GB2581474A

GB2581474A - Engine cooling circuit and method of cooling an engine

Info

Publication number: GB2581474A
Application number: GB1901966.0A
Authority: GB
Inventors: Richard Hutchins William
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2019-02-13
Filing date: 2019-02-13
Publication date: 2020-08-26
Anticipated expiration: 2039-02-13
Also published as: GB2581474B; GB201901966D0

Abstract

A cooling circuit 105 for an engine 110 comprises a main circuit 105M having a main coolant inlet and outlet connected to the engine, a main coolant flowpath between the main coolant inlet and outlet, a radiator 120, and a coolant flow control valve 140. The main circuit is operable in a radiator cooling configuration and a radiator bypass configuration by controlling the coolant flow control valve. An auxiliary circuit 105A has an auxiliary coolant inlet 132, an auxiliary pump 137, and an auxiliary coolant outlet 134 in fluid communication with the main circuit portion upstream of the coolant flow control valve. The auxiliary coolant outlet may comprise an ejector portion or jet pump (134E, Fig.2(b)) having a nozzle (134EN). Controller 105C may cause the auxiliary pump to operate when the main circuit is in a radiator bypass configuration and to not operate when the main circuit is in a radiator cooling configuration. The controller may cause a primary pump 117 to pump coolant through the main circuit in the radiator cooling configuration. The cooling circuit may cause the auxiliary pump to not operate when the primary pump is being operated. The auxiliary circuit may comprise a cabin heater 130.

Description

ENGINE COOLING CIRCUIT AND METHOD OF COOLING AN ENGINE

TECHNICAL FIELD

The present disclosure relates to an engine cooling circuit and method of cooling an engine. Aspects of the invention relate to at least an engine cooling circuit, a control system, a motor vehicle and a method.

BACKGROUND

It is known to provide a cooling system (or cooling circuit) for cooling an engine of a motor vehicle. Cooling systems typically include a thermostatic pressure relief valve that controls the flow of coolant fluid through a radiator of the cooling system in order to maintain the coolant fluid, and therefore the engine, at an acceptable temperature. Thermostatic pressure relief valves are typically of the wax pellet type and arranged such that a valve permitting flow of coolant fluid through the radiator is opened by thermal expansion of a wax pellet at a predetermined coolant fluid temperature, the predetermined temperature being determined by the construction of the valve and thermal expansion properties of the wax pellet.

When a motor vehicle engine is started from cold, an engine driven coolant pump is typically employed to pump coolant through the engine, bypassing a radiator forming part of the cooling circuit. When the coolant has warmed to a sufficiently high temperature, the thermostatic pressure relief valve opens, permitting coolant flow through the radiator and therefore enhanced cooling of the coolant.

The present applicant has recognised that the engine driven coolant pump requires a considerable amount of power to drive it. The pumping capacity of the engine driven pump is considerably more than is necessary in order to pump coolant through the engine when the radiator is bypassed, due at least in part to the reduced amount of coolant being pumped and the reduced length of coolant circuit through which the coolant must be pumped.

It is an aim of the present invention to address disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects of the invention relate to a cooling circuit or system, a vehicle, a method, a controller and a control system. Embodiments of the invention may be understood with reference to the appended claims.

In one aspect of the invention for which protection is sought there is provided a cooling circuit for an engine comprising: a main circuit portion having an inlet arranged to be provided in fluid communication with a coolant outlet of the engine and an outlet arranged to be provided in fluid communication with a coolant inlet of the engine, the main circuit portion providing a flowpath for coolant from the inlet of the main circuit portion to the outlet of the main circuit portion, the main circuit portion comprising a radiator and a coolant flow control valve, the coolant flow control valve being provided upstream of the radiator with respect to flow of coolant from the inlet of the main circuit portion; and an auxiliary circuit portion, wherein the main circuit portion is operable in a radiator cooling configuration in which the coolant flow control valve causes coolant flow through the main circuit portion via the radiator and a bypass configuration in which the coolant flow control valve causes coolant flow through the main circuit portion substantially bypassing the radiator, the auxiliary circuit portion having an inlet arranged to be provided in fluid communication with the coolant outlet of the engine and an outlet provided in fluid communication with the main circuit portion at a location of the main circuit portion upstream of the coolant flow control valve in a coolant flowpath from the inlet of the main circuit portion to the coolant flow control valve.

Embodiments of the present invention have the advantage that, when the cooling circuit is operated in the radiator cooling configuration, coolant that has passed through the auxiliary circuit portion is caused to flow through the radiator where it is subject to cooling before being returned to the engine. It is to be understood that, if the outlet of the auxiliary circuit portion were instead provided in fluid communication with the main circuit portion at a location downstream of the coolant flow control valve and downstream of the radiator, in a flowpath of coolant from the coolant flow control valve to the coolant inlet of the engine, the (relatively hot) coolant emerging from the auxiliary circuit portion would re-enter the engine before having passed through the radiator. This has the effect that the rate of cooling of the engine by the cooling circuit is reduced.

Optionally, the auxiliary circuit portion comprises pumping means arranged to pump coolant from the inlet of the auxiliary circuit portion, through the auxiliary circuit portion and to the outlet of the auxiliary circuit portion.

The cooling circuit may be configured wherein coolant is injected into the main circuit portion by the auxiliary circuit portion in a direction having at least a component in the direction of a flowpath from the coolant outlet of the engine to the coolant inlet of the engine such that coolant is caused to be drawn through the main circuit portion from the inlet of the main circuit portion to the outlet of the main circuit portion.

This feature has the advantage that pumping of coolant through the main circuit portion may be effected by pumping of coolant through the auxiliary circuit portion. Thus, a separate pumping means is not required to be employed in order to pump coolant through the main portion.

The cooling circuit may comprise control means configured automatically to cause the main circuit portion to operate in the bypass configuration or the radiator cooling configuration.

Optionally, the control means is configured automatically to cause the pumping means of the auxiliary circuit portion to operate when the main circuit portion is in the bypass configuration.

The cooling circuit may be configured automatically to cause the pumping means of the auxiliary circuit portion not to operate when the main circuit portion is in the radiator cooling 25 configuration.

Optionally, the control means is configured to cause a primary pumping means to operate when the main circuit portion is operated in the radiator cooling configuration, the primary pumping means being arranged to cause pumping of coolant through the main circuit portion.

The cooling circuit may be configured to cause the pumping means of the auxiliary circuit portion not to operate when the primary pumping means is being operated.

The cooling circuit may be configured to cause the primary pumping means not to operate when the main circuit portion is operated in the bypass configuration.

Optionally the cooling circuit comprises the primary pumping means.

In a further aspect of the invention for which protection is sought there is provided a cooling circuit according to another aspect coupled to an engine.

Optionally, the engine is arranged to drive and/or comprises the primary pumping means.

Optionally, the control means comprises at least one electronic processor and at least one electronic memory device including computer program instructions configured to cause the main circuit portion to operate in the radiator cooling configuration or the bypass configuration.

In a still further aspect of the invention for which protection is sought there is provided a vehicle comprising a cooling circuit according to another aspect.

In an aspect of the invention for which protection is sought there is provided a method of cooling an engine comprising causing a flow of coolant through a coolant circuit, the coolant circuit comprising: a main circuit portion having an inlet arranged to be provided in fluid communication with a coolant outlet of the engine and an outlet arranged to be provided in fluid communication with a coolant inlet of the engine, the main circuit portion providing a flowpath for coolant from the inlet of the main circuit portion to the outlet of the main circuit portion, the main circuit portion comprising a radiator and a coolant flow control valve, the coolant flow control valve being provided upstream of the radiator with respect to flow of coolant from the inlet of the main circuit portion; and an auxiliary circuit portion, the method comprising operating the main circuit portion in one of a radiator cooling configuration in which the coolant flow control valve causes coolant flow through the main circuit portion via the radiator, and a bypass configuration in which the coolant flow control valve causes coolant flow through the main circuit portion substantially bypassing the radiator, the method comprising pumping coolant through the auxiliary circuit portion from an inlet thereof provided in fluid communication with the coolant outlet of the engine to an outlet provided in fluid communication with the main circuit portion at a location of the main circuit portion upstream of the coolant flow control valve in a coolant flowpath from the inlet of the main circuit portion to the coolant flow control valve.

In another aspect of the invention for which protection is sought there is provided a controller comprising: at least one electronic processor; and at least one electronic memory device including computer program instructions, the at least one electronic memory device and the computer program instructions configured to, with the at least one electronic processor, cause the cooling circuit to perform the method of another aspect.

In a further aspect of the invention for which protection is sought there is provided a control system comprising: at least one electronic processor; and at least one electronic memory device including computer program instructions, the at least one electronic memory device and the computer program instructions configured to, with the at least one electronic processor, cause the control system to perform the method of another aspect.

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.

For the avoidance of doubt, it is to be understood that features described with respect to one aspect of the invention may be included within any other aspect of the invention, alone or in appropriate combination with one or more other features.

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: FIGURE 1 is a schematic illustration of a vehicle according to an embodiment of the present invention; FIGURE 2(a) is a schematic illustration of an engine cooling circuit of the vehicle of the embodiment of FIG. 1 with a coolant fluid flow control valve in a first position whereby fluid flows substantially only through the engine and not through a radiator or degasification (degas) tank; FIGURE 2(b) is a schematic illustration of an ejector coupling that couples a coolant outlet of an auxiliary portion of the cooling circuit to a main portion of the cooling circuit; FIGURE 3 is a schematic illustration of the engine cooling circuit of the vehicle of the embodiment of FIG. 1 with the coolant fluid flow control valve in a second position whereby coolant fluid flows through the engine, radiator and degas tank; and FIGURE 4 is a schematic illustration of the engine cooling circuit of the vehicle of the embodiment of FIG. 1 with the coolant fluid flow control valve in a first intermediate position between the first and second positions.

DETAILED DESCRIPTION

FIG. 1 shows a vehicle 100 according to an embodiment of the present invention. The vehicle 100 has an internal combustion engine 110 cooled by means of a cooling circuit 105.

The cooling circuit has a main portion 105M and an auxiliary portion 105A.

FIG. 2(a) shows the cooling circuit 105 of the vehicle 100 of FIG. 1. A primary fluid pump 117 is provided for pumping coolant fluid (or 'coolant') when the engine 110 is running, when required. In the present embodiment the primary fluid pump is an electrically driven pump although other types of pump may be used in some alternative embodiments. The primary pump 117 draws coolant through an inlet 1171N of the pump 117 and forces the coolant through a coolant inlet 110IN of the engine 110. The primary pump 117 may be selectively switched on and off, as required, during operation of the vehicle 100, by means of an electronic controller 105C. In some embodiments the primary pump 117 may be an engine-driven coolant pump capable of being switched on an off as required. It is to be understood that, whether the primary coolant pump 117 is electrically driven or engine driven, when the pump 117 is switched off coolant is still permitted to flow into the engine 110 either via the primary pump 117 or (in some embodiments) via a primary pump bypass circuit.

The coolant outlet 110OUT of the engine 110 is coupled by means of a T-connector to an engine outlet coolant conduit 152 and to a cabin heater coolant inlet conduit 132. The engine outlet conduit 152 is in turn coupled to an engine outlet coolant inlet 142 of a coolant flow control valve unit (or 'assembly') 140.

The cabin heater coolant inlet conduit 132 supplies coolant to a cabin heater 130. A coolant outlet of the cabin heater 130 is coupled by means of a cabin heater coolant outlet conduit 134 to the engine outlet coolant conduit 152 at a location proximate the engine outlet coolant inlet 142 of the coolant flow control valve unit 140, upstream of the valve unit 140. An electric heater coolant pump 137 (also referred to as a secondary coolant pump or secondary pump 137) is coupled to the cabin heater coolant outlet conduit 134 between the coolant outlet of the cabin heater 130 and the engine outlet coolant conduit 152. In the present embodiment the heater coolant pump 137 may be selectively switched on and off, as required, during operation of the vehicle 100, by means of controller 105C.

In the present embodiment, the heater coolant pump 137 is arranged to consume less power (albeit with correspondingly reduced coolant pumping speed). It is to be understood that, in the present embodiment, the heater coolant pump 137 is only required to be able to pump sufficient coolant to cause adequate circulation of coolant during engine warm up as will be discussed in further detail below.

The cabin heater coolant inlet conduit 132, cabin heater 130 and cabin heater coolant outlet conduit 134 form an 'auxiliary portion' 105A of the cooling circuit 105. The remaining components of the circuit 105 are considered to be the 'main portion' 105M.

The cabin heater coolant outlet conduit 134 is arranged to inject coolant into the engine outlet coolant conduit 152 by means of an ejector coupling 134E that is illustrated further in FIG. 2(b).

The ejector coupling 134E includes a nozzle portion 134EN that protrudes into a conduit 134EC defined by a housing of the ejector coupling 134E and through which coolant flowing along the engine outlet coolant conduit 152 is arranged to flow when the ejector coupling 134E is coupled in the outlet conduit 152 in an 'inline' configuration. The nozzle portion 134EN is coupled to the cabin heater coolant outlet conduit 134 and is arranged to direct coolant pumped through the cabin heater coolant outlet conduit 134 by the heater coolant pump 137 into the conduit 134EC of the ejector coupling 134E and thereby into the engine outlet coolant conduit 152 in a direction towards the coolant flow control valve unit 140. The arrangement is such as to promote, via the 'Venturi effect,' flow of coolant from the engine through the coolant outlet 110OUT of the engine 110 into the engine outlet coolant conduit 152 and thereby through the conduit 134EC of the ejector coupling 134E. In the embodiment of FIG. 2(b) the nozzle portion 134E narrows towards an outlet 134EOUT thereof.

The ejector coupling 134E may be configured to provide a 'jet pump' arrangement for drawing coolant through the engine outlet coolant conduit 152 towards the coolant flow control valve unit 140, the coolant passing through the nozzle portion 134E constituting the motive fluid of the ejector/jet pump arrangement.

The coolant flow control valve unit 140 has an engine inlet coolant outlet 144 that is coupled to the primary fluid pump 117 by means of engine inlet coolant conduit 154.

The coolant flow control valve unit 140 also has a radiator inlet coolant outlet 146 that is coupled to a coolant inlet of the radiator 120 by means of a radiator coolant inlet conduit 156. In addition, the coolant flow control valve unit 140 has a radiator coolant outlet inlet 148 that is coupled to a coolant outlet of the radiator 120 by means of a radiator coolant outlet conduit 158.

The coolant flow control valve unit 140 comprises a substantially hollow housing or body 140H in which is provided a rotatable flow diverter (or 'diverting') portion 140D. The flow diverter portion 140D may also be described as a baffle portion. In the embodiment of FIG. 2(a) and (b) the diverter portion 140D is rotatable about an axle 140P through an angle of substantially 90 degrees between first and second rotational positions. In the embodiment of FIG. 2(a) and (b) the diverter portion 140D is substantially symmetrical about the axle 140P although this is not an essential feature of all embodiments. The valve may be referred to as an X-type' valve or 'X-valve' since the respective first and second positions of the diverter portion 140D may be considered represent the letter 'X'.

In the embodiment of FIG. 2(a) and (b) the coolant flow control valve also has a degasification (or 'degas') tank coolant inlet 149 that permits coolant flow via a degas tank outlet conduit 172 from the degas tank 170 to the valve unit 140. Pockets of gas forming in the upper region of the valve unit 140 may rise within the conduit 17210 the degas tank 170. A second degas tank outlet conduit 174 couples a further coolant outlet of the degas tank 170 to an inlet formed in the radiator coolant outlet conduit 158 that is provided proximate the radiator outlet inlet 148 of the flow control valve unit 140. A T-piece may be inserted in the outlet conduit 158 in order to achieve this connection in some embodiments.

The degas tank 170 has a gas vent 170V arranged to allow gas entrained in the flow of coolant into the tank 170 to be released from the tank 170 to atmosphere. The purpose of the degas tank 170 is to allow venting of gas bubbles that form in the cooling circuit 105. It is to be understood that the various cross-sectional areas for fluid flow through the components associated with the degas tank 170 such as the inlet and outlet conduits 172, 174 are sized so as to permit only a relatively low flow rate of coolant therethrough relative to the flow rate of coolant through the radiator 120.

In some alternative embodiments only one of the two outlet conduits 172, 174 is provided, such as only the second outlet conduit 174 and not the first outlet conduit 172. Alternatively, only the first outlet conduit 172 may be provided and not the second outlet conduit 174.

The degas tank 170 is also coupled to a top portion of the radiator 120 by means of a radiator degas outlet conduit 176. This conduit 176 permits gas, trapped in the coolant flowing through the radiator 120, to flow to the degas tank where it may be vented to atmosphere via the gas vent 170V. It is to be understood that a flow of coolant from the radiator 120 to the degas tank 170 will be established, gas trapped in the radiator 120 becoming entrained in this flow of coolant to the degas tank 170.

With the diverter portion 140D of the control valve unit 140 in the first position, illustrated in FIG. 2(a), the diverter portion 140D directs coolant entering the control valve unit 140 through the engine coolant outlet inlet 142 to flow out from the control valve unit 140 through engine coolant inlet outlet 144 of the valve unit 140. Flow of coolant through the valve unit to the radiator inlet outlet 146 is substantially prevented.

Thus it is to be understood that, with the diverter portion 140D in the first position, the control valve unit 140 causes recirculation of coolant through the engine 110 without passing through the radiator 120, permitting the coolant and in turn the engine 110 to warm relatively rapidly to the required operating temperature range.

With the diverter portion 140D in the first position, the controller 105C is arranged to maintain the primary coolant pump 117 switched off, and the heater coolant pump 137 switched on. The heater coolant pump 137 therefore draws coolant through the cabin heater 130 and injects coolant into the engine outlet coolant conduit 152. This in turn draws coolant from the coolant outlet 110OUT of the engine 110, drawing coolant through the engine 110. Coolant is therefore caused to flow through the engine 110 and the cabin heater 130. Thus, warming of the cabin heater occurs as the engine 110 is warmed. Furthermore, the amount of electrical power required to pump coolant through the engine 110 (and cabin heater 130) is lower than would be in the case that the primary coolant pump 117 was employed. This advantage may be particularly significant in hybrid electric vehicles (HEVs) where reduced electrical power consumption by vehicle components may be important.

With the diverter portion 140D in the second position, illustrated in FIG. 3, the diverter portion 140D directs coolant entering the control valve unit 140 through the engine coolant outlet inlet 142 to flow out from the control valve unit 140 through radiator inlet outlet 146. Flow of coolant directly to the engine coolant inlet outlet 144 of the control valve unit 140 is therefore substantially prevented.

Similarly, coolant flowing into the control valve unit 140 through the radiator coolant outlet inlet 148 is caused to flow out from the control valve unit 140 through the engine coolant inlet outlet 144. Thus, with the diverter portion 140D of the valve unit 140 in the second position, the circuit 105 causes circulation of coolant from the engine 110 to the radiator 120 via the valve unit 140 and, simultaneously, back from the radiator 120 to the engine 110 again via the control valve unit 140.

It is to be understood that, when the control valve is operated with the diverter portion 140D in the second position, the controller 105C causes the primary coolant pump 117 to be switched on and the heater coolant pump 137 to be switched off. Flow of coolant through the cabin heater 130 is still permitted even with the heater coolant pump 137 switched off, coolant being directed to bypass the coolant pump 137 in this case.

In some alternative embodiments, the heater coolant pump 137 remains switched on even if the primary coolant pump is operating, with the diverter portion 140D in the second position. Other arrangements may be useful in some embodiments.

As noted above, the control valve unit 140 has a degas tank coolant inlet 149 that permits coolant flow from the degas tank 170. The degas tank coolant inlet 149 is provided in an upper region of the housing 140H of the control valve unit 140 at a location such that, with the diverter portion 140D of the control valve unit 140 in the first position as shown in FIG. 2(a), the inlet 149 is on an opposite side of the diverter portion 140D to the flowpath (first flowpath Fl, FIG. 2(a)) of coolant from the engine coolant outlet inlet 142 to the engine coolant inlet outlet 144. Thus, coolant flowing into the control valve unit 140 through the engine coolant outlet inlet 142 is substantially prevented from flowing to the degas tank 170.

In some embodiments, the valve unit 140 is not provided with a degas tank coolant inlet 149. Rather, coolant flowing out from the degas tank 170 flows into the radiator coolant outlet conduit 158 via degas outlet conduit 174 as described above.

Thus it can be seen that the present embodiment has the feature that recirculation of coolant through the engine 110 with the diverter portion 140D of the control valve unit 140 in the first position does not permit circulation of coolant through the degas tank 170. This has the advantage that the time taken for coolant (and therefore the engine) to warm to a desired operating temperature range may be reduced relative to known cooling systems in which circulation of coolant through a degas tank occurs even when flow through a radiator is substantially prevented.

However, it is to be understood that, in the present embodiment, the valve unit 140 is arranged such that, with the diverter portion 140D in the first position, a coolant leak path past the diverter portion 140D is provided such that a relatively small amount of coolant flowing through the engine coolant outlet inlet 142 On the present embodiment, about 1% of flow) is permitted to leak beyond the diverter portion 140D. In the embodiment of FIG. 2 coolant leaks via a gap 140D0 between the diverter portion 140D and housing 140H of the control valve unit 140. Coolant that leaks in this manner, being warmer than coolant with which it comes into contact on the opposite side of the diverter portion 140D to the first flow path Fl, tends to pool within the upper volume 140U of the control valve unit 140 on this (opposite) side of the diverter portion 140D to flow path Fl. The coolant "leaking' in this manner thus tends to follow flow path F2 illustrated schematically in FIG. 2. Whilst component tolerances may facilitate sufficient fluid leakage, in some embodiments one or more apertures or perforations may be provided in the diverter portion 140D to allow limited coolant flow through the diverter portion 140, facilitating the fluid following flow path F2. The apertures may provide a leak path that is in addition to, or instead of, a path provided by a gap such as gap 140DG between the diverter portion 140D and housing 140H.

As shown in FIG. 2(a), the degas tank inlet 149 of the control valve unit 140 is located in a wall of the housing 140H of the control valve unit 140 in an upper region thereof on the side of the diverter portion 140D opposite that over which coolant flows along the first flow path, when the diverter portion 140D is in the first position. The inlet 149 is located such that pockets of gas pooling in the upper volume 140U of the control valve unit 140 are able to pass out from the control valve unit 140 through the degas tank inlet 149 and rise to the degas tank 170 itself where the gas may be vented.

The position of the diverter portion 140D of the control valve unit 140 is controlled by means of electronic controller 1050. The control valve unit 140 is provided with an electric motor 140M that is powered by the controller 105C and arranged to cause the diverter portion 140D to be rotated about axis 140P from the first position to the second position as required. The controller 1050 receives a signal from a temperature sensor 110T that is coupled to the engine 110 and arranged to output a signal indicative of the temperature of coolant flowing through the engine 110. In some embodiments the temperature sensor 110T may be provided at another location, such as at the coolant outlet 1100UT of the engine 110 or within the coolant outlet conduit 152 of the cooling circuit 105. The controller 1050 in combination with the temperature sensor 110T may be considered to form a control system.

The controller 1050 is configured to cause the diverter portion 140D to assume the first position whilst the signal from temperature sensor 110T indicates the coolant temperature is below a first predetermined temperature value which may be any suitable value such as 80 Celsius, 90 Celsius, 100 Celsius or any other suitable temperature. When the temperature exceeds this first predetermined temperature, the controller 1050 is configured to cause the diverter portion 140D to rotate towards the second position (shown in FIG. 3) in a predetermined number of stages. In the present embodiment the controller 1050 is configured to cause the diverter portion 140D to rotate towards the second position in two stages.

Firstly, the controller 1050 causes the diverter portion 140D to rotate from the first position to a first intermediate position between the first and second positions when the signal from temperature sensor 110T indicates the coolant temperature is above the first predetermined temperature value. In the present embodiment the first intermediate position is an angular distance of substantially 45 degrees from the first position and the second position is an angular distance of substantially 90 degrees from the first position although other angles may be useful in some embodiments.

In the present embodiment, the controller maintains the heater coolant pump 137 on and the primary coolant pump 117 off when the diverter portion 140D is in the first or the first intermediate position. In some alternative embodiments the heater coolant pump 137 is switched off and the primary coolant pump 117 is switched on when the diverter portion 140D is in the first intermediate position. Other arrangements may be useful in some embodiments.

In the first intermediate position, illustrated schematically in FIG. 4, the diverter portion 140D causes coolant flowing into the valve unit 140 through the engine outlet inlet 142 of the valve unit 140 to be split between the first and second flow paths Fl, F2 shown in FIG. 2(a) and FIG. 4, but with a greater proportion of coolant flowing along the second flow path F2 (approximately 2% of flow in the present embodiment) compared with that with the diverter portion 140D in the first position. Coolant again pools in the upper volume 140U of the valve unit 140, and the circuit 105 is configured such that at least some coolant begins to flow through the radiator 120 along flowpaths F3 and F4 as shown in FIG. 4. Thus, relatively cold coolant flowing along flowpath F4 from the radiator 120 mixes with warmer coolant flowing through the valve unit 140 along flowpath Fl, causing dilution (and cooling) of the warmer coolant.

It is to be understood that the controller 1050 causes the diverter portion 140D to rotate towards the second position in two stages rather than a single stage (i.e. rather than a single stage from the first position directly to the second position) so as to reduce the risk of adverse thermal shock to the engine 100 that may be caused when relatively cold, undiluted coolant within the radiator 120 flows into the engine 110 as the engine is warming. By rotating first to the first intermediate position, the valve unit 140 causes at least some warm coolant from the coolant outlet of the engine 100 that flows through the valve unit 140 along the second flow path F2 to flow through the radiator 100 along the third flow path F3 and relatively cold coolant within the radiator 120 to flow along the fourth flow path F4 to the engine 110 (FIG. 4). In turn, as noted above, coolant from the radiator 120 flowing along the fourth flow path mixes with some of the warmed coolant from the engine 100 flowing along the second flowpath F2 before flowing through the engine 110. The circuit 105 thus begins to cause warming of coolant within the radiator 120. This reduces thermal shock to the engine 110 when the diverter portion 140D of the valve unit 140 finally assumes the second position and substantially all the warmed coolant from the engine 110 is caused to flow through the radiator 120.

With the diverter portion 140D in the first intermediate position (FIG. 4), the controller 105C continues to monitor coolant temperature by means of the temperature sensor 110T. If the coolant temperature subsequently exceeds a second predetermined temperature, being a predetermined value that is higher than the first predetermined temperature, the controller 105C causes the diverter portion 140D to rotate to the second position, an angle of approximately 90 degrees from the first position. The second predetermined temperature may be a predetermined number of degrees higher than the first predetermined temperature, such as 5 Celsius, 10 Celsius or any other suitable number of Celsius higher.

It is to be understood that, in one embodiment, the first and second predetermined temperatures are 80 Celsius and 90 Celsius, respectively. Other values of the first and second predetermined temperatures may be useful in some embodiments.

It is to be understood that the diverter portion 140D may be caused to return to the first intermediate position from the second position if the temperature of the engine 100 falls from a temperature at or above the second predetermined temperature to a temperature below the second predetermined temperature. In order to prevent mode chattering (i.e. rapid switching of the position of the diverter portion 140D between positions) the controller 105C may be configured to cause the diverter portion 140D to switch from the second position to the first intermediate position if the coolant temperature falls a predetermined threshold amount below the second intermediate temperature, where the threshold amount may be any suitable value such as 2 Celsius, 3 Celsius or any other suitable value. Similarly, the controller may be configured to cause the diverter portion 140D to switch from the first intermediate position to the first position if the coolant temperature falls a predetermined threshold amount below the first intermediate temperature where the threshold amount may again be any suitable value such as 2 Celsius, 3 Celsius or any other suitable value.

In some embodiments, the control valve unit 140 may be actuated by means of a thermally reactive mechanical actuator such as a wax thermostat element or bimetallic strip. Other arrangements may be useful in some embodiments.

Embodiments of the present invention have the advantage that an amount of power consumed by the cooling circuit in circulating coolant as the engine 110 warms from cold may be reduced relative to known cooling circuits and systems due to the employment of a pump located in an auxiliary portion (or 'coolant line') of the cooling circuit as opposed to a main portion. The pump employed in the auxiliary portion may be a pump of lower pumping capacity, thus consuming less energy. This may be particularly beneficial in the case of hybrid electric vehicles where electrically driven coolant pumps may be employed. It is to be understood that electrically driven coolant pumps may be employed to pump coolant through an engine (such as a diesel or petrol engine) as well as one or more electric machines used for motive traction and/or electrical power generation.

Furthermore, because the degas tank 170 is not provided in the flow path of coolant when the coolant is relatively cold, the amount of time taken for the engine 100 to achieve a desired operating temperature (which is typically a temperature above ambient temperature) may be reduced. This can have one or more of the advantages of reducing unwanted vehicle emissions, reducing engine component wear and reducing the time taken for cabin warming where a cabin heater is provided that is heated at least in part by means of engine coolant.

It is to be understood that some embodiments of the present invention need not include a coolant flow control valve unit of the type described herein. Instead, one or more conventional valve arrangements may be used, such as other electrically operated valves or thermostatic valves such as conventional wax-based thermostatic valves. Some embodiments of the invention are also suitable for cooling circuits not having a degas tank arrangement of the type described. Indeed, some embodiments of the invention may be suitable for cooling circuits not having a degas tank arrangement.

For the purpose of this disclosure, it is to be understood that the controller(s) 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 controller(s) may be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controller(s) or control unit(s) to implement the control techniques described herein (including the described method(s)). 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 processor(s). 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 one 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 computer-readable storage medium (e.g., a non-transitory computer-readable 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 and EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS1. A cooling circuit for an engine comprising: a main circuit portion having an inlet arranged to be provided in fluid communication with a coolant outlet of the engine and an outlet arranged to be provided in fluid communication with a coolant inlet of the engine, the main circuit portion providing a flowpath for coolant from the inlet of the main circuit portion to the outlet of the main circuit portion, the main circuit portion comprising a radiator and a coolant flow control valve; and an auxiliary circuit portion, wherein the main circuit portion is operable in a radiator cooling configuration in which the coolant flow control valve causes coolant flow through the main circuit portion via the radiator and a bypass configuration in which the coolant flow control valve causes coolant flow through the main circuit portion substantially bypassing the radiator, the auxiliary circuit portion having an inlet arranged to be provided in fluid communication with the coolant outlet of the engine and an outlet provided in fluid communication with the main circuit portion at a location of the main circuit portion upstream of the coolant flow control valve in a coolant flowpath from the inlet of the main circuit portion to the coolant flow control valve.
2. A cooling circuit according to claim 2 wherein the auxiliary circuit portion comprises pumping means arranged to pump coolant from the inlet of the auxiliary circuit portion, through the auxiliary circuit portion and to the outlet of the auxiliary circuit portion.
3. A cooling circuit according to claim 1 or claim 2 configured wherein coolant is injected into the main circuit portion by the auxiliary circuit portion in a direction having at least a component in the direction of a flowpath from the coolant outlet of the engine to the coolant inlet of the engine such that coolant is caused to be drawn through the main circuit portion from the inlet of the main circuit portion to the outlet of the main circuit portion.
4. A cooling circuit according to claim 2 comprising control means configured automatically to cause the main circuit portion to operate in the bypass configuration or the radiator cooling configuration.
5. A cooling circuit according to claim 4 wherein the control means is configured automatically to cause the pumping means of the auxiliary circuit portion to operate when the main circuit portion is in the bypass configuration.
6. A cooling circuit according to claim 5 configured automatically to cause the pumping means of the auxiliary circuit portion not to operate when the main circuit portion is in the radiator cooling configuration.
7. A cooling circuit according to any one of claims 4 to 6 wherein the control means is configured to cause a primary pumping means to operate when the main circuit portion is operated in the radiator cooling configuration, the primary pumping means being arranged to cause pumping of coolant through the main circuit portion.
8. A cooling circuit according to claim 7 configured to cause the pumping means of the auxiliary circuit portion not to operate when the primary pumping means is being operated.
9. A cooling circuit according to any claim 7 or claim 8 configured to cause the primary pumping means not to operate when the main circuit portion is operated in the bypass configuration.
10. A cooling circuit according to any one of claims 7 to 9 comprising the primary pumping means.
11. A cooling circuit according to any preceding claim coupled to an engine.
12. A cooling circuit according to any one of claims 7 to 9 coupled to an engine, wherein the engine comprises the primary pumping means. 25
13. A cooling circuit according to claim 4 or any one of claims 5 to 12 depending through claim 4 wherein the control means comprises at least one electronic processor and at least one electronic memory device including computer program instructions configured to cause the main circuit portion to operate in the radiator cooling configuration or the bypass configuration.
14. A vehicle comprising a cooling circuit according to any of claims 1 to 13.
15. A method of cooling an engine comprising causing a flow of coolant through a coolant circuit, the coolant circuit comprising: a main circuit portion having an inlet arranged to be provided in fluid communication with a coolant outlet of the engine and an outlet arranged to be provided in fluid communication with a coolant inlet of the engine, the main circuit portion providing a flowpath for coolant from the inlet of the main circuit portion to the outlet of the main circuit portion, the main circuit portion comprising a radiator and a coolant flow control valve, the coolant flow control valve being provided upstream of the radiator with respect to flow of coolant from the inlet of the main circuit portion; and an auxiliary circuit portion, the method comprising operating the main circuit portion in one of a radiator cooling configuration in which the coolant flow control valve causes coolant flow through the main circuit portion via the radiator, and a bypass configuration in which the coolant flow control valve causes coolant flow through the main circuit portion substantially bypassing the radiator, the method comprising pumping coolant through the auxiliary circuit portion from an inlet thereof provided in fluid communication with the coolant outlet of the engine to an outlet provided in fluid communication with the main circuit portion at a location of the main circuit portion upstream of the coolant flow control valve in a coolant flowpath from the inlet of the main circuit portion to the coolant flow control valve.
16. A controller comprising: at least one electronic processor; and at least one electronic memory device including computer program instructions, the at least one electronic memory device and the computer program instructions configured to, with the at least one electronic processor, cause the cooling circuit to perform the method of claim 15.
17. A control system comprising: at least one electronic processor; and at least one electronic memory device including computer program instructions, the at least one electronic memory device and the computer program instructions configured to, with the at least one electronic processor, cause the control system to perform the method of claim 15.