WO2000060236A1

WO2000060236A1 - Heat-storage device for a liquid-cooled internal combustion engine

Info

Publication number: WO2000060236A1
Application number: PCT/SE2000/000585
Authority: WO
Inventors: Torbjörn SVERKER
Original assignee: Thermostore I Lulea Ab
Priority date: 1999-04-06
Filing date: 2000-03-24
Publication date: 2000-10-12
Also published as: SE511803C2; AU3993400A; SE9901218D0; SE9901218L

Abstract

The invention concerns a heat-storage device for a liquid-cooled internal combustion engine (2) designed to heat the engine or other parts that are included in its circuit before the engine is started, that includes a heat-insulated container (7) with an inner volume reserved for storing heated coolant, a displaceable mobile piston device (8) placed into the inner volume that limits the volumes of a first (6) and a second (9) chamber that can be put into and taken out of communication with an inlet and an outlet for the coolant channels of the engine block, a pump (10) by which coolant can be led from the coolant channels of the engine block to the storage container, whereby a valve function is arranged in the storage container so that heated coolant can be made to flow into the storage container while the engine is in use. In order to reduce the number of moving parts, the outlet of the connection that is arranged in the storage container is designed as a channel (24) allowing the first and second chambers (6, 9) to communicate with each other when the piston device (8) is located at a particular position in the storage container, whereby the said channel is arranged to be blocked when the engine is stopped.

Description

Heat-storage device for a liquid-cooled internal combustion engine

The present invention concerns a heat-storage device for a liquid-cooled internal combustion engine according to the preamble to claim 1.

The problems associated with the cold-start of internal combustion engines in, for example, vehicles, are well known, and these problems are solved by raising the temperature of the engine before it is started by connection to a separate energy source such as an electrical heater element or suchlike placed in the coolant system. Devices are also known that preserve coolant that has been warmed by the engine by storing the liquid inside a heat- insulated container arranged to communicate with the coolant system of the engine. Such an arrangement is known from, for example, SE 502 957, which also provides the technology from which the present invention originates, according to the preamble to claim 1. The said patent document describes a heat-storage device that includes a heat- insulated storage container with an inner volume designed for storage of the heated coolant. A displaceable mobile piston device is located in the inner volume and limits the volumes of a first chamber and a second chamber, which can be connected to and disconnected from an inlet and an outlet to the coolant channels in the engine block. A pump is also included in the arrangement with the aid of which coolant can be led from the channels in the engine block to the storage container so that stored warm coolant can be pumped from the storage container to the engine block while at the same time cold coolant from the engine gradually fills and replaces the liquid that is removed from the container. In order to ensure that the volume in the container always has essentially the same temperature as the rest of the coolant circulating in the engine, the storage container is designed such that coolant can be caused to flow into and out of the storage container during operation of the engine. In order to make this possible, a piston device is provided with a valve device by means of which the first and second chambers of the storage container can be connected to each other when the piston device is located at certain predetermined positions in the storage container.

Although the heat-storage device described in the above-mentioned document has proved to function well, it is still desirable to reduce as far as is possible the number of moving parts in the storage container itself. The reason for this, naturally, is that all moving parts experience wear as time passes and that these can bind due to the presence of particles, and other dirt and sediment, in the coolant. Another reason that it is desirable to reduce the number of moving parts inside the storage container is that it makes it possible to produce a container that cannot be disassembled, which in turn means that the storage container can be hermetically sealed and in this way achieve considerably improved properties of heat insulation.

Consequently, one intention of the present invention is to achieve a heat-storage device of the type described in the introduction in which the number of moving parts in the storage container has been reduced to a minimum, while maintaining the satisfactory functioning of the device.

This intention of the invention is achieved by a heat-storage device that exhibits the special properties and characteristics that are specified in claim 1. The dependent claims reveal other properties and advantages of the invention.

In a somewhat modified embodiment of the invention, it is worth considering replacing, for example, the channel that runs axially and that, in the preferred embodiment of the invention described below forms part of the cavity of a tube-formed element that stretches through the storage container, with a channel formed on the inner surface of the wall that limits the inner volume of the storage container. An alternative would be to replace the tube- shaped element by a rod-shaped element and to form the channel on the outer surface of the said rod.

In a further embodiment it is worth considering arranging at least one additional channel in the storage container. In this case it would be suitable that the additional channel be situated in association with the end of the storage container from which the stored liquid is led out when the storage container is emptied of its contents. In other words, this channel would be able to form a flow-through connection between the chambers and this makes it possible not only to draw off the volume of liquid that is stored in the chamber of the storage container, but also the volume of liquid that is stored in the cavity of the ring-shaped element.

The invention will now be described more closely with reference to the enclosed drawings in which fig. 1 shows a partially sectioned schematic illustration of a liquid-filled internal combustion engine to which a heat-storage device according to the present invention is attached, fig. 2 shows a longitudinal section of the heat-storage device through which circulating coolant passes while the engine is running, fig. 3 shows a view equivalent to fig. 2 whereby stored coolant is led from the device to the internal combustion engine, fig. 4 shows a somewhat modified embodiment of the heat-storage device according to the invention and fig. 5 shows a view equivalent to fig. 4 whereby stored coolant is led from the device to the internal combustion engine.

With reference to the figures, 1 identifies a liquid-cooled internal combustion engine, the engine block 2 of which contains in a known manner a coolant pump 3, channels for circulating coolant (not shown in detail), and an air-cooled heat exchanger 4 known as a radiator, attached to the engine.

One end of the coolant channels of the engine block 2 is connected by a conduit 5 to a first chamber 6 of a heat-insulated storage container 7 that is part of the heat-storage device according to the invention. The said first chamber 6 forms part of a defined inner volume in the storage container that, through a reciprocatingly moving piston device 8 that is inside of it, also limits the volume of a second chamber 9, which in turn is connected, though a pump 10 and a conduit 11, to the other end of the coolant channels of the engine block 2.

As fig. 2 and fig. 3 make clear, the heat-insulated storage container 7 is equipped with inlet- and outlet orifices 12, 13 that are located at the end 14 of the container and to which heat-insulating closure devices or valve devices 15, 16 are arranged in order to prevent heat conduction from the storage container 7. The heat-insulating closure devices or valve devices 15, 16 are influenced for their manoeuvring by an actuator and manoeuvring device that is not shown in the figure and is not described in more detail here. This actuator and manoeuvring device is symbolised in the figures by double-headed arrows. It is appropriate that the said actuator and manoeuvring device is of a type whose influence on motion occurs electromagnetically, and it is a further advantage if it is designed so that the cone that is part of each valve is brought into the open position when the electromagnet is activated, and into the closed position by the influence of a return spring that is part of each valve, when the electromagnet is deactivated. One valve device 16 is arranged in the centre of the end 14 of the storage container 7, and a tube-shaped element 17 originates from the same and stretches axially through the central volume of the storage container 7. The said tube-shaped element 17 is provided at the end that is furthest away from the valve device 16 with a first and a second set of radial orifices, 18 and 19 respectively, that stretch radially through the wall, distributed at equal mutual distances from each other around the circumference of the said tube-shaped element 17. As the figures make clear, each set of orifices 18, 19 is arranged lying in a plane that cuts the principal axis of the tube-shaped element 17 at right angles, the said planes being parallel and situated at a distance from each other and at a distance from the inner surface of what in the figure comprises the upper end wall 20 of the storage container that is determined by parameters that will become clearer in the description that follows.

The piston device 8 can slide axially guided by the tube-shaped element 17 through its co-operation with a hole 22 equipped with a bush 21 that stretches axially through the piston device 8. A spring device 23 is arranged at the end of the storage container that is farthest from the valve devices 15, 16. This spring device 23 is active between the piston device 8 and the inner surface of the end wall 20, and has a spring characteristic that is chosen to limit the motion of the cylinder device 8 in the direction towards the end wall of the storage device and chosen such that the piston device 8 is pushed out away from the end wall 20.

In order to make it possible for heated coolant to flow into and out of the storage container 7 while the engine is running, and to make it possible prior to cold-start of the engine for stored warm coolant to be led out from the first chamber 6 of the storage container 7 to the engine block 2, while the other chamber 9 of the storage container at the same time is filled with an equivalent volume of cold coolant from the engine block 2, it must be possible to put the first and the second chambers of the storage container in flow communication with each other, depending on the position of the piston device in the inner volume of the storage container.

This occurs in the embodiment of the invention that is described here by the first connection between the storage container 7 and the engine block 2 having its outlet that is arranged in the storage container designed as a channel 24 that passes axially through the storage container. To be more exact, the channel 24 is so placed in the storage container that it forms a flow connection between the chambers 6, 9 when the piston device 8 has taken up a position in front of the channel 24 such that the orifices 18, 19 on each side of the piston device are open. This is clearly seen by studying more closely the partially sectioned view from fig. 2 that is shown enlarged, whereby the channel 24 that is formed is shown by a double-headed arrow. More accurately, in the preferred embodiment of the invention that is described, the channel 24 forms part of the cavity 25 of the tube-shaped element 17; in other words, it stretches between the two sets of orifices 18, 19 that are arranged in the said tube- shaped element 17.

The heat-storage device according to the invention is shown in fig. 4 and fig. 5 in a somewhat modified embodiment, where items with figures over 100 on the diagram essentially agree with items belonging to the embodiment of the invention that has been described above. New items, on the other hand, are specified with consecutively running numbers, and the differences that do exist between this embodiment and the embodiment described earlier become most clear if the partial enlargement that has been taken out of fig. 4 is studied in more detail. As this enlargement shows, what were previously a first and second set of radial orifices 18 and 19 that passed through the wall of the tube-formed element have been replaced by two tracks 26 that run axially and diametrically opposite each other. In order to ensure that the volume of liquid that can be stored in the first chamber 106 of the storage container 107 is as large as possible while at the same time the volume of the second chamber 109 is brought down to a minimum, the tracks 26 have been given such a placement that the open orifices 118, 119 are offered to each side of the piston device 108 when the same is positioned in contact with the inner surface of the end wall 120 of the storage container. In this way a channel 124 is formed by the orifices 118, 119 and the cavity 125 of the tube- formed element that allows the first chamber 106 and the second chamber 109 of the storage container 107 freely to communicate with each other. One end surface of the piston device 108 is provided with a ring-shaped recess 27 that, together with the inner surface of the end wall 120, limits the second chamber 109 when the piston device is in contact with the said end wall 120. The function of the present heat-storage device will now be described with reference to figs. 1 to 3.

^"While the engine 1 is in use, the coolant that is led through the channels of the engine block 2 is heated. The heated coolant is made to circulate by the effect of the coolant pump 3 of the engine through the engine block 2, the heat-exchanger 4, the special heat-exchanger whose task is to heat fresh air that is led into the interior of the vehicle (not shown in the diagram) and through the storage container 7 of the present heat-storage device.

The position of the piston device 8 in the storage container 7 before the internal combustion engine is started is suggested in fig. 2 by a dashed line, whereby both valve devices 15, 16 are open and the piston device 8 is placed as suggested in its lowest position. Liquid is driven by the influence of the coolant pump 3 of the engine in the direction that is shown by the arrow 26, and thus into the first chamber 6 of the storage container, whereby the piston device 8 moves in the direction that is upwards in the figure, at the same time as the other chamber 9, seen in the figure as the upper chamber, is emptied of its liquid contents. Emptying of the second chamber 9 occurs by the liquid that is present in it being led into the cavity 25 of the tube-shaped element 17 through the orifices 18,19, in order then to pass the valve device 16, the pump 10, and finally to be returned to the coolant channels of the engine block 2 via the conduit 11.

When the piston device 8 has moved to the position that is shown by the full lines in fig. 2, namely to a position midway between the upper 19 and lower 18 set of orifices in the tube-shaped element 17, a flow communication is established between the two chambers 6, 9 of the storage container 7. It should be clear that the pressure in the two chambers will be essentially equal due to the free communication that is established in this way. However, the pressure will be somewhat lower in the second chamber 9 due to the effect of the flow and due to the effect of the fall in pressure after (with respect to the direction of flow of the fluid) the piston device 8, whereby the piston device 8 will consequently attempt to move upwards in the figure, that is, in the direction towards the spring device 23. As has been mentioned above, the spring device 23 has a spring constant and/or general design that have been chosen so that the piston device 8 is located between the upper and lower sets of orifices 18, 19, seen in the figure, when the coolant flows into and out of the container 7.

The position of the piston device 8 after the engine has stopped is shown with a full line in fig. 3. As the figure shows, the spring device 23 has pushed the piston device in a direction away from what in the figure is the upper end wall 20 to a position in which the lower set of orifices 18 are blocked by the piston device, whereby the flow communication between the chambers 6 and 9 is broken. The valve devices 15, 16 are in this condition in a closed position whereby the coolant that is present in the first chamber 6 of the storage container is stored for future use.

Before the engine 1 is restarted, the valve devices 15, 16 are manoeuvred to their open positions and then the pump 10 is activated so that cold coolant from the engine is led by the action of the pump and through the conduit 11 from the second end of the engine block 2 into the second chamber 9 of the storage container through the cavity 25 of the tube-shaped element 17, as is shown by the arrow 27 in fig. 3. The piston device 8 is moved by the effect of the flow of the coolant and the relative rise in pressure on the side of the piston device 8 that is in flow connection with the second chamber 9, in a direction that is downwards in the figure, such that warm fluid that is stored in the first chamber 6 is led into the first end of the engine block 2, at the same time as cold coolant from the engine block is led into and fills the second chamber 9 of the storage device 7. In this way, cold coolant in the engine block 2 is replaced by warm stored coolant from the heat-insulated storage container 7, and thus the engine 1 is ready to be started. Once the engine has been started, coolant is led in the opposite direction, namely, into the first chamber 6 of the storage container 7, by the liquid pump 3 of the engine, whereby the moveable piston device 8 is again moved to a position above the channel 24, through the effect of the flow, that is, to the upper position shown in fig. 2. In this way, the first chamber 6 and the second chamber 9 are again free to communicate with each other through the flow communication 24 that is formed, allowing coolant to circulate into and out of the storage container 7.

The present invention is not limited to that which has been described above and shown in the drawings, but can be changed and modified in a number of different ways within the framework of the innovative concepts specified in the following claims.

Claims

1. A heat-storage device for a liquid-cooled internal combustion engine (2), intended for heating the engine or other parts that are included in the coolant circuit prior to starting the engine, comprising a heat-insulated container (7) having an inner volume reserved for storing heated coolant, a displaceable mobile piston device (8) placed into the inner volume and functioning to devide the inner volume into a first (6) and a second (9) chamber that can be put into and taken out of communication with an inlet and an outlet respectively for the coolant channels of the engine block, a pump (10) by which coolant can be led from the coolant channels of the engine block to the storage container, whereby heated coolant is made to flow into and out of the storage container while the engine is in use, characterised in that the outlet of the connection that is arranged in the storage container (7) is designed as a channel (24) allowing the first and second chambers (6, 9) to communicate with each other when the piston device (8) is located at a particular position in the storage container, whereby the said channel is arranged to be blocked when the engine is stopped.

2. Heat- storage device according to claim 1, characterised in that the storage container (7) includes at least one spring element (23), which has the task of pushing the piston device (8) backwards away from the outlet, once the engine has stopped, to a position where the communication between the first and the second chambers (6, 9) is interrupted.

3. Heat-storage device according to any of the preceding claims, characterised in that the outlet includes two sets of orifices (18, 19) arranged at an axial distance from each other in the storage container (7), or a continuous track (26) running axially in the storage container.

4. Heat-storage device according to claim 3, characterised in that the piston device (8) has an orifice (22) with which it is guided to slide when taken up on an element

(17) that stretches axially through the centre of the inner volume of the storage container (7), whereby the orifices (18, 19) or the axially running track (26) are formed in the said element (17).

5. Heat-storage device according to claim 4, characterised in that the element (17) is tube-formed and that the first and the second chambers (6, 9) communicate with each other through the cavity (25) of the tube-shaped element (17).

6. Heat storage device according to claim 5, characterised in that the coolant that is led into and out from the storage container (7) passes through the tube-shaped element