GB2571985A

GB2571985A - Vehicle engine cooling

Info

Publication number: GB2571985A
Application number: GB1804181.4A
Authority: GB
Inventors: August Albrecht Matthew
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2018-03-15
Filing date: 2018-03-15
Publication date: 2019-09-18
Anticipated expiration: 2038-03-15
Also published as: GB201804181D0; GB2571985B

Abstract

A vehicle engine coolant pump 100 comprises a housing 4. Coolant flows through an inlet 6 towards an eye 22 of a rotatable impeller 2 and is ejected through an outlet 8. A flow restrictor comprises a cylindrical shroud 110 surrounding a circumference of the impeller, and a back flow sealing plate 12 on an opposite side of the eye of the impeller. The shroud is movable in a direction of the axis of rotation of the impeller from a closed position restricting coolant flow from inlet to outlet and an open position allowing coolant flow from inlet to outlet. The flow restrictor has at least one aperture 115 which allows a restricted flow of coolant from inlet to outlet when the shroud is in the closed position. The apertures may be castellations in the shroud 110, or may be holes (215, Fig. 5D) in the sealing plate 12 with associated valves (218, Fig. 5D) operable between open and closed positions. A vehicle engine cooling system, a vehicle comprising a vehicle engine cooling system, and a method of cooling a vehicle engine are also claimed.

Description

(57) A vehicle engine coolant pump 100 comprises a housing 4. Coolant flows through an inlet 6 towards an eye 22 of a rotatable impeller 2 and is ejected through an outlet 8. A flow restrictor comprises a cylindrical shroud 110 surrounding a circumference of the impeller, and a back flow sealing plate 12 on an opposite side of the eye of the impeller. The shroud is movable in a direction of the axis of rotation of the impeller from a closed position restricting coolant flow from inlet to outlet and an open position allowing coolant flow from inlet to outlet. The flow restrictor has at least one aperture 115 which allows a restricted flow of coolant from inlet to outlet when the shroud is in the closed position. The apertures may be castellations in the shroud 110, or may be holes (215, Fig. 5D) in the sealing plate 12 with associated valves (218, Fig. 5D) operable between open and closed positions. A vehicle engine cooling system, a vehicle comprising a vehicle engine cooling system, and a method of cooling a vehicle engine are also claimed.

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VEHICLE ENGINE COOLING

TECHNICAL FIELD

The present disclosure relates to a vehicle engine coolant pump, a vehicle engine cooling system, a vehicle comprising such a vehicle engine cooling pump or system, and a method of cooling a vehicle engine. In particular, it relates to a vehicle engine coolant pump comprising an impeller which can be driven to rotate by revolutions of the vehicle engine, as well as to systems, methods and vehicles comprising such a pump.

BACKGROUND

Vehicle engine coolant pumps are designed to pump a coolant, usually in a closed loop, around a vehicle engine. The coolant is typically a mixture of water and anti-freeze. It is common in the art for an impeller of a vehicle engine coolant pump to be driven to rotate directly from the engine which the pump is designed to cool, for example via a belt from a crankshaft of the engine to a driveshaft of the impeller. This has the advantage that as the rate of revolution of the engine increases, which therefore also tends to increase the temperature of the engine, the rate of rotation of the impeller, and hence also the rate of flow of engine coolant through the pump and thus also the flow rate of coolant around the engine from the pump both increase proportionally. However, this straightforward proportional relationship between engine temperature and flow rate of coolant generally only applies when the engine has already been running for some time, after a “warm-up” period, during which time oil which is used to lubricate the engine must firstly reach its correct operating temperature range and viscosity after the engine has been switched on.

It is undesirable for the engine to be cooled when the engine is still in its “warm-up” period, since this would delay the lubricating oil from reaching its correct operating temperature range and viscosity. Reducing the flow of coolant through the pump to zero during this period can therefore provide fuel efficiency gains of up to about 30%. On the other hand, since the pump’s impeller has traditionally been driven to rotate directly from the engine which the pump is designed to cool, it is not mechanically straightforward just to disconnect the driveshaft of the pump from the crankshaft of the engine in order to switch the pump off when the engine is still in its “warm-up” period and to reconnect the pump driveshaft to the engine crankshaft to switch the pump on only once the lubricating oil has reached its correct operating temperature range and viscosity, without introducing excessive complication into the simple mechanical connection between the pump driveshaft and the engine crankshaft, which would have associated negative implications in both reliability and cost.

One solution to this problem has therefore been to keep the pump’s impeller running at all times that the engine is running by keeping the pump’s driveshaft permanently connected to the engine’s crankshaft, but to occlude the flow of coolant through the pump in some way. One way in which the flow of coolant through the pump has been occluded in the prior art is by surrounding a circumference of the impeller with a cylindrical shroud within the pump housing. This shroud is movable relative to the impeller and to the pump housing in a direction of the axis of rotation of the impeller between a first, closed position, in which the shroud prevents the flow of coolant from an inlet for the coolant into the pump housing to an outlet for the coolant from the pump housing, and a second, open position, which instead allows the flow of coolant from the inlet to the outlet. This shroud can be actuated to move between these two positions by any of hydraulic, mechanical or electromechanical means, under the control of a cooling system controller.

Occluding the flow of coolant through the pump in this way reduces the flow of coolant through the pump to zero and therefore allows the lubricating oil to reach its correct operating temperature range and viscosity more quickly. However, keeping the pump’s impeller running at all times that the engine is running when the shroud is in its first, closed position forces the impeller to do work against the shroud, which adversely affects fuel efficiency. Moreover, with improvements in engine design and engine lubrication oil, engine “warm-up” periods have become shorter. This is also reflected by planned changes in the official test drive cycle which is used to measure vehicle emissions. The New European Driving Cycle (NEDC - also referred to as the MVEG (Motor Vehicle Emissions Group) drive cycle) is a driving cycle, which was last updated in 1997 and which is designed to assess the exhaust emission levels and fuel economy of engines in passenger cars. The NEDC has a relatively long “warm-up” period. However, the NEDC is soon due to be replaced by the World Light Vehicle Test Procedure (WLTP), which is intended to reflect real-world driving conditions more accurately than the NEDC, and which also has a shorter “warm-up” period. The benefits to be obtained from reducing coolant flow through a vehicle engine coolant pump to zero during the engine “warm-up” period are therefore also correspondingly less.

It would be most desirable to be able to control the flow of coolant through the pump in a continuously variable manner, instead of simply switching the flow on and off in the manner of the prior art. However, such a continuously variable coolant flow rate would be complex and expensive to engineer and difficult to control with closed-loop control, for little efficiency gain. The present invention has been conceived against this background.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a vehicle engine coolant pump, a vehicle engine cooling system, a vehicle comprising such a pump and such a vehicle engine cooling system, and a method of cooling a vehicle engine, as claimed in the appended claims.

According to an aspect of the invention, there is provided a vehicle engine coolant pump comprising: an impeller; a pump housing containing the impeller and having an inlet for admitting coolant towards an eye of the impeller and an outlet for coolant ejected by the impeller; a flow restrictor, comprising a cylindrical shroud able to surround a circumference of the impeller within the pump housing, and a back-flow sealing plate located on an opposite side of the impeller from the eye of the impeller. The impeller is rotatable within the pump housing to pump coolant from the inlet to the outlet. The shroud is movable relative to the impeller and to the pump housing in a direction of the axis of rotation of the impeller from a closed position restricting flow of coolant from the inlet to the outlet to an open position allowing flow of coolant from the inlet to the outlet. The flow restrictor has at least one aperture formed therein to allow restricted flow of coolant from the inlet to the outlet when the shroud is in its closed position.

The flow restrictor, therefore, provides a “cup”, in which the impeller can be contained, with the eye of the impeller exposed to an interior of the pump housing by the mouth of the cup. The impeller can be driven to rotate within the cup by a drive shaft passing through a sealed hole in the centre of the back-flow sealing plate. This cup, however, is “leaky” because the flow restrictor has at least one aperture formed therein to allow restricted flow of coolant from the inlet to the outlet of the pump housing, even when the shroud is in its closed position. This provides the advantage that if the impeller is running and the shroud is in its closed position, the impeller is not forced to work so hard against the closed shroud, which can be used to improve fuel efficiency during engine “warm-up” periods. In fact, there is a trade-off between the reduction in fuel consumption provided by decreasing the “warm-up” time of the engine and the increase in fuel consumption resulting from operating the pump when the shroud in its closed position. However, a net reduction in fuel consumption can be obtained over some drive cycles by allowing the pump to provide a restricted flow of cooling fluid to the engine during the engine “warm-up” period. The point at which the best net reduction in fuel consumption is obtained can be determined empirically for any given engine and design of pump.

The at least one aperture may be formed in at least one of the shroud and the back-flow sealing plate. Alternatively, the aperture in the flow restrictor may be a gap between the cylindrical shroud and the back-flow sealing plate. For example, the external circumference of the plate may be less than the internal circumference of the shroud, thereby providing an annular gap in a radial direction. This annular gap may be sufficient to prevent or at least reduce any restriction on relative movement between the shroud and the sealing plate, but small enough so as to inhibit fluid flow there-through. Alternatively (or additionally), when the shroud is in its closed position there may be a separation between the cylindrical shroud and the back-flow sealing plate in an axial direction. It will be appreciated that a gap between the cylindrical shroud and the back-flow sealing plate may in some cases be provided in addition to apertures in the shroud and/or the back-flow sealing plate.

The back-flow sealing plate may be fixed to and movable with the shroud in the direction of the axis of rotation of the impeller. Alternatively, the back-flow sealing plate may instead be separate from the shroud and remain unmoved relative to the impeller when the shroud moves in the direction of the axis of rotation of the impeller, with the back-flow sealing plate remaining contained within the cylindrical shroud as it moves from its open to its closed position, and the circumference of the back-flow sealing plate touches or approaches an inner surface of the shroud.

In embodiments, for the same rate of rotation of the impeller, the rate of flow of coolant when the shroud is in the closed position may be between 10% and 50% of the rate of flow of coolant when the shroud is in the open position.

The at least one aperture may comprise one or more castellations. In such an embodiment, the castellations may be provided on the rim of the shroud closest to the inlet.

Alternatively or additionally, the at least one aperture may comprise one or more throughholes in the back-flow sealing plate.

If so, at least one of the one or more through-holes in the back-flow sealing plate may have associated with it a respective valve operable between a closed position and an open position when the shroud is in its closed position.

If so, for the same rate of rotation of the impeller, the rate of flow of coolant from the inlet to the outlet of the pump housing when the one or more valves are in their closed position and the shroud is in its closed position may be between 40% and 60% of the rate of flow of coolant from the inlet to the outlet of the pump housing when the one or more valves are in their open position and the shroud is in its closed position.

The one or more valves may be resiliently biassed towards their closed position, for example by being spring-loaded.

In another aspect, there is provided a vehicle engine cooling system comprising a vehicle engine coolant pump as described herein and a temperature sensor for determining a temperature of an engine around which coolant is circulated by the pump, wherein the shroud is arranged to move between its open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor.

If the pump contains one or more valves, the one or more valves may be arranged to move between their open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor.

In order to determine the temperature of the engine, the temperature sensor may be positioned either to measure the temperature of coolant circulated around the engine by the pump either before the coolant arrives at the engine or after the coolant leaves the engine, or to measure the temperature of exhaust gas from the engine recirculated to the engine.

The vehicle engine cooling system may further comprise a cooling system controller configured to control movement of the shroud between its open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor using either open or closed loop control.

If the pump contains one or more valves, the cooling system controller may be configured to control movement of the one or more valves between their open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor using either open or closed loop control.

In further aspects, the invention also provides a vehicle comprising a vehicle engine coolant pump as described herein and a vehicle comprising a vehicle engine cooling system as described herein.

According to yet another aspect of the invention, there is provided a method of cooling a vehicle engine, the method comprising pumping coolant around the engine with a pump as described herein by driving rotation of the impeller from revolutions of the engine, determining a temperature of the engine, and moving the shroud between its open and closed positions in dependence on the temperature of the engine.

If the pump contains one or more valves, the method may comprise moving the one or more valves between their open and closed positions in dependence on the temperature of the engine.

The temperature of the engine may be determined by measuring the temperature of coolant circulated around the engine by the pump either before the coolant arrives at the engine or after the coolant leaves the engine, or by measuring the temperature of exhaust gas from the engine recirculated to the engine.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1A is a schematic longitudinal cross-sectional view of a vehicle engine coolant pump of the prior art in a first state;

Fig. 1B is a schematic longitudinal cross-sectional view of the vehicle engine coolant pump of Fig. 1A in a second state;

Fig. 1C is a schematic skeleton isometric view of a shroud and a back-flow sealing plate of the vehicle engine coolant pump of Figs. 1A and 1B;

Fig. 2A is a schematic longitudinal cross-sectional view of an embodiment of a vehicle engine coolant pump in a first state;

Fig. 2B is a schematic longitudinal cross-sectional view of the vehicle engine coolant pump of Fig. 2A in a second state;

Fig. 2C is a schematic skeleton isometric view of a shroud and a back-flow sealing plate of the vehicle engine coolant pump of Figs. 2A and 2B;

Fig. 3A is a schematic longitudinal cross-sectional view of another embodiment of a vehicle engine coolant pump in a first state;

Fig. 3B is a schematic longitudinal cross-sectional view of the vehicle engine coolant pump of Fig. 3A in a second state;

Fig. 3C is a schematic skeleton isometric view of a shroud and a back-flow sealing plate of the vehicle engine coolant pump of Figs. 3A and 3B;

Fig. 4A is a schematic longitudinal cross-sectional view of a further embodiment of a vehicle engine coolant pump in a first state;

Fig. 4B is a schematic longitudinal cross-sectional view of the vehicle engine coolant pump of Fig. 4A in a second state;

Fig. 4C is a schematic skeleton isometric view of a shroud and a back-flow sealing plate of the vehicle engine coolant pump of Figs. 4A and 4B;

Fig. 5A is a schematic longitudinal cross-sectional view of yet another embodiment of a vehicle engine coolant pump in a first state;

Fig. 5B is a schematic longitudinal cross-sectional view of the vehicle engine coolant pump of Fig. 5A in a second state;

Fig. 5C is a schematic longitudinal cross-sectional view of the vehicle engine coolant pump of Fig. 5A in a third state;

Fig. 5D is a schematic skeleton isometric view of a shroud, a back-flow sealing plate and valves of the vehicle engine coolant pump of Figs. 5A, 5B and 5C;

Fig. 6 is a schematic diagram of an embodiment of a vehicle engine cooling system comprising a vehicle engine coolant pump such as any of those shown in Figs. 2A to 5D;

Fig. 7 is a schematic perspective view of an embodiment of a vehicle comprising a vehicle engine cooling system such as that shown in Fig. 6;

Fig. 8 is a flow diagram schematically representing an embodiment of a method of cooling a vehicle engine; and

Fig. 9 is a flow diagram schematically representing another embodiment of a method of cooling a vehicle engine.

DETAILED DESCRIPTION

Fig. 1A schematically shows a vehicle engine coolant pump 1 of the prior art. The pump 1 comprises an impeller 2, a pump housing 4, a cylindrical shroud 10, and a back-flow sealing plate 12. The cylindrical shroud 10 and the back-flow sealing plate 12 are integrally formed. The pump housing 4 contains the impeller 2 and has an inlet 6 for admitting coolant towards an eye 22 of the impeller 2 and an outlet 8 for coolant ejected by the impeller 2. The impeller 2 is rotatable within the pump housing 4 to pump coolant from the inlet 6 to the outlet 8. The cylindrical shroud 10 can surround a circumference of the impeller 2 within the pump housing 4. The shroud 10 has the form of a hollow cylinder, open at one end. The back-flow sealing plate 12 is located across the other end of the cylindrical shroud 10 on an opposite side of the impeller 2 from the eye 22 thereof and has the form of a disc.

The shroud 10 and the back-flow sealing plate 12 are movable relative to the impeller 2 and to the pump housing 4 in a direction A-A’ of the axis of rotation of the impeller 2 from a closed position preventing flow of coolant from the inlet 6 to the outlet 8 to an open position allowing flow of coolant from the inlet 6 to the outlet 8. Fig. 1A shows the shroud 10 in its open position, whereas Fig. 1B shows the shroud 10 in its closed position.

The impeller 2 is driven to rotate by a driveshaft 14, which passes through the pump housing 4, as well as through a through-hole 124 formed in the centre of back-flow sealing plate 12, as is more readily visible in the isometric view of Fig. 1C. The point of entry of the driveshaft 14 to the interior of the pump housing 4, as well as the driveshaft through-hole 124 in the back-flow sealing plate 12 are both sealed against leaks of coolant, for example by rubber gaskets and/or O-rings, not shown in Figs. 1A to 1C. The back-flow sealing plate 12 has a circumference 102, which is joined to an inner surface of the shroud 10. An inner surface of the pump housing 4 which comes into contact with the shroud 10 when the shroud 10 is in the closed position thereof (in other words, the position shown in Fig. 1B) is also provided with a seat, also not shown in the figures, which seals the shroud 10 against the inner surface of the pump housing 4 when in this position. Other conventional pump elements, such as bearings for the driveshaft 14, vanes on the impeller 2 and so on, have also been omitted from the schematic views of Figs. 1A to 1C for improved clarity and ease of representation. The elements of the pump 1 represented in Fig. 1C have also all been shown in skeleton outline, as if they were all made of a transparent material, for improved clarity and ease of representation. In practice, however, the shroud 10 and the back-flow sealing plate 12 would most likely be opaque.

Fig. 2A schematically shows an embodiment of a vehicle engine coolant pump 100. Like the pump 1 of Figs. 1A to 1C, the pump 100 comprises an impeller 2, a pump housing 4, and a back-flow sealing plate 12. As before, the pump housing 4 contains the impeller 2 and has an inlet 6 for admitting coolant towards an eye 22 of the impeller 2 and an outlet 8 for coolant ejected by the impeller 2. However, instead of cylindrical shroud 10, the pump 100 comprises a cylindrical shroud 110. Like the shroud 10 in the pump 1 of Figs. 1A to 1C, the cylindrical shroud 110 can surround a circumference of the impeller 2 within the pump housing 4 and also has the form of a hollow cylinder, open at one end. As before, the impeller 2 is also rotatable within the pump housing 4 to pump coolant from the inlet 6 to the outlet 8. Also as before, the back-flow sealing plate 12 is located across the other end of the cylindrical shroud 110 on an opposite side of the impeller 2 from the eye 22 and has the form of a disc. However, in this embodiment, the cylindrical shroud 110 additionally comprises a plurality of castellations 115 on a rim of the shroud 110 on the same side of the impeller 2 as the eye 22.

The shroud 110 and the back-flow sealing plate 12 are movable relative to the impeller 2 and to the pump housing 4 in a direction A-A’ of the axis of rotation of the impeller 2 from a closed position restricting flow of coolant from the inlet 6 to the outlet 8 to an open position allowing flow of coolant from the inlet 6 to the outlet 8. Fig. 2A shows the shroud 110 in its open position, whereas Fig. 2B shows the shroud 110 in its closed position. However, as may be seen from Fig. 2B, when the shroud 110 is in the closed position thereof, coolant is still able to leak from the inlet 6 to the outlet 8 through the castellations 115 in the manner indicated by the dashed line and arrow shown in Fig. 2B. Thus, the castellations 115 provide apertures in the shroud 110, which allow restricted flow of coolant from the inlet 6 to the outlet 8 when the shroud 110 is in its closed position. The size, shape and number of the castellations 115, as well as their spacing around the rim of the shroud 110, may all be varied according to design requirements, in order to vary the flow rate and flow path, pattern of turbulence and other parameters of the flow of coolant from the inlet 6 to the outlet 8 when the shroud 110 is in its closed position. Thus, for example, the rate of restricted flow of coolant when the shroud 110 is in its closed position can be adjusted to be between about 10% and about 50%, for example about 30%, of the rate of flow of coolant when the shroud 110 is in its open position, at the same rate of rotation of the impeller 2 in each case, just by varying the size, shape and number of the castellations 115.

As in the case of the pump 1 of Figs. 1A to 1C, the impeller 2 of the pump 100 shown in Figs. 2A and 2B is also driven to rotate by a driveshaft 14, which passes through the pump housing 4, as well as through a through-hole 124 formed in the centre of back-flow sealing plate 12, as is more readily visible in the isometric view of Fig. 2C. The point of entry of the drive shaft 14 to the interior of the pump housing 4 is sealed against leaks of coolant, for example by rubber gaskets and/or O-rings, not shown in Figs. 2A and 2B. Other conventional pump elements, such as bearings for the driveshaft 14, vanes on the impeller 2 and so on, have also been omitted from the schematic views of Figs. 2A to 2C for improved ease of representation. However, in this embodiment, in view of the castellations 115 on a circular end of the shroud 110, there is no need to seal the shroud 110 against the inner surface of the pump housing 4 when the shroud 110 is in its closed position (in other words, the position shown in Fig. 2B). For the same reason, there is no need to seal the driveshaft through-hole 124 formed in the centre of the back-flow sealing plate 12. This has the advantage of improving the reliability and lowering the manufacturing cost of the pump 100 in comparison to the pump 1.

Fig. 3A schematically shows another embodiment of a vehicle engine coolant pump 200. Like the pump 1 of Figs. 1A to 1C, the pump 200 comprises an impeller 2, a pump housing 4, and a cylindrical shroud 10. As before, the pump housing 4 contains the impeller 2 and has an inlet 6 for admitting coolant towards an eye 22 of the impeller 2 and an outlet 8 for coolant ejected by the impeller 2. The impeller 2 is rotatable within the pump housing 4 to pump coolant from the inlet 6 to the outlet 8. The cylindrical shroud 10 can surrounds a circumference of the impeller 2 within the pump housing 4. The shroud 10 has the form of a hollow cylinder, open at one end. However, instead of back-flow sealing plate 12, the pump 200 comprises a back-flow sealing plate 212. As before, the back-flow sealing plate 212 is located across the other end of the cylindrical shroud 10 on an opposite side of the impeller 2 from the eye 22 and has the form of a disc. However, in this embodiment, the back-flow sealing plate 212 additionally comprises a plurality of through-holes 215 formed in the backflow sealing plate 212.

The shroud 10 and the back-flow sealing plate 12 are movable relative to the impeller 2 and to the pump housing 4 in a direction A-A’ of the axis of rotation of the impeller 2 from a closed position restricting flow of coolant from the inlet 6 to the outlet 8 to an open position allowing flow of coolant from the inlet 6 to the outlet 8. Fig. 3A shows the shroud 10 in its open position, whereas Fig. 3B shows the shroud 10 in its closed position. However, as may be seen from Fig. 3B, when the shroud 10 is in its closed position, coolant is still able to leak from the inlet 6 to the outlet 8 through the through-holes 215 formed in the back-flow sealing plate 212 in the manner indicated by the dashed line and arrow shown in Fig. 3B. Thus, the through-holes 215 provide apertures in the back-flow sealing plate 212, which allow restricted flow of coolant from the inlet 6 to the outlet 8 when the shroud 10 is in its closed position. The size, shape and number of the through-holes 215, as well as their pattern on the back-flow sealing plate 212, may all be varied according to design requirements, in order to vary the flow rate and flow path, pattern of turbulence and other parameters of the flow of coolant from the inlet 6 to the outlet 8 when the shroud 10 is in its closed position. Thus, for example, the rate of restricted flow of coolant when the shroud 10 is in its closed position can be adjusted to be between about 10% and about 50%, for example about 30%, of the rate of flow of coolant when the shroud 10 is in its open position, at the same rate of rotation of the impeller 2 in each case, just by varying the size, shape and number of the throughholes 215 formed in the back-flow sealing plate 212.

As in the case of the pumps 1 and 100 shown in Figs. 1A to 2C, the impeller 2 of the pump 200 shown in Figs. 3A and 3B is also driven to rotate by a driveshaft 14, which passes through the pump housing 4, as well as through a further through-hole 224 formed in the centre of back-flow sealing plate 212, as is more readily visible in the isometric view of Fig. 3C. The point of entry of the drive shaft 14 to the interior of the pump housing 4 is sealed against leaks of coolant, for example by rubber gaskets and/or O-rings, not shown in Figs. 3A and 3B. Other conventional pump elements, such as bearings for the driveshaft 14, vanes on the impeller 2 and so on, have also been omitted from the schematic views of Figs.

3A to 3C for improved ease of representation. However, in this embodiment, in view of the through-holes 215 formed in the back-flow sealing plate 212, there is no need to seal the driveshaft through-hole 224 formed in the centre of back-flow sealing plate 212. For the same reason, there is no need to seal the shroud 10 against the inner surface of the pump housing 4 when the shroud 10 is in its closed position (in other words, the position shown in Fig. 3B). This has the advantage of improving the reliability and lowering the manufacturing cost of the pump 200 in comparison to the pump 1.

Fig. 4A schematically shows a further embodiment of a vehicle engine coolant pump 300. This embodiment combines some of the features of the first and second embodiments described above. Thus, the pump 300 comprises an impeller 2 and a pump housing 4 like the pump 1 shown in Figs. 1A to 1C. However, the pump 300 also comprises a shroud 110 like the pump 100 shown in Figs. 2A to 2C and a back-flow sealing plate 212 like the pump 200 shown in Figs. 3A to 3C. The shroud 110 and the back-flow sealing plate 212 in this third embodiment are constructed and function just as their respective counterparts in the first and second embodiments do. Thus, the shroud 110 and the back-flow sealing plate 212 of the pump 300 are movable relative to the impeller 2 and to the pump housing 4 in a direction A-A’ of the axis of rotation of the impeller 2 from a closed position restricting flow of coolant from the inlet 6 to the outlet 8 to an open position allowing flow of coolant from the inlet 6 to the outlet 8. Fig. 4A shows the shroud 110 in its open position, whereas Fig. 4B shows the shroud 110 in its closed position.

As may be seen from Fig. 4B, when the shroud 110 is in its closed position, coolant is still able to leak from the inlet 6 to the outlet 8 through the castellations 115 on the end of the shroud 110 and through the through-holes 215 formed in the back-flow sealing plate 212, in the manner indicated by the two dashed lines and arrows shown in Fig. 4B. Thus, the castellations 115 and the through-holes 215 respectively provide apertures in the shroud 110 and in the back-flow sealing plate 212, which allow restricted flow of coolant from the inlet 6 to the outlet 8 when the shroud 10 is in its closed position. The size, shape and number of the castellations 115 and of the through-holes 215, as well as their respective spacings and patterns, may all be varied according to design requirements, in order to vary the flow rate and flow path, pattern of turbulence and other parameters of the flow of coolant from the inlet 6 to the outlet 8 when the shroud 110 is in its closed position. Thus, for example, the rate of partial flow of coolant when the shroud 10 is in its closed position can be adjusted to be between about 20% and about 80%, for example about 50%, of the rate of flow of coolant when the shroud 110 is in its open position, at the same rate of rotation of the impeller 2 in each case, just by varying the size, shape, number and configuration of the castellations 115 and of the through-holes 215.

As in the case of the pumps 1, 100 and 200 shown in Figs. 1A to 3C, the impeller 2 of the pump 300 shown in Figs. 4A and 4B is also driven to rotate by a driveshaft 14, which passes through the pump housing 4, as well as through a further through-hole 224 formed in the centre of back-flow sealing plate 212, as is more readily visible in the isometric view of Fig. 4C. The point of entry of the drive shaft 14 to the interior of the pump housing 4 is sealed against leaks of coolant, for example by rubber gaskets and/or O-rings, not shown in Figs. 4A and 4B. Other conventional pump elements, such as bearings for the driveshaft 14, vanes on the impeller 2 and so on, have also been omitted from the schematic views of Figs. 4A to 4C for improved ease of representation. However, in this embodiment, in view of the castellations 115 on the end of the shroud 110 as well as of the through-holes 215 in the back-flow sealing plate 212, there is no need to seal the driveshaft through-hole 224 in the centre of back-flow sealing plate 212. For the same reason, there is no need to seal the end of the shroud 110 against the inner surface of the pump housing 4 when the shroud 110 is in its closed position (in other words, the position shown in Fig. 4B). This has the advantage of improving the reliability and lowering the manufacturing cost of the pump 300 in comparison to the pump 1.

Fig. 5A schematically shows yet another embodiment of a vehicle engine coolant pump 400. This embodiment exhibits all the same features as the embodiment described above in relation to Figs. 4A to 4C, but has the additional feature that each of the through-holes 215 formed in the back-flow sealing plate 212 has a respective valve 218 operable between a closed position and an open position thereof when the shroud 110 is in its closed position. When the shroud 110 is in its open position, shown in Fig. 5A, these valves 218 may be in either their closed or their open position, and their respective positions will have little or no effect on the flow of coolant through the pump 400. However, when the shroud 110 is in its closed position, shown in both Figs. 5B and 5C, the valves 218 serve to open and close the through-holes 215 formed in the back-flow sealing plate 212. Fig. 5B shows the valves 218 in their closed position, whereas Fig. 5C shows the valves 218 in their open position. When the valves 218 are in their closed position, coolant is only able to leak from the inlet 6 to the outlet 8 through the castellations 115 on the rim of the shroud 110, in the manner indicated by the dashed line and arrow shown in Fig. 5B. Thus, when the valves 218 are in their closed position, only the castellations 115 provide apertures allowing restricted flow of coolant from the inlet 6 to the outlet 8 when the shroud 110 is in its closed position. However, when the valves 218 are in their open position, coolant can also leak from the inlet to the outlet 8 through the through-holes 215 formed in the back-flow sealing plate 212. Thus, when the valves 218 are in their open position, both the castellations 115 and the through-holes 215 provide apertures allowing restricted flow of coolant from the inlet 6 to the outlet 8 via two different routes, in the manner indicated by the two dashed lines and arrows shown in Fig. 5C.

In this way, the rate of flow of coolant through the pump 400 can be switched between any one of three different possible values: full flow corresponding to the configuration of the pump 400 shown in Fig. 5A, restricted flow at a first rate, which is determined by the size, shape, number and configuration of the castellations 115 on the rim of the shroud 110, as shown in Fig. 5B, and restricted flow at a second, higher rate, which is determined not only by the size, shape number and configuration of the castellations 115, but also by the size, shape, number and configuration of the through-holes 215 formed in the back-flow sealing plate 212. For example, the first rate of restricted flow of coolant when the shroud 110 is in its closed position and the valves 218 are also in their closed position, can be adjusted to be between about 20% and about 40%, for example about 30%, of the rate of flow of coolant when the shroud 110 is in its open position, and the second, higher rate of restricted flow of coolant when the shroud 110 is in its closed position but the valves 218 are in their open position, can be adjusted to be between about 40% and about 80%, for example about 60%, of the rate of flow of coolant when the shroud 110 is in its open position, at the same rate of rotation of the impeller 2 in each case. Typically, the rate of restricted flow of coolant from the inlet 6 to the outlet 8 of the pump housing 4 when the valves 218 are closed and the shroud 110 is in its closed position can thus be selected to be between about 30% and about 70%, for example about 50%, of the rate of restricted flow of coolant from the inlet 6 to the outlet 8 of the pump housing 4 when the valves 218 are open and the shroud 110 is in its closed position, at the same rate of rotation of the impeller in each case.

Fig. 5D schematically shows an isometric view of the shroud 110, back-flow sealing plate 212, and valves 218 when the valves 218 are in their open position. However, for improved clarity and ease of representation, no means for actuating the valves 218 between their open and closed positions have been shown in Fig. 5D, even though such actuation means are nonetheless required to operate the valves 218. For example, the valves 218 may be spring-loaded to their closed position and actuated to move to their open positions by any of hydraulic, mechanical or electromechanical means.

Whereas in all of the embodiments of a vehicle engine coolant pump shown in Figs. 2A to 5D, the back-flow sealing plate 12, 212 is fixed to and movable with the shroud 10, 110 in the direction A-A’ of the axis of rotation of the impeller 2, in alternative possible embodiments, the back-flow sealing plate may instead be separate from the shroud 10, 110 and remain unmoved relative to the impeller 2 when the shroud moves in the direction A-A’ of the axis of rotation of the impeller 2, provided that the back-flow sealing plate 12, 212 remains contained within the cylindrical shroud 10, 110 as it moves from its open to its closed position with the circumference 102, 202 of the back-flow sealing plate 12, 212 touching an inner surface of the shroud 10, 110.

Fig. 6 schematically shows an embodiment of a vehicle engine cooling system 50 comprising a vehicle engine coolant pump 500, such as any of those shown in Figs. 2A to 5D and described above. The vehicle engine cooling system 50 therefore comprises a vehicle engine coolant pump 500 and a temperature sensor 52 for determining a temperature of an engine 60 around which coolant is circulated by the pump 500. The engine 60 has an exhaust duct 62, from which exhaust gas from the engine 60 is recirculated back to the engine via a recirculation duct 64. In order to determine the temperature of the engine 60, the temperature sensor 52 may be positioned at any of the locations X, Y and Z represented in Fig. 6, either to measure the temperature of coolant circulated around the engine 60 by the pump 500 either before the coolant arrives at the engine 60 or after the coolant leaves the engine 60, or to measure the temperature of exhaust gas from the engine recirculated to the engine 60 via recirculation duct 64. The shroud of the pump 500 is arranged to move between its open and closed positions in dependence on the temperature of the engine 60, as determined by the temperature sensor 52. If the pump 500 comprises one or more valves 218 of the type described above in relation to Figs. 5A to 5D, the one or more valves 218 may also be arranged to move between their open and closed positions in dependence on the temperature of the engine 60 as determined by the temperature sensor 52. It should be noted that whereas Fig. 6 shows the temperature sensor 52 positioned in three different possible locations X, Y and Z, in practice, the temperature sensor 52 will only be in one of these different possible locations in any given embodiment.

Fig. 7 schematically shows an embodiment of a vehicle 70 comprising a vehicle engine cooling system such as that shown in Fig. 6. The vehicle 70 therefore comprises an internal combustion engine and a vehicle engine coolant pump such as any of those shown in Figs. 2A to 5D, neither of which is visible in the view of Fig. 7. The vehicle 70 additionally comprises a cooling system controller, also not visible in Fig. 7. This cooling system controller is configured to control movement of the shroud of the pump in dependence on the temperature of the engine as determined by the temperature sensor of the cooling system using either open or closed loop control. If the pump of the cooling system comprises one or more valves of the type described above in relation to Figs. 5A to 5D, the cooling system controller may also be configured to control movement of these valves in dependence on the temperature of the engine as determined by the temperature sensor of the cooling system using either open or closed loop control as well.

Fig. 8 schematically represents an embodiment of a method of cooling a vehicle engine. The method comprises pumping 1001 coolant around the engine with a vehicle engine coolant pump according to an embodiment of the invention by driving rotation of the impeller 2 from revolutions of the engine, determining 1002 a temperature of the engine, and moving 1003 the position of the shroud in the pump between the open and closed positions thereof in dependence on the temperature of the engine as thus determined in block 1002. The temperature of the engine may be determined in one of several different ways. For example, the temperature of the engine may be determined by measuring the temperature of coolant circulated around the engine by the pump either before the coolant arrives at the engine or after the coolant leaves the engine, or by measuring the temperature of exhaust gas from the engine, which is recirculated to the engine.

Fig. 9 schematically represents another embodiment of a method of cooling a vehicle engine, using a vehicle engine coolant pump which has one or more valves such as those 218 described above in relation to the embodiment of a pump shown in Figs. 5A to 5D. The method comprises carrying out the same operations as described above in relation to Fig. 8, but also comprises an operation 1004 of opening and closing the one or more valves in dependence on the temperature of the engine as determined in block 1002.

For purposes of this disclosure, it is to be understood that the control systems described herein can each comprise a control unit or computational device having one or more electronic processors. A vehicle and/or a system thereof may comprise a single control unit or electronic controller or alternatively different functions of the controllers may be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controllers or control units to implement the control techniques described herein, including the described methods. The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software to be executed by one or more electronic processors. For example, a first controller may be implemented in software run on one or more electronic processors, and one or more other controllers may also be implemented in software run on or more electronic processors, optionally the same one or more processors as the first controller. It will be appreciated, however, that other arrangements are also useful, and therefore, the present disclosure is not intended to be limited to any particular arrangement. In any event, the set of instructions described above may be embedded in a computerreadable storage medium (e.g., a non-transitory storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, including, without limitation: a magnetic storage medium (e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM ad EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

The blocks illustrated in Figs. 8 and 9 may represent steps in a method and/or sections of code in a computer program. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

For example, in other possible alternative embodiments, the shroud could alternatively or additionally be provided with through-holes in the cylindrical surface thereof and/or the backflow sealing plate could alternatively or additionally be provided with castellations around its circumference, in order to provide one or both of the shroud and the back-flow sealing plate with at least one aperture allowing restricted flow of coolant from the inlet to the outlet of the pump housing when the shroud is in its closed position.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features, whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features 5 hereinbefore referred to and/or shown in the drawings, whether or not particular emphasis has been placed thereon.

Claims

1. A vehicle engine coolant pump comprising:

an impeller;

a pump housing containing the impeller and having an inlet for admitting coolant towards an eye of the impeller and an outlet for coolant ejected by the impeller;

a flow restrictor, comprising a cylindrical shroud able to surround a circumference of the impeller within the pump housing, and a back-flow sealing plate located on an opposite side of the impeller from the eye of the impeller;

wherein:

the impeller is rotatable within the pump housing to pump coolant from the inlet to the outlet;

the shroud is movable relative to the impeller and to the pump housing in a direction of the axis of rotation of the impeller from a closed position restricting flow of coolant from the inlet to the outlet to an open position allowing flow of coolant from the inlet to the outlet; and the flow restrictor has at least one aperture formed therein to allow restricted flow of coolant from the inlet to the outlet when the shroud is in its closed position.

2. A vehicle engine coolant pump according to claim 1, wherein the at least one aperture is formed in at least one of the shroud and the back-flow sealing plate.

3. A vehicle engine coolant pump according to claim 1 or claim 2, wherein the back-flow sealing plate is fixed to and movable with the shroud in the direction of the axis of rotation of the impeller.

4. A vehicle engine coolant pump according to claim 1 or claim 2, wherein the back-flow sealing plate is separate from the shroud and remains unmoved relative to the impeller when the shroud moves in the direction of the axis of rotation of the impeller, the back-flow sealing plate remaining contained within the cylindrical shroud as it moves from its open to its closed position.

5. A vehicle engine coolant pump according to claim 4, wherein a circumference of the back-flow sealing plate touches or approaches an inner surface of the shroud.

6. A vehicle engine coolant pump according to any one of the preceding claims, wherein for the same rate of rotation of the impeller, the rate of flow of coolant from the inlet to the outlet when the shroud is in the closed position is between 10% and 50% of the rate of flow of coolant when the shroud is in the open position.

7. A vehicle engine coolant pump according to any one of the preceding claims, wherein the at least one aperture comprises one or more castellations on a rim of the shroud.

8. A vehicle engine coolant pump according to claim 7, wherein the castellations are provided on the rim of the shroud closest to the inlet.

9. A vehicle engine coolant pump according to any one of the preceding claims, wherein the at least one aperture comprises one or more through-holes in the back-flow sealing plate.

10. A vehicle engine coolant pump according to claim 9, wherein at least one of the one or more through-holes in the back-flow sealing plate has associated with it a respective valve operable between a closed position and an open position when the shroud is in its closed position.

11. A vehicle engine coolant pump according to claim 10, wherein for the same rate of rotation of the impeller, the rate of flow of coolant from the inlet to the outlet of the pump housing when the one or more valves are in their closed position and the shroud is in its closed position is between 40% and 60% of the rate of flow of coolant from the inlet to the outlet of the pump housing when the one or more valves are in their open position and the shroud is in its closed position.

12. A vehicle engine coolant pump according to claim 10 or claim 11, wherein the one or more valves are resiliently biased towards their closed position.

13. A vehicle engine cooling system comprising a vehicle engine coolant pump according to any one of the preceding claims and a temperature sensor for determining a temperature of an engine around which coolant is circulated by the pump, wherein the shroud is arranged to move between its open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor.

14. A vehicle engine cooling system according to claim 13 as dependent on any one of claims 10 to 12, wherein the one or more valves are arranged to move between their open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor.

15. A vehicle engine cooling system according to claim 13 or claim 14, wherein in order to determine the temperature of the engine, the temperature sensor is positioned either to measure the temperature of coolant circulated around the engine by the pump either before the coolant arrives at the engine or after the coolant leaves the engine, or to measure the temperature of exhaust gas from the engine recirculated to the engine.

16. A vehicle engine cooling system according to any one of claims 13 to 15, comprising a cooling system controller configured to control movement of the shroud between its open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor using either open or closed loop control.

17. A vehicle engine cooling system according to claim 16 as dependent on any one of claims 10 to 12, wherein the cooling system controller is configured to control movement of the one or more valves between their open and closed positions in dependence on the temperature of the engine as determined by the temperature sensor using either open or closed loop control.

18. A vehicle comprising a vehicle engine coolant pump according to any one of claims 1 to 12.

19. A vehicle comprising a vehicle engine cooling system according to any one of claims 13 to 17.

20. A method of cooling a vehicle engine, the method comprising:

pumping coolant around the engine with a pump according to any one of claims 1 to

12 by driving rotation of the impeller from revolutions of the engine;

determining a temperature of the engine; and moving the shroud between its open and closed positions in dependence on the temperature of the engine.

21. A method of cooling a vehicle engine according to claim 20 as dependent on any one of claims 10 to 12, comprising:

moving the one or more valves between their open and closed positions in dependence on the temperature of the engine.

22. A method of cooling a vehicle engine according to claim 20 or claim 21, wherein the temperature of the engine is determined by measuring the temperature of coolant circulated around the engine by the pump either before the coolant arrives at the engine or after the

5 coolant leaves the engine, or by measuring the temperature of exhaust gas from the engine recirculated to the engine.

Intellectual Property Office

Application No: GB1804181.4

Claims searched: 1-22

Examiner: Dr Rhys Williams

Date of search: 22 August 2018

Patents Act 1977: Search Report under Section 17

Documents considered to be relevant:

Category Relevant to claims Identity of document and passage or figure of particular relevance A - US 2002/0192072 Al (TESMA INTERNATIONAL) Noting impeller 120 & shroud 170. A - WO 01/55597 Al (TESMA INTERNATIONAL) Noting impeller 120 & shroud 140. A - US 6074167 Al (WOODWARD GOVERNOR CO) See whole document.

Categories:

X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention. same category. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.

Field of Search:

Search of GB, EP, WO & US patent documents classified in the following areas of the UKCX :