Switchable mechanical coolant waterpump

Abstract

A switchable mechanical waterpump for use in internal combustion engines and the like utilizes a shutter which translates between an engaged position, in which the shutter surrounds an impeller to block or inhibit coolant flow, and a disengaged position, in which the shutter does not surround the impeller thereby not impeding coolant flow. An embedded secondary pump system delivers the required pressure to move the shutter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Application No. 63 / 686,086 filed August 22, 2024.FIELD OF THE DISCLOSURE

[0002] This disclosure relates generally to the field of mechanical water pumps.BACKGROUND

[0003] Automotive internal combustion engines can employ switchable mechanical water pumps (SMWP) driven by belts or chains. The SMWP can be enabled or disabled. For example, the SMWP can be disabled when the engine is first started to preclude or substantially reduce coolant flow to the engine and thus enable faster warm up, which reduces the amount of undesirable combustion gases that are emitted by the engine in comparison to a water pump that is always enabled. Once the engine has warmed up, the SMWP can be enabled to deliver its rated coolant flow.

[0004] Examples of SMWPs are disclosed in, for example, US 10,400,659 to Nidec GPM GmbH and in EP 4,067,665 to Airtex Products. These SMWPs utilize a shutter or shield which translates axially between an engaged position, in which the shutter or shield surrounds a centrifugal style impeller to block or inhibit coolant flow, and a disengaged position, in which the shutter or shield does not surround the impeller thereby not impeding coolant flow. Such SMWPs require secondary pumping systems to build sufficient pressure to translate the shutter or shield. The complexity of such secondary pumping systems can affect the robustness and / or cost of these designs. For example, the Nidec SMWP employs a piston pump that is arranged axially parallel to the main impeller drive shaft, adding complexity and cost to the design. The Airtex SMWP utilizes a collector system driven by the impeller to feed a secondary impeller, also adding complexity and cost.

[0005] It would be desirable to offer an SMWP with an alternative secondary pumping system that may increase the robustness and / or decrease potential manufacturing cost.SUMMARY

[0006] According to the invention, a switchable mechanical waterpump is provided that is suitable for use in an automotive vehicle. The waterpump includes a housing, a primary pumping element, and a mechanical drive subsystem mounted to the housing for rotating the primary pumping element about a rotational axis. An enclosure, connected to the housing, provisions a pressure chamber. A moveable shutter is operatively connected to the pressure chamber, with the shutter being moveable between an engaged position, in which the shutter at least partially covers the primary pumping element to inhibit fluid flow, and a disengaged position, in which the shutter does not cover the primary pumping element so as to not inhibit fluid flow. The pressure chamber has an ingress fluid path and an egress fluid path which fluidly connect the pressure chamber to a cooling circuit when the pump is mounted for operation. At least one of the pressure chamber ingress fluid path and the pressure chamber egress fluid path are occludable, for example, by way of an electronically controlled valve functionally disposed in one of the ingress or egress fluid paths. A secondary pumping element is disposed in the pressure chamber and is operatively connected to the mechanical drive subsystem for generating pressure in the pressure chamber to move the shutter to the engaged position when at least one of the pressure chamber ingress fluid path and the pressure chamber egress fluid path is occluded. The enclosure includes an exterior wall, exposed to the cooling circuit, which includes at least one conduit that provisions a portion of the pressure chamber ingress fluid path.

[0007] According to another aspect, the switchable mechanical waterpump may be realized by featuring a sealing flange on the housing and provisioning an O-ring to seal the housing against a pump mounting surface, such as an engine block, wherein the at least one conduit that provisions a portion of the pressure chamber ingress fluid path is disposed radially inward of the sealing flange.

[0008] The mechanical drive subsystem can include a shaft that is journalled in the housing; the primary pumping element can be an impeller; the secondary pumping element can be a gerotor; and the gerotor can be operatively connected to the shaft via an interruptible connection.

[0009] The gerotor can include an inner rotor and an outer rotor. The interruptible connection can include a drive coupling fixed to the shaft. The drive coupling can have a first set of fingers and the inner gerotor can have a second set of fingers, with the first and second set of fingers being interdigitated, wherein at least one of the first and second sets of fingers is flexible or sacrificial so as to temporarily or permanently disrupt the drive between the shaft and the gerotor above a certain torque level.

[0010] The enclosure can be provisioned by a base and a lid fastened to the base, with the shaft extending through the base and the lid.

[0011] The base can include a circumferential outer wall, a circumferential inner wall and a radial toroidal wall interconnecting the circumferential outer and inner walls so as to form a toroidal rebate into which the moveable shutter is seated.

[0012] A spring can be disposed between the lid and the shutter to bias the shutter to the disengaged position.

[0013] The base can include a radial wall inward of the circumferential inner wall, with the circumferential inner wall, the lid and the radial wall defining a secondary pump chamber in which the gerotor is ensconced.

[0014] The pressure chamber ingress fluid path can include at least one conduit provisioned in or on the base circumferential outer wall, at least one conduit provisioned in or on the base radial toroidal wall, at least one conduit provisioned in or on the base circumferential inner wall, and at least one opening provisioned in the base radial wall.

[0015] The pressure chamber egress fluid path can include a pumping chamber outlet and a passageway formed in the base.

[0016] The pressure chamber egress fluid path can include a first conduit formed in the housing and a second conduit, formed in the housing, and an electronically controlled valve can be functionally disposed between the first and second conduits to selectively occlude the pressure chamber egress fluid path .

[0017] According to another aspect, a switchable mechanical water pump can be provided which includes: a housing; an impeller; a mechanical drive subsystem, including a shaft, mounted to the housing for rotating the impeller about an axis defined by the shaft; an enclosure, connected to the housing, which provisions a pressure chamber; a moveable shutter operatively connected to the pressure chamber, with the shutter being moveable between an engaged position in which the shutter at least partially covers the primary pumping element to inhibit fluid flow, and a disengaged position in which the shutter does not cover the primary pumping element so as to not inhibit fluid flow. When the pump is mounted for operation, the pressure chamber can be fluidly connected to a cooling circuit via a pressure chamber ingress fluid path and a pressure chamber egress fluid path. The pressure chamber egress fluid path can be occluded, for example, by an electrically controlled valve functional disposed within the pressure chamber egress fluid path. A gerotor can be disposed in the pressure chamber and operatively connected to the shaft for generating pressure in the pressure chamber to move the shutter to the engaged position when the pressure chamber egress fluid path is occluded. The enclosure can be provisioned as a subassembly bounded by a base and a lid fastened to the base, wherein the base includes a rebate into which the moveable shutter is seated and the base includes a pumping chamber disposed inward of and fluidly connected to the rebate, with the gerotor being ensconced in the pumping chamber.

[0018] The gerotor can be connected to the shaft via an interruptible connection such as described above. The gerotor and the interruptible connection can be formed from cost-effective plastic, or example, reinforced plastic.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The foregoing and other aspects of the invention will now be described in greater detail, by way of non-limiting example only, with reference to the attached drawings, in which: Figure 1 is a perspective view of a switchable mechanical water pump (SMWP) according to a first embodiment; Figure 2A is an exploded view of the SMWP shown in Figure 1; Figure 2B is another exploded view of the SMWP shown in Figure 1, taken along a view angle opposite to the view angle used in Figure 2A; Figure 3 is an exploded view of a subassembly of the SMWP shown in Figure 1; Figure 4A is cross-sectional view of the SMWP shown in Figure 1, with the SMWP shown mounted against an engine block and in a disengaged position; Figure 4B is cross-sectional view of the SMWP shown in Figure 1, with the SMWP shown mounted against the engine block and in an engaged position; and Figure 5 is a partial isolation, partial cut-away view of the SMWP shown in Figure 1, illustrating certain internal conduits. DESCRIPTION OF EXAMPLE EMBODIMENT(S)

[0020] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well- known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0021] Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: "or" as used throughout is inclusive, as though written "and / or"; singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; "exemplary" should be understood as "illustrative" or "exemplifying" and not necessarily as "preferred" over other embodiments. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description.

[0022] Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, "each" refers to each member of a set or each member of a subset of a set.

[0023] The indefinite article "a" is not intended to be limited to mean "one" of an element. It is intended to mean "one or more" of an element, where applicable, (i.e. unless in the context it would be obvious that only one of the element would be suitable).

[0024] Terms such as "connected to", "fixed to", "bears against" and "supported by" do not mean that a first part has to directly touch or contact a second part in order for the first and second parts to be considered connected together, fixed together, bear against one another, or supported by one or the other, respectively. Unless the context clearly dictates otherwise, two parts may considered connected together, fixed together, bear against one another, or supported by one or the other through one or more intermediate parts which function to bear or transfer loads between the first and second parts.

[0025] Any reference to upper, lower, top, bottom or the like are intended to refer to a relative orientation of a particular element in relation to other elements and not necessarily in absolute terms, or to orientation during manufacture, shipping or use. The upper surface of an element, for example, can still be considered an upper surface in relation to another surface even when the element is lying on its side or upside down.

[0026] Figures 1-5 disclose an example of an embodiment of a switchable mechanical coolant pump (SMWP) 100.

[0027] The SMWP 100 is mountable to a surface which features an opening to an engine cooling circuit. For example, Figures 4A and 4B show the SMWP 100 mounted to an engine block 10 (partially shown) which has a cylindrical opening 12 into a fluid-filled cavity 14 that forms part of an engine cooling circuit. When mounted, a primary pumping element 104 of the SMWP 100 can be disposed in the fluid filled cavity 14. The SMWP 100 can include a housing 120 (see Figs. 2A, 2B) which can be sealed against the mounting surface such as engine block 10. For example, as illustrated, the housing 120 can include a flange 134 for seating the housing 120 against the engine block 10. An O-ring 136 can be installed interiorly adjacent to the flange 134 to seal the housing 120 against the engine block 10 to inhibit coolant leakage.

[0028] Referring to Figure 1, the SMWP 100 includes a mechanical drive subsystem 102 (partially shown in Figure 1) that drives the primary pumping element 104. The primary pumping element 104 can be a centrifugal type impeller 105, as shown, which ingresses fluid in an axial direction A and egresses fluid in a radial direction R. The opposite arrangement is also possible where an impeller can ingress fluid radially and egress fluid axially. Alternative types of primary pumping elements are also possible, such as vaned rotors that ingress and egress fluid radially or axially. In the illustrated embodiment, the impeller 105 rotates about a central axis A-A (see Fig. 4A), which defines the axial direction.

[0029] The SMWP 100 can include a moveable shutter 106 such as a shroud 107 that is movable between a disengaged position, such as seen in Figures 1 and 4A, and an engaged position, such as seen in Figure 4B. In the engaged position the moveable shutter 106 can surround or overlap at least a portion of the primary pumping element 104. For example, in the illustrated embodiment the shroud 107 surrounds a substantial portion of a circumferential extent 105C of the impeller 105, thus blocking or inhibiting the egress (or ingress) of fluid from the impeller 105. In the disengaged position the moveable shutter 106 is retracted from the engaged position so as to substantially not surround or overlap the primary pumping element 104. For example, in the illustrated embodiment the shroud 107 does not surround the circumferential extent 105C of the impeller 105 and thus does not block or inhibit the egress (or ingress, for reverse flow) of fluid from the impeller 105.

[0030] The moveable shutter 106 can be operatively coupled to a pressure subsystem 110 that generates fluid pressure in order to move the shutter 106. Referring additionally to Figures 2A, 2B and 3, as shown in the illustrated embodiment, the pressure subsystem 110 can include a pressure chamber 112, a secondary pumping element 114 disposed within the pressure chamber 112 and operatively connected to the mechanical drive subsystem 102, and an electronically controlled valve 116 that enables or disables an occludeable fluid path to or from the engine cooling circuit such that when the occludeable fluid path is occluded fluid pressure can build in the pressure chamber 112 to move or maintain the shutter 106 in the engaged position and when the occludeable fluid path is not occluded pressure cannot build in the pressure chamber 112 leaving the shutter 106 in a biased state, which can be the disengaged position.

[0031] As seen best in the exploded views of Figures 2A and 2B, the mechanical drive system 102 can include a drive shaft 124 for rotating the primary pumping element 104. For example, as seen in the illustrated embodiment, the housing 120 can include an integrally formed cylindrical tube 122 and a ball, roller or slide bearing 126 can be mounted in the tube 122 with the shaft 124 installed into the bearing 126.

[0032] In other embodiments a bushing (not shown) can be substituted for the bearing 126 or the shaft 124 may be journalled directly in the tube 122.

[0033] Impeller 105 can be fixed to the shaft 124 in any desirable manner. For example, one end 124A of the shaft 124 can be installed into a central bore 105B of the impeller 105. Optionally, the shaft 124 can be installed into a hub 128 that can be mounted in the central bore 105B.

[0034] A mechanical drive element 130 such as a pulley 132 can be fixed to the shaft 124, for example, to an opposite end 124B of the shaft 124 in order to rotate the shaft 124 and the impeller 105. In alternative embodiments other drive elements can be employed such as a gear or gear set driven by a corresponding engine drive element such as a crankshaft or power take-off feature.

[0035] The pressure chamber 112 can be disposed about the shaft 124. For example, as seen in the illustrated embodiment, pressure chamber 112 can be formed by an enclosure 140 provisioned by a base 142 and a lid 144. Alternatively, the pressure chamber 112 can be formed by other arrangements of radial and circumferential walls constituting the enclosure. For example, the housing 120 may be used as one element of the enclosure 140 or indeed provision the entirety of the enclosure defining the pressure chamber 112.

[0036] A shaft seal 146 functions to seal the shaft against leakage of coolant.

[0037] As seen in the illustrated embodiment, the base 142 can include a toroidally shaped rebate 142R (seen best in Figures 2B and 3) formed from inner and outer circumferential walls 142I and 142E, respectively (seen best in Figure 2A).

[0038] As seen in the illustrated embodiment the shroud 107 can be partially disposed in the rebate 142R (seen best in Figures 4A and 4B). More particularly, as seen in Figure 3, the shroud 107 can include a cover section 107C configured to surround the impeller 105 when in the engaged position, and a skirt section 107S which, as seen in Figure 4A, can be fully seated in the rebate 142R when the shroud 107 is in the disengaged position. The skirt section 107C can include a circumferentially arranged ring portion 107F (see Fig. 2A) to cap the pressure chamber 112. Accordingly, the ring portion 107F can be configured to have a decent fit against the inner and outer toroidal walls 142I and 142E. The ring portion 107F can also include an axially flared or concave end portion 107G (see Fig. 4A) configured to substantially evenly receive and distribute force axially and circumferentially arising from pressure build up in the pressure chamber 112.

[0039] A biasing member such as a spring can be employed to bias the shroud 107 in one of the engaged or disengaged positions. For example, a coil spring 148 as shown in the illustrated embodiment can be backstopped against the lid 144 to bias the shroud 107 to the disengaged position.

[0040] The secondary pumping element 114 can be operatively connected to the drive shaft 124 and disposed in the pressure chamber 112, and more particularly, in a pumping chamber 150 (seen best in Figures 2B and Figures 4A, 4B). For example, as shown in the illustrated embodiment the base 142 can include a central opening 1420 (seen best in Figure 2B and 3) inward of the rebate 142R in which the secondary pumping element 114 can be ensconced.

[0041] The secondary pumping element 114 can be any component, such as an impeller or rotor, that induces sufficient pressure within the pressure chamber 112 to move the shutter 106 such as shroud 107 into the engaged position. As shown in the illustrated embodiment the secondary pumping element 114 can be a gerotor 152 that includes an inner rotor 152A and an outer rotor 152B which provide positive displacement pumping action as known in the art per se. The inner rotor 152A can be fixed or otherwise operatively connected to the shaft 124. For example, the inner rotor 152A can be connected to the shaft 124 via an interruptible connection, such as a sacrificial or disrupt-able connection. For example, as shown in the illustrated embodiment a drive coupling 154 (as seen best in the exploded views of Figures 2A, 2B and 3) can be fixed to the shaft 124 and operatively connected to the inner rotor 152A via interdigitated fingers 156A and 156B disposed on the drive coupling 154 and the inner rotor 152A, respectively. One of the fingers 156A and 156B can be made of much harder material than the other such that the softer fingers will break or yield if the gerotor somehow becomes obstructed thus enabling the shaft 124 to continue to rotate whilst leaving the SMWP 100 operational to continue to pump cooling fluid. Alternatively, one or both of the fingers 156A and 156B can be flexible so as to bend or otherwise yield above a predetermined torque level to thereby disrupt the connection between the drive coupling 154 and the inner rotor 152A. Other forms of permanent or temporary interruptible connections are also possible as will be appreciated and understood by persons skilled in the art. For example, the inner rotor 152A can be a sacrificial part by being fixed to the shaft 124 and scored circumferentially to break apart above a pre-determined level of torque.

[0042] Advantageously, the gerotor 152 can be formed from reinforced plastic in an injection molding process. Likewise, the drive coupling 154 can also be formed from plastic, enabling ready manufacture of the interdigitated fingers 156A and 156B.

[0043] The pressure chamber 112 can be fluidly connected to the cooling circuit cavity 14 via a pressure chamber ingress fluid path and a pressure chamber egress fluid path. In the illustrated embodiment the occlude-able fluid path is the pressure chamber egress fluid path.

[0044] The pressure chamber ingress fluid path can be provisioned by any passageway(s) that leads to the pumping chamber 150 from the cooling circuit cavity 14. For example, at least one opening can be provisioned behind the primary pumping element 104 into the pumping chamber 150. Alternatively, a passageway(s) can be provisioned in the housing 120 that leads to the pumping chamber 112 from the cooling circuit cavity 14. Alternatively, a passageway(s) can be formed in the wall(s) forming the pressure chamber 112 which leads to the pumping chamber 150 from the cooling circuit cavity 14. For example, as shown in the illustrated embodiment a pumping chamber ingress fluid path 160 (stippled line seen in Figure 4A) can be provisioned by at least one axially orientated conduit, such as channel or indentation 160A (seen best in the exploded views) on or in or provisioned as a passageway in an outer circumferential wall 142E of the base 142, at least one radially orientated conduit such as channel or indentation 160B formed on or in or provisioned as a passageway in a toroidally radial wall 142W (seen best in Figure 2A) of the base 142, at least one axially orientated conduit such as channel or indentation 160C (seen best in Figure 2A) on or in or provisioned as a passageway in an inner circumferential wall 142I of the base 142, and at least one opening 160D in a radial top wall 142T of the base 142. Note how the O-ring 136 effectively seals against fluid leakage by seating against two sided, transversely orientated seal surfaces 164A (radially orientated) and 164B (axially orientated) along the flange 134 and against mounting surface 164C (radially orientated), allowing fluid to ingress through the conduits 160A disposed on or in the outer circumferential wall 142E of the pumping chamber enclosure 140 which are located radially inward of the seal surfaces 164A, 164B, and 164C.

[0045] The pressure chamber egress fluid path can likewise be provisioned by any passageway(s) that leads to the cooling circuit cavity 14 from the pumping chamber 150 provided the electronically controlled valve 116 can be functionally disposed therein. For example, the illustrated embodiment shows a pressure chamber egress fluid path 170 (stippled line seen best in Figure 4A) comprising a pumping chamber outlet 170A (seen best in the cross-sectional views of Figures 4A and 4B) that leads to an axially orientated passageway 170B in the base 142. The passageway 170B can interconnect with an orifice 170C in the housing 120 (seen best in the partial cutaway view of the housing shown in Figure 5) that can lead to a first conduit 170D formed in the housing 120 which can terminate at an electronically controlled valve receptacle 170E. The housing 120 can also incorporate a second conduit 170F which can extend between the electronically controlled valve receptacle 170E and an orifice 170G that fluidly connects to the cooling circuit cavity 14 when the SMWP 100 is operationally installed. The electronically controlled valve 116, when installed in the receptacle 170E, can be controlled to fluidly connect the first conduit 170D to the second conduit 170F or to fluidly disconnect the first conduit 170D from the second conduit 170F.

[0046] Advantageously, as shown by the illustrated embodiment of the SMWP 100 and with particular reference to Figure 3, the pressure chamber 112 can be provisioned as a substantially complete subunit 180, comprising the pressure chamber enclosure 140, the secondary pumping element 114, the moveable shutter 106, and the biasing member 148 which can be fastened together by fasteners 182. The subunit 180 can then be mounted as a unitary body to the housing 112 with other fasteners (not shown) through mounting holes 184A, 184B. Advantageously, the subunit 180 incorporates the pressure chamber fluid ingress path 160 and a portion of the pumping chamber egress path 170.

[0047] The illustrated SMWP 100 operates as follows: Assuming the electronically controlled valve 116 is set to fluidly connect the first conduit 170D to the second conduit 170F, the shroud 107 will initially be in the disengaged position, as shown in Figure 4A. The pulley 132 receives rotational power from the engine and rotates the shaft 124, which in turn rotates the impeller 105. In this state the impeller 105 is operative to induce flow in the cooling circuit. As the shaft 124 rotates, the gerotor 152 also rotates, inducing ingress of coolant into the pumping chamber 150 via the pumping chamber ingress fluid path 160 (including along conduits 160A - 160D) into the pumping chamber 150. However, the rotation of the gerotor 152 does not cause pressure to build up in the pressure chamber 112 as the pressure chamber egress fluid path 170 is not occluded. Accordingly, fluid is pumped from the pumping chamber 150 through the pumping chamber egress path 170 (including outlet 170A, passageway 170B, first conduit 170D, second conduit 170F, and orifice 170G) to the cooling circuit cavity 14. In this condition, there is thus insufficient pressure build-up in the pressure chamber 112 and the shroud 107 remains in the disengaged state shown in Figure 4A.

[0048] When the electronically controlled valve 116 is controlled to fluidly disconnect the first conduit 170D from the second conduit 170F, fluid is substantially precluded from being pumped to the cooling circuit cavity 14 from the pumping chamber 150. Accordingly, pressure builds in the pressure chamber 112, including in the region of the toroidal rebate 142R, causing the shroud 107 to translate to the engaged position as shown in Figure 4B to thereby preclude or limit the ability of the impeller 105 to induce flow in the coolant circuit. The pressure, and position of the shroud 107, can be maintained until the electronically controlled valve 116 is set to not occlude the pressure chamber egress fluid path 170.

[0049] Persons skilled in the art will appreciate that numerous modifications and variations may be made to the particular embodiments disclosed herein without departing from the scope of the appended claims.

Examples

Embodiment Construction

[0020]For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well- known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illu...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Application No. 63 / 686,086 filed August 22, 2024.FIELD OF THE DISCLOSURE

[0002] This disclosure relates generally to the field of mechanical water pumps.BACKGROUND

[0003] Automotive internal combustion engines can employ switchable mechanical water pumps (SMWP) driven by belts or chains. The SMWP can be enabled or disabled. For example, the SMWP can be disabled when the engine is first started to preclude or substantially reduce coolant flow to the engine and thus enable faster warm up, which reduces the amount of undesirable combustion gases that are emitted by the engine in comparison to a water pump that is always enabled. Once the engine has warmed up, the SMWP can be enabled to deliver its rated coolant flow.

[0004] Examples of SMWPs are disclosed in, for example, US 10,400,659 to Nidec GPM GmbH and in EP 4,067,665 to Airtex Products. These SMWPs utilize a shutter or shield which translates axially between an engaged position, in which the shutter or shield surrounds a centrifugal style impeller to block or inhibit coolant flow, and a disengaged position, in which the shutter or shield does not surround the impeller thereby not impeding coolant flow. Such SMWPs require secondary pumping systems to build sufficient pressure to translate the shutter or shield. The complexity of such secondary pumping systems can affect the robustness and / or cost of these designs. For example, the Nidec SMWP employs a piston pump that is arranged axially parallel to the main impeller drive shaft, adding complexity and cost to the design. The Airtex SMWP utilizes a collector system driven by the impeller to feed a secondary impeller, also adding complexity and cost.

[0005] It would be desirable to offer an SMWP with an alternative secondary pumping system that may increase the robustness and / or decrease potential manufacturing cost.SUMMARY

[0006] According to the invention, a switchable mechanical waterpump is provided that is suitable for use in an automotive vehicle. The waterpump includes a housing, a primary pumping element, and a mechanical drive subsystem mounted to the housing for rotating the primary pumping element about a rotational axis. An enclosure, connected to the housing, provisions a pressure chamber. A moveable shutter is operatively connected to the pressure chamber, with the shutter being moveable between an engaged position, in which the shutter at least partially covers the primary pumping element to inhibit fluid flow, and a disengaged position, in which the shutter does not cover the primary pumping element so as to not inhibit fluid flow. The pressure chamber has an ingress fluid path and an egress fluid path which fluidly connect the pressure chamber to a cooling circuit when the pump is mounted for operation. At least one of the pressure chamber ingress fluid path and the pressure chamber egress fluid path are occludable, for example, by way of an electronically controlled valve functionally disposed in one of the ingress or egress fluid paths. A secondary pumping element is disposed in the pressure chamber and is operatively connected to the mechanical drive subsystem for generating pressure in the pressure chamber to move the shutter to the engaged position when at least one of the pressure chamber ingress fluid path and the pressure chamber egress fluid path is occluded. The enclosure includes an exterior wall, exposed to the cooling circuit, which includes at least one conduit that provisions a portion of the pressure chamber ingress fluid path.

[0007] According to another aspect, the switchable mechanical waterpump may be realized by featuring a sealing flange on the housing and provisioning an O-ring to seal the housing against a pump mounting surface, such as an engine block, wherein the at least one conduit that provisions a portion of the pressure chamber ingress fluid path is disposed radially inward of the sealing flange.

[0008] The mechanical drive subsystem can include a shaft that is journalled in the housing; the primary pumping element can be an impeller; the secondary pumping element can be a gerotor; and the gerotor can be operatively connected to the shaft via an interruptible connection.

[0009] The gerotor can include an inner rotor and an outer rotor. The interruptible connection can include a drive coupling fixed to the shaft. The drive coupling can have a first set of fingers and the inner gerotor can have a second set of fingers, with the first and second set of fingers being interdigitated, wherein at least one of the first and second sets of fingers is flexible or sacrificial so as to temporarily or permanently disrupt the drive between the shaft and the gerotor above a certain torque level.

[0010] The enclosure can be provisioned by a base and a lid fastened to the base, with the shaft extending through the base and the lid.

[0011] The base can include a circumferential outer wall, a circumferential inner wall and a radial toroidal wall interconnecting the circumferential outer and inner walls so as to form a toroidal rebate into which the moveable shutter is seated.

[0012] A spring can be disposed between the lid and the shutter to bias the shutter to the disengaged position.

[0013] The base can include a radial wall inward of the circumferential inner wall, with the circumferential inner wall, the lid and the radial wall defining a secondary pump chamber in which the gerotor is ensconced.

[0014] The pressure chamber ingress fluid path can include at least one conduit provisioned in or on the base circumferential outer wall, at least one conduit provisioned in or on the base radial toroidal wall, at least one conduit provisioned in or on the base circumferential inner wall, and at least one opening provisioned in the base radial wall.

[0015] The pressure chamber egress fluid path can include a pumping chamber outlet and a passageway formed in the base.

[0016] The pressure chamber egress fluid path can include a first conduit formed in the housing and a second conduit, formed in the housing, and an electronically controlled valve can be functionally disposed between the first and second conduits to selectively occlude the pressure chamber egress fluid path .

[0017] According to another aspect, a switchable mechanical water pump can be provided which includes: a housing; an impeller; a mechanical drive subsystem, including a shaft, mounted to the housing for rotating the impeller about an axis defined by the shaft; an enclosure, connected to the housing, which provisions a pressure chamber; a moveable shutter operatively connected to the pressure chamber, with the shutter being moveable between an engaged position in which the shutter at least partially covers the primary pumping element to inhibit fluid flow, and a disengaged position in which the shutter does not cover the primary pumping element so as to not inhibit fluid flow. When the pump is mounted for operation, the pressure chamber can be fluidly connected to a cooling circuit via a pressure chamber ingress fluid path and a pressure chamber egress fluid path. The pressure chamber egress fluid path can be occluded, for example, by an electrically controlled valve functional disposed within the pressure chamber egress fluid path. A gerotor can be disposed in the pressure chamber and operatively connected to the shaft for generating pressure in the pressure chamber to move the shutter to the engaged position when the pressure chamber egress fluid path is occluded. The enclosure can be provisioned as a subassembly bounded by a base and a lid fastened to the base, wherein the base includes a rebate into which the moveable shutter is seated and the base includes a pumping chamber disposed inward of and fluidly connected to the rebate, with the gerotor being ensconced in the pumping chamber.

[0018] The gerotor can be connected to the shaft via an interruptible connection such as described above. The gerotor and the interruptible connection can be formed from cost-effective plastic, or example, reinforced plastic.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The foregoing and other aspects of the invention will now be described in greater detail, by way of non-limiting example only, with reference to the attached drawings, in which: Figure 1 is a perspective view of a switchable mechanical water pump (SMWP) according to a first embodiment; Figure 2A is an exploded view of the SMWP shown in Figure 1; Figure 2B is another exploded view of the SMWP shown in Figure 1, taken along a view angle opposite to the view angle used in Figure 2A; Figure 3 is an exploded view of a subassembly of the SMWP shown in Figure 1; Figure 4A is cross-sectional view of the SMWP shown in Figure 1, with the SMWP shown mounted against an engine block and in a disengaged position; Figure 4B is cross-sectional view of the SMWP shown in Figure 1, with the SMWP shown mounted against the engine block and in an engaged position; and Figure 5 is a partial isolation, partial cut-away view of the SMWP shown in Figure 1, illustrating certain internal conduits. DESCRIPTION OF EXAMPLE EMBODIMENT(S)

[0020] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well- known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0021] Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: "or" as used throughout is inclusive, as though written "and / or"; singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; "exemplary" should be understood as "illustrative" or "exemplifying" and not necessarily as "preferred" over other embodiments. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description.

[0022] Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, "each" refers to each member of a set or each member of a subset of a set.

[0023] The indefinite article "a" is not intended to be limited to mean "one" of an element. It is intended to mean "one or more" of an element, where applicable, (i.e. unless in the context it would be obvious that only one of the element would be suitable).

[0024] Terms such as "connected to", "fixed to", "bears against" and "supported by" do not mean that a first part has to directly touch or contact a second part in order for the first and second parts to be considered connected together, fixed together, bear against one another, or supported by one or the other, respectively. Unless the context clearly dictates otherwise, two parts may considered connected together, fixed together, bear against one another, or supported by one or the other through one or more intermediate parts which function to bear or transfer loads between the first and second parts.

[0025] Any reference to upper, lower, top, bottom or the like are intended to refer to a relative orientation of a particular element in relation to other elements and not necessarily in absolute terms, or to orientation during manufacture, shipping or use. The upper surface of an element, for example, can still be considered an upper surface in relation to another surface even when the element is lying on its side or upside down.

[0026] Figures 1-5 disclose an example of an embodiment of a switchable mechanical coolant pump (SMWP) 100.

[0027] The SMWP 100 is mountable to a surface which features an opening to an engine cooling circuit. For example, Figures 4A and 4B show the SMWP 100 mounted to an engine block 10 (partially shown) which has a cylindrical opening 12 into a fluid-filled cavity 14 that forms part of an engine cooling circuit. When mounted, a primary pumping element 104 of the SMWP 100 can be disposed in the fluid filled cavity 14. The SMWP 100 can include a housing 120 (see Figs. 2A, 2B) which can be sealed against the mounting surface such as engine block 10. For example, as illustrated, the housing 120 can include a flange 134 for seating the housing 120 against the engine block 10. An O-ring 136 can be installed interiorly adjacent to the flange 134 to seal the housing 120 against the engine block 10 to inhibit coolant leakage.

[0028] Referring to Figure 1, the SMWP 100 includes a mechanical drive subsystem 102 (partially shown in Figure 1) that drives the primary pumping element 104. The primary pumping element 104 can be a centrifugal type impeller 105, as shown, which ingresses fluid in an axial direction A and egresses fluid in a radial direction R. The opposite arrangement is also possible where an impeller can ingress fluid radially and egress fluid axially. Alternative types of primary pumping elements are also possible, such as vaned rotors that ingress and egress fluid radially or axially. In the illustrated embodiment, the impeller 105 rotates about a central axis A-A (see Fig. 4A), which defines the axial direction.

[0029] The SMWP 100 can include a moveable shutter 106 such as a shroud 107 that is movable between a disengaged position, such as seen in Figures 1 and 4A, and an engaged position, such as seen in Figure 4B. In the engaged position the moveable shutter 106 can surround or overlap at least a portion of the primary pumping element 104. For example, in the illustrated embodiment the shroud 107 surrounds a substantial portion of a circumferential extent 105C of the impeller 105, thus blocking or inhibiting the egress (or ingress) of fluid from the impeller 105. In the disengaged position the moveable shutter 106 is retracted from the engaged position so as to substantially not surround or overlap the primary pumping element 104. For example, in the illustrated embodiment the shroud 107 does not surround the circumferential extent 105C of the impeller 105 and thus does not block or inhibit the egress (or ingress, for reverse flow) of fluid from the impeller 105.

[0030] The moveable shutter 106 can be operatively coupled to a pressure subsystem 110 that generates fluid pressure in order to move the shutter 106. Referring additionally to Figures 2A, 2B and 3, as shown in the illustrated embodiment, the pressure subsystem 110 can include a pressure chamber 112, a secondary pumping element 114 disposed within the pressure chamber 112 and operatively connected to the mechanical drive subsystem 102, and an electronically controlled valve 116 that enables or disables an occludeable fluid path to or from the engine cooling circuit such that when the occludeable fluid path is occluded fluid pressure can build in the pressure chamber 112 to move or maintain the shutter 106 in the engaged position and when the occludeable fluid path is not occluded pressure cannot build in the pressure chamber 112 leaving the shutter 106 in a biased state, which can be the disengaged position.

[0031] As seen best in the exploded views of Figures 2A and 2B, the mechanical drive system 102 can include a drive shaft 124 for rotating the primary pumping element 104. For example, as seen in the illustrated embodiment, the housing 120 can include an integrally formed cylindrical tube 122 and a ball, roller or slide bearing 126 can be mounted in the tube 122 with the shaft 124 installed into the bearing 126.

[0032] In other embodiments a bushing (not shown) can be substituted for the bearing 126 or the shaft 124 may be journalled directly in the tube 122.

[0033] Impeller 105 can be fixed to the shaft 124 in any desirable manner. For example, one end 124A of the shaft 124 can be installed into a central bore 105B of the impeller 105. Optionally, the shaft 124 can be installed into a hub 128 that can be mounted in the central bore 105B.

[0034] A mechanical drive element 130 such as a pulley 132 can be fixed to the shaft 124, for example, to an opposite end 124B of the shaft 124 in order to rotate the shaft 124 and the impeller 105. In alternative embodiments other drive elements can be employed such as a gear or gear set driven by a corresponding engine drive element such as a crankshaft or power take-off feature.

[0035] The pressure chamber 112 can be disposed about the shaft 124. For example, as seen in the illustrated embodiment, pressure chamber 112 can be formed by an enclosure 140 provisioned by a base 142 and a lid 144. Alternatively, the pressure chamber 112 can be formed by other arrangements of radial and circumferential walls constituting the enclosure. For example, the housing 120 may be used as one element of the enclosure 140 or indeed provision the entirety of the enclosure defining the pressure chamber 112.

[0036] A shaft seal 146 functions to seal the shaft against leakage of coolant.

[0037] As seen in the illustrated embodiment, the base 142 can include a toroidally shaped rebate 142R (seen best in Figures 2B and 3) formed from inner and outer circumferential walls 142I and 142E, respectively (seen best in Figure 2A).

[0038] As seen in the illustrated embodiment the shroud 107 can be partially disposed in the rebate 142R (seen best in Figures 4A and 4B). More particularly, as seen in Figure 3, the shroud 107 can include a cover section 107C configured to surround the impeller 105 when in the engaged position, and a skirt section 107S which, as seen in Figure 4A, can be fully seated in the rebate 142R when the shroud 107 is in the disengaged position. The skirt section 107C can include a circumferentially arranged ring portion 107F (see Fig. 2A) to cap the pressure chamber 112. Accordingly, the ring portion 107F can be configured to have a decent fit against the inner and outer toroidal walls 142I and 142E. The ring portion 107F can also include an axially flared or concave end portion 107G (see Fig. 4A) configured to substantially evenly receive and distribute force axially and circumferentially arising from pressure build up in the pressure chamber 112.

[0039] A biasing member such as a spring can be employed to bias the shroud 107 in one of the engaged or disengaged positions. For example, a coil spring 148 as shown in the illustrated embodiment can be backstopped against the lid 144 to bias the shroud 107 to the disengaged position.

[0040] The secondary pumping element 114 can be operatively connected to the drive shaft 124 and disposed in the pressure chamber 112, and more particularly, in a pumping chamber 150 (seen best in Figures 2B and Figures 4A, 4B). For example, as shown in the illustrated embodiment the base 142 can include a central opening 1420 (seen best in Figure 2B and 3) inward of the rebate 142R in which the secondary pumping element 114 can be ensconced.

[0041] The secondary pumping element 114 can be any component, such as an impeller or rotor, that induces sufficient pressure within the pressure chamber 112 to move the shutter 106 such as shroud 107 into the engaged position. As shown in the illustrated embodiment the secondary pumping element 114 can be a gerotor 152 that includes an inner rotor 152A and an outer rotor 152B which provide positive displacement pumping action as known in the art per se. The inner rotor 152A can be fixed or otherwise operatively connected to the shaft 124. For example, the inner rotor 152A can be connected to the shaft 124 via an interruptible connection, such as a sacrificial or disrupt-able connection. For example, as shown in the illustrated embodiment a drive coupling 154 (as seen best in the exploded views of Figures 2A, 2B and 3) can be fixed to the shaft 124 and operatively connected to the inner rotor 152A via interdigitated fingers 156A and 156B disposed on the drive coupling 154 and the inner rotor 152A, respectively. One of the fingers 156A and 156B can be made of much harder material than the other such that the softer fingers will break or yield if the gerotor somehow becomes obstructed thus enabling the shaft 124 to continue to rotate whilst leaving the SMWP 100 operational to continue to pump cooling fluid. Alternatively, one or both of the fingers 156A and 156B can be flexible so as to bend or otherwise yield above a predetermined torque level to thereby disrupt the connection between the drive coupling 154 and the inner rotor 152A. Other forms of permanent or temporary interruptible connections are also possible as will be appreciated and understood by persons skilled in the art. For example, the inner rotor 152A can be a sacrificial part by being fixed to the shaft 124 and scored circumferentially to break apart above a pre-determined level of torque.

[0042] Advantageously, the gerotor 152 can be formed from reinforced plastic in an injection molding process. Likewise, the drive coupling 154 can also be formed from plastic, enabling ready manufacture of the interdigitated fingers 156A and 156B.

[0043] The pressure chamber 112 can be fluidly connected to the cooling circuit cavity 14 via a pressure chamber ingress fluid path and a pressure chamber egress fluid path. In the illustrated embodiment the occlude-able fluid path is the pressure chamber egress fluid path.

[0044] The pressure chamber ingress fluid path can be provisioned by any passageway(s) that leads to the pumping chamber 150 from the cooling circuit cavity 14. For example, at least one opening can be provisioned behind the primary pumping element 104 into the pumping chamber 150. Alternatively, a passageway(s) can be provisioned in the housing 120 that leads to the pumping chamber 112 from the cooling circuit cavity 14. Alternatively, a passageway(s) can be formed in the wall(s) forming the pressure chamber 112 which leads to the pumping chamber 150 from the cooling circuit cavity 14. For example, as shown in the illustrated embodiment a pumping chamber ingress fluid path 160 (stippled line seen in Figure 4A) can be provisioned by at least one axially orientated conduit, such as channel or indentation 160A (seen best in the exploded views) on or in or provisioned as a passageway in an outer circumferential wall 142E of the base 142, at least one radially orientated conduit such as channel or indentation 160B formed on or in or provisioned as a passageway in a toroidally radial wall 142W (seen best in Figure 2A) of the base 142, at least one axially orientated conduit such as channel or indentation 160C (seen best in Figure 2A) on or in or provisioned as a passageway in an inner circumferential wall 142I of the base 142, and at least one opening 160D in a radial top wall 142T of the base 142. Note how the O-ring 136 effectively seals against fluid leakage by seating against two sided, transversely orientated seal surfaces 164A (radially orientated) and 164B (axially orientated) along the flange 134 and against mounting surface 164C (radially orientated), allowing fluid to ingress through the conduits 160A disposed on or in the outer circumferential wall 142E of the pumping chamber enclosure 140 which are located radially inward of the seal surfaces 164A, 164B, and 164C.

[0045] The pressure chamber egress fluid path can likewise be provisioned by any passageway(s) that leads to the cooling circuit cavity 14 from the pumping chamber 150 provided the electronically controlled valve 116 can be functionally disposed therein. For example, the illustrated embodiment shows a pressure chamber egress fluid path 170 (stippled line seen best in Figure 4A) comprising a pumping chamber outlet 170A (seen best in the cross-sectional views of Figures 4A and 4B) that leads to an axially orientated passageway 170B in the base 142. The passageway 170B can interconnect with an orifice 170C in the housing 120 (seen best in the partial cutaway view of the housing shown in Figure 5) that can lead to a first conduit 170D formed in the housing 120 which can terminate at an electronically controlled valve receptacle 170E. The housing 120 can also incorporate a second conduit 170F which can extend between the electronically controlled valve receptacle 170E and an orifice 170G that fluidly connects to the cooling circuit cavity 14 when the SMWP 100 is operationally installed. The electronically controlled valve 116, when installed in the receptacle 170E, can be controlled to fluidly connect the first conduit 170D to the second conduit 170F or to fluidly disconnect the first conduit 170D from the second conduit 170F.

[0046] Advantageously, as shown by the illustrated embodiment of the SMWP 100 and with particular reference to Figure 3, the pressure chamber 112 can be provisioned as a substantially complete subunit 180, comprising the pressure chamber enclosure 140, the secondary pumping element 114, the moveable shutter 106, and the biasing member 148 which can be fastened together by fasteners 182. The subunit 180 can then be mounted as a unitary body to the housing 112 with other fasteners (not shown) through mounting holes 184A, 184B. Advantageously, the subunit 180 incorporates the pressure chamber fluid ingress path 160 and a portion of the pumping chamber egress path 170.

[0047] The illustrated SMWP 100 operates as follows: Assuming the electronically controlled valve 116 is set to fluidly connect the first conduit 170D to the second conduit 170F, the shroud 107 will initially be in the disengaged position, as shown in Figure 4A. The pulley 132 receives rotational power from the engine and rotates the shaft 124, which in turn rotates the impeller 105. In this state the impeller 105 is operative to induce flow in the cooling circuit. As the shaft 124 rotates, the gerotor 152 also rotates, inducing ingress of coolant into the pumping chamber 150 via the pumping chamber ingress fluid path 160 (including along conduits 160A - 160D) into the pumping chamber 150. However, the rotation of the gerotor 152 does not cause pressure to build up in the pressure chamber 112 as the pressure chamber egress fluid path 170 is not occluded. Accordingly, fluid is pumped from the pumping chamber 150 through the pumping chamber egress path 170 (including outlet 170A, passageway 170B, first conduit 170D, second conduit 170F, and orifice 170G) to the cooling circuit cavity 14. In this condition, there is thus insufficient pressure build-up in the pressure chamber 112 and the shroud 107 remains in the disengaged state shown in Figure 4A.

[0048] When the electronically controlled valve 116 is controlled to fluidly disconnect the first conduit 170D from the second conduit 170F, fluid is substantially precluded from being pumped to the cooling circuit cavity 14 from the pumping chamber 150. Accordingly, pressure builds in the pressure chamber 112, including in the region of the toroidal rebate 142R, causing the shroud 107 to translate to the engaged position as shown in Figure 4B to thereby preclude or limit the ability of the impeller 105 to induce flow in the coolant circuit. The pressure, and position of the shroud 107, can be maintained until the electronically controlled valve 116 is set to not occlude the pressure chamber egress fluid path 170.

[0049] Persons skilled in the art will appreciate that numerous modifications and variations may be made to the particular embodiments disclosed herein without departing from the scope of the appended claims.

Examples

Embodiment Construction

[0020]For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well- known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illu...

Claims

1. A pump, including: a housing (120); a primary pumping element (104); a mechanical drive subsystem (102) mounted to the housing (120) for rotating the primary pumping element (104) about a rotational axis (A-A); an enclosure (140), connected to the housing (120), which provisions a pressure chamber (112); a moveable shutter (106) operatively connected to the pressure chamber (112), the shutter (106) being moveable between an engaged position, in which the shutter (106) at least partially covers the primary pumping element (104) to inhibit fluid flow, and a disengaged position, in which the shutter (106) does not cover the primary pumping element (104) so as to not inhibit fluid flow; a pressure chamber ingress fluid path (160) and a pressure chamber egress fluid path (170) for fluidly connecting the pressure chamber (112) to a cooling circuit (14) when the pump is mounted for operation, at least one of the pressure chamber ingress fluid path (160) and the pressure chamber egress fluid path (170) being occludable; a secondary pumping element (114) disposed in the pressure chamber (112) and operatively connected to the mechanical drive subsystem (102) for generating pressure in the pressure chamber (112) to move the shutter (106) to the engaged position when at least one of the pressure chamber ingress fluid path (160) and the pressure chamber egress fluid path (170) is occluded; characterized in that the enclosure (140) includes an exterior wall (142E), exposed to the cooling circuit, which includes at least one conduit (160A) that provisions a portion of the pressure chamber ingress fluid path (160).

2. A pump according to claim 1, wherein the housing (120) includes a sealing flange (134) and an O-ring (134) seals the housing (120) against a pump mounting surface (164A), wherein said at least one conduit (160A) is disposed radially inward of the sealing flange (134).

3. A pump according to any of claims 1 - 2, wherein: the mechanical drive subsystem includes a shaft (124) that is journalled in the housing (120); the primary pumping element (104) is an impeller (105); the secondary pumping element is a gerotor (152); and the gerotor (152) is operatively connected to the shaft (124) via an interruptible connection (154).

4. A pump according to claim 3, wherein: the gerotor (152) includes an inner rotor (152A) and an outer rotor (152B); the interruptible connection (154) includes a drive coupling (154) fixed to the shaft (124); and the drive coupling (154) has a first set of fingers (156A) and the inner gerotor has a second set of fingers (156B), the first and second set of fingers (156A, 156B) being interdigitated, and at least one of the first and second sets of fingers (156A, 156B) being flexible or sacrificial so as to temporarily or permanently disrupt the drive between the shaft (124) and the gerotor (152) above a torque level.

5. A pump according to any of claims 3-4, wherein the enclosure (140) is provisioned by a base (142) and a lid (144) fastened to the base, the shaft (124) extending through the base and the lid.

6. A pump according to claims 5, wherein the base (142) includes a circumferential outer wall (142E), a circumferential inner wall (142I) and a radial toroidal wall (142W) interconnecting the circumferential outer and inner walls (142E, 142I) so as to form a toroidal rebate (142R) into which the moveable shutter (106) is seated.

7. A pump according to claim 6, wherein a spring (148) is disposed between the lid (144) and the shutter (106) to bias the shutter (106) to the disengaged position.

8. A pump according to claim 6 or claim 7, wherein: the base (142) includes a radial wall (142T) inward of the circumferential inner wall (142I); and the circumferential inner wall (142I), the lid (144) and the radial wall (142T) define a secondary pump chamber (150) in which the gerotor (152) is ensconced.

9. A pump according to claim 8, wherein the pressure chamber ingress fluid path (160) includes at least one conduit (160A) provisioned in or on the base circumferential outer wall (142E), at least one conduit (160B) provisioned in or on the base radial toroidal wall (142W), at least one conduit (160C) provisioned in or on the base circumferential inner wall (142I), and at least one opening (160D) provisioned in the base radial wall (142T).

10. A pump according to claim 8, wherein the pressure chamber egress fluid path (170) includes including a pumping chamber outlet (170A) and a passageway (170B) formed in the base (142).

11. A pump according to any of the previous claims where the pressure chamber egress fluid path (170) include a first conduit (170D) formed in the housing (120) and a second conduit (170F), formed in the housing (120), and an electronically controlled valve (116) is functionally disposed between the first and second conduits (170D, 170F) to selectively occlude the pressure chamber egress fluid path (170).

12. A switchable mechanical water pump, including: a housing (120); an impeller (105); a mechanical drive subsystem (102), including a shaft (124), mounted to the housing (120) for rotating the impeller (105) about an axis (A-A) defined by the shaft; an enclosure (140), connected to the housing (120), which provisions a pressure chamber (112); a moveable shutter (106) operatively connected to the pressure chamber (112), the shutter (106) being moveable between an engaged position, in which the shutter (106) at least partially covers the primary pumping element (104) to inhibit fluid flow, and a disengaged position, in which the shutter (106) does not cover the primary pumping element (104) so as to not inhibit fluid flow; a pressure chamber ingress fluid path (160) and a pressure chamber egress fluid path (170) for fluidly connecting the pressure chamber (112) to a cooling circuit (14) when the pump is mounted for operation, the pressure chamber egress fluid path (170) being occludable; a gerotor (152) disposed in the pressure chamber (112) and operatively connected to the shaft (124) for generating pressure in the pressure chamber (112) to move the shutter (106) to the engaged position when the pressure chamber egress fluid path (170) is occluded; characterized in that the enclosure (140) is provisioned as a subassembly bounded by a base (142) and a lid (144) fastened to the base, wherein the base (142) includes a rebate (142R) into which the moveable shutter (106) is seated and the base (142) includes a pumping chamber (150) disposed inward of and fluidly connected to the rebate (142R), the gerotor (152) being ensconced in the pumping chamber (150).

13. A pump according to claim 12, wherein the gerotor (152) is connected to the shaft (124) via an interruptible connection (154).

14. A pump according to claim 13, wherein the gerotor (152) and the interruptible connection (154) are formed from plastic.

15. A pump according to claim 13 or 14, wherein: the gerotor (152) includes an inner rotor (152A) and an outer rotor (152B); the interruptible connection (154) includes a drive coupling (154) fixed to the shaft (124); and the drive coupling (154) has a first set of fingers (156A) and the inner gerotor has a second set of fingers (156B), the first and second set of fingers (156A, 156B) being interdigitated, and at least one of the first and second sets of fingers (156A, 156B) being flexible or sacrificial so as to temporarily or permanently disrupt the drive between the shaft (124) and the gerotor (152) above a torque level.

Images