Patent Description:
Coolant pumps for combustion engine vehicles may have a mechanical sealing of a main drive shaft to prevent the fluid from leaking to a driving pulley or the like. The mechanical sealing requires a proper refrigeration to avoid premature failing. Fluid near the mechanical sealing of the main drive shaft may be fully or partially trapped and isolated because flow on that area may be restricted. A restricted flow does not allow the proper refrigeration of the mechanical sealing so a premature failure can be expected.

Some coolant pumps developed for reducing global fuel consumption and/or exhaust emissions in combustion engine vehicles are based on adjusting or regulating elements that fully or partially cover the outlet area of an impeller. This way, suitable operating temperatures of the engine may be achieved in a shorter period of time, e.g. a cold start. A variety of solutions have been proposed to activate that adjusting element, for instance those mentioned in the background of the application <CIT>.

The adjusting or regulating elements may be driven in several ways. For instance, those elements may be driven based on pressurizing coolant drawn from the cooling system of the engine. The coolant may be pressurized by an auxiliary pump. If the amount of coolant obtained from the cooling system is below a threshold value, the regulating element cannot be operated properly.

Moreover, if an auxiliary pump is mounted to the shaft, between the mechanical sealing and the impeller, it may be even more difficult for the fluid to reach the mechanical sealing and so the proper refrigeration thereof. The auxiliary pump may hinder the renewal of the coolant to the seal.

It is an object of the present disclosure to provide examples of variable coolant pumps that avoid or at least reduce the afore-mentioned drawbacks.

<CIT> discloses a rotary pump with adjustable delivery volume.

<CIT> discloses a coolant pump assembly which has a housing assembly with a main pump and a secondary pump for adjusting the a control slide.

<CIT> discloses a controllable coolant pump that comprises an actuator that can be adjusted in order to set a volume flow of the coolant pump.

<CIT> discloses a coolant pump with a control device for regulating the volume flow. The control device has a slide element that can be driven via a hydraulic control device.

According to the invention, a variable coolant pump as specified in claim <NUM> is provided. The variable coolant pump comprises: a housing comprising an impeller area and a driving area, wherein the housing has a locking plate to define the impeller area at least partially; a shaft to rotate around an axis of rotation of the housing, wherein the shaft is operatively connected to a driving element arranged in the driving area; a main impeller to drive coolant in the impeller area, the main impeller being assembled around the shaft; a shutter displaceable in axial direction along the shaft to cover, at least partially, an outflow region of the main impeller such that an amount of the coolant delivered by the pump is variable; a control pressure pump to increase hydraulic pressure to displace the shutter, wherein the control pressure pump is assembled in the shaft; a first fluid path to feed the control pressure pump with coolant from the impeller area; a collector to collect driven coolant in a region between the main impeller and the locking plate, wherein the collector is in fluid communication with the first fluid path; wherein the first fluid path is in fluid communication with a collector intake through a duct; wherein the duct is defined between the locking plate and a collector cover, the collector cover being configured to separate the coolant captured by the collector from remaining coolant driven by the main impeller.

The coolant is driven by rotation of the main impeller. The coolant flows through the impeller area, namely through an intermediate region arranged between the main impeller and the locking plate, with respect to the length of the shaft. The coolant flowing in that intermediate region may flow following an angular direction or path with respect to the length of the shaft. The path of the driven coolant may be substantially parallel to the locking plate, or at least a component thereof.

The collector may capture and conduct or lead a portion of the driven coolant circulating in the impeller area. Thanks to the collector, the kinetic energy carried by the driven coolant in the intermediate region may be used to enhance the flow rate through the first fluid path. This way, a suitable coolant flow rate to feed the control pressure pump may be achieved more easily and simply than a fluid path without a collector.

In a case where a pump is void of a collector as defined in the invention, an orifice in the locking plate may be provided such that the direction followed by the circulating fluid in the intermediate region is substantially perpendicular to a first fluid path. Thus, it may be complex to absorb through an orifice in the locking plate the coolant circulating in the intermediate region as it is in motion. A resistance may be generated to absorb coolant through the first fluid path. To overcome that resistance, the pressure control pump has to generate a sufficient level of suction to obtain desired or predefined flow working requirements to actuate the shutter, e.g. a predefined volume of coolant.

This may mean oversizing the pressure control pump.

Since the collector as herein disclosed may allow for easy collection of the moving coolant, the control pressure pump does not have to be oversized to ensure the proper amount of pressurized coolant to drive the shutter. If the control pressure pump is not to be oversized, the size of the control pressure pump may be kept significantly reduced. A control pressure pump of reduced size may require less energy for activation. Therefore, a more efficient coolant pump may be achieved. Furthermore, a control pressure pump of reduced size may occupy less room. Therefore, a space-saving coolant pump may be achieved.

A separation of coolant streams may be obtained through the pump according to the invention.

A separation of the coolant that is driven by the main impeller and the coolant that may be sucked by the control pressure pump is provided, so that the coolant from the main impeller (which may have a higher speed) does not drag/disturb the coolant to be sucked by the control pressure pump (which may have a lower speed to enter the first fluid path). The collector may also act as a stagnation point. The collector may slow down or even stop the collected coolant relative to the rest of the coolant. This way, the collected coolant may avoid escaping, i.e. the collector may be a closed cavity that may create a backwater in which the collected coolant has proper or suitable conditions to be sucked in such as speed.

The collector may guide the collected coolant. The collector may have a shape that favors the entry and channeling of the coolant to the first fluid path.

A collector's intake may be configured, for example oriented or faced, so as to draw or capture the coolant moving through the intermediate region. A portion of the coolant flowing in the intermediate region may pass through the collector intake. The collector intake may be configured as a gate to capture the driven coolant.

The collector may be arranged over the locking plate or on the locking plate, for example the collector may lead at least a part of the coolant in a substantially parallel direction to the locking plate.

The locking plate may be substantially perpendicular to the length of the shaft.

According to the invention, the first fluid path is in fluid communication with the collector intake through a duct. A duct may mean a channel, passage, or conduit.

The collector and the first fluid path may be arranged with respect to each other such that an angle may be defined in the path of the coolant passing from the collector to the first fluid path, viewed in a longitudinal section of the pump. In some examples, the angle may be substantially about <NUM> degrees. However, this angle may vary. In examples, the collector and the first fluid path may be arranged to form an L-shaped junction therebetween.

The coolant may flow through the collector in a direction substantially parallel to the locking plate and may subsequently flow through a portion of the first fluid path substantially parallel to the shaft of the pump.

The collector may be arranged in such a way that a coolant flowing inside the collector may run substantially aligned with the driven coolant in the intermediate region, when seen in longitudinal cross section.

In examples, the variable coolant pump may comprise: a shaft seal to prevent the coolant of the impeller area from reaching the driving area of the housing, wherein the shaft seal may be disposed in a seal chamber of the housing; wherein the seal chamber may be in fluid communication with the first fluid path, such that the coolant for feeding the secondary impeller passes at least partially through the seal chamber. This way, the shaft seal may receive a coolant flow. A coolant flow may cool or keep the shaft seal's temperature within a suitable value range, i.e. a proper refrigeration of the shaft seal may be obtained. Therefore, a premature failure of the coolant pump may be avoided. The seal's life may be extended.

The seal may be cooled by the collected coolant before reaching the control pressure pump. Coolant exiting from the control pressure pump, i.e. through the second fluid path, may be at a higher pressure than the coolant in the first fluid path. If the seal was cooled with coolant from the outlet of the control pressure pump, the seal could be subjected to more pressure than it may withstand and could fail or collapse. Owing to the present example, the seal is not cooled by coolant from the outlet of the control pressure pump.

According to some examples, the control pressure pump may have a pump element slidably connected in axial direction to the shaft, the housing may comprise a cavity to receive the pump element, wherein the cavity may be configured to allow a relative displacement between the pump element and the shaft in axial direction. The pump element may be connected to the shaft and may be displaceable along axial direction, i.e. length of the shaft. As no axial attachment between the pump element and the shaft may be defined, a mechanical transmission of the shaft rotation to the pump element may be done in a way that torque may be transmitted substantially without axial stress.

In some examples, the variable coolant pump may comprise: a second fluid path to discharge coolant from the control pressure pump into the impeller area; wherein the second fluid path may comprise a discharge bore arranged in the locking plate in such a way that a discharged coolant flows parallel to the shaft, at least partially.

In this way the coolant circulating in the intermediate region may help to expel the coolant from the second fluid path, due to the Venturi effect. Thanks to this, the coolant may avoid getting stuck in the second fluid path. If the pressurized coolant remains in the second flow path, this could lead to accidental activation of the plug.

Throughout the present disclosure, expressions such as above, below, beneath, under, upper, top, bottom, lower, side, etc are to be understood taking into account the arrangement of a variable coolant pump or the like in an operating condition as a reference.

Throughout the present disclosure, expressions such as axis of rotation, shaft length or longitudinal axis are interchangeably used.

In these figures, the same reference signs have been used to designate matching elements. Some parts have not been illustrated for the sake of clarity.

In the present description a first and second fluid path has been respectively depicted with arrows in the accompanying drawings for the sake of clarity. These arrows may schematically indicate the path that the coolant may travel before and after passing through a pressure control pump.

In the following some examples of a variable coolant pump <NUM> will be described.

Although those examples may be related to an internal combustion engine, the variable coolant pump <NUM> could be related to any kind of engine or the like. The variable coolant pump <NUM> may be used for conveying and circulating a coolant or coolants.

<FIG> schematically illustrates a partial longitudinal cross section view of a variable coolant pump <NUM> with a collector <NUM> according to an example when a regulation function is deactivated.

The variable coolant pump <NUM> of <FIG> comprises:.

The coolant driven by the main impeller <NUM> may describe a generally annular path in the intermediate region IR in the direction of the length of the shaft <NUM>. In <FIG>, the direction that the driven coolant may follow around the axis of rotation AR has been depicted as the arrow DC. In the example of <FIG>, the collector <NUM> protrudes, at least partially, from the locking plate <NUM> toward the main impeller <NUM>. This way, a step may be formed between the collector <NUM> and the locking plate <NUM>. The collector <NUM> may have a collector intake <NUM> located in the step. By arranging the collector intake <NUM> on the step, the collection of driven coolant may be optimized.

An intake bore <NUM> may be arranged between the collector <NUM> and the first fluid path <NUM>.

The intake bore <NUM> may be located in the locking plate <NUM>. The intake bore <NUM> may be funnel-shaped. The intake bore <NUM> may act as the first fluid path's intake, so as to feed the first fluid path <NUM>.

The first fluid path <NUM> is in fluid communication with the collector intake <NUM> through a duct <NUM>. The duct <NUM> may adopt any suitable shape to lead the coolant driven by the main impeller <NUM>. In the example of <FIG>, the duct <NUM> is nozzle shaped or bell-shaped. In this way, the inlet of the moving coolant between the main impeller <NUM> and the locking plate <NUM> may be facilitated.

The duct <NUM> is defined between the locking plate <NUM> and a collector cover <NUM>. The collector cover <NUM> may be generally flat and attached to the locking plate. The collector cover <NUM> may protrude with respect to the locking plate <NUM> towards the main impeller <NUM>.

In some examples, the locking plate <NUM> and/or the collector cover <NUM> may have a recess to form the duct <NUM>. In the attached drawings, the collector cover <NUM> is the one with a recess defining the path of the first fluid path <NUM>. The latter can be seen for instance in <FIG> and <FIG>. The collector cover <NUM> may have a notch to define the track of the duct <NUM>.

The collector cover <NUM> separates the coolant captured by the collector <NUM> from the remaining coolant driven by the main impeller <NUM>. Thus, the characteristics of the captured coolant such as speed and/or pressure may be suitably adjusted before entering the first fluid path <NUM>.

In some examples, the duct <NUM> may be arranged such that a section of its length is perpendicular to the shaft <NUM>. The path that the collected coolant follows through the interior of the collector may change direction when it enters the first fluid path <NUM> of the pump <NUM>.

In some examples, the duct <NUM> may be arranged such that a section of its length is substantially parallel to the locking plate <NUM>.

According to some examples, the duct <NUM> may be arranged such that a portion of its length is rounded about the shaft <NUM> or tangential to the shaft <NUM>. In this way, the coolant collected by the collector <NUM> may be smoothly conveyed to the first fluid path <NUM>. The intake bore <NUM> may be generally rounded and/or elongate to follow, at least partially, the rounded portion of the duct <NUM>.

In examples, which do not fall within the scope of the claims, the collector intake <NUM> may be directly connected to the first fluid path <NUM>.

In these examples, the pump <NUM> does not comprise a duct.

In some examples, the collector <NUM> may be arranged, at least partially, on the locking plate <NUM>.

The duct <NUM> may present a generally curved layout when viewed in plan, as seen in <FIG>. This curved layout may be adapted to the circular path that the coolant may follow in the intermediate region. This curved shape may facilitate the collection of driven coolant.

In some examples, the collector intake <NUM> may comprise at least one rounded wall. This rounded wall may be a side wall of the curved layout. The rounded wall may provide a significantly smooth entry of the collected coolant.

According to some examples, the variable coolant pump <NUM> may comprise:.

The first fluid path <NUM> followed by the coolant from the impeller area <NUM> to the inlet <NUM> may comprise the seal chamber <NUM> where the shaft seal <NUM> is placed. Therefore, the coolant suctioned by the secondary pump <NUM> may keep the shaft seal <NUM> at a proper temperature to avoid a premature failure.

In some examples, the control pressure pump <NUM> may have a pump element <NUM> slidably connected in axial direction to the shaft <NUM>, the housing <NUM> may comprise a cavity <NUM> to receive the pump element <NUM>. The cavity <NUM> may be configured to allow a relative displacement between the pump element <NUM> and the shaft <NUM> in axial direction as depicted by arrows <NUM>. This may facilitate installation tasks or smooth operation of the pump as clearances between parts may be compensated or absorbed by axial displacement of pump element <NUM> relative to shaft <NUM>. The pump element <NUM> may be made of a material with flexible features.

In some examples, the control pressure pump <NUM> may comprise a secondary impeller as the pump element <NUM> which may be arranged coaxially with the shaft <NUM>, the secondary impeller may be driven by the shaft <NUM>.

In some other examples, the locking plate <NUM> may be arranged between the impeller area <NUM> and the cavity <NUM>. In the example of <FIG>, the locking plate <NUM> is provided between the impeller area <NUM> and the control pressure pump <NUM>. In this example the locking plate <NUM> extends beyond the cavity <NUM> in plan view but the locking plate <NUM> may be limited to the extension of the cavity <NUM> in plan view. The locking plate <NUM> may be attached in a fixed manner to the housing <NUM>, for instance, by several fixation elements <NUM>.

A lid <NUM> may define along with the cavity <NUM> a room to receive the control pressure pump <NUM> as can be seen in <FIG>. The lid <NUM> may be arranged between the cavity <NUM> and the locking plate <NUM> in axial direction. The lid <NUM> may comprise an annular body.

According to some examples, a return spring <NUM> may be placed between the shutter <NUM> and the housing <NUM> as seen in <FIG>. The return spring <NUM> may push the shutter <NUM> back to its deactivated position. This may occur when the control valve <NUM> is deactivated after having been activated.

In some examples, the variable coolant pump <NUM> may further comprise a control valve <NUM> to control the flow rate or pressure of the coolant from the outlet <NUM> of the control pressure pump <NUM> to the impeller area <NUM>. The control valve <NUM> may control the flow rate and/or pressure of the second fluid path <NUM>. An example of control valve <NUM> can be seen in <FIG>. The control valve <NUM> may be any type of valve which may allow controlling the flow of coolant such as a solenoid valve.

If a pressure value equal to or above a pressure threshold builds up in the second fluid path <NUM>, it is possible to overcome the resistance offered by the return spring <NUM> to actuate the plug <NUM>. If the control valve <NUM> is deactivated, i.e., at least partially open, coolant is allowed to flow from the outlet <NUM> to the impeller area <NUM>, see <FIG>. As the pressurized coolant by the control pressure pump <NUM> is evacuated through the discharge bore <NUM>, no pressurized coolant accumulates in the second fluid path <NUM> and therefore does not build up sufficient pressure to overcome the resistance offered by the return spring <NUM>.

If the control valve <NUM> is actuated, i.e., at least partially closed, pressurized refrigerant begins to accumulate driven by the control pressure pump <NUM>, see <FIG>. A pressure is generated in the second fluid path <NUM> that may reach the pressure threshold. Once the pressure threshold is reached, the return spring <NUM> may be compressed, so that the plug <NUM> may gradually limit the outflow of refrigerant from the output region OR. See for instance, <FIG>. If the control valve <NUM> is subsequently opened, the coolant may follow the second fluid path <NUM> until the discharge bore <NUM>.

The discharge bore <NUM> may be positioned in the locking plate so that there is substantially no fluid interference between the collector intake and the discharge bore <NUM>. For example, the collector intake and the discharge bore may be arranged diametrically opposite each other.

The following describes the operation of the pump <NUM> according to an example.

The pump shaft <NUM> may rotate thanks to the impulse received through the driving element <NUM>, for example, from the crankshaft of the combustion engine. The main impeller <NUM> may also rotate due to the rotation transmitted by the shaft <NUM>. The coolant present in the impeller area <NUM> may in turn be driven due to the rotation of the main impeller <NUM>. Part of that driven coolant flows in the intermediate region IR between the main impeller <NUM> and the locking plate <NUM>. In that region, part of the driven coolant may follow a substantially annular path around the shaft <NUM> due to the impulse that may be applied by the main impeller <NUM>. The collector <NUM> may receive part of the coolant flowing through the intermediate region IR. The coolant collected by the collector <NUM> may continue through the duct <NUM> in case the pump <NUM> has one. In the duct <NUM>, the properties of the coolant such as pressure and/or speed may be modified with respect to those of the coolant flowing through the intermediate region IR. If the duct <NUM> has a rounded or curved portion around the shaft <NUM>, the collected coolant may follow a path or way similar to that carried by the coolant that runs through the intermediate region IR.

The collected coolant may pass through the intake bore <NUM> and enter the first fluid path <NUM>. The collected coolant may retain at least a part of the kinetic energy obtained due to the rotation of the main impeller <NUM>. The collected coolant may continue along the first fluid path <NUM>. In the example of the attached figures, the coolant passes through the seal chamber <NUM> and from there goes to the inlet <NUM> of the pressure control pump <NUM>. In the case of not passing through the seal chamber, the coolant would go to the inlet <NUM>. When the coolant flows through the seal chamber <NUM> it may cool the shaft seal <NUM>. The path of the first fluid path <NUM> may be implemented thanks to the kinetic energy carried by the coolant as explained above and to the suction exerted by the control pressure pump <NUM>.

Coolant may exit the control pressure pump through the outlet <NUM>. Passage through the control pressure pump <NUM> may cause the pressure of the coolant to increase. The coolant pressurized by the control pressure pump <NUM> may continue through the second flow path <NUM> as shown in <FIG>. If the control valve <NUM> is open or inactive, the shutter <NUM> remains in its retracted position as shown in <FIG>. The coolant may continue through the second flow path <NUM> as shown in <FIG> and <FIG> until it reaches the discharge bore <NUM>.

If the control valve <NUM> is activated or closed, at least partially, it does not allow at least a portion of the coolant pressurized by the pressure control pump <NUM> to reach the discharge bore <NUM>. A pressure may build up in the section of the second fluid path <NUM> from the outlet <NUM> to the control valve <NUM> as seen in <FIG>. If a pressure threshold is reached, the resistance of the return spring <NUM> can be overcome and the plug <NUM> may be extended to at least partially shut off the outflow region OR as shown in <FIG>. A motor control unit (not shown) may send a command to actuate the control valve <NUM>. When the control valve <NUM> is opened, pressure inside the second fluid path <NUM> may be reduced because coolant may be allowed to flow through the control valve <NUM> as seen in <FIG>.

The first fluid path <NUM> and the second fluid path <NUM> may have several sections or regions as set forth in the following:
In a first section FF of the first fluid path <NUM>, the coolant may flow towards the driving area <NUM> and substantially parallel to the shaft <NUM>. This first section FS may start at the intake bore <NUM>. In a second section SF of the first fluid path <NUM>, the coolant may flow substantially perpendicular and towards the shaft <NUM>, so that it may enter the seal chamber <NUM> if the pump <NUM> is provided with one. After leaving the seal chamber <NUM> the coolant flows in a third section TF of the first fluid path <NUM> in a substantially perpendicular direction and from the shaft <NUM>. In a fourth section OF of the first fluid path <NUM> the coolant may circulate substantially parallel to the shaft <NUM> and towards the impeller area <NUM>. The fourth section OF of the first fluid path <NUM> may terminate at the inlet <NUM> of the control pressure pump <NUM>.

In a first section FS of the second fluid path <NUM>, the coolant may circulate towards the driving area <NUM> and substantially parallel to the shaft <NUM>. This first section FS may start at the outlet <NUM> of the pressure control pump <NUM>. In a second section SS of the second fluid path <NUM>, the coolant may circulate through a control valve channel <NUM> towards the control valve <NUM>, see <FIG>. If the control valve <NUM> is at least partially open, the coolant may pass into a third section TS comprising an outlet valve channel <NUM> disposed between the control valve <NUM> and a fourth section OS comprising a discharge channel <NUM>, see <FIG>. In the fourth section OS the coolant circulates substantially parallel to the shaft <NUM> and towards the driving area <NUM>. The fourth section OS may terminate in the discharge bore <NUM>.

The housing <NUM> may have a piston chamber <NUM> to receive at least one end portion of the shutter <NUM>, the end portion being arranged at an opposite side to the main impeller <NUM>, see <FIG>. The piston chamber <NUM> may be annular shaped around the axis of rotation AR.

The shutter <NUM> may have a pressure ring <NUM> around the axis of rotation AR, see <FIG>. The pressure ring <NUM> may be configured to move within the piston chamber <NUM> in a direction of the length of the shaft <NUM>. The pressuring ring <NUM> may move within the piston chamber <NUM> when the shutter moves to or from the main impeller <NUM>. The pressure ring <NUM> may be in fluid communication with the second section SS of the second fluid path <NUM> through a shutter feeding channel <NUM>. This way, if the control valve <NUM> is at least partially closed, the pressure inside at least the second section SS may rise as above described and the built-in pressure coolant may apply a force and so a pressure to the pressure ring <NUM>. The applied pressure to the ring <NUM> above the pressure threshold may compress the spring <NUM>.

The pressure ring <NUM> may have a cross section having an indentation <NUM> in the side of the coolant which may create a ring channel <NUM> about the axis of rotation AR. The pressurized coolant may flow through the ring channel <NUM> around the axis of rotation AR. In this way the pressure within the ring channel <NUM> may be distributed substantially homogeneously. This may mean that the activation of the shutter <NUM> may be uniform around the axis of rotation AR, i.e., the outflow region OR may be shut off uniformly around the axis of rotation AR.

The shutter feeding channel <NUM> may be oriented towards the ring channel <NUM> to further improve the filling of the ring channel <NUM> and so a homogeneous distribution of the pressurized coolant between the piston chamber <NUM> and the pressure ring <NUM> may be achieved.

The indentation <NUM> may be generally U- or V-shaped.

The pressure ring <NUM> may have a planar surface in the side of the spring <NUM>.

Claim 1:
A variable coolant pump (<NUM>) comprising:
a housing (<NUM>) comprising an impeller area (<NUM>) and a driving area (<NUM>), wherein the housing has a locking plate (<NUM>) to define the impeller area at least partially;
a shaft (<NUM>) to rotate around an axis of rotation (AR) of the housing, wherein the shaft is operatively connected to a driving element (<NUM>) arranged in the driving area;
a main impeller (<NUM>) to drive coolant in the impeller area, the main impeller being assembled in the shaft;
a shutter (<NUM>) displaceable in axial direction along the shaft to cover, at least partially, an outflow region (OR) of the main impeller such that an amount of the coolant delivered by the pump is variable;
a control pressure pump (<NUM>) to increase hydraulic pressure to displace the shutter, wherein the control pressure pump is assembled around the shaft;
a first fluid path (<NUM>) to feed the control pressure pump with coolant from the impeller area;
a collector (<NUM>) to collect driven coolant in a region between the main impeller and the locking plate, wherein the collector is in fluid communication with the first fluid path;
wherein the first fluid path is in fluid communication with a collector intake (<NUM>) through a duct (<NUM>);
characterized in that
the duct is defined between the locking plate (<NUM>) and a collector cover (<NUM>), the collector cover being configured to separate the coolant captured by the collector (<NUM>) from remaining coolant driven by the main impeller (<NUM>).