SE541028C2 - A cooling system for a vehicle and a method for filling the cooling system - Google Patents

Abstract

The present invention relates to a cooling system for a vehicle and a method for filling the cooling system. The cooling system comprises a coolant circuit configured to cool a combustion engine (2), a pump (3) circulating the coolant in the coolant circuit, an expansion tank (13), a static line (14) extending between the expansion tank (13) and a part of the coolant circuit, at least one deaeration line (18, 19) extending between a upper part of the coolant circuit and the expansion tank (13), and a filling nipple (21) arranged in the coolant circuit. The cooling system comprises a valve member (20) arranged in the static line (14) comprising a valve body (20a) which is configured to be moved to a closed position and to block the coolant flow via the static line (14) to the expansion tank (13) during a first part of a coolant filling process, via said filling nipple (21), to the coolant circuit.

Description

A cooling system for a vehicle and a method for filling the cooling system BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relates to a cooling system for a vehicle and a method for filling the cooling system according to the preamble of claim 1.

A cooling system in a vehicle may comprise a coolant circuit for cooling of a combustion engine, a coolant pump circulating the coolant in the coolant circuit and an expansion tank connected to the coolant circuit via at least a partly vertical line called the "static line". Generally, the expansion tank is situated at a level above the coolant pump. Such a design results in a vertical column of coolant extending from the level of the pump up to the level of expansion tank. This column of coolant provides assurance that the coolant close to the inlet of the pump will be at a positive pressure. The fact that the coolant close to the pump inlet is at a positive pressure eliminates the risk of cavitation when the pump is started.

In some cases, coolant is to be supplied to an empty cooling system. The coolant may be supplied to the cooling system via the expansion tank or via a filling nipple arranged at a lower part of the coolant circuit. In certain vehicles, the expansion tank is arranged at a lower level than the highest located part of the coolant circuit. In such a vehicle, specific tools has to be used for filling the cooling system in order to prevent that the coolant flows out of the expansion tank before the coolant circuit is completely filled with coolant.

WO 2011/099899 shows a method for filling a coolant system for an internal combustion engine. The method comprises the steps of filling the coolant system with liquid coolant, removing air pockets by creating an underpressure in the coolant system by pumping out liquid coolant from the expansion tank to a reservoir tank and compensating the removed air pockets and the pumped out liquid coolant from the expansion tank with liquid coolant.

SUMMARY OF THE INVENTION The object of the present invention is to provide a cooling system making it possible to fill it up with coolant in a relatively simple manner even when it comprises an expansion tank arranged at a relatively low level.

This object is achieved by the cooling system defined in the characterizing portion of claim 1. When a cooling system is empty and it is to be filled with coolant, an external coolant filling device may be connected to a filling nipple of the coolant circuit. The filling nipple is preferably arranged at a low level of the coolant circuit. The cooling system comprises a valve member which is arranged in the static line. The valve member is configured to be moved to a closed position during a first part of a coolant filling process of the cooling system. In the closed position, the valve member prevents coolant to reach the expansion tank via the static line. Consequently, it is possible to completely fill up the coolant circuit with coolant during the first part of the coolant filling process while the expansion tank is still empty. Thus, there is no risk that the coolant flows out of the expansion tank before the coolant circuit is completely filled with coolant. As soon as the coolant circuit is completely filled with coolant, a second part of the coolant filling process is started at which the expansion tank is filled with coolant. During the second part of the coolant filling process, coolant is directed from the coolant circuit, via at least one deaeration line, to the expansion tank. The coolant entering the expansion tank also fills up an upper part of the static line arranged at a higher level than the valve member. When the coolant level reaches a predetermined level in the expansion tank, the coolant supply to the cooling system is stopped.

Alternatively, it is possible to supply coolant to the cooling system, via the expansion tank instead of via filling nipple, during the second part of the coolant filling process.

According to the invention, the valve member is configured to be automatically moved to the closed position during the first part of the coolant filling process and to an open position at least when the pump starts to circulate coolant in the coolant circuit. In this case, an operator does only need to attach the external coolant filling device to the filling nipple and activate an external pump or the like which supplies coolant to the cooling system and to inactivate the external pump when the coolant circuit has been completely filled during the first part of the coolant filling process and the expansion tank during the second part of the coolant filling process. Alternatively, the valve member may be manually moved between the closed position and the open position by the operator.

The valve member may be moved to the closed position by the coolant when a lower part of the static line, which is arranged below the valve member, has been completely filled with coolant. In this case, the valve member is automatically moved to the closed position when the coolant level reaches the level of the valve member in the static line. During the following raising of the coolant level in the coolant circuit, the coolant may act with a pressure on the valve member keeping the valve member in the closed position until the coolant circuit is completely filled with coolant. The valve member may be moved to the open position by the coolant when an upper part of the static line, which is arranged above the valve member, has been at least partly filled with coolant. As soon as the coolant circuit is completely filled with coolant, coolant is directed from the coolant circuit, via at least one deaeration line, to the expansion tank and the upper part of the static line arranged above the valve member. When the upper part of the static line is filled with coolant, the coolant pressure on the upper side of the valve member eliminates the coolant pressure on the lower side of the valve member and the valve member is moved to the opening position.

The automatic movements of the valve member between the open position and the closed position may be performed in alternative ways. The attachment of the external coolant filling device to the filling nipple may, for example, initiate, via a suitable mechanical mechanism, a movement of the valve member to the closed position. In a corresponding manner, the detachment of the external coolant filling device from the filling nipple may initiate an automatic movement of the valve member to the open position. Alternatively, a sensor may detect when the external coolant filling device has been attached to the filling nipple and initiate a movement of the valve member to the closed position. As soon as the sensor detects that the external coolant filling device has been detached from the filling nipple, it may initiate a movement of the valve member to the open position.

According to an embodiment of the invention, the valve body is movably arranged in an axial direction between the open position and the closed position. The valve body may be piston shaped. The coolant supplied to the lower portion of the static line may move such a valve member in an axial direction in the static line from the open position to the closed position The existence of such a valve member does not significantly disturb the coolant flow in the static line during operation of the cooling system. Alternatively, the valve body may be pivotally arranged between the closed position and the open position. Such a valve body may be a butterfly valve or the like.

According to an embodiment of the invention, the valve body has a somewhat lower density than the coolant such that it floats in the coolant. Such a valve body will be in the closed position due to its floating properties during the first part and the second part of the filling process. Such a valve body is moved to the open position by the coolant flow when the pump starts to circulate coolant in the cooling circuit. Such a valve body may be ball-shaped.

According to an embodiment of the invention, the valve member comprises a stop member defining the closed position for the valve body. The stop member may have a stop surface to come in contact with a surface of the valve body when it reaches the closed position. Preferably, the stop surface of the stop member and a contact surface of the valve body are complementary shaped such that they prevent coolant leakage past the valve member.

According to an embodiment of the invention, the deaeration line is an engine deaeration line or a radiator deaeration line. The uppermost parts of the coolant circuit may be arranged in the combustion engine and / or a radiator where the coolant is cooled. It is important to deaerate the uppermost portions of the coolant circuit in order prevent formation of air pockets in the coolant circuit. At least one of said deaeration lines may direct the coolant to the expansion tank when the coolant circuit has been completely filled.

According to an embodiment of the invention, the expansion tank is located at a lower level that at least a part of the coolant circuit. In such a cooling system, the use of the present arrangement facilitates the coolant filling process of the cooling system significantly. The expansion tank may, for example, be located at a lower level than the coolant circuit in the combustion engine and /or the radiator. The coolant circuit through the compression engine and/or the radiator is in some kinds of vehicles arranged at a higher level than the expansion tank. Such a vehicle may be a bus.

Busses have many times a design making it difficult to arrange an expansion tank at a higher level than the highest parts of the coolant circuit.

According to an embodiment of the invention, the coolant circuit comprises a further valve member of the initially mentioned kind which is arranged in a part of the coolant circuit which is to be filled with coolant after that a higher located part of the coolant circuit has been filled with coolant. In certain cases, it is suitable to fill lower located part at a later stage than a higher located part in the coolant circuit. In this case, it is possible to arrange a valve member of the initially defined kind in a line directing coolant to the lower located part.

The initially mentioned object is also achieved by the method defined in claim 12.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, a preferred embodiment of the invention is described as an example and with reference to the figures, on which: Fig. 1 shows a cooling system according to the invention, Fig. 2a - 2b show a first embodiment of the valve member in Fig. 1, Fig. 3a - 3b show a second embodiment of the valve member in Fig. 1 and Fig. 4a - 4b show a third embodiment of the valve member in Fig. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE BINVENTION Fig. 1 shows schematically a vehicle 1 powered by a combustion engine 2. The vehicle 1 is with advantage a heavy vehicle. The vehicle 1 may, for example, be a bus. The engine 2 may be a diesel engine. The combustion engine 2 is cooled by a cooling system. The cooling system comprises a pump 3 circulating coolant in a coolant circuit. The coolant pump 3 directs the coolant in the cooling circuit to the combustion engine 2 which comprises cooling channels 2a for cooling of the cylinders and the cylinder heads. The coolant leaves the combustion engine 2, via an engine outlet line 4. In this case, the engine outlet line 4 comprises a heat exchanger 5 for a retarder. The coolant leaving the heat exchanger 5 enters a thermostat 6. During operating conditions when the coolant has a lower temperature than a regulating temperature of thermostat 6, the thermostat 6 directs the coolant, via a radiator bypass line 7, to the coolant pump 3. The coolant pump 3 is situated in an engine inlet line 8. In this case, the coolant is circulated in the coolant circuit without being cooled. During operating conditions when the coolant has a higher temperature than the regulating temperature of thermostat 6, the thermostat 6 directs the coolant, via a radiator inlet line 9, to a radiator 10 arranged at a front portion of the vehicle 1. The coolant is cooled by a cooling air flow in the radiator 10. The cooling air flow is provided by a radiator fan 1 1 and the draught caused by the forward movement of the vehicle 1. After the coolant has been cooled in the radiator 10, it is directed, via a return line 12, back to the engine inlet line 8 and the coolant pump 3.

The volume of the coolant in the coolant circuit varies with the temperature of the coolant. The cooling system is provided with an expansion tank 13 with an internal space accommodating the varying volume of the coolant. The expansion tank 13 is connected, via a static line 14, to the engine inlet line 8 at a suction side of the coolant pump 3. The expansion tank 13 has at an upper portion a removable cover 15 to make it possible to replenish the cooling system with coolant. The cover 15 is provided with a schematically depicted pressure regulating valve 16 which opens when the pressure in the expansion tank exceeds a highest acceptable pressure of the cooling system. The expansion tank comprises also a valve 17, which provides assurance that the pressure in the expansion tank corresponds to at least that of the surrounding air. It therefore opens and lets air in if a negative pressure occurs in the expansion tank.

The cooling channels 2a in the combustion engine 2 is connected to the expansion tank 13, via an engine deaeration line 18. The radiator is connected to the expansion tank 13, via a radiator deaeration line 19. The static line 14 is provided with a valve member 20. An upper part 14a of the static line is arranged above the valve member 20 and a lower part 14b of the static line is arranged below the valve member 20. The engine inlet line 8 is provided with a filling nipple 21 for attachment of a coupling member 22a of an external coolant filling device 22. The coupling member 22a may be a quick connector for a simple and quick attachment to the filling nipple 21. The external coolant filling device 22 includes further a hose 22b supporting said coupling member 22a, a coolant source 22c and a pump 22d pumping coolant via the hose and the coupling member to the filling nipple 21 and the coolant circuit. The filling nipple 21 is arranged at a lower level than the expansion tank 13.

Fig. 2a-2b show an embodiment of the valve member 20 more in detail. In this case, the valve member 20 comprises a disc shaped valve body 20a pivotally arranged around a pivot 20b. Fig. 2a shows the valve body 20a in the open position. Fig. 2b shows the valve body 20a in the closed position. A first stop member 20c defines the closed position of the valve body 20a. In case the cooling system is empty and it is to be filled with coolant, an operator removes the cover 15 from the expansion tank 13. Furthermore, the operator attaches the coupling member 22a of the external coolant filling device 22 to the filling nipple 21. During the filling process, the cover 15 must be open in order to evacuate air from the coolant circuit. Thereafter, the operator starts the external pump 22c such that it supplies coolant from the coolant source 22d, via the hose 22b, the coupling member 22a and the filling nipple 21, to a lower part of the coolant circuit. In this case, the coolant is supplied to the return line 8. The coolant is supplied with a pressure to the coolant circuit.

The supplied coolant provides a successively increasing coolant level in the coolant circuit and in the lower part 14b of the static line. When the coolant level in the coolant circuit level and the lower part 14b of the static line reaches the valve member 20, the coolant moves the valve body 20a from the open position to the closed position. The movement of the valve body 20a to the closed position is stopped by the first stop member 20c. The valve body 20a blocks completely the static line 14 in the closed position. Thus, it is not possible for the coolant level to continue to rise in the static line 14 when the valve body has reached the closed position. The further supply of coolant to the coolant circuit results in a successively higher level in the coolant circuit. The increasing coolant level in the coolant circuit presses out the air in the coolant circuit successively via the deaeration lines 18, 19. The coolant in the lower part of the static line 14a acts with a pressure on the lower part of the valve body 20a. The pressure on the lower part of the valve body 20a is related to the difference between the pressure from the filling device 22 as for the coolant level in the coolant circuit and the ambient pressure in the expansion tank 13 which is similar as in the upper part of static line 14a. A first part of the coolant filling process to the cooling system ends when the coolant circuit is completely filled with coolant.

As soon as the coolant circuit is completely filled with coolant, a second part of the coolant filling process is started. The further supply of coolant to the coolant circuit result in a coolant flow from the coolant circuit, via at least one of the deaeration lines 18, 19, to the expansion tank 13. The coolant entering the expansion tank 13 is initially directed to the upper part 14a of the static line. The operator deactivates the operation of the external pump 22c when the coolant level in the expansion tank 13 reaches a predetermined level. Finally, the operator disconnect the external connection member 22a from the filling nipple 21 and reset the cover 15 on the expansion tank 13.

Fig. 3a-3b show a further embodiment of the valve member 20. In this case, the valve member 20 comprises a piston-shaped valve body 20a. Fig. 3a shows the valve body 20a in an open position. Fig. 3b shows the valve body 20a in a closed position. A first stop member 20c defines the closed position of the valve body 20a and a second stop member 20d defines the open position of the valve body. The piston shaped valve body 20a comprises a head portion 20a1configured to come in contact with the first stop member 20c in the form of a valve seat. The valve body 20a comprises through holes 20a2. The coolant flows past the valve body 20a, via said holes 20a2, when it is in the open position. The piston-shaped valve body 20a is moved to the closed position and to the open position by the coolant in a corresponding manner as the valve member 20a in Fig 2a-2b.

Fig. 4a-4b show a further embodiment of the valve member 20. In this case, the valve member 20 comprises a ball-shaped valve body 20a. Fig. 3a shows the valve body 20a in an open position. Fig. 3b shows the ball-shaped valve body 20a in a closed position. A first stop member 20c defines the closed position of the ball-shaped valve body 20a and a second stop member 20d defines the open position of the valve body. The first stop member 20c is designed as a valve seat. The ball-shaped valve body 20a has a somewhat lower density than coolant. Thus, the ball-shaped valve body floats in coolant and it tends to move upwardly in the static line 14 to the closed position.

Consequently, the ball-shaped valve body 20 is moved to the closed position as soon as coolant fills up the lower part 14b of the static line 14. The ball-shaped valve body 20 is maintained in the closed position also during the second part of the filling process. However, when the pump 3 starts to circulate coolant in the cooling circuit, coolant flows from the static line to the pump 3. This cooling flow moves the ballshaped valve body 20a from the closed position to the open position. The lower stop member 20d defines an open position of the ball-shaped valve body 20a in which it does not block the coolant flow to the lower part 14b of the static line 14.

The invention is in no way restricted to the embodiment to which the drawing refers, but may be varied freely within the scopes of the claims. The valve member be can be freely positioned and must not be perfectly vertical if the described functionality is fulfilled.

Claims (10)

Claims

1. A cooling system for a vehicle, wherein the cooling system comprises a coolant circuit configured to cool a combustion engine (2), a pump (3) circulating the coolant in the coolant circuit, an expansion tank (13), a static line (14) extending between the expansion tank (13) and a part of the coolant circuit, at least one deaeration line (18, 19) extending between an upper part of the coolant circuit and the expansion tank (13), and a filling nipple (21) arranged in the coolant circuit, characterised in that the cooling system comprises a valve member (20) arranged in the static line (14) comprising a valve body (20a) which is configured to be automatically moved to a closed position and to block the coolant flow through the static line (14) to the expansion tank (13) during at least a first part of a coolant filling process at which coolant is supplied to the coolant circuit via said filling nipple (21) and to an open position at least when the pump (3) starts to circulate coolant in the coolant circuit.

2. A cooling system according to claim 1, characterised in that the valve body (20a) is movably arranged in an axial direction in the static line (14) between the closed position and the open position.

3. A cooling system according to claim 1, characterised in that the valve body (20a) is pivotally arranged between the closed position and the open position around a pivot (20b).

4. A cooling system according to any one of the preceding claims, characterised in that the valve body (20a) has a lower density than the coolant such that it floats in the coolant.

5. A cooling system according to claim 4, characterised in that the valve body (20a) is ball-shaped.

6. A cooling system according to any one of the preceding claims, characterised in that the valve member (20) comprises a first stop member (20c) defining the closed position for the valve body (20a).

7. A cooling system according to any one of the preceding claims, characterised in that the valve member (20) comprises a second stop member (20d) defining the open position for the valve body (20a).

8. A cooling system according to any one of the preceding claims, characterised in that the deaeration line is an engine deaeration line (18) or a radiator deaeration line (19).

9. A cooling system according to any one of the preceding claims, characterised in that the expansion tank (13) is located at a lower level that at least a part of the coolant circuit.

10. A cooling system according to any one of the preceding claims, characterised in that the vehicle (1) is a bus. 1 1. A method for filling a cooling system in a vehicle, wherein the cooling system comprises a coolant circuit configured to cool a combustion engine (2), a pump (3) circulating the coolant in the coolant circuit, an expansion tank (13), a static line (14) extending between the expansion tank (13) and a part of the coolant circuit, at least one deaeration line (18, 19) extending between a upper part of the coolant circuit and the expansion tank (13), and a filling nipple (21) arranged in the coolant circuit, characterised by the step of blocking the coolant flow through the static line to the expansion tank (13) during at least a first part of a coolant filling process at which coolant is supplied to the coolant circuit via said filling nipple (21) and to not blocking the cooling flow through the static line (14) at least when the pump (3) starts to circulate coolant in the coolant circuit.