Cooling system for a vehicle

Abstract

A cooling system 100 for a vehicle (10, Figure 1) includes a plurality of conduits 12a- 12c defining a coolant flow path around the cooling system with a pump 16 configured to drive coolant along the

Description

TECHNICAL FIELD The present disclosure relates to a cooling system. Aspects of the invention relate to a cooling system, to a vehicle and to a method. BACKGROUND It is known to provide cooling systems in vehicles. In such cooling systems, efficient heat dissipation is important in maintaining performance and longevity. Typically, a cooling fluid, e.g. a coolant, is circulated through the vehicle (e.g. vehicle engine) and a heat exchanger (e.g. radiator) to transfer heat away from or between vehicle components. Gas, for example gas bubbles, can accumulate in the cooling system. For example, gas may be dissolved in the coolant or air pockets may be introduced during start-up or maintenance. The presence of gas within the coolant, e.g. gas bubbles, can impair the effectiveness of the heat transfer process. Gas bubbles may also restrict the flow of coolant, resulting in localised heating points. Traditional methods to reduce the presence of gas bubbles includes bleeding of the system, for example using tanks designed to accumulate gas that is present in the coolant. These tanks are typically connected to an upper point of the heat exchanger, aiming to remove gas from a region of the cooling system in which a large accumulation of gas is expected. Despite these measures, ensuring a significant removal of gas bubbles remains a challenge, particularly in modern cooling systems where precise thermal management is desired. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a fastener, a vehicle body assembly and a vehicle as claimed in the appended claims. According to an aspect of the invention, there is provided a cooling system for a vehicle, the cooling system comprising: a plurality of conduits defining a coolant flow path around the cooling system; a pump configured to drive coolant along the coolant flow path; and a degas tank in fluid communication with the coolant flow path for venting gas from the coolant; wherein the degas tank is connected to the coolant flow path via a bleed line extending from a bleed point at an upper portion of at least one conduit of the plurality of conduits. Optionally, the cooling system comprises at least one vehicle component configured to be cooled by the cooling system. Optionally, the cooling system comprises a heat exchanger for removing excess heat from the coolant. The heat exchanger may be a radiator. The heat exchanger may be a low temperature radiator (LTR). The heat exchanger may comprise one or more tubes configured to direct coolant through the heat exchanger. The tubes may define an internal diameter of about 1 mm. The tubes may define a generally convoluted or tortuous path through the heat exchanger. Optionally, the at least one conduit defines a substantially horizontal portion of the coolant flow path adjacent to and upstream of the bleed point. Advantageously, this configuration reduces the presence of gas, for example air, in the coolant flow path, which increases the efficiency of the cooling system. It is well established to direct gas from an upper end of the heat exchanger (e.g. radiator) to the degas tank, for example the bleed point may be provided in an upper surface of the heat exchanger. This location may be the uppermost point of the cooling system and thus it was conventionally understood that this would be the point at which the greatest amount of gas would accumulate (resulting in the most air removed from the system via the bleed point). Directing gas from a conduit in the system has surprisingly been found to result in improved gas removal from the system compared with the conventional arrangement. Specifically, it has been found that more gas can be removed more quickly from the system, which is particularly advantageous during maintenance to the cooling system and / or one or more vehicle components. The conventional arrangement typically requires flowing the coolant through various winding tubes in the heat exchanger upstream of the bleed point. The convoluted flowpath of the coolant in such winding tubes reduces the ability of the air to separate from the coolant and accumulate so as to be removed at the bleed point. In comparison, the substantially horizontal portion of the at least one conduit provides a less convoluted flow-path for the coolant, allowing the air therein to separate and accumulate at an upper portion of the conduit for removal at the bleed point. As such, greater air removal is obtained, and the cooling system is more efficient. It will be understood that the “upper portion” of the at least one conduit refers to a region of the respective conduit in which less dense material (e.g. air) may accumulate. For example, whilst the coolant, which is denser than air, will likely flow over a “lower portion” of the conduit, e.g. due to gravity, air may accumulate in the “upper portion” of the conduit. Optionally, the cooling system is for a vehicle comprising a longitudinal axis and a lateral axis that define a horizontal plane of the vehicle. The substantially horizontal portion may extend in a direction substantially parallel with the horizontal plane. Optionally, the at least one conduit defines a primary coolant flow path through the cooling system. It will be understood that the primary coolant flow path refers to the main route through which the coolant moves within the system under normal conditions. As such, locating the bleed point in such a conduit maximises the amount of coolant (and thus air located therein) that passes the bleed point, thereby improving the removal of air from the system. Optionally, at least 50%, optionally at least 75%, optionally at least 80%, optionally at least 90% of the volume of coolant in the cooling system flows along the primary coolant flow path. Advantageously, locating the bleed point in such a location ensures that a significant amount of coolant passes the bleed point, increasing the removal of air from the system. Optionally, the coolant flow path is arranged such that substantially all of the coolant in the cooling system flows along the primary coolant flow path during use. Advantageously, locating the bleed point in such a location ensures that substantially all of the coolant (and thus air that moves within the coolant) in the system passes the bleed point, increasing the removal of air therefrom. Optionally, the at least one conduit is a return line configured to direct fluid from the one or more vehicle components to the heat exchanger. Advantageously, the bleed point is located in the return line of the coolant flow path, which has been found to be an effective location to improve gas removal from the system. It will be understood that a significant flow of coolant in the coolant flow path will be directed through the return line. As such, locating the bleed point in such a line exposes a significant amount of the coolant (and thus any gas present therein) to the bleed point. Optionally, the at least one conduit is in fluid communication with a bypass line of the coolant flow path for selectively directing at least a portion of coolant to bypass the heat exchanger. The bleed point may be located upstream of the bypass line. The bleed point may be located so as to be upstream of a point at which the bypass line branches off the at least one conduit. It will be understood that in some arrangements, the cooling system may be configured to operate in a bypass mode such that at least a portion of the coolant bypasses the heat exchanger and is instead directed into a bypass line (e.g. back to the one or more vehicle components). As such, in the conventional arrangement of having the bleed point in the heat exchanger, not all of the coolant (and thus not all of the gas) in the system may be present in the heat exchanger. Locating the bleed point in the return line upstream of the bypass line means a significant amount of gas can be removed in the bleed line, even when the system is operating in a bypass mode, e.g. since coolant will pass through the bleed point irrespective of whether the system is in bypass mode or normal operation. The bleed point may be positioned so as to be substantially aligned with a point at which the bypass line branches off the conduit. Optionally, the substantially horizontal portion defines an internal diameter that is greater than an internal diameter defined by one or more tubes of the heat exchanger. Optionally, the substantially horizontal portion defines an internal diameter in the range of about 16 mm to 20 mm. The substantially horizontal portion may define an internal diameter of about 18 mm. Advantageously, the configuration of the substantially horizontal portion conduit has been found to improve the removal of air from the system compared with the conventional arrangement. Specifically, as noted above, the conventional arrangement involves locating the bleed point at an upper end of the heat exchanger. This is typically after flowing the coolant through various winding tubes in the heat exchanger, the tubes having an internal diameter of less than 1 mm. This comparatively lower diameter results in a higher flow velocity of coolant through these tubes, compared with flowing through the substantially horizontal portion (assuming a constant flow-rate). The increased velocity has been found to reduce the time for the gas to separate from the coolant and accumulate in the tubes prior to reaching the bleed point in the heat exchanger. In contrast, the lower velocity of coolant in the substantially horizontal portion provides additional time for the air to accumulate at an upper portion of the conduit for removal at the bleed point. As such, greater gas removal is obtained, and the cooling system is more efficient. Optionally, the bleed point is located at a position lower than an uppermost point of the coolant flow path. Advantageously, it has been found that the uppermost point of the system may not be the most effective location for the bleed point. For example, in many systems, the upper end of the heat exchanger is the uppermost point of the system. However, it has been found that locating the bleed point in a different location (i.e. a conduit having a substantially horizontal portion) provides an improved removal of gas from the system. As such, more flexibility to the design of the system is provided, as the bleed point does not have to be located at the uppermost point. It will be understood that the term “uppermost point” refers to the highest point of the cooling system relative to a vertical axis of the vehicle (i.e. the axis transverse to the longitudinal and lateral axes of the vehicle). It will be understood that the uppermost point of the cooling system may be the furthest point away (in the vertical direction) from the ground over which the vehicle travels in use. Optionally, the substantially horizontal portion is directly adjacent to and immediately upstream of the bleed point. Advantageously, gas accumulated in an upper region of the horizontal portion can be immediately removed at the bleed point, improving the extent of air removal. Optionally, the substantially horizontal portion extends along a minimum length of 25 mm. The substantially horizontal portion may extend along a length L of about 40 mm to 80 mm, optionally, a length of about 50 mm to 70 mm, optionally a length of about 60 mm. Advantageously, having a substantially horizontal portion that extends for at least 25 mm has been found to provide sufficient time for gas in the coolant to separate from the coolant and accumulate in an upper portion of the conduit, facilitating an increased removal of the gas in the bleed line via the bleed point. As such, the efficiency of the cooling system is increased. Optionally, the substantially horizontal portion defines an angle in the range of+ / - 45° relative to a horizontal plane of the vehicle. The angle p may be in the range + / - 30°. The angle p may be in the range + / - 20°, optionally, + / -15°, optionally + / -10° relative to a horizontal plane of the vehicle. Advantageously, the substantially horizontal portion can be slightly angled in the vertical direction, allowing for improved design tolerance, without significantly impacting the extent of air accumulation in the conduit. Optionally, the bleed line extends at an obtuse angle relative to the substantially horizontal portion of the coolant flow path. Advantageously, the angled bleed line has been found to improve the ability of the bleed line to collect air from the conduit, providing an improved means for directing air from the conduit into the bleed line. Optionally, the cooling system further comprises a flow restrictor located in the bleed line. Advantageously, the flow restrictor can assist in reducing the amount of coolant that inadvertently enters the bleed line, ensuring a significant amount of coolant continues along the coolant flow path. Optionally, the at least one vehicle component comprises one or more of an electric drive unit and a traction battery. Advantageously, the arrangement of the bleed point and conduit has been found to provide particularly improved air removal in a cooling system for an electric vehicle. In such arrangements, the bleed point is typically taken from an upper region of a low temperature radiator (LTR). An LTR has small tubes, resulting in the coolant flowing therethrough too quickly for effective removal of gas to take place via a bleed point at the top of the heat exchanger. It has been found that gas is removed from the system more quickly when the bleed point is located at an upper portion of a conduit having a substantially horizontal portion adjacent to and upstream of the bleed point, compared with bleeding from an upper portion of the flow path in the heat exchanger. This is particularly advantageous during maintenance of the cooling system and / or vehicle component, since bleeding the system is quicker and thus maintenance operations can be performed more efficiently. In this way, the system described provides particularly improved gas removal when cooling components of an electric vehicle. Optionally, a conduit immediately downstream of the bleed point may include a substantially horizontal portion. The substantially horizontal portion of the downstream conduit may include any and all of the features of the substantially horizontal portion of the at least one conduit upstream of the bleed point. Advantageously, such an arrangement reduces significant flow disruption in a region proximal the bleed point, improving the stability of flow upstream of the bleed point and thus improving gas removal at the bleed point. Optionally, a region of the at least one conduit having the bleed point may define a region of increased diameter of the conduit. Advantageously, the increased flow area about the bleed point decreases flow velocity proximal the bleed point, thereby providing additional time for the accumulation of gas at the upper portion of the at least one conduit. Optionally, a guide may be provided in the at least one conduit to direct gas in the upper portion of the conduit into the bleed line. Advantageously, the guide has been found to reduce flow turbulence proximal to the bleed point and improve the amount of gas removal. According to an aspect of the invention, there is provided a vehicle comprising the cooling system as described herein. The vehicle benefits from the advantages of the cooling system described herein. Optionally, the vehicle comprises one or more vehicle components configured to be cooled by the cooling system. Optionally, the one or more vehicle components comprises one or more of an electric drive unit and a traction battery. According to an aspect of the invention, there is provided a method of degassing a cooling system for a vehicle, the method comprising: providing a cooling system having a plurality of conduits defining a coolant flow path around the cooling system; providing a degas tank in fluid communication with the coolant flow path for venting gas from the coolant; and connecting the degas tank to the coolant flow path via a bleed line extending from a bleed point at an upper portion of at least one conduit of the plurality of conduits; wherein the at least one conduit defines a substantially horizontal portion of the coolant flow path adjacent to and upstream of the bleed point. The method benefits from the advantages of the cooling system outlined herein. 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: Figure 1 shows a schematic perspective view of a vehicle according to an embodiment; Figure 2 shows a schematic of a cooling system according to an embodiment; Figure 3 shows a schematic of a cooling system according to an embodiment; Figure 4A shows a schematic of a section of a cooling system according to an embodiment; Figure 4B shows a schematic of a section of a cooling system according to an embodiment; Figure 4C shows a schematic of a section of a cooling system according to an embodiment; Figure 5A shows a cross-sectional view of a section of a cooling system according to an embodiment; Figure 5B shows a cross-sectional view of a section of a cooling system according to an embodiment; Figure 6 shows a flow chart of degassing a cooling system for a vehicle. DETAILED DESCRIPTION Figure 1 shows a vehicle 10. The vehicle 10 may be a battery electric vehicle (BEV) that is powered by electrical power alone and has no internal combustion engine. The vehicle 10 has an electric machine arranged to provide propulsive torque to the wheels of the vehicle. In some cases, the vehicle 10 may have two or more electric machines, such as a first electric machine to provide torque to the front wheels and a second electric machine to provide torque to the rear wheels. The electric machines may be powered by batteries, which may be arranged between the wheels, e.g. underneath a passenger compartment. In some arrangements, the batteries may locate in a front structure of the vehicle, or toward a rear of the vehicle (e.g. in the boot or trunk). The electric machines may be electric motors or motor-generators and may also be referred to as an electric engine. The vehicle 10 has at least one vehicle drive unit. The drive unit may be an electric drive unit. The electric drive unit may contain an electric machine and one or more drivetrain components. It shall be appreciated that in alternative embodiments, the vehicle may include an internal combustion engine (ICE) or the like, and / or the vehicle 10 may be a hybrid electric vehicle (HEV) or any alternative vehicle. The vehicle 10 defines a central longitudinal axis x. The longitudinal axis x extends between a front end of the vehicle 10 and a rear end of the vehicle 10 with respect to a principal direction of travel of the vehicle 10, i.e. the x-axis extends along the length of the vehicle. The vehicle 10 defines a central lateral axis y that is transverse to the longitudinal axis. The central lateral axis y extends between a left side of the vehicle 10 and a right side of the vehicle 10, i.e. the y-axis extends in the width direction of the vehicle 10. The vehicle 10 defines a vertical axis z. The vertical axis z extends between a lower side of the vehicle 10 and an upper side of the vehicle 10, i.e. the z-axis extends in the height direction of the vehicle. The vertical axis z is transverse to the longitudinal and lateral axes x, y of the vehicle 10. The longitudinal and lateral axes define a horizontal plane of the vehicle 10. The horizontal plane of the vehicle 10 is substantially parallel to aground surface over which the vehicle 10 moves under normal operating conditions. The vehicle 10 includes one or more components 200 that require cooling. For this reason, the vehicle 10 includes a cooling system 100. The cooling system 100 is configured to cool at least one vehicle component 200. The at least one vehicle component may include the electric drive unit and / or a battery, e.g. a traction battery, of the vehicle 10. Figure 2 shows an arrangement of the cooling system 100. The cooling system 100 includes a plurality of conduits 12 defining a coolant flow path around the cooling system 100. In the figures, the conduits 12 are represented by lines extending between components. Arrows on the lines indicate an example coolant flow path. It will be appreciated that the conduits 12 may be in the form of tubing or pipes configured to transfer fluids (e.g. coolant) around the cooling system 100 so as to define the coolant flow path. The coolant flow path may be substantially cyclical in some arrangements, such that the cooling system 100 defines a cooling circuit. The conduits 12 may be configured to transfer any suitable coolant about the cooling system 100. The coolant may be a liquid, for example, water or oil. The cooling system 100 includes at least one vehicle component 200 configured to be cooled by the cooling system. The vehicle component 200 may be a component of the vehicle engine. As noted above, the at least one vehicle component 200 may be a component of an electric vehicle 10, e.g. the battery, the electric drive unit. It will be appreciated that the cooling system 100 is configured to cool components of hybrid electric vehicles, vehicles having an internal combustion engine, or components of any other vehicle type. The cooling system 100 includes a heat exchanger 14 for removing excess heat from the coolant. The heat exchanger 14 is configured to dissipate thermal energy absorbed by the coolant (e.g. during cooling of the at least one vehicle component 200) away from the engine. The heat exchanger 14 may be positioned and configured to utilise airflow generated while the vehicle 10 is in motion to enhance the dissipation of heat. In some arrangements, the heat exchanger 14 is mounted at or toward the front end of the vehicle 10. The heat exchanger 14 may be provided in the form of a radiator, such as a conventional motor vehicle radiator. A fan (not shown) may be provided to increase airflow across the heat exchanger. The heat exchanger 14 may include a series of tubes (not shown) through which coolant can flow from an inlet to an outlet of the heat exchanger 14. The tubes may extend along a tortuous or circuitous between the heat exchanger 14 inlet and the heat exchanger 14 outlet so as to increase the surface area for effective cooling. The heat exchanger 14 may be configured in any suitable form to dispense heat from the coolant in the cooling system 100. The coolant may enter the heat exchanger 14 via conduit 12b. The coolant may exit the heat exchanger 14 (e.g. to be recirculated to one or more vehicle components 200) via conduit 12c. The coolant in conduit 12c may be at a lower temperature than the coolant in conduit 12b. In some arrangements, the heat exchanger 14 may be utilised in a heat pump circuit. In this case, the coolant in conduit 12c may be at a higher temperature than the coolant in conduit 12b. Conduit 12b may be referred to as a heat exchanger inlet line, and conduit 12c may be referred to as a heat exchanger outlet line. In some arrangements, the heat exchanger 14 may be referred to as a radiator. The heat exchanger 14 may be a low temperature radiator (LTR) in some arrangements. A pump 16 is provided in the cooling system 100. The pump 16 is configured to drive coolant along the coolant flow path. The pump 16 may be configured to circulate coolant through the engine, e.g. to one or more vehicle components 200 and through the heat exchanger 14. In some arrangements, the pump 16 is provided along the heat exchanger outlet line 12c as shown in the figures. It will be appreciated that the pump 16 may be located in any position within the cooling system 100. In some cases, a plurality of pumps may be provided in different locations throughout the cooling system 100. The pump 16 may be any device suitable for driving fluid around the plurality of conduits 12. For example, the pump 16 may be a centrifugal pump. The cooling system 100 includes a degas tank 18 in fluid communication with the coolant flow path for venting gas from the coolant. The degas tank 18 may be referred to as an expansion tank in some arrangements. The degas tank 18 may be connected to the coolant flow path via a bleed line 20. The bleed line 20 may be a fluid conduit configure to fluidly connect the coolant flow path to the degas tank 18. The degas tank 18 may be include a vent arrangement for releasing a gas stream 22 present in the tank 18 therefrom. The vent arrangement may include a pressure relief cap. The bleed line 20 may include a flow restrictor 30, e.g. a valve. The flow restrictor 30 facilitates control over the amount of coolant that enters the degas tank 18, ensuring a significant amount of coolant continues along the coolant flow path. The bleed line 20 extends from a bleed point 24 in the coolant system 100 to the degas tank 18. It is conventionally understood that it is most advantageous to locate the bleed point 24 at or proximal to the uppermost point of the coolant flow path in the cooling system 100, e.g. at a region of the coolant flow path that is furthest from the ground over which the vehicle travels during normal operation. This was understood to be the location at which the greatest amount of gas in the coolant flow path would accumulate, thereby resulting in the greatest amount of gas being removed from the system 100 via the bleed line 20 and degas tank 18 (e.g. as gas stream 22). For this reason, the bleed point 24 is typically provided at an upper region of the coolant flow path in the heat exchanger 14, so that the bleed line 20 extends therefrom to the degas tank 18. In contrast to typical arrangements, the bleed point 24 of the cooling system 100 described herein is provided at an upper portion of at least one conduit 12a of the plurality of conduits 12. The at least one conduit 12a defines a substantially horizontal portion 26 of the coolant flow path adjacent to and upstream of the bleed point 24. Such an arrangement has surprisingly been found to result in greater gas removal from the cooling system 100 at higher coolant flow velocities compared with the conventional arrangement. This has been found to be particularly advantageous when the cooling system is used to cool a traction battery, e.g. in an electric vehicle. In such arrangements, the bleed point is typically taken from an upper region of an LTR. The LTR has small tubes, resulting in the coolant flowing therethrough too quickly for effective removal of gas to take place via a bleed point at the top of the heat exchanger. For example, it has been found that gas is removed from the system 100 more quickly when the bleed point 24 is located at an upper portion of a conduit 12a having a substantially horizontal portion 26 adjacent to and upstream of the bleed point 24, compared with bleeding from an upper portion of the flow path in the heat exchanger 14. This is particularly advantageous during maintenance of the cooling system 100 and / or vehicle component 200, since bleeding the system is quicker and thus maintenance operations can be performed more efficiently. The substantially horizontal portion 26 of the coolant flow path results in improved accumulation of gas in the upper portion of the at least one conduit 12a compared with the accumulation of gas at an upper region of the heat exchanger 14. While the heat exchanger 14 may include a series of winding tubes through which coolant flows tortuously through prior to reaching the conventionally located bleed point, the at least one conduit 12a provides a substantially horizontal length along which the gas may separate from the coolant, accumulating in an upper region of the conduit 12a prior to being removed at the bleed point 24. It will be understood that the “upper portion” of the at least one conduit 12a refers to a region of the respective conduit in which less dense material (e.g. air) may accumulate. For example, whilst liquid coolant, which is typically liquid and thus denser than gas, will likely flow over a “lower portion” of the conduit, e.g. due to gravity, air may accumulate in the “upper portion” of the conduit. The upper portion ofthe at least one conduit 12a may be the point ofthe conduit 12a that is distal from the ground along which the vehicle 10 transverses in normal use. The upper portion ofthe at least conduit 12a may be defined by an uppermost half of the circumferential extent ofthe conduit 12a. In some arrangements, the upper portion is defined by an uppermost quarter ofthe circumferential extent ofthe conduit 12a. It will be understood that the term “bleed point” refers to a location at which gas in the coolant flow path may be removed from the system 100. The bleed point 24 may be provided as an opening in an upper region of the at least one conduit 12a. In some arrangements, the bleed point 24 may be provided by a flow diverter or splitter. The bleed point 24 can be seen as the location at which the bleed line 20 is connected to the coolant flow path. In some arrangements, a plurality of bleed points are provided. For example, one or more additional bleed points may be provided in the cooling system 10 in addition to the bleed point 24 in the conduit 12a. In some arrangements, an additional bleed point may be provided in the heat exchanger 14. The substantially horizontal portion 26 may extend in a direction substantially parallel with the horizontal plane defined by the (longitudinal) x-axis and the (lateral) y-axis ofthe vehicle 10. The substantially horizontal portion 26 may extend along a minimum length L of about 25 mm. Such a minimum length provides sufficient time for the gas in the coolant flow path to accumulate in an upper region ofthe conduit 12a, facilitating an increased removal of gas atthe bleed point 24. In some arrangements, the substantially horizontal portion 26 may extend along a length L of about 40 mm to 80 mm, optionally, a length of about 50 mm to 70 mm, optionally a length of about 60 mm. In some arrangements, the bleed line 20 may define an angle a relative to the substantially horizontal portion 26 ofthe coolant flow path or relative to the horizontal plane defined by the longitudinal and lateral axes ofthe vehicle 10. The angle a may be non-perpendicular. The angle a may be an obtuse angle. Arranging the bleed line 20 at an obtuse angle relative to the horizontal provides an improved means for directing gas from the upper region ofthe conduit 12a into the bleed line 20. The angle a may be between 91° and 130°.The angle a may be 110°. In alternative arrangements, the bleed line 20 may define a substantially perpendicular or acute angle relative to the substantially horizontal portion 26 of the coolant flow path. The bleed point 24 is located at a position lower than an uppermost point of the cooling system 100 or the coolant flow path. In conventional arrangements, the uppermost point of the coolant flow path is in the heat exchanger 14. It will be understood that the term “uppermost point” refers to the highest point of the coolant flow path relative along the (vertical z-axis of the vehicle 10. The uppermost point of the coolant flow path may be the furthest point away (along the vertical z-axis) from the ground over which the vehicle travels during normal use. The bleed point 24 is positioned lower than the uppermost point, e.g. closer to the ground along the z-axis. The substantially horizontal portion 26 may define an internal diameter greater than an internal diameter defined by the tubes of the heat exchanger 14. The substantially horizontal portion may define an internal diameter in the range of about 16 to 20 mm. The substantially horizontal portion 26 may define an internal diameter of about 18 mm. The tubes of the heat exchanger 14 may have an internal diameter of less than 1 mm. As noted above, the bleed point has traditionally been taken from an uppermost region of the heat exchanger 14. The comparatively lower internal diameter of the heat exchanger tubes results in a higher flow velocity of coolant through the heat exchanger 14 compared with flow through the substantially horizontal portion 26 of the conduit 12a (assuming a constant flowrate of coolant). The increased velocity of coolant through the heat exchanger 14 has been found to reduce the extent of separation of gas from the coolant, reducing the accumulation and removal of gas at the conventionally located bleed point. In contrast, the coolant moves at a lower velocity through the substantially horizontal portion 26 of the conduit 12a, providing additional time for the air to accumulate for removal at the bleed point 24. The resulting cooling system 100 is more efficient since greater gas removal is obtained. In some arrangements, the at least one conduit 12a having the substantially horizontal portion 26 defines a primary coolant flow path through the cooling system 100. The primary coolant flow path may define the main route through which coolant moves within the system 100. The coolant flow path may be arranged such that substantially all of the coolant in the cooling system 100 flows along the primary coolant flow path during use. Locating the bleed point 24 in such a conduit 12a can increase the removal of gas from the system 100, since a large proportion of coolant in the system 100 (e.g. substantially all the coolant in some arrangements) will pass the bleed point 14. It will be appreciated that, in some arrangements, a portion of coolant may be introduced to the primary coolant flow path downstream of the bleed point 24 (e.g. due to space constraints) and so not all of the coolant in the cooling system 100 flows along the primary coolant flow path. At least 50%, optionally at least 75%, optionally at least 80%, optionally at least 90%, of the volume of coolant in the cooling system 100 may flow along the primary coolant flow path, e.g. along conduit 12a. The at least one conduit 12a may be a return line configured to direct fluid (e.g. coolant) from the one or more vehicle components 200 to the heat exchanger 14. In the figures, the bleed line 20 extends from an upper region of the return line 12a. In the arrangement of Figure 2, coolant is directed from the one or more components 200 to the heat exchanger 14 via the return line 12a and heat exchanger inlet line 12b, which is located downstream of the bleed point 24. An arrangement of tubes (not shown) in the heat exchanger 14 may direct coolant therethrough so as to dispense heat from the heat exchanger 14 and cool the coolant. Following cooling, heat exchanger outlet line 12c directs coolant back to the one or more vehicle components 200 to provide further cooling thereto. It will be appreciated that the cooling system 100 of the figures is substantially simplified. In some arrangements, the cooling system 100 is arranged to cool a plurality of vehicle components 200. The components may be arranged in series or in parallel within the cooling system 100. In arrangements in which the components are in parallel, conduits arranged in parallel (not shown) may be fluidly connected to the conduit 12a such that a single line directs coolant to the heat exchanger 14. In such an arrangement, the bleed point 24 may be provided downstream of connections between the conduit 12a and parallel conduits. In some arrangements, the bleed point 24 may be upstream of some connections and downstream of others (e.g. due to space constraints in the vehicle 10). In some arrangements, a plurality of conduits may be connected to the heat exchanger 14 such that the heat exchanger 14 has a plurality of coolant inlet lines. In such an arrangement, a plurality of bleed points 24 may be provided (e.g. a bleed point 24 may be provided on each parallel conduit). In some arrangements, the cooling system 100 may include a bypass line 12d, for example as shown in Figure 3. The bypass line 12d may be configured to selectively direct at least a portion of coolant to bypass the heat exchanger 14. The coolant in the bypass line 12d may be recirculated to other areas of the cooling system 100, e.g. back to the one or more vehicle components 200. The bypass line 12d may include a flow restrictor 28, e.g. a valve, to control the flow of coolant that bypasses the heat exchanger 14. The flow restrictor 28 may be controlled by a controller (not shown) that selectively directs at least a portion of coolant away from the heat exchanger 14. The bypass line 12d may be particularly advantageous in arrangements in which a plurality of vehicle components are provided in the cooling system 100. For example, some components may require heating, while others may require cooling. In such an arrangement, the coolant may increase in temperature by cooling the component requiring cooling. Rather than dissipating the heat via the heat exchanger 14, the bypass line 12d may recirculate the coolant to the component requiring heating. In this way, the coolant acts to transfer heat between different vehicle components. In an electric vehicle 10, the cooling system 100 may be arranged so that the coolant transfers heat from an electric drive unit to a battery. In arrangements in which a bypass line 12d is provided, the bleed point 24 may be located upstream of the bypass line 12d. The bleed point 24 may be located so as to be upstream of a point at which the bypass line 12d branches off the conduit 12a. Put another way, gas is removed from the coolant flow path via the bleed point 24 before the flow is split or diverted into the bypass line 12d. Such an arrangement increases the amount of flow that is exposed to the bleed point 24, thereby increasing the removal of gas from the cooling system 100. This is in contrast to conventional arrangements in which the bleed point 24 is provided in the heat exchanger 14, and coolant that is bypassed through the bypass line 12d does not pass the bleed point 24, reducing gas removal. In this way, the positioning of the bleed point 24 is beneficial in providing significant gas removal irrespective of whether the system is operating in a bypass mode or normal operation. It will be appreciated that the bypass line 12d may be positioned such that the point at which the bypass line 12d branches off the conduit 12a is substantially aligned with the bleed point 24. In some arrangements, the bypass line 12d may not be provided or may be positioned to branch off the conduit 12a at a point upstream of the bleed point 24. Referring to Figure 4A, the conduit 12a may include one or more flow control elements 32. For example, the conduit 12a may include one or more pumps, valves, restrictors, or branches (e.g. for connection of parallel conduits or the bypass line 12d to the conduit 12a). The one or more flow control elements 32 may be a feature of the conduit 12a itself, e.g. a substantially vertical portion or a substantially convoluted portion. The flow control elements may alter the flow characteristics of the coolant in the conduit 12a, e.g. flow velocity, flow regime, or the like. The flow control elements 32 may reduce the accumulation of gas in an upper portion of the conduit 12a. In arrangements in which the conduit 12a includes one or more flow control elements 32, the substantially horizontal portion 26 may be provided between the most downstream flow control element 32 and the bleed point 24. Such an arrangement provides a length of conduit for the coolant flow to stabilise after any disruption caused by the flow control element 32, thereby improving the accumulation of gas at the bleed point 24. The substantially horizontal portion 26 of the at least one conduit 12a may be provided directly adjacent to and immediately upstream of the bleed point 24, as is shown in Figures 2, 3 and 4A. In such an arrangement, the bleed point 24 is taken from an upper portion of the substantially horizontal portion 26 of the conduit 12a. Such an arrangement facilitates the immediate removal of gas that has been accumulated along the horizontal portion 26. Alternative arrangements are envisaged. For example, the substantially horizontal portion 26 may be provided proximate the bleed point 24, with the conduit 12a defining an alternative profile (e.g. non-horizontal) immediately adjacent to and upstream of the bleed point 24. In such an arrangement, the region of conduit 12a extending between the substantially horizontal portion 26 and the bleed point 24 may be configured so as to not significantly alter the flow characteristics of the coolant in the conduit 12a. For example, the region of the conduit 12a that extends between the substantially horizontal portion 26 and the bleed point 24 may be free from any flow control elements 32. An example of such an arrangement is shown in Figure 4B, in which the bleed point 24 is not in the substantially horizontal portion 26, but rather in an inclined section of the conduit 12a between the substantially horizontal portion 26 and the bleed line 20. Effective gas removal is obtainable in such an arrangement, since gas has time to accumulate in the horizontal portion 26 upstream of the bleed point 24. The portion of conduit 12a immediately adjacent to and upstream of the bleed point 24 may be nonvertical, e.g. define a non-perpendicular angle relative to the substantially horizontal portion 26 of the coolant flow path. In some arrangements, the substantially horizontal portion 26 may be referred to as a settling portion, which is configured to facilitate the settling of the coolant and the accumulation of gas in an upper region of the portion. It will be understood that the substantially horizontal portion 26 may not be parallel to the horizontal plane of the vehicle 10 in some arrangements. For example, the substantially horizontal portion 26 may define a non-zero angle p relative to the horizontal plane of the vehicle 10, as is shown in the arrangement of Figure 4B. The angle p may be an acute angle. The angle p may be in the range + / - 45° relative to a horizontal plane of the vehicle 10. The angle p may be in the range + / - 30° in some arrangements. In some arrangements, the angle p is in the range + / - 20°, optionally, + / -15°, optionally + / -10° relative to a horizontal plane of the vehicle 10. In this way, the substantially horizontal portion can be slightly angled in the vertical direction, allowing for increased design tolerance, without significantly impacting the extent of gas removal. In arrangements in which the substantially horizontal portion 26 is inclined, the substantially horizontal portion 26 may be inclined away from the horizontal plane of the vehicle 10 to improve gas accumulation at the bleed point 24. In some embodiments, the minimum length L of the horizontal portion 26 may be increased as the angle p increases, so as to provide additional length for gas to accumulate in the upper region of the conduit 12a. In some arrangements, the conduit 12b downstream of the bleed point 24 (e.g. the heat exchanger inlet line 12b) may include a substantially horizontal portion downstream of the bleed point 24. The substantially horizontal portion of the conduit 12b may be immediately adjacent to and downstream of the bleed point 24. Such an arrangement has been found to reduce any significant disruption to the flow in the region proximal bleed point 24, improving the stability of the flow upstream of the bleed point 24, and thus improving gas accumulation and removal at the bleed point. It will be appreciated that the substantially horizontal portion of the conduit 12b downstream of the bleed point 24 may include any and all of the features described in relation to the substantially horizontal portion 26. A region of the conduit 12a having the bleed point 24 may be configured to promote the accumulation of gas in the upper portion of the conduit 12a and the collection of gas in the bleed line 20. In one arrangement, the bleed point 24 may be provided at a region of increased diameter of the conduit 12. Such an arrangement provides an increased flow area, decreasing a velocity of fluid therein and thereby allowing more time for gas to separate from coolant and accumulate at the bleed point 24. The diameter of the conduit 12a may be gradually increased around the bleed point 24, as shown in the cross-sectional view of the conduit 12a in Figure 5A. In some arrangements, a guide 34 may be provided in the conduit 12a to direct gas in the upper portion of the conduit 12a into the bleed line 20. The guide 34 may be connected to or integrally formed with the bleed line 20 so as to extend partially along a length of the upper portion of the conduit 12a. The guide 34 may extend in a direction substantially parallel to the direction of flow in the conduit 12a adjacent to the bleed point 24. The guide 34 may be configured to reduce turbulence of flow in the conduit 12a at the bleed point 24. It will be appreciated that the arrangement of Figure 5A and 5B may be used in combination in some arrangements. A method of securing vehicle components to a vehicle body structure is illustrated in Figure 6. The method includes the following steps: (a) providing a cooling system 100 having a plurality of conduits 12 defining a coolant flow path around the cooling system 100; (b) providing a degas tank 18 in fluid communication with the coolant flow path for venting gas 22 from the coolant; and (c) connecting the degas tank 18 to the coolant flow path via a bleed line 20 extending from a bleed point 24 at an upper portion of at least one conduit 12a of the plurality of conduits 12; 5 It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. It should also be noted that whilst the appended claims set out particular combinations of features described above, the scope of the present disclosure is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features herein disclosed. 10

Claims

1. A cooling system for a vehicle, the cooling system comprising:a plurality of conduits defining a coolant flow path around the cooling system;a pump configured to drive coolant along the coolant flow path;at least one vehicle component configured to be cooled by the cooling system;a heat exchanger for removing excess heat from the coolant; anda degas tank in fluid communication with the coolant flow path for venting gas from the coolant;wherein the degas tank is connected to the coolant flow path via a bleed line extending from a bleed point at an upper portion of at least one conduit of the plurality of conduits; andwherein the at least one conduit defines a substantially horizontal portion of the coolant flow path adjacent to and upstream of the bleed point.

2. The cooling system according to claim 1, wherein the at least one conduit defines a primary coolant flow path through the cooling system.

3. The cooling system according to claim 2, wherein the coolant flow path is arranged such that substantially all of the coolant in the cooling system flows along the primary coolant flow path during use.

4. The cooling system according to any preceding claim, wherein the at least one conduit is a return line configured to direct fluid from the one or more vehicle components to the heat exchanger.

5. The cooling system according to claim 4, wherein the at least one conduit is in fluid communication with a bypass line of the coolant flow path for selectively directing at least a portion of coolant to bypass the heat exchanger, and wherein the bleed point is located upstream of the bypass line.

6. The cooling system according to any preceding claim, wherein the substantially horizontal portion defines an internal diameter in the range of about 16 mm to 20 mm.

7. The cooling system according to any preceding claim, wherein the bleed point is located at a position lower than an uppermost point of the coolant flow path.

8. The cooling system according to any preceding claim, wherein the substantially horizontal portion is directly adjacent to and immediately upstream of the bleed point.

9. The cooling system according to any preceding claim, wherein the substantially horizontal portion extends along a minimum length of 25 mm.

10. The cooling system according to any preceding claim, wherein the substantially horizontal portion defines an angle in the range of+ / - 45° relative to a horizontal plane of the vehicle.

11. The cooling system according to any preceding claim, wherein the bleed line extends at an obtuse angle relative to the substantially horizontal portion of the coolant flow path.

12. The cooling system according to any preceding claim, further comprising a flow restrictor located in the bleed line.

13. The cooling system according to any preceding claim, wherein the at least one vehicle component comprises one or more of an electric drive unit and a traction battery.

14. A vehicle comprising the cooling system according to any preceding claim.

15. A method of degassing a cooling system for a vehicle, the method comprising:providing a cooling system having a plurality of conduits defining a coolant flow path around the cooling system;providing a degas tank in fluid communication with the coolant flow path for venting gas from the coolant; andconnecting the degas tank to the coolant flow path via a bleed line extending from a bleed point at an upper portion of at least one conduit of the plurality of conduits;wherein the at least one conduit defines a substantially horizontal portion of the coolant flow path adjacent to and upstream of the bleed point.IntellectualPropertyOfficeApplication GB2501670.0Search report under Section 17 of the Patents Act 1977Date search completed: 05 August 2025Claims searched: 1-15International classificationSubclass and subgroup Valid from B60K11 / 02 01 / 01 / 2006 F01P11 / 04 01 / 01 / 2006 F01P7 / 14 01 / 01 / 2006Field of searchWorldwide search of patent documents classified in the following areas of the IPC:B60K, B60H, F01PDatabases used in the preparation of this search report:SEARCH-PATENTDocuments considered to be relevantPatent literatureCategory Relevant claims Document of relevanceIntellectual Property Office is an operating name of the Patent Officewww.gov.uk / ipoA - DE 102015116407A1 (FORD GLOBAL TECH), See whole document, especially pump 5, engine 6, radiator branch 8, bypass branch 9, bleed line 11, degasser tank 12, return circuit heater branch 14, valve 20, 21 and Figures 1-6. A - FR 3052185 A1 (PEUGEOT CITROEN), See whole document, especially degassing box 4, bleed screw 8, pump 13, radiator 15, pipes 14, 16, 17, bypass tube 19 and Figures 1-2. A - EP 4446150 A1 (AMPERE SAS), See whole document, especially engine 11, radiator 15, pump 41, degassing vessel 50, bleed screws 111 and Figures 4-5.Categories Letter or symbol Description X Document indicating lack of novelty or inventive step. Y Document indicating lack of inventive step, if combined with another document of the same category. & Member of the same patent family. A Document indicating technological background. P Document published on or after the priority date but before the fling date of the present application. E Earlier application published on or after the filing date of the present application.

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