WO2013056856A1

WO2013056856A1 - Adjustable coolant pump

Info

Publication number: WO2013056856A1
Application number: PCT/EP2012/054514
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: DE102011084854A1; US20140241862A1

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 coolant pump has a second adjusting unit (13, 22), the piston (11) being displaceable by means of the first or the second adjusting unit (12, 13, 22, 24).

Description

Name of the invention

Adjustable coolant pump Description

FIELD OF THE INVENTION The present invention relates to a controllable coolant pump for a cooling circuit of an internal combustion engine, comprising a hollow bearing shaft formed in a bearing sleeve, which carries a drive wheel at one end and is fixedly connected at its opposite end to an impeller having an abutment face at the end , wherein the space between the stop surface and impeller 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 Has conveyor cross section as a function of 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 coolant is pumped through cooling channels. The axial positioning of the piston takes place by means of a magnet.

When such an adjustable coolant pump uses an electric actuator having an engine and a downstream transmission, supplying a component of the actuator in most cases results in self-locking, so that recovery can not be ensured in the event of a failure of the electric motor or a transmission component. However, this state is critical for the internal combustion engine, since the delivery cross-section is closed when the piston is extended, so that no coolant is pumped through the cooling channels. In case of failure of a component of the actuator therefore there is a risk of overheating of the internal combustion engine. The invention is therefore based on the object to provide a controllable coolant pump, which has an increased reliability.

Summary of the invention

To solve this problem is provided according to the invention in a controllable coolant pump of the type mentioned that it has a second actuator and the piston by means of the first or the second actuator is displaceable.

The invention is based on the recognition that the risk of overheating of the internal combustion engine can be considerably reduced by providing a second, separate actuator as an actuator. By means of the second setting unit, in the event of a failure of the first setting unit, a secure return to a starting or ground state can be ensured in which the conveying cross section for the cooling medium is opened. Thus, the required cooling of the internal combustion engine is guaranteed even in case of failure of the first actuator. A particularly reliable function is obtained if the controllable coolant pump according to the invention has a lever pivotable about an axis of rotation which can be pivoted by means of the first or the second actuating unit. In one operation, a spindle is preferably displaced axially by means of an adjusting unit, wherein the spindle pivots the lever. Since the lever touches the piston, a pivoting of the lever by an adjusting unit to a movement, in particular to a displacement of the piston, whereby the conveyor cross section is adjusted.

An embodiment of the controllable coolant pump according to the invention can provide that the first or the second actuating unit forms the axis of rotation of the lever. In particular, the lever, in particular one end of the lever, may be arranged on a spindle connected to the electric motor. The lever is thus pivoted about a non-fixed axis of rotation. The lever and the actuator are hinged together.

A particularly reliable embodiment of the coolant pump according to the invention provides that the piston and the lever have a common attachment point, which is located between a contact point between the lever and the first or the second actuator and an attachment point of the lever and the respective other actuator. In this way, an actuation of the piston can be done by one of two actuators.

An alternative embodiment of the coolant pump according to the invention provides that the piston pivot points remote and the first and the second actuator preferably spaced from each other are arranged close to the rotor. Alternatively, the two actuators can also be arranged at the same position of the lever.

A particularly high reliability of the coolant pump according to the invention is obtained when one of the two actuators is actuated in case of failure of each other actuator for opening the conveyor cross section of the impeller. Any failure of an actuator can be detected by a resistance measurement or a position sensor. The position sensor can detect, for example, the position of a spindle of the first or the second setting unit, so that it is possible to deduce the position of the lever and thus also the position of the piston. Additionally or alternatively, the sensor may detect the position of the piston in the axial direction. If a discrepancy between the actual piston position and the target position of the piston is detected, the respective other actuator can be activated to adjust the piston by pivoting the lever. A particularly simple adjustment of the piston and thus a precise adjustment of the desired conveying cross section results when the first and / or the second adjusting unit has an axially displaceable spindle whose end portion touches the lever or is coupled to the lever. It can It may also be provided that the spindle is coupled to a spindle nut driven by an electric motor, if appropriate also a ratio between a pinion of an output shaft of the electric motor and a spindle nut can be provided.

Short description of the drawing

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. Show it:

1 shows a conventional controllable coolant pump in a sectional view;

Figure 2 shows a first embodiment of a controllable coolant pump according to the invention;

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

FIG. 4 shows the coolant pump shown in FIGS. 2 and 3 in the event of the failure of an actuating unit;

Figure 5 shows a second embodiment of a controllable coolant pump according to the invention;

FIG. 6 shows the coolant pump shown in FIG. 5 in the deflected state;

and

Figure 7, the coolant pump shown in Figures 5 and 6 in case of failure of an actuating element.

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 fixedly connected to an impeller (impeller) 5 at its other end. 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, a piston 7 which is axially displaceable by an actuating unit (not shown) is arranged, which has at its outer end a guide disk 8 which has a projection 9 for completely or partially closing the conveying cross section as a function of the position of the piston 7.

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, the coolant flow which 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 exemplary embodiments of coolant pumps are basically constructed like the coolant pump shown in FIG. However, le, which play no role 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 components of a coolant pump, the piston 1 1 is axially displaceable. Not shown in Figure 2, the bearing sleeve in which the piston 1 1 is movable. The coolant pump comprises a first actuating unit 12 and a second actuating unit 13, wherein each actuating unit 12, 13 has an electric motor with an axially extendable spindle 14, 15. FIG. 2 shows the adjusting device of the coolant pump in a basic position. The free end of the spindle 14 is pivotally connected to a lever 16. The contact point between the lever 16 and the free end of the spindle 14 forms an axis of rotation 17 for the lever 16. Similarly, the free end of the spindle 15 of the second actuator 13 is pivotally connected to the other end of the lever 16.

Upon actuation of the first control unit 12, an output shaft of the electric motor and thus also the spindle 14 are set in rotation, whereby the length of the protruding spindle section of the spindle 14 is increased or decreased. During a movement of the spindle 14, the lever 16 performs a rotation about an axis of rotation 18 in the region of the attachment of the lever at the free end of the spindle 15. Conversely, when the spindle 15 is moved axially, the lever 16 makes a rotation about the axis of rotation 17. Upon rotation or pivoting of the lever 16, the piston 1 1 is inevitably pivoted axially.

Figure 3 shows the state when the spindle 15 of the second actuator 13 is fully deflected. In this state, the piston 1 1 has been moved by the distance x compared to the basic position shown in Figure 2.

The actuator 13 acts as a main actuator to control the axial position of the piston 1 1. The actuator 12, however, is not needed in normal operation. The piston 1 1 is a schematically illustrated in Figure 3 sensor 19th assigned, which detects the current position of the piston 1 1 in the axial direction. The sensor 19 is a non-contact sensor, for example a magnetic field sensor or a Hall sensor or a capacitive sensor. Figure 4 shows the unlikely but not impossible case of a failed actuator unit 13. If the actuator unit 13 fails, the piston 1 1 can not be retracted by means of the spindle 15. In this state, the piston 1 1 is fully or almost completely extended, accordingly, the conveying cross section for the cooling medium between the stop surface and impeller is closed or at least approximately closed. Since no coolant can be pumped into cooling channels in this state, there is a risk of excessive heating of the internal combustion engine, which can lead to lasting damage. In order to avoid damaging the internal combustion engine, as shown in FIG. 4, the spindle 14 of the actuating unit 12 can be withdrawn. For this purpose, the spindle 14 is moved by means of the electric motor in the housing of the adjusting unit 12, whereby the coupled with the spindle 14 end of the lever 16 is pivoted about the axis of rotation 18, in the view of Figure 4 in the counterclockwise direction. Since the piston 1 1 is pivotally coupled to the lever 16, the piston 1 1 is retracted during this pivotal movement of the lever 16, in the view shown in Figure 4 to the left. As a result, the conveying cross section between the stop surface and the impeller is released, so that coolant flows through the cooling channels again. In this way, a failure of the coolant pump can be avoided. After the failure of a control element, a fault message can be issued so that the user can initiate a repair or an exchange. Meanwhile, however, the function of the coolant pump is completely maintained by the second actuator. Studies have shown that the probability of failure of such a coolant pump is smaller by a factor of 10 compared to a conventional coolant pump.

FIGS. 5-7 show a second exemplary embodiment of the actuating units of a coolant pump. A lever 20 is pivotally connected at one end 21 to the spindle 23 of an actuating unit 22. The hinge at the end 21 of the lever 20 also serves as a fulcrum of the lever 20 when a second actuator 24 having a spindle 25 is actuated.

FIG. 6 shows the actuating units of FIG. 5 in the deflected state. Upon actuation of the actuator 24, the spindle 25 is extended, accordingly, the lever 20 performs a pivoting movement about its end 21 as a fulcrum. In the view shown in FIG. 6, a rotation takes place in the clockwise direction. In the vicinity of its free end, the lever 20 contacts the piston 1 1, which is necessarily axially displaced to the right in the view of Figure 6, whereby the conveying cross section between the stop surface and the impeller is changed. When the piston is displaced in the direction shown in FIG. 6, the delivery cross section is reduced.

In case of failure of the actuator 24 in the position shown in Figure 6, the other actuator 22 can be operated as a Hilfsaktuator to move the piston 1 1 back to the normal position. For this purpose, the spindle 23 is as shown in Figure 7, extended, so that the lever 20 performs a pivoting movement about the contact point 26 with the spindle 25, while the lever 20 slides over the end portion of the spindle 25. Consequently, the lever 20 with coupled piston 1 1 retracted, in the view shown in Figure 7 to the left, whereby the conveyor cross section is released again.

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 piston

12 control unit

13 control unit

14 spindle

15 spindle

16 levers

17 axis of rotation

18 axis of rotation

19 sensor

20 levers

21 end

22 actuator

23 spindle

24 control unit

25 spindle

26 touch point

Claims

claims

A controllable coolant pump (1) for a cooling circuit of an internal combustion engine, having a hollow, received in a bearing sleeve bearing shaft (3) which carries at one end a drive wheel (4) and is fixedly connected at its opposite end with an impeller (5) The front end has a stop surface (6), wherein the space between the stop surface (6) and impeller (5) is designed as a conveying cross section for a cooling medium and in the hollow bearing shaft (3) by an adjusting unit axially displaceable piston (7) is arranged, the Has at its outer end a guide plate (8) which has a to the impeller (5) facing projection (9) for complete or partial closing of the conveyor cross section as a function of the position of the piston (7), characterized in that the coolant pump is a second actuator (13, 22) and the piston (1 1) by means of the first or the second actuating unit (12, 13, 22, 24) is displaceable t.

Controllable coolant pump according to claim 1, characterized in that it comprises a pivotable about a rotation axis (17, 18) lever (16, 20) which is pivotable by means of the first or the second actuating unit (12, 13, 22, 24).

Controllable coolant pump according to claim 1 or 2, characterized in that the first or the second actuating unit (12, 13, 22, 24) forms one or the axis of rotation of the lever (16, 20).

Controllable coolant pump according to one of the preceding claims, characterized in that the piston (1 1) and the lever (16) have a common attachment point extending between a contact point between the lever (16) and the first or the second actuator (12, 13) and an attachment point of the lever (16) and the respective other actuating unit (12, 13).

5. Controllable coolant pump according to claim 1 or 2, characterized in that the piston (1 1) pivot points remote and the first and the second actuator (22, 24) preferably spaced from each other are arranged close to the point of rotation.

6. Controllable coolant pump according to one of the preceding claims, characterized in that one of the two actuating units (12, 13, 22, 24) in case of failure of the other actuating unit (12, 13, 22, 24) for opening the conveying cross section of the impeller is actuated ,

7. Controllable coolant pump according to one of the preceding claims, characterized in that the first and / or the second actuating unit (12, 13, 22, 24) has an axially displaceable spindle (14, 15, 23, 25) whose end portion of the lever (16, 20) touched or with the

Lever (16, 20) is coupled.

8. Controllable coolant pump according to claim 7, characterized in that the spindle (14, 15, 23, 25) is coupled to a driven by an electric motor spindle nut.

9. Controllable coolant pump according to one of the preceding claims, characterized in that it comprises a sensor (19) for detecting the axial position of the piston (1 1).