US20110182757A1 - Apparatus for a pump, and a water pump - Google Patents

Abstract

An apparatus is proposed for a pump, in particular a water pump of a motor vehicle having a rotating pump wheel which can be driven, and having a switchable clutch arrangement for switchable connection of the pump wheel to a drive side. According to the invention, the pump wheel is mounted such that it can rotate on a rotatable driveshaft.

Description

• This application claims the benefit under 35 USC §119(a)-(d) of German Application No. 10 2010 005 936.6 filed Jan. 26, 2010, the entirety of which is incorporated herein by reference.
FIELD OF THE INVENTION
• The invention relates to an apparatus for a pump, in particular a water pump of a motor vehicle, and a water pump.
BACKGROUND OF THE INVENTION
• European Patent Application Publication No. 2 105 624 A1 discloses a clutch, which can be operated electromagnetically, for a water pump in the cooling water circuit of an internal combustion engine having a drive wheel which can be mounted such that it can rotate in the area of or on the water pump, and having an armature disk which interacts with a coil. The clutch is designed to create a so-called “fail safe” arrangement, in which a water pump can be driven via the clutch even when no current is flowing in the coil, for example, if the electrical voltage supply fails.
SUMMARY OF THE INVENTION
• The invention is based on the object of providing an apparatus for a pump, in particular a water pump, in a motor vehicle having a clutch arrangement, thus resulting in a switchable pump of compact design.
• The invention is based on an apparatus for a pump in a motor vehicle, in particular a water pump, for example for the cooling water circuit of an internal combustion engine. The pump comprises a rotating pump wheel which can be driven, and a switchable clutch arrangement for switchable connection of the pump wheel to a drive side. The essence of the invention is now that the pump wheel is mounted such that it can rotate on a rotatable driveshaft, such that a relative movement can take place between the pump wheel and the driveshaft. The pump wheel can therefore rotate on the driveshaft. This measure makes it possible to integrate a clutch arrangement at least partially in a simple manner in a pump, in particular within a pump housing. Roller bearings or journal bearings can be used to bear the pump wheel on the driveshaft. A low-cost journal bearing is preferably used, since the operating time in which the pump wheel is at a considerably lower rotation speed than the driveshaft as a result of an appropriately switched clutch is short in comparison to the total usage time. Any increased wear which occurs to a journal bearing, in comparison to a roller bearing, can therefore be coped with.
• When the clutch is engaged, the pump wheel preferably rotates at the same speed as the driveshaft, or at least approximately at the same speed as the driveshaft. However, ideally, there is no slip between the driveshaft and the pump wheel. In the disengaged state, there is at least a relative rotation speed between the pump wheel and a driveshaft which rotates as before. The pump wheel is preferably stationary, or is in a state with a low drag rotation speed, as a result of friction forces which occur as before.
• In order to, produce a disengaged or engaged state of the pump wheel, it is furthermore proposed that the pump wheel be movable axially on the driveshaft. It is therefore feasible for a friction section of the pump wheel to interact with friction means by axial movement, which friction means are arranged on the driveshaft such that they rotate together.
• In order to produce switching states of the clutch arrangement, it is furthermore proposed that an electromagnetic coil be provided, and act on a magnetically permeable armature element when current is flowing. An armature element is advantageously arranged within a pump housing. The electromagnetic coil can likewise be arranged within the pump housing, for a compact and low-cost design. However, an arrangement outside the pump housing is also feasible, and has advantages in terms of an electrical supply to the coil.
• It is also preferable for the armature element to be movable axially by an electromagnetic influence of the coil, wherein the switching state of the pump wheel can be predetermined by a selected axial position of the armature element. By way of example, this allows the pump wheel to move axially or the armature element to move a further element which acts on the pump wheel in order to produce a switching state.
• In order to transmit a torque from the driveshaft to the pump wheel, a further preferred refinement of the invention proposes that contact means, in particular friction means, are arranged on the driveshaft such that they rotate together, and are designed for a force fit and/or an interlock, in particular a force fit, with a friction section on the pump wheel which can rotate on the driveshaft.
• In this context, it is also preferable if the armature element and the friction means are matched to one another such that a friction fit is created between the driveshaft and the pump wheel, as a function of an axial position of the armature element.
• One particularly preferred refinement of the invention proposes a displacement member, by means of which a contact section, for example a friction section of the pump wheel, makes a friction contact with the friction means. The displacement member, for example a spring, and in particular a compression spring, preferably acts in the axial direction on the pump wheel when no current is flowing through the electromagnetic coil, as a result of which a friction section of the pump wheel is displaced against friction means which are connected to the driveshaft such that they rotate together. This results in a “fail safe” arrangement which ensures that the pump wheel rotates even when the voltage supply for the electromagnetic coil fails on a running internal combustion engine with a rotating driveshaft. Particularly when the pump is used in a cooling water circuit of an internal combustion engine, this makes it possible to ensure high operational reliability.
• It is also advantageous if the armature element is arranged on a spring element which is connected to the driveshaft such that they rotate together, wherein the spring element is designed to exert an axial pressure effect on the pump wheel. This likewise makes it possible to create a friction fit between a friction means, which is arranged on the spring element, and a corresponding friction section on the pump wheel when no current is flowing through the electromagnetic coil, and there is therefore no force acting on the armature element, thus creating a “fail safe” arrangement. For example, when current is flowing in the coil, the armature element can be moved axially such that friction means which press in a sprung manner against the pump wheel are lifted off it, thus allowing the pump wheel to rotate freely or essentially freely on the driveshaft.
• In a further preferred embodiment, it is advantageous for the armature element to be arranged on the pump wheel. The armature element can be fitted on the induction side or on the side of the pump wheel remote from the induction side.
• When no current is flowing through the electric coil, a displacement member, in particular a spring element, allows the pump wheel to be displaced to an engaged state.
• Furthermore, for defined positioning of the pump wheel, it is preferable for an axial bearing stop to be formed on the driveshaft for the pump wheel. The bearing stop preferably acts as a rotating bearing, thus allowing to rotate essentially freely in a situation in which the pump wheel is pressing against the bearing stop with an axial pressure force and, furthermore, for example, the friction means are not producing any further friction forces.
• In one preferred embodiment, the friction means on the driveshaft comprise a wedge element which can make a friction fit with a friction section on the pump wheel. This allows the pump wheel to be made to rotate at the same speed as the driveshaft with a comparatively small axial displacement force, by means of a “wedge drive effect” of a friction surface in the form of a wedge, by means of a friction fit.
• The apparatus according to the invention is preferably used for pumps in a motor vehicle, in particular water pumps. In the case of internal combustion engines, the preferred application is the water pump for the water cooling circuit. A switchable cooling water pump allows the engine to be raised to the operating temperature more quickly when it is being started up from the cold state. For this purpose, in this phase of engine operation, the cooling water circuit is switched off by disengaging the pump wheel. As soon as the engine is then at a predetermined operating temperature, the pump wheel is engaged, as a result of which the cooling water circuit starts to run.
BRIEF DESCRIPTION OF THE DRAWINGS
• A plurality of exemplary embodiments of the invention are illustrated in the figures and will be explained in more detail in the following text, indicating further advantages and details.
• FIG. 1 shows a schematic illustration of a partially sectioned side view of parts of a cooling water pump with a clutch arrangement, and
• FIGS. 2 and 3 show a corresponding illustration of two further embodiments for comparable parts.
DETAILED DESCRIPTION OF THE INVENTION
• FIG. 1 shows elements of a cooling water pump with a clutch arrangement within a pump housing, which is not illustrated. The cooling water pump comprises apump shaft1 on which apump wheel2 is borne such that it can rotate via a slidingbush3 which extends axially and radially. The radial section3aof the slidingbush3 can rest on a radial bearing stop4, for example in the form of a steel disk. A sliding ring seal or a similar seal can also preferably be integrated in the bearing stop. Thepump wheel2 is preferably in the form of an impeller, as is illustrated inFIG. 1, which is surrounded by an appropriately shaped housing (not illustrated).
• Acompression spring5 is mounted on the driveshaft such that they rotate together and has anengagement section6 which can interact in an interlocking and/or force-fitting manner with thepump wheel2. In the present case, agroove2ain the form of a V or wedge is incorporated in an annular shape into thepump wheel2, and anengagement section6 enters thisgroove2ain order to produce a friction fit between the appropriately matchedengagement section6 and thegroove2a.
• However, it is also feasible for theengagement section6 to have shaped elements which fit corresponding shaped elements in the V-shaped groove2a, thus resulting in an interlock in the engaged state.
• A magneticallypermeable armature element7, for example an annular element which interacts with anelectromagnet8, is fitted to theengagement section6. Theelectromagnet8 may be fitted inside or outside the pump housing. If arranged outside the pump housing, a magnetic circuit must be ensured through the pump housing to thearmature element7, in order to allow a magnetic force to act on thearmature element7 when current flows through theelectromagnet8.
• Stop elements, for example in the form of finger-like stop elements, are preferably provided to limit the movement of thecompression spring5 on which theengagement section6 and thearmature element7 are arranged, which stop elements axially limit axial movement of thearmature element7 when an attraction force is applied by theelectromagnet8.
• A water pump arrangement as shown inFIG. 1 operates as follows:
• Because the engagement section is pressed against thepump wheel2 when no current is flowing through theelectromagnet8, this results in a “fail safe” arrangement, in which the pump wheel runs at the same rotation speed as thepump shaft1 when no current is flowing, because of the friction effect of theengagement section6.
• In order to “disengage” the pump wheel, a voltage is applied to the electromagnet and can be increased in an initial time interval in order to draw the armature element against theelectromagnet8. This releases the friction fit between theengagement section6 and the wedge-shapedgroove2, and the pump wheel is borne such that it can then rotate freely on thepump shaft1. The axial stop fingers, which are not illustrated, in the area of thecompression spring5 limit the axial movement of thearmature element7, such that it cannot come into contact with theelectromagnet8 when current is flowing through the electromagnet.
• FIG. 2 shows an embodiment in which the wedge-shapedgroove2aand theengagement section6 have been replaced by awedge element9, which interacts with aconical recess10, which matches thewedge element9, on thepump wheel2. A bearingstop11 which is opposite the radial section3aof the bearingbush3 can move axially and is pressed by a compression spring in the axial direction against thepump wheel2. Thepump wheel2 is therefore moved axially in the direction of thewedge element9, thus resulting in a friction fit between thewedge element9 and theconical recess10. In this state, thepump wheel2 preferably runs at the same rotation speed as thepump shaft1.
• The friction torque between thepump wheel2 and thewedge element9 drives thepump wheel2. When current is passed through theelectromagnet8, thepump wheel2 is drawn in the direction of theelectromagnet8 via anarmature element13 which is arranged in or on thepump wheel2, thus releasing the force that is transmitted between thewedge element9 and theconical recess10. For example, thearmature element13 can be encapsulated in thepump wheel2. The pump wheel is pressed against the bearingstop11, for example in the form of a steel disk, with the bearing stop being designed such that no or essentially no drive torque is transmitted to the pump wheel when thepump shaft1 is rotating. In this case, the pump wheel is disengaged, and no pump effect takes place.
• FIG. 3 shows an embodiment which operates analogously to the embodiment shown inFIG. 2, with the difference that theelements8,11,12,13 have been transferred to the induction side while, in contrast, thewedge element9 and theconical recess10 which matches it are arranged on theside15 remote from theinduction side14.
• In a corresponding manner to that in the exemplary embodiment shown inFIG. 2, when no current is flowing through theelectromagnet8, thecompression spring12 presses thepump wheel2 against thewedge element9, by means of which the drive torque of thepump shaft1 can be transmitted to thepump wheel2 by a friction fit. When current is passed through theelectromagnet8, thepump wheel2 can be disengaged, with thepump wheel2 being pulled away from thewedge element9 via thearmature element13, by means of an axial movement of thepump wheel2 on thepump shaft1. This represents the disengaged state.
LIST OF REFERENCE SYMBOLS
• 1 Pump shaft
• 2 Pump wheel
• 2aGroove
• 3 Bearing bush
• 3aRadial section
• 4 Bearing stop
• 5 Compression spring
• 6 Engagement section
• 7 Armature element
• 8 Electromagnet
• 9 Wedge element
• 10 Conical recess
• 11 Bearing stop
• 12 Compression spring
• 13 Armature element
• 14 Induction side
• 15 Remote side

Claims (12)

1. An apparatus for a pump of a motor vehicle, in particular a water pump having a rotating pump wheel which can be driven, and having a switchable clutch arrangement for switchable connection of the pump wheel to a drive side, wherein the pump wheel is mounted such that it can rotate on a rotatable driveshaft.

2. An apparatus according toclaim 1, wherein the pump wheel is arranged on the driveshaft such that it can move axially.

3. An apparatus according toclaim 1, wherein an electromagnetic coil is provided, and acts on a magnetically permeable armature element when current is flowing.

4. An apparatus according toclaim 3, wherein the armature element can be moved axially by a magnetic influence of the coil, wherein the switching state of the pump wheel can be predetermined by a selected axial position of the armature element.

5. An apparatus according toclaim 1, wherein contact means are arranged on the driveshaft such that they rotate together, and are designed for a force fit and/or an interlock with a contact section on the pump wheel which can rotate on the driveshaft.

6. An apparatus according toclaim 3, wherein the armature element and the contact means are matched to one another such that a force fit and/or an interlock can be predetermined between the driveshaft and the pump wheel, as a function of an axial position of the armature element.

7. An apparatus according toclaim 1, wherein a displacement member is provided, by means of which a contact section on the pump wheel can be made to interlock and/or have a friction fit with the contact means.

8. An apparatus according toclaim 3, wherein the armature element is arranged on a spring element which is connected to the driveshaft such that they rotate together, wherein the spring element is designed to press axially on the pump wheel.

9. An apparatus according toclaim 3, wherein the armature element is arranged on the pump wheel.

10. An apparatus according toclaim 1, wherein an axially acting bearing stop is formed on the driveshaft for the pump wheel.

11. An apparatus according toclaim 5, wherein the contact means on the driveshaft comprise a friction means in the form of a wedge element which can make a friction fit with a friction section on the pump wheel.

12. A pump for a motor vehicle, in particular a water pump having an apparatus according toclaim 1.

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