EP3431768B1

EP3431768B1 - Adjustable coolant pump

Info

Publication number: EP3431768B1
Application number: EP18382529.8A
Authority: EP
Inventors: Carlos PERIBÁÑEZ SUBIRÓN; Irene López Bosque; Fernando Miguel Gracia; Joaquín Roche Royo; José Luis Pomar Miguel; Carlos Lozano Beltrán
Original assignee: Airtex Products SA
Current assignee: Airtex Products SA
Priority date: 2017-07-17
Filing date: 2018-07-16
Publication date: 2022-03-30
Anticipated expiration: 2038-07-16
Also published as: EP3431768A1; ES2921006T3

Description

The present disclosure relates to coolant pumps, particularly adjustable coolant pumps. The present disclosure further relates to methods of operation of adjustable coolant pumps.

BACKGROUND

Some of the recent developed pumps for reducing global fuel consumption in combustion engine vehicles are based on adjusting or regulating elements that total or partially cover the outlet area of the main impeller. A variety of solutions have been proposed to activate this adjusting element, for instance those mentioned in the background of the application DE102005062200 .
The aforementioned application presents a controllable coolant pump where the adjustment element is mechanically activated by means of a vacuum. This negative pressure is applied to an annular membrane which is deformed due to the pressure gradient respect to the atmospheric pressure at the other side of the annular membrane.
As result of this deformation, the membrane pushes a support element connected, through several rods, to the adjustment element, covering the output of the impeller of the pump, which never stops spinning. Therefore the hydraulic resistance of the circuit is increased due to the adjustment element, and this is reflected in a reduction of the flow rate.
The problem with controllable pumps that work under the principle described above is that final position of the adjustment element, when vacuum is applied, depends on the accumulated clearances of all the chain of assembled components from the annular membrane to the adjustment element.
Due to the lack of a well-defined final position, there is a potential risk of interference between the impeller and the adjustment element which could lead to severe damages and/or undesired noise and wear.
In addition, the flexible material of the membranes may be prone to suffer from wear which may cause inaccuracy of the function of regulation of the shutter and even a failure of the membrane.
Furthermore, some examples of pumps comprise a plate positioned between the impeller and the shutter or adjustment element to avoid the risk of interference. However, this plate generates a bulky and complex configuration of the adjustable coolant pump.
Besides that potential risk of interference, known solutions for regulating coolant pumps also suffer from other drawbacks. Final response of the pump regulation is directly related to the finally covered output area of the impeller, therefore, differences in this final position due to manufacturing and assembly tolerances could become in a product with a low repeatability in the regulation function.
Furthermore, in that type of configuration of adjustable pump, there are also some other drawbacks. When regulation system is activated, namely when the impeller is covered by the adjustment element, the coolant fluid is still driven by the impeller and retained by the adjustment element. It is known that the driven fluid which is retained by the adjustment element tends to generate a backflow between the adjustment element and the housing of the pump. This way, the adjustment capability of the adjustment element is reduced.
Known solutions as the above mentioned application, include gaskets and static sealing elements which seal the gap between the housing and the adjustment element when the adjustment element reaches the end of stroke. The end of stroke of the adjustment element can be reached in an activated condition of the regulation system when covering the impeller. These solutions have at least three drawbacks:

Firstly, the known solutions are highly dependent on the manufacturing and assembly tolerances along the whole chain of parts that contribute in a final activated position of the adjustment element. The latter makes it complex and low repeatable to assure the sealing between the housing and the adjustment element.
Secondly, the static sealing systems are solutions which are hardly adjustable to different requirements of the stroke of the shutter. Therefore, the resulting designs of pumps are barely adaptable and flexible.

And thirdly, static sealing systems, which are solutions where sealing is only achieved at the end of the stroke, allow the fluid migration between zones at different pressures during the shutter displacement in axial direction, resulting in a slower and more inefficient activation of the system and in a reduction of the adjustment capability during the activation.
Examples of prior-art pumps are disclosed in DE102013111939 B3 , DE102011052678 A1 and DE102015106669 A1 .
It is an object of the present disclosure to provide examples of adjustable coolant pumps and methods for operating such pumps that avoid or at least reduce the aforementioned drawbacks.

SUMMARY

In a first aspect, an adjustable coolant pump is provided according to claim 1.
According to this aspect, a repeatable regulation response during all the actuations may be obtained, the end-stop element may provide a perfectly defined and fixed end-stop position for the adjustment element or shutter, when covering, at least partially the impeller.
Furthermore, an adjustable coolant pump comprising the end-stop element may avoid any possible contact of the shutter and the impeller, for instance, when the impeller may spin and at least a portion of the outflow region may be covered.
The adjustable coolant pump according to this aspect may absorb at the same time the clearances and tolerances of the manufacturing and assembly of the components in such a way that a regulation function may not be affected.
Last but not least, the adjustable coolant pump according to this aspect does not comprise any plate between the impeller and the shutter, so a simple, compact and reliable configuration may be achieved.
In some examples of the adjustable coolant pump, the housing may further comprise an annular wall extending from the bottom face in axial direction in such a way that a cavity to receive the shutter may be defined at least by the annular wall and the bottom face; wherein the adjustable coolant pump may further comprise an adjustment sealing arrangement provided between the shutter and the annular wall, the sealing arrangement comprising a ring seal attached either to the shutter or the annular wall, in such a way that a dynamic sealing between the shutter and the housing is defined. Thanks to the adjustment sealing arrangement, a gap between the annular wall of the housing and the shutter may be eliminated. Thus, a backflow of the coolant between the shutter and the housing is avoided or at least reduced, even when the shutter is displaced along the axis of rotation. Therefore, the adjustment capability of the shutter is not reduced.
As there may be a relative motion between the annular wall and the shutter the adjustment sealing arrangement may provide a dynamic sealing between the shutter and the housing along the stroke of the shutter. The sealing may be achieved in the annular wall which may be substantially parallel to the direction of a relative motion between the annular wall and the shutter.
A sealing function of the adjustment sealing arrangement may be independent of the aforementioned clearances and tolerances of the manufacturing and assembly of the components. Therefore, the sealing function of the adjustment sealing arrangement may be achieved and maintained regardless of the clearances and tolerances between the shutter and the housing.
The sealing function of the adjustment sealing arrangement is present regardless of the relative position between the shutter and the housing. The sealing function is also achieved in the end points of the stroke of the shutter.
In some examples, the adjustable coolant pump may further comprise an annular piston displaceable in axial direction, an annular groove inside of which the annular piston is displaceable, wherein the annular groove is divided in at least a first and a second pressure chamber by the annular piston, wherein the annular piston is mechanically connected to the shutter such that a displacement of the annular piston in axial direction is transmitted to the shutter.
According to that further example, the adjustable coolant pump does not comprise any membrane but an annular piston displaceable inside the annular groove. Therefore, an accurate and predictable displacement of the piston may be achieved. Furthermore, according to that further example a reliable function of regulation of the shutter may be obtained. The risk of failure and wear related to the membranes may be avoided.
According to another aspect, a method of operation of an adjustable coolant pump is provided according to claim 13.
According to this aspect, a method with an accurate adjustment function of the shutter may be achieved. The shutter may be displaced until a predefined end of stroke by means of the end-stop element.
Throughout the present disclosure, the terms "shutter" and "adjustment element" are used interchangeably.
Throughout the present disclosure, a coolant is to be understood as a fluid such as a liquid used to remove heat.
Throughout the present disclosure, by "dynamic sealing" is meant a sealing provided at least between two surfaces and there is a relative motion between them.
Throughout the present disclosure, by "static sealing" is meant a sealing provided at least between two surfaces and there is no relative motion between them.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting examples of the present disclosure will be described in the following, with reference to the appended drawings, in which:

Figure 1 schematically shows a longitudinal cross section view of an adjustable coolant pump according to an example when a regulation function is deactivated;
Figure 2 schematically shows a longitudinal cross section view of the adjustable coolant pump of the figure 1 when a regulation function is activated;
Figures 3A-3B schematically show enlarged details A and B of connections between a rod and respectively an annular piston and a shutter of the adjustable coolant pump of the figure 1 when a regulation function is deactivated;
Figures 4A-4B schematically show enlarged details C and D of connections between a rod and respectively an annular piston and a shutter of the adjustable coolant pump of the figure 2 when a regulation function is activated;
Figure 5 is a flow chart of an exemplary method of operation of an adjustable coolant pump.
Figure 6 schematically shows a longitudinal cross section view of an adjustable coolant pump according to a further example when a regulation function is deactivated;
Figure 7 schematically shows a longitudinal cross section view of the adjustable coolant pump of the figure 6 when a regulation function is activated;
Figure 8 schematically shows an enlarged detail E of an adjustment sealing arrangement of the adjustable coolant pump of the figure 6; and
Figure 9 schematically shows an enlarged detail F of an adjustment sealing arrangement of the adjustable coolant pump of the figure 7.

DETAILED DESCRIPTION OF EXAMPLES

In the following some examples of an adjustable coolant pump 1 will be described. Although those examples may be related to an internal combustion engine, the adjustable coolant pump 1 could be related to any kind of engine or the like. The adjustable coolant pump 1 may be used for conveying and circulating a coolant or coolants.
Figure 1 schematically shows a longitudinal cross section view of an adjustable coolant pump 1 according to an example when a regulation function is deactivated and figure 2 schematically shows a longitudinal cross section view of the adjustable coolant pump of the figure 1 when a regulation function is activated.
When the regulation function is deactivated, the pump 1 may be able to provide its flow rate of coolant. Conversely, when the regulation function is activated the pump 1 may be able to provide a percentage of its flow rate or even nothing.
The adjustable coolant pump 1 according to some examples may be pneumatically actuated.
An exemplary adjustable coolant pump 1 comprises:

a housing 12. This housing may be directly or indirectly attached to an engine or the like and may be made from metallic material;
a shaft 13 to rotate around an axis of rotation AR of the housing 12. The shaft 13 may be driven by the pulley 17 which in turn may be driven by a crankshaft (not illustrated) of an engine through a belt (not illustrated). However, alternative power sources to drive the shaft 13 may be envisaged. This shaft 13 may be positioned, at least partially, in the housing 12. The axis of rotation AR may match the longitudinal axis of the housing 12 in some examples;
an impeller 14 assembled in the shaft 13. This may be understood as the impeller 14 may be attached or fixed to the shaft 13 or even the impeller 14 may be integrally formed with the shaft 13. The impeller 14 may be placed in the shaft 13 at the end opposite to the pulley 17 as can be seen in figures 1-2. The construction of the impeller 14 may be similar to that one of impellers available in the market, so no further explanation will be provided. A shaft seal 11 may be disposed for instance around the shaft 13 for preventing the coolant from going from the impeller area to the pulley area. This shaft seal 11 may be fitted in a fix manner in the housing 12;
a shutter 2 displaceable along the axis of rotation AR to cover, at least partially, an outflow region OR of the impeller 14 such that an amount of the coolant (not illustrated) delivered by the pump 1 may be adjustable. The shutter 2 may comprise a cup-like construction or any other shape which allows covering, at least partially, the outflow region OR of the impeller 14. An outflow region OR may comprise a portion of the impeller area where the outgoing coolant may leave the impeller 14. This impeller area may be associated, for instance, with a coolant circuit of an engine;
at least one end-stop element 3 attached to a portion of the housing 12 to define an end of stroke for the shutter 2 when covering, at least partially, the outflow region OR. The end-stop element 3 may also act as a guide for the shutter 2 when displacing along the axis of rotation AR. By way of example, the pump 1 illustrated in figures 1 and 2 may comprise three end-stop elements 3 disposed around and parallel to the axis of rotation AR at 120° the one to the other;
wherein the housing 12 may comprise a top face 15 and a bottom face 16 disposed substantially perpendicular to the axis of rotation AR, the bottom face 16 may be provided between the top face 15 and the shutter 2. The end-stop element may be attached to the bottom face 16.

The axis of rotation AR may match or at least be parallel to the longitudinal axis of the shaft 13, according to one example.
According to some examples, the housing 12 may also comprise side walls to join the top face 15 and the bottom face 16 such that the housing 12 may comprise a cylinder-shaped body.
The end-stop element 3 comprises a shank 31 fixed at one end to the portion of the housing 12 and further comprises a widening 32 at the other end to stop the shutter 2 when covering, at least partially, the outflow region OR.
In some examples, the shank 31 may have a predefined length such that this predefined length of the shank 31 may correspond to a predefined end of stroke for the shutter 2 when covering, at least partially, the outflow region OR. The predefined length of the shank 31 may be chosen depending on the expected reduction percentage of flow rate and therefore on the amount of coverage. By adopting different lengths of the shank 31 the end of stroke of the shutter 2 may be located at different positions related to the impeller 14 (and the housing 12). The reduction percentage of the flow rate may be easily adjusted by adopting a different length of the shank 31. For instance, a shank 31 with a short length (shorter stroke of shutter 2) may achieve less reduction percentage than a shank 31 with longer length (longer stroke of shutter 2).
According to some examples of the adjustable coolant pump 1, the end-stop element 3 may comprise a bolt; alternatively the end-stop element 3 may be a rivet or any analogous element. This bolt or rivet may be fixed to a corresponding orifice in the bottom face 16.
As can be seen in figures 1 and 2, the adjustable coolant pump 1 may further comprise:

an annular piston 4 which may be displaceable in axial direction. The annular piston 4 may be made from any suitable material. The axial direction may be coaxial or not to a pump center axis. The pump center axis may be the same as the axis of rotation AR;
an annular groove 5 inside of which the annular piston 4 may be displaceable. The annular groove 5 may be shaped so as to allow a swinging or back and forth movement of the annular piston 4 in axial direction;
wherein the annular groove 5 may be divided in at least a first 51 and a second 52 pressure chambers by the annular piston 4. The presence of the annular piston 4 may define those pressure chambers 51, 52. Although the overall size (volume) of the annular groove 5 may remain unchanged during operation of the pump 1, the size of each of those pressure chambers may change depending on whether the regulation function may be activated or not. In some examples, the second pressure chamber 52 may be positioned closer to the impeller 14 and the first pressure chamber 51 may be positioned farther (taking into account the length of the axis of rotation AR);
wherein the annular piston 4 may be mechanically connected to the shutter 2 such that a displacement of the annular piston 4 in axial direction may be transmitted to the shutter 2. The length of displacement of the annular piston 4 may vary depending on the case. The amount of displacement defines the percentage of regulation of the outflow region OR of the impeller 14.

Both the annular piston 4 and the annular groove 5 may be disposed around the shaft 13 or the axis of rotation AR thereof, as depicted in figures 1-2.
According to some examples, the adjustable coolant pump 1 may further comprise at least one rod 6 to mechanically connect the annular piston 4 to the shutter 2.
The rod 6 may comprise two notches 61, 62 respectively at its ends to allow a fixation respectively to the annular piston 4 and the shutter 2. These notches 61, 62 may match a corresponding hole 22 in the shutter 2 or slot 42 in the annular piston 4. Alternatively, the relative fixation of the rod 6 to the annular piston 4 and the shutter 2 may be achieved by welding, bonding or the like.
Although the rod 6 has been depicted as a single element, alternatively it may be envisaged as a plurality of parts that allow a mechanical connection between the shutter 2 and the piston 4.
According to some examples, the rod 6 may slidably move along a rod bearing 63 to facilitate the transmission of movement from annular piston 4 and the shutter 2. This rod bearing 63 may be positioned between the rod 6 and the housing 12. Some rod seals may be disposed for preventing the coolant from going from the impeller area to the annular groove 5.
Figures 3A-3B schematically show enlarged details of connections between the rod 6 and respectively the annular piston 4 and the shutter 2 when a regulation function is deactivated. Meanwhile, figures 4A-4B schematically show enlarged details of those connections between the rod 6 and respectively the annular piston 4 and the shutter 2 when the regulation function is activated.
The use of notches 61, 22 may bring the presence of some clearances C1, C2 in the area of connection of those notches 61, 62 to hole 22 and slot 42. These clearances may facilitate the assembling of the pump 1. Such clearances C1, C2 may vary depending on the status of the pump 1 as will be explained later.
In some other examples of the adjustable coolant pump 1, the first pressure chamber 51 may comprise an opening 55 to allow atmospheric air entering the first pressure chamber 51 and the second pressure chamber 52 may be associated with a vacuum source (not illustrated). The second pressure chamber 52 may comprise a vacuum connection 54 to allow the fluid connection to the vacuum source.
In further examples, the piston 4 may comprise a piston seal 41 for sealing the first 51 and the second 52 pressure chambers from each other. The piston seal 41 may be a lip seal or the like which may contact the walls of the annular groove 4.
According to one example, the adjustable coolant pump 1 may further comprise a resilient element 7 to push the annular piston 41 in axial direction and away from the impeller 14, wherein the resilient element 7 may be located in a corresponding accommodation 53 opened out to the annular groove 5. As depicted in figures 1 and 2, there may be a plurality of resilient elements 7 such as three, around and parallel to the axis of rotation AR at 120° the one to the other.
The resilient element 7 may comprise a spring, for instance.
According to an example, the shutter 2 may comprise at least one bore 21 to slidably receive the corresponding end-stop element 3. The number of bores 21 may be the same as the number of end-stop elements 3.
Thanks to the configuration of the shank 31 with a predefined length it may be possible to easily adjust the reduction percentage above mentioned without adjusting the output delivered by the power source which drives the shaft 13, and/or without adjusting the vacuum source associated to the second pressure chamber 52.
Figure 6 schematically shows a longitudinal cross section view of an adjustable coolant pump 1 according to a further example when a regulation function is deactivated and figure 7 schematically shows a longitudinal cross section view of the adjustable coolant pump 1 of the figure 6 when a regulation function is activated.
In some examples of the adjustable coolant pump 1 such as the pumps of figures 6 and 7, the housing 12 may further comprise an annular wall 122 extending from the bottom face 16 in axial direction in such a way that a cavity 121 to receive the shutter 2 may be defined at least by the annular wall 122 and the bottom face 16; wherein the adjustable coolant pump 1 may further comprise an adjustment sealing arrangement provided between the shutter 2 and the annular wall 122, the sealing arrangement comprising a ring seal 123 attached either to the shutter 2 or the annular wall 122, in such a way that a dynamic sealing between the shutter 2 and the housing 12 may be defined. The dynamic sealing may be achieved along the stroke of the shutter 2
In some examples, the ring seal 123 may be disposed about the axis of rotation AR.
In some examples, the annular wall 12 may be integrally formed with the rest of the housing 12 or may be a separate part which can be attached to the rest of the housing 12.
In the example illustrated in figures 6 and 7, the ring seal 123 is attached to the annular wall 122. Alternatively, the ring seal 123 may be attached to the shutter 2, particularly in a sidewall of the cup-like shutter 2.
As there may be a relative motion between the shutter 12 and the annular wall 122 of the housing 2, and the ring seal 123 may be attached either to the shutter 2 or the annular wall 122, there may be a relative motion between the ring seal 123 and the annular wall 122 or the shutter 2.
Figure 8 schematically shows an enlarged detail E of an adjustment sealing arrangement of the adjustable coolant pump 1 of the figure 6 and figure 9 schematically shows an enlarged detail F of an adjustment sealing arrangement of the adjustable coolant pump 1 of the figure 7.
In figures 8 and 9, it can be seen an annular recces 125 in the annular wall 122 where the ring seal 123 may be received. More particularly, the annular recess 125 is formed in an inner face of the annular wall 122, the inner face forming the cavity 121 where the shutter 2 may be housed. The inner face is facing the shutter 2.
The ring seal 123 may comprise a flange 124 or lip to contact the shutter 2. Alternatively the ring seal 123 may be an O-ring, "X" or squared cross-section shaped or the like. The ring seal 123 may be manufactured from a resilient material. The flange 124 may protrude from the rest of ring seal 123 to obtain a better contact with the shutter 2. In figures 8 and 9 it is shown that the flange 124 also protrudes from the inner wall of the annular wall 122. In those figures it is also shown that the ring seal 123 may be configured so as to allow an empty space 126 or void defined in the annular recess 125 and covered at least partially by the flange 124. The flange 124 may be received by the empty space 126 when it is bent due to the relative motion between the shutter 2 and the housing 12.
Figure 5 is a flow chart of an exemplary method of operation of an adjustable coolant pump. Although figure 5 shows a specific sequence, it should be understood that other sequences may be followed not deviating from the scope of the present disclosure.
The method of operation 100 may be related to the herein disclosed examples of adjustable coolant pump 1, for instance those examples which may comprise:

a housing 12;
a shaft 13 which may rotate around an axis of rotation AR of the housing 12;
an impeller which may be assembled in the shaft 13;
a shutter 2 which may be displaceable along the axis of rotation AR to cover, at least partially, an outflow region OR of the impeller 14 such that an amount of the coolant delivered by the pump 1 may be adjustable;
at least one end-stop element 3 which may be attached to a portion of the housing 12 to define an end of stroke for the shutter 2 when covering, at least partially, the outflow region OR;
wherein the housing 12 may comprise a top face 15 and a bottom face 16 disposed substantially perpendicular to the axis of rotation AR, the bottom face 16 may be provided between the top face 15 and the shutter 2. The end-stop element may be attached to the bottom face 16.

According to those examples the method 100 may comprise:

rotating the shaft 101 for rotating the impeller 14 to set in motion an amount of coolant. The rotation of the shaft 13 may be driven as explained before;
displacing the shutter 102 along the axis of rotation AR for covering, at least partially, the outflow region OR of the impeller 14 so as to adjust the amount of the coolant delivered by the pump 1. The displacement of the shutter 2 can be seen in figures 1 and 2. In figure 1, the shutter 2 does not cover the outflow region OR of the impeller 14 yet. In figure 2, the shutter has been displaced along the axis of rotation AR and towards the impeller 14 in order to cover at least partially the outflow region OR. The shank 31 may act as a guide for an accurate displacement of the shutter 2;
stopping the displacement of the shutter 104 at a predefined end of stroke by means of the end-stop element 3, when the shutter 2 covers, at least partially, the outflow region OR. In figures 2 and 4B, the shutter 2 has reached the end of stroke which may be determined by the widening 32 of the end-stop element 3. The sum of end-areas of each end-stop element 3 may define an activation stroke limit and may provide a planar contact surface for the shutter 2, particularly for the face of the shutter opposite to the annular piston 4.

In some further examples, the method 100 related, for instance, to those herein disclosed examples in which the adjustable coolant pump 1 may further comprise:

an annular piston 4 which may be displaceable in axial direction;
an annular groove 5 inside of which the annular piston 4 may be displaceable;
wherein the annular groove 5 may be divided in at least a first 51 and a second 52 pressure chambers by the annular piston 5;
wherein the annular piston 4 may be mechanically connected to the shutter 2 such that a displacement of the annular piston 4 in axial direction may be transmitted to the shutter 2.

According to those examples the method 100 may further comprise:
reducing the pressure 103 of the second pressure chamber 52 to at least one predefined level lower than the pressure of the first pressure chamber 1 for displacing the annular piston 4 in axial direction to the impeller 14 and covering, at least partially, the outflow region OR of the impeller 14 by the shutter 2. Reducing the pressure of the second pressure chamber 52 may comprise actuating a vacuum source (not illustrated) associated to the second pressure chamber 52 and allowing atmospheric air entering the first pressure chamber 51 through an opening 55 thereof. By actuating the vacuum source, for instance, a gas may be removed from the second pressure chamber 52. Meanwhile, the opening 55 may allow atmospheric air entering the first pressure chamber 51. Owing to the difference of pressures between the first and second pressure chambers, the annular piston 4 may move in axial direction towards the impeller 14, so the size (volume) of the second pressure chamber 52 may become smaller than the first pressure chamber 51. As the shutter 2 may be mechanically associated to the annular piston 4, the shutter 2 may describe a similar displacement.
By way of example, for activating the adjustment of the coolant, the pressure inside the second pressure chamber 52 may be kept below the atmospheric pressure of the environment of the pump 1.
Once the regulation function may be deemed as not necessary it may be deactivated. The vacuum source may be no longer activated. Then the resilient elements 7 may displace the annular piston 4 away from the impeller 14 in axial direction. The force generated by the springs 15 may be lower than the force created by the vacuum pressure of the vacuum source when the regulation function is activated so as to displace the shutter 2 towards the impeller 14 and at the same time this force may be sufficient as to return both annular piston 4 and shutter or adjusting element 2 when regulation function is deactivated. The first pressure chamber 51 may become smaller than the second pressure chamber 52.
When the regulation function is deactivated, the face of the shutter opposite to the impeller 14 may contact the bottom face 16 which may act as deactivation stroke limit.
All in all, a difference of pressure between the first 51 and the second 52 chambers may cause the displacement of the annular piston 4 in axial direction. Thus, the first pressure chamber may be fed with air directly taken from the environment of the pump (for instance atmospheric air) or a gas at a pressure higher than the gas inside the second pressure chamber 52 may be forced to enter the first chamber 51.
In some examples, the control unit may determine that a regulation of the flow-rate of the pump 1 may be activated. The control unit may send a command to the vacuum source to remove a predefined quantity of fluid form the second pressure chamber 52. This way, the outflow region OR may be at least partially occluded. Owing to the displacement of the piston 4, an atmospheric pressure fluid (such as ambient air) may enter the first pressure chamber 51 or an atmospheric pressure fluid may be forced to enter. The force of the generated vacuum may be greater than the opposite force of the resilient elements 7 to displace the piston towards the impeller 14.
When the control unit may determine that the regulation function may be no longer needed, it may send a command to the vacuum source to stop generating vacuum. Upon stopping the vacuum generation, the atmospheric pressure fluid (such as ambient air) may enter the second pressure chamber 52, for instance through the vacuum connection 54 which may be in fluid communication with an atmospheric air intake (not illustrated). The aperture/closure of the atmospheric air intake may be ruled by the control unit. This way, the difference of pressure between the first 51 and the second 52 chambers may no longer exist and both chambers 51, 52 may contain fluid at substantially the same pressure. Then resilient elements 7 may push the piston away from the impeller 14 in axial direction.
As above mentioned, the clearances C1, C2 may vary depending on the status of the pump 1. For instance, in figures 3A-3B the function may be deactivated but in figures 4A-4B activated. The size of the clearance C1, C2 may be the same in both cases but their distribution may vary like the size of the first and second pressure chambers 51, 52 by activation or deactivation of regulation.
In some examples, when the regulation is activated (see figures 4A-4B), clearance C1, C2 may be larger in the connection area disposed closer to the impeller 14. Conversely, when the regulation is activated (see figures 3A-3B), clearance C1, C2 may be larger in the connection area disposed farther from the impeller 14.
Thanks to the presence of the end-stop elements 3, an end of the stroke of the annular piston 4 and thus the shutter 2 may be accurately defined despite the clearances C1, C2 (for instance, when the regulation is activated). Furthermore, thanks to the bottom face 16, the other end of stroke of the annular piston 4 and thus the shutter 2 may be accurately defined despite the clearances C1, C2 (for instance, when the regulation is deactivated).
In the examples of the adjustable coolant pump 1 with a housing 12 comprising an annular wall 122 and an adjustment sealing arrangement, when the shutter 2 is displaced along the axis of rotation AR a dynamic sealing may be achieved between the shutter 2 and the housing 12, more particularly, between the shutter 2 and the annular wall 122. This way, a sealing function of the adjustment sealing arrangement may be maintained not only at the end points of the stroke of the shutter 2 but also along said stroke.
In the examples of figures 6 to 9, the flange 124, and particularly the cross section of the flange 124, may be bent or deformed when the shutter 2 is displaced along the axis of rotation AR.
In some cases, the adjustable coolant pump 1 according to herein disclosed examples may be configured to carry out the method 100.
If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

An adjustable coolant pump (1) comprising:
a housing (12);

a shaft (13) to rotate around an axis of rotation (AR) of the housing;

an impeller (14) assembled in the shaft;

a shutter (2) displaceable along the axis of rotation to cover, at least partially, an outflow region (OR) of the impeller such that an amount of the coolant delivered by the pump is adjustable;

at least one end-stop element (3) attached to a portion of the housing to define an end of stroke for the shutter when covering, at least partially, the outflow region;

wherein the housing comprises:
a top face (15) and a bottom face (16) disposed substantially perpendicular to the axis of rotation, the bottom face being provided between the top face and the shutter;

wherein the end-stop element is attached to the bottom face;

characterized in that

the end-stop element comprises a shank (31) fixed at one end to the portion of the housing and further comprising a widening (32) at the other end to stop the shutter when covering, at least partially, the outflow region.
The adjustable coolant pump (1) according to claim 1, wherein the housing further comprises an annular wall (122) extending from the bottom face in axial direction in such a way that a cavity (121) to receive the shutter is defined at least by the annular wall and the bottom face;
wherein the adjustable coolant pump further comprises:
an adjustment sealing arrangement provided between the shutter and the annular wall, the sealing arrangement comprising a ring seal (123) attached either to the shutter or the annular wall, in such a way that a dynamic sealing between the shutter and the housing is defined.
The adjustable coolant pump (1) according to claim 1, wherein the shank has a predefined length such that the predefined length of the shank corresponds to a predefined end of stroke for the shutter when covering, at least partially, the outflow region.
The adjustable coolant pump (1) according to any of claims 1 - 2, wherein the end-stop element comprises a bolt or a rivet.
The adjustable coolant pump (1) according to any of claims 1 - 4, further comprising:
an annular piston (4) displaceable in axial direction;

an annular groove (5) inside of which the annular piston is displaceable;

wherein the annular groove is divided in at least a first (51) and a second (52) pressure chamber by the annular piston;

wherein the annular piston is mechanically connected to the shutter such that a displacement of the annular piston in axial direction is transmitted to the shutter.
The adjustable coolant pump (1) according to claim 5, further comprising at least one rod (6) to mechanically connect the annular piston to the shutter.
The adjustable coolant pump (1) according to any of claims 5 - 6, wherein the first pressure chamber comprises an opening (55) to allow atmospheric air entering the first pressure chamber and the second pressure chamber is associated with a vacuum source.
The adjustable coolant pump (1) according to any of claims 5 - 7, wherein the piston comprises a piston seal (41) for sealing the first and the second pressure chambers from each other.
The adjustable coolant pump (1) according to any of claims 5 - 8, further comprising:
a resilient element (7) to push the annular piston in axial direction and away from the impeller, wherein the resilient element is located in a corresponding accommodation opened out to the annular groove.
The adjustable coolant pump (1) according to claim 9, wherein the resilient element comprises a spring.
The adjustable coolant pump (1) according to any of claims 1 - 10, wherein the shutter comprises at least one bore (21) to slidably receive the corresponding end-stop element.
The adjustable coolant pump (1) according to any of claims 1 - 11, which is pneumatically actuated.
A method of operation (100) of an adjustable coolant pump (1), the adjustable coolant pump comprising:
a housing (12);

a shaft (13) to rotate around an axis of rotation (AR) of the housing;

an impeller (14) assembled in the shaft;

a shutter (2) displaceable along the axis of rotation to cover, at least partially, an outflow region (OR) of the impeller such that an amount of the coolant delivered by the pump is adjustable;

at least one end-stop element (3) attached to a portion of the housing to define an end of stroke for the shutter when covering, at least partially, the outflow region;

wherein the housing comprises:
a top face (15) and a bottom face (16) disposed substantially perpendicular to the axis of rotation, the bottom face being provided between the top face and the shutter;

wherein the end-stop element is attached to the bottom face; wherein the end-stop element comprises a shank (31) fixed at one end to the portion of the housing and further comprising a widening (32) at the other end to stop the shutter when covering, at least partially, the outflow region;

wherein the method comprises:
rotating the shaft (101) for rotating the impeller to set in motion an amount of coolant;

displacing the shutter (102) along the axis of rotation for covering, at least partially, the outflow region of the impeller so as to adjust the amount of the coolant delivered by the pump;

stopping the displacement of the shutter (104) at a predefined end of stroke by means of the end-stop element, when the shutter covers, at least partially, the outflow region.
The method according to claim 13, the adjustable coolant pump (1) further comprising:
an annular piston (4) displaceable in axial direction;

an annular groove (5) inside of which the annular piston is displaceable;

wherein the annular groove is divided in at least a first (51) and a second (52) pressure chambers by the annular piston;

wherein the annular piston is mechanically connected to the shutter such that a displacement of the annular piston in axial direction is transmitted to the shutter;

wherein the method further comprises:
reducing the pressure (103) of the second pressure chamber to at least one predefined level lower than the pressure of the first pressure chamber for displacing the annular piston in axial direction to the impeller and covering, at least partially, the outflow region of the impeller by the shutter;

wherein reducing the pressure of the second pressure chamber comprises actuating a vacuum source associated to the second pressure chamber and allowing atmospheric air entering the first pressure chamber through an opening thereof.