Patent Application
20160222866
This invention relates to a fluid cooling system for an engine, and to an engine and a vehicle comprising the same.
In order to prevent mechanical wear, engines will frequently make use of lubricants. The lubricants are interspersed between the moving parts of the engine in order that the parts can move more smoothly with respect to one another. The viscosity of the lubricants in an engine will vary with temperature, and usually the lubricants are chosen such that they will perform well at the engine's typical operating temperature. However, for an engine which generates a significant amount of heat, such as an internal combustion engine, the engine will typically begin at an ambient temperature before rising to its typical operating temperature as the engine generates heat. Therefore there is a period when the engine is started during which the lubricants within the engine are beneath their optimum operating temperature. For this reason it is often desirable to allow components such as pistons and cylinders to heat up as quickly as possible when the engine is started, in order to ensure that the lubricating oils within the pistons are as effective as possible.
However, pistons and cylinders are also at risk of becoming too hot. In particular, the components contained at the head of the cylinder such as spark plugs and sensing apparatus are often very sensitive to being overheated. Therefore cylinders in modern engines are provided with an outer shell, or jacket, which is filled with a fluid, typically water. These water jackets provide cooling as the heat from the piston and the cylinder is absorbed by the water. The warmed water is then pumped out of the jacket and replaced with colder water to absorb more heat.
However, during engine start up, the jacket is still full of water, and as such the jacket tends to absorb heat, slowing the warming of the piston and the cylinder, and therefore slowing the warming of the lubricant and reducing the efficiency of the lubricant shortly after the engine is started. This effect is worsened if cooler water is allowed to flow into the jacket during the warming up period.
It is important therefore to provide a water jacket that can provide effective cooling for the vehicle while also minimising heat loss during the early stages after the internal combustion engine is started.
In accordance with an aspect of the present invention there is provided a fluid cooling system for an engine. The fluid cooling system comprises a first cooling jacket, a second cooling jacket and a junction, the junction comprising: a primary duct suitable for conveying fluid into the junction; and a secondary duct and a tertiary duct, the secondary and tertiary ducts being in fluid communication with the primary duct and being suitable for conveying fluid out of the junction. The secondary duct is in further fluid communication with the first cooling jacket and the tertiary duct is in further fluid communication with the second cooling jacket. The secondary duct is arranged at a substantially oblique angle to the primary duct at the point at which the secondary duct meets the primary duct, and the tertiary duct is arranged at a substantially acute angle to the primary duct at the point at which the tertiary duct meets the primary duct.
In this way a junction is provided in which fluid is able to travel easily from the primary duct into the secondary duct, but in which fluid travelling into the tertiary duct encounters a greater resistance due to the acute change of direction which the fluid must undergo. As such, more fluid will tend to flow through the secondary duct than the tertiary duct. This difference can be provided based solely on the shape and relationship of the ducts, without the need for complicated valve systems which may be subject to mechanical failure after repeated use. As such, when fluid is flowing under pressure through the junction, for example because it is being pumped, more fluid will tend to be supplied to the first cooling jacket, through the secondary duct, than will be supplied to the second cooling jacket, through the tertiary duct. The larger quantities of fluid flowing through the first cooling jacket will tend to cause the first cooling jacket to absorb more heat than the second cooling jacket, all other factors being equal. In use, therefore, an engine component which is contained inside the first cooling jacket will tend to have more heat energy removed than an engine component which is contained inside the second cooling jacket.
By substantially oblique it is meant that fluid flowing from the primary duct into the secondary duct will undergo a translation in direction of travel which is less than ninety degrees. It may be that fluid flowing from the primary duct into the secondary duct will undergo a translation in direction of travel which is less than thirty degrees. By substantially acute it is meant that fluid flowing from the primary duct into the tertiary duct will undergo a translation in direction of travel which is greater than ninety degrees. It may be that fluid flowing from the primary duct into the tertiary duct will undergo a translation in direction of travel which is greater than one hundred and fifty degrees. It may be that the tertiary duct is arranged with respect to the primary and secondary ducts, for example by virtue of required translation in direction of travel of fluid and/or by virtue of size, so that a majority of the flow from the primary duct enters the secondary duct.
Typically, the primary and secondary ducts form a single duct. Where this is the case, it may be that a hole is bored in the single duct that forms the primary and secondary ducts, with the tertiary duct being attached to the primary and secondary ducts at the hole in order to form the junction.
It may be that the engine is an internal combustion engine. However a cooling system according to the invention may be used with any engine or system which requires cooling, particularly where such engine or system requires or would benefit from cooling at least at two differing rates.
Where the engine is an internal combustion engine, it may be a piston driven internal combustion engine. Where this is the case, the fluid cooling system may comprise a first water jacket for a piston cylinder head, the secondary duct being in fluid communication with the first water jacket. The fluid cooling system may comprise a second water jacket for a piston cylinder, the tertiary duct being in fluid communication with the second water jacket. Typically, such a second water jacket is intended to cool a section of the piston cylinder through which the piston travels.
It may be that the tertiary duct is connected to a lower portion of the second water jacket. Lower here means lower with respect to gravity. It may be that the tertiary duct is connected to the bottom half of the second water jacket. It may be that the tertiary duct is connected to the bottom of the second water jacket, or it may be that the tertiary duct is connected adjacent the bottom of the second water jacket.
Typically, the fluid cooling system further comprises a pump, the pump being in fluid communication with the primary duct and suitable for pumping fluid into the junction. It may be that the pump is in fluid communication with at least one of the first and second water jackets and is suitable for pumping fluid out of the first and/or second water jacket.
Alternatively, the fluid may be moved around the system using some other method, for example by relying upon convection currents.
It may be that the fluid comprises water. Typically, such fluid is primarily water by mass. The fluid may comprise other fluids such as additives intended to lower the freezing point of the water.
It may be that the secondary duct has a bore substantially the same as the bore of the primary duct. It will be appreciated that this means that it has the same cross-sectional area. It may be that the tertiary duct has a bore smaller than the bore of the secondary duct. It may be that the tertiary duct has a bore smaller than the bore of the primary duct. A smaller cross sectional area in the bore of the tertiary duct helps to further reduce the flow of fluid through the tertiary duct as compared to the secondary duct.
It may be that the second cooling jacket comprises a heater. The heater may be located inside the second cooling jacket. Alternatively, the heater may be located adjacent to the second cooling jacket. The heater may be an electrical heater.
The second cooling jacket may comprise a first compartment and a second compartment, the second compartment being joined to the first compartment by one or more capillaries or ducts, the tertiary duct being connected to the first compartment. Where a heater is provided, the heater will typically be located in or next to the second compartment, such that the heater can heat fluid within the second compartment.
It may be that the fluid cooling system has a typical orientation for use, wherein the tertiary duct reaches the second cooling jacket at a point substantially lower than the junction when the fluid cooling system is in the typical orientation.
In an aspect, the invention provides a method of cooling an engine, the method comprising:
In an aspect, the invention provides an engine which comprises a fluid cooling system as described above. In an, the invention provides a vehicle which comprises an engine, the engine comprising a fluid cooling system as described above.
Exemplary embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:
The first secondary duct is further connected to a first water jacket 106, which is intended to fit around and provide cooling for a piston cylinder head (not shown). The first water jacket 106 is provided with a first outflow 107.
The first tertiary duct 104 is further connected to a second water jacket 108 which is intended to fit around and provide cooling for the section of a piston cylinder through which a piston head travels (also not shown). The second water jacket 108 is provided with a second outflow 109, which comprises a valve 110.
In use, water is pumped around the first cooling system 101 in the directions shown by the arrows 111, so that the water will absorb excess heat from the piston cylinder and the piston cylinder head. The water then travels via the first and second outflows 107, 109, to a radiator where the water is allowed to cool before being pumped through the first cooling system 101 again. This prevents the piston cylinder and the piston cylinder head from becoming hot enough to damage the components contained therein.
However when the engine is cold, which typically occurs immediately following an engine start, it may be advantageous to encourage rapid warming of the piston cylinder. When the engine is cold, therefore, the valve 110 may be closed to prevent outflow of water from the second water jacket 108 through the second outflow 109. Hence water in the second water jacket 108 will tend to be trapped there. The water trapped in the second water jacket 108 then absorbs heat from the piston cylinder. This still slows the rate at which the piston cylinder will heat up, but since the warmed water is retained next to the piston cylinder, the piston cylinder is able to heat up faster than would be the case if the valve 110 was open.
Typically, even immediately after start up it is still necessary to pump water through the first primary and first secondary ducts 102, 103 to the first water jacket 106. This is because the cylinder head tends to generate a lot of heat very rapidly, and also contains equipment which is sensitive to overheating.
The first tertiary duct 104 and the second water jacket 108 are designed to reduce syphoning of water into and out of the second water jacket 108, and so more effectively trap water, particularly warmer water, in the second water jacket 108.
Firstly, the first tertiary duct 104 is connected to the junction 105 at an acute angle to the first primary duct 102. As a result, the flow of water through the first tertiary duct 104, when such a flow occurs, is also at an acute angle to the flow of water through the first primary duct 102. Therefore water flowing through the first primary duct 102 to the junction 105 must alter its course substantially in order to enter the first tertiary duct 104, as indicated by the arrows 111. In contrast, the first secondary duct 103 is arranged as a continuation of the first primary duct 102, so that water flowing from the first primary duct 102 into the first secondary duct 103 does not need to alter its course. The inventor has found that this relationship between the ducts tends to reduce the amount of water which flows into the second water jacket 108, in particular when the valve 110 is closed.
Secondly, the first tertiary duct 104 is connected to the bottom of the second water jacket 108. As the water in the second water jacket 108 absorbs heat from the piston cylinder, the hottest water will tend to rise to the top of the second water jacket 108, which is also the top of the diagram shown in
Once the piston cylinder has achieved a desired temperature, the valve 110 can be opened to allow a flow of water out of the second water jacket 108. Some of the colder water being pumped through the first primary duct 102 will then travel down the first tertiary duct 104 and into the second water jacket 108, where it can absorb heat from the piston cylinder and so help to regulate the temperature of the piston cylinder.
However, even once the valve 110 is open the water flow through the first tertiary duct 104 will still be less than the water flow through the first secondary duct 103, due to the acute angle between the first tertiary duct 104 and the first primary duct 102. As such, more cooling water is delivered to the first water jacket 106 than to the second water jacket 108. As such the piston cylinder loses less heat than, and can be maintained at a higher temperature than the piston cylinder head. The precise relationship between the water pumped through the secondary and tertiary ducts can be controlled by adjusting the angle of the tertiary duct relative to the primary duct.
The first tertiary duct 104 is also narrower than the first secondary duct 103, in that it has a bore with a smaller cross-sectional area. This has the effect of further restricting the water flow into the second water jacket 108. The relationship between the water pumped through the first secondary duct 103 and the first tertiary duct 104 can therefore also be controlled by changing the bore of the tertiary duct relative to the bore of the secondary duct.
As with the first cooling system 101, the second tertiary duct is connected to the bottom of the fourth water jacket to reduce thermal syphoning. The second tertiary duct 204 is also arranged at an acute angle to the second primary duct 202 in order to reduce water flow from the second primary duct 202 into the second tertiary duct 204.
As with previous embodiments, the quaternary ducts 312 are connected to the bottom of the sixth water jacket 308 to reduce thermal syphoning. The third tertiary duct 304 is also arranged at an acute angle to the second primary duct 302 in order to reduce water flow from the third primary duct 302 into the third tertiary duct 304.
In an embodiment, one of the quaternary ducts 312 may be sealed, so that no water may flow through it. Water can then still reach the sixth water jacket 308 through the open quaternary duct 312, while the sealed quaternary duct 312 serves only to support the water cooling system by maintaining the spatial relationship between the sixth water jacket 308 and the ducts 302, 303, 304, 312.
In extreme cold conditions, it can become very difficult to start an internal combustion engine. In particular, at -40 degrees centigrade and below, a petrol engine may be unable to start. Therefore it can be helpful to provide further assistance to an engine in these conditions.
The fourth cooling system 401 comprises a seventh water jacket 406 and an eighth water jacket 408. The eighth water jacket 408 comprises a first compartment 413 and a second compartment 414. The first and second compartments 413, 414 are joined by several capillaries 415, such that fluid can flow between the first and second compartments by passing through the capillaries. When installed in an engine, the first compartment 413, second compartment 414 and the capillaries 415 enclose a piston cylinder (not shown) as is described above with reference to
The fourth cooling system 401 further comprises a heating element 416, which is located in the second compartment 414. The heating element 416 comprises a conductor which, when provided with an electrical current, produces heat. The heating element 416 is electrically insulated from the fluids in the heating element 416 in order to prevent the element discharging into the cooling fluid inside the eighth water jacket 408.
At very low ambient temperatures such as -40 degrees centigrade, therefore, the heating element 416 can be used to help heat fluid in the eighth water jacket 408. The heated fluid then in turn heats the piston cylinder, and so assists the engine in starting.
Fluid heated by the heating element 416 tends to rise as indicated by arrow 417. The fluid heated by the heating element 416 can also flow from the second compartment 414 into the first compartment 413 through the capillaries 415 as indicated by the arrow 418. However the small size of the capillaries 415 means that the transit of liquid between the two compartments is slow, especially when the valve 410 is closed so that there is no overall flow of fluid through the eighth water jacket 408. Hence the heated fluid tends to accumulate at the top of the second compartment 414, well away from the fourth tertiary duct 404. This tends to reduce thermal syphoning of warm fluid out of the eighth water jacket 408. As such the location of the fourth tertiary duct 404 again helps to maintain and increase the temperature of the piston cylinder as is discussed above with reference to other embodiments.
Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do 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. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1317165.7 | Sep 2013 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/066180 | 7/28/2014 | WO | 00 |
