In order to enable a highly accurate axial positioning of the piston and thus an accurate adjustment of the delivery cross section, the coolant pump according to the invention may comprise a sensor for detecting the axial position of the piston. Preferably, the sensor is designed for contactless detection of the position. Short description of the drawing

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. FIG. 1 shows a conventional controllable coolant pump in a sectional view;

Figure 2 shows a first embodiment of a coolant pump according to the invention in a sectional view;

FIG. 3 shows the coolant pump shown in FIG. 2 with the piston deflected;

Figure 4 is a cross-sectional view of the coolant pump shown in Figures 2 and 3;

Figure 5 shows a second embodiment of a coolant pump according to the invention; FIG. 6 shows the coolant pump shown in FIG. 5 in the deflected state;

Figure 7 is a cross-sectional view of the coolant pump shown in Figures 5 and 6;

Figure 8 shows a third embodiment of a coolant pump in a sectional view;

FIG. 9 shows the coolant pump shown in FIG. 8 in the deflected state;

and

FIG. 10 shows a further operating state of the coolant pump shown in FIGS. 8 and 9.

Detailed description of the drawing

The structure and mode of action of a controllable coolant pump will be explained with reference to FIG. FIG. 1 shows a sectional view of a conventional coolant pump 1 with a bearing shaft 3 mounted in a pump housing 2, which carries a drive wheel 4 at one end and is firmly connected at its other end to an impeller (impeller) 5. The front side, the impeller 5 has a stop surface 6, the space between the stop surface 6 and impeller 5 is designed as a conveyor cross-section for a cooling medium, in particular cooling water. In the hollow bearing shaft 3 (not shown) by an actuator unit axially displaceable piston 7 is arranged, which has at its outer end a guide plate 8, which has a projection 9 for complete or partial closing of the conveyor cross section in dependence of the position of the piston. 7 having.

In the position of the piston 7 shown in FIG. 1, the delivery cross section between the arrows 10 is released. When the piston 7 is displaced by an electromechanical actuating element in the direction of the abutment surface 6, the conveying cross section is reduced or completely closed. In this way For example, the coolant flow that is pumped into cooling passages of an internal combustion engine can be controlled or regulated.

After the start of the internal combustion engine coupled via a belt with the crankshaft drive wheel 4 is rotated. Accordingly, the bearing shaft 3 rotates the impeller 5, so that coolant is conveyed. At cold start, a promotion of the coolant, however, initially undesirable, so that the piston 7 is displaced in the direction of the impeller 5, whereby the delivery cross section is closed. In this state, no coolant is conveyed, whereby the heating of the engine is accelerated. During normal operation, the delivery section is partially or fully released, so that the coolant is pumped through engine cooling channels and cools the engine. The following embodiments of coolant pumps are basically constructed like the coolant pump shown in Figure 1, individual components that play no part in the understanding of the invention, however, are not shown in the accompanying drawings for reasons of clarity. In particular, the drive wheel, the impeller and the guide plate have been omitted for reasons of simplification.

Figure 2 shows a coolant pump 1 1 in a sectional view. A hollow bearing shaft 12 receives an axially displaceable piston 13. The bearing shaft 12 is mounted by means of rolling bearings 14 in a bearing sleeve 15.

The coolant pump 1 1 comprises a release lever 16, which is pivotable about a rotation axis 17. A first lever arm 18 of the release lever 16 is pivotable by means of an electromechanical actuator. The electromechanical actuating element comprises an electric motor 19 whose output shaft 20 comprises a pinion 21 which meshes with a spindle nut 22. Upon rotation of the spindle nut 22, a spindle 23 is axially displaced, one end of the spindle 23 acts on the first lever arm 18 of the release lever 16, whereby the release lever 16 is pivoted about its axis of rotation 17. A second lever arm 24 of the release lever 16 acts on a thrust bearing 25 a. The second lever arm 24 and the thrust bearing 25 are located within the bearing sleeve 15 in contrast to the first lever arm 18 of the release lever 16, which is located outside of the bearing sleeve 15. In the region of the axis of rotation 17, the bearing sleeve 15 has a recess which is penetrated by the release lever 16.

The thrust bearing 25 comprises a first disc 26, rolling elements 27 and a second disc 28, which is connected to a transverse pin 29, which passes through the piston 13 in the transverse direction. In this way, the first disc 26 of the thrust bearing 25 with the release lever 16 in contact, the second disc 28 of the thrust bearing 25 is connected to the transverse pin 29 and thus with the piston 13 in contact. The rolling elements 27 may be replaced by a disc in the simplest case.

FIG. 2 shows the coolant pump with the delivery cross section open and released, so that the coolant is pumped into cooling channels. If the conveyor cross-section is to be reduced or closed, the electromechanical actuator is actuated. The output shaft 20 of the electric motor 19 rotates the pinion 21, whereby the spindle nut 22 is rotated. Accordingly, the spindle 23 is displaced axially, in the view shown in Figure 2 to the left. As a result, the release lever 16 is pivoted from the position shown in Figure 2 in the position shown in Figure 3. The release lever 16 pivots about the axis of rotation 17. The second lever arm 24 of the release lever 16 abuts against the disc 26 of the thrust bearing and pushes it in the view shown in Figure 3 to the right. Since the second disc 28 of the thrust bearing 25 is coupled by means of the transverse pin 29 with the piston 13, the piston 13 is displaced axially, in the view shown in Figure 3 to the right. Since a guide disk (not shown) is located at the end of the piston, the conveying cross-section is reduced or closed. FIG. 4 shows a cross-sectional view of the coolant pump 11. It can be seen that the schematically illustrated second lever arm 24 of the release lever 16 is fork-shaped and touches the disc 26. Figure 5 shows a second embodiment of a coolant pump in a sectional view. The structure and function of the coolant pump 30 shown in Figure 5 basically corresponds to that of the first embodiment, matching components and their operation will therefore not be explained again at this point.

In contrast to the preceding embodiment, the axis of rotation 31 of the release lever 32 is located at a position remote from the actuator position of the bearing sleeve 15. The release lever 32 is articulated to a point opposite the actuator.

Figure 7 shows a cross-sectional view of the coolant pump 30, in which it is shown that the release lever 32 is fork-shaped and has a central region of increased diameter, wherein the bearing shaft 12 and the piston 13 are enclosed by the release lever 32.

In order to set the delivery cross section, the electric motor 19 is actuated. Accordingly, the spindle 23 is displaced to the right in the view shown in FIG. The spindle 23 acts on the release lever 32 and pivots it about its axis of rotation 31 in a clockwise direction. A central, to the thrust bearing 25 convexly curved portion 33 of the release lever 32 touches the thrust bearing 25 and moves it in the view shown in Figure 5 to the right. Because of the coupling of the thrust bearing 25 with the piston 13, this is pushed out of the bearing shaft 12 axially. Figure 6 shows the coolant pump 30 after actuation by the actuator. De release lever 32 has been deflected by the spindle 23 maximum, the thrust bearing 25 has been moved axially within the bearing sleeve 15 to the right. However, a further shift is prevented by the transverse pin 29. In this position of the piston 13, the conveyor cross section is closed, so that no coolant is conveyed.

FIGS. 8, 9 and 10 show a third exemplary embodiment of a coolant pump. The coolant pump 34 is similar in its basic structure to the embodiment illustrated in FIGS. 5-7, which is why matching components will not be described again in detail.

The release lever 35 is pivotable about an axis of rotation 36, which is located outside of the bearing sleeve 15, at the end of the spindle 37.

FIG. 8 shows the coolant pump 34 in a basic position. The adjustment of the piston 13 is analogous to the preceding embodiment by means of the electric motor 19 and the spindle 23. When the spindle 23 is moved axially, the disengagement lever 35 moves the piston 3 via the thrust bearing 25 in the axial direction, in the view shown in Figure 8 right, whereby the conveyor cross section is reduced and optionally closed.

Figure 9 shows the coolant pump 34 at full deflection, the spindle 23, the release lever 35 and the piston 13 are displaced or deflected maximum. Since no coolant can be delivered in this state, a failure of the actuator, comprising the electric motor, the pinion, the spindle nut and the spindle 23, potentially dangerous for the internal combustion engine, since then there is a risk of overheating. In order to increase the reliability, therefore, a second actuator is provided, which is constructed identically to the first actuator. Accordingly, the second actuator comprises an electric motor 38 which drives the spindle 37 via a pinion and a spindle nut. A possible failure of the first actuator can be detected for example via a resistance measurement. The position of a spindle can be detected by means of a position sensor. Alternatively or additionally, a position sensor assigned to the piston 13 may also be provided. In the event of a detected failure of the first setting unit, a return in the initial state can take place by means of the second setting unit. This condition is shown in FIG. There it can be seen that the position of the spindle 23 of the first actuator is unchanged compared to the state shown in FIG. The spindle 37, however, was displaced axially by the electric motor 38, in the view shown in Figure 10 to the left. As a result, the axis of rotation 36 forming the end of the release lever 35 has been moved to the left. This results in a displacement of the axial bearing 25 and the piston 13 to the left, so that the conveyor cross section is released again. The second actuator with the electric motor 38 and the spindle 37 can take over the control of the coolant pump when the first actuator has failed.

LIST OF REFERENCE NUMBERS

1 coolant pump

2 pump housings

3 bearing shaft

4 drive wheel

5 impeller

6 stop surface

7 pistons

8 guide disc

9 cantilever

10 arrow

1 1 coolant pump

12 bearing shaft

13 pistons

14 rolling bearings

15 bearing sleeve

16 release lever

17 axis of rotation

18 first lever arm

19 electric motor

20 output shaft

21 pinions

22 spindle nut

23 spindle

24 second lever arm

25 thrust bearings

26 disc

27 rolling elements

28 disc

29 cross pin

30 coolant pump

31 axis of rotation Release lever Convex section Coolant pump Release lever Rotary axis

spindle

electric motor

Claims

claims

A controllable coolant pump for a cooling circuit of an internal combustion engine, having a hollow, received in a bearing sleeve bearing shaft which carries at one end a drive wheel and is connected at its opposite end fixed to an impeller having an end face a stop surface, wherein the space between the stop surface and impeller is designed as a conveyor cross-section for a cooling medium and in the hollow bearing shaft a piston axially displaceable by an actuator piston is arranged, which has at its outer end a guide disc, the impeller pointing to the projection for complete or partial closing of the conveyor cross section as a function of the position of the piston characterized in that the actuating unit has a by means of an electromechanical actuating element about an axis of rotation (17, 31, 36) pivotable release lever (16, 32, 35), by the pivoting of the piston (13) is axially positionable ,

Controllable coolant pump according to claim 1, characterized in that the release lever (16, 32) is pivotally mounted on the bearing sleeve (15), preferably at a position close to the actuator or at a position remote from the actuator.

Controllable coolant pump according to claim 1 or 2, characterized in that the release lever (16) has a first lever arm (18) and a second lever arm (24), wherein between the second lever arm (24) of the release lever (16) and the piston (13 ) An axial bearing (25) is arranged.

Controllable coolant pump according to claim 3, characterized in that the axial bearing (25) comprises two discs (26, 28) between which rolling elements (27) are accommodated. Controllable coolant pump according to claim 3 or 4, characterized in that the second lever arm (24) of the release lever (16) has two spaced-apart end portions which on the thrust bearing (25), in particular on a disc (26) of the thrust bearing (25), issue.

Controllable coolant pump according to one of the preceding claims, characterized in that the electromechanical actuating element has an on the release lever (16, 32, 35) acting axially displaceable spindle (23, 37).

Controllable coolant pump according to claim 5, characterized in that the spindle (23, 37) with one of an electric motor (19) driven spindle nut (22) is coupled.

Controllable coolant pump according to claim 7, characterized in that the electric motor (19) has a with the spindle nut (22) meshing pinion (21).

Controllable coolant pump according to one of the preceding claims, characterized in that it comprises a second, independent of the first electro-mechanical actuator independent electromechanical actuator for pivoting the release lever (35).

Controllable coolant pump according to one of the preceding claims, characterized in that it comprises a sensor for detecting the axial position of the piston (13).