SE541445C2

SE541445C2 - A cooling system for a vehicle

Info

Publication number: SE541445C2
Application number: SE1651258A
Authority: SE
Inventors: Mats Ekman; Zoltan Kardos
Original assignee: Scania Cv Ab
Priority date: 2016-09-23
Filing date: 2016-09-23
Publication date: 2019-10-01
Also published as: DE112017004129T5; WO2018056885A1; DE112017004129B4; SE1651258A1

Abstract

The present invention relates to a cooling system in a vehicle. The cooling system (3) comprises an engine circuit (4) comprising a first coolant pump (6), an engine inlet line (4a) directing coolant to a combustion engine (2) and an engine outlet line (4b) receiving coolant from the combustion engine (2), and a cab heating circuit (10) comprising a first inlet line (10a) receiving coolant from the engine outlet line (4b) in the engine circuit (4), a second coolant pump (13) configured to circulate coolant in the cab heating circuit (10), a coolant heater (15) configured to heat the coolant in the cab heating circuit (10) and a heat exchanger (16) in which heat is transferred from the coolant to air in a cab (11) of the vehicle (1). The cab heating circuit (10) comprises a second inlet line (10b) receiving coolant from the engine inlet line (4b) and a valve device (12) directing coolant from the first inlet line (10a) or the second inlet line (10b) to the coolant heater (15).

Description

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

A cooling system in a vehicle for a combustion engine can be provided with an engine circuit cooling a combustion engine and a cab heating circuit heating a cab in the vehicle. The cab heating circuit may comprise a coolant heater which heats the coolant before it is directed to a heat exchanger in which heat is transferred from the coolant to the air in a cab of the vehicle. The coolant heater can use diesel as fuel for generating heat. The presence of the coolant heater makes it possible to heat the coolant and the cab when the combustion engine is not in operation. Furthermore, the coolant heater makes it possible to heat the combustion engine and the cab before start of the combustion engine.

A conventional cab heating circuit has a relatively complex design and it occupies a relatively large space in the vehicle. A conventional cab heating circuit with a coolant heater may comprise check valves, a thermostat, several narrow bent hoses and T-joints. Furthermore, the coolant receives a relatively high pressure drop when it circulates through the cab heating circuit which may cause an insufficient low coolant flow at idle speed or that the dimensions for the circuit must be larger to keep the pressure drop low. The coolant outlet to the cab circuit can be placed after or before the engine. If the outlet to the cab circuit is placed after the engine the heater circuit equipped with an electric pump in series can be used also for warming up the engine at cold start because the coolant circulate through the engine. This position though give a lower pressure drop when running the engine which gives a lower coolant flow. If the coolant outlet is placed after the coolant pump and before the engine, the pressure drop over the cab circuit is higher which gives a higher coolant flow, but then it is not possible to use the coolant heater for warming the engine at cold start.

EP 0796752 shows a vehicular heating apparatus able to perform heating operation sufficiently within a desired period of time in a vehicle. A heat generator provided in the vehicle has a relatively small capacity and is designed to enhance the heating capacity when cooling water for an engine has not been warmed up sufficiently, for example, at the time of a cold start.

SUMMARY OF THE INVENTION The object of the present invention is to provide a cooling system for a combustion engine including a cab heating circuit having a simple design with a low pressure drop, settable it in two different modes when the combustion engine is not in operation and which ensures a sufficient coolant flow to the cab heating circuit when the combustion engine is in operation.

The above mentioned object is achieved by the cooling system according to claim 1. The cab heating circuit comprises a first inlet line by which it is possible to direct coolant to the cab heating circuit from a downstream positon of the combustion engine and a second inlet line by which it is possible to direct coolant to the cab heating circuit from an upstream positon of the combustion engine and a valve device by which it is possible to direct coolant from a selected one of said inlet lines to the cab heating circuit. Such a design of cab heating circuit is simple and it results in low pressure drops for the cab heating circuit.

During occasions when a driver wants to rest or sleep in the cab, it may be desired to set the cooling system in a cab heating mode. In this mode, the valve device is moved to a position in which it receives coolant from an upstream position of the combustion engine via the second inlet line. The coolant is heated in the coolant heater before it is directed to a heat exchanger heating the air in the cab. In this case, the coolant flows through the cab heating circuit substantially separated from the engine circuit. In this mode, the required energy supply for circulating and heating of the coolant will be low since the coolant does not need to circulate through the combustion engine.

Before start of the combustion engine, it is possible to set the cooling system in a cab and engine heating mode. The valve device is moved to a position in which it receives coolant from a downstream position of the combustion engine via the first inlet line. In this case, the coolant is heated by the coolant heater in the cab heating circuit before it enters the heat exchanger and heats the air in the cab. The coolant leaving the heat exchanger is directed to the engine circuit where it heats the combustion engine.

According to the invention, the valve device is configured to direct coolant from the second inlet line to the coolant heater during operation of the combustion engine. In case the cab heating circuit receives coolant from a position upstream of the combustion engine the proportion of the coolant flow to be directed to the cab heating circuit will be higher than if it receives coolant from a position downstream of the combustion engine due to the pressure drop through the combustion engine. It is usually always possible to direct a sufficient coolant flow, via the second inlet line, to the cab heating circuit during operation of the combustion engine.

According to an embodiment of the invention, the valve device may be a three way valve. Such a three way valve comprises a first inlet receiving coolant from the first inlet line, a second inlet receiving coolant from the second inlet line and one outlet directing coolant to the coolant heater in the second line. In this case, it is very easy to direct coolant from two different positions in the engine circuit to the cab heating circuit. Alternatively, the valve device may be a first two way valve arranged in the first inlet line and a second two way valve arranged in the second inlet line. In this case, when one of the valves is open the other valve is to be closed. However, it is possible to close both valves when there is no heating demand of the cab. According to a further alternative, the valve device may comprise a first two way valve in the first inlet line and a check valve in the second inlet line. In this case, the cab heating circuit will have a further simplified design.

According to an embodiment of the invention, the cab heating circuit directs coolant back to the engine inlet line in a position upstream of the first coolant pump. In this case, it is possible to use the first coolant pump to circulate coolant in the cab heating circuit as well as in the engine circuit when the combustion engine is in operation. The first coolant pump may be driven by the combustion engine.

According to an embodiment of the invention, the second coolant pump is electrically driven. Such a pump may be dimensioned to circulate the coolant flow in the cooling system when the combustion engine is not in operation. The speed and the coolant flow rate in the cooling system may be varied in a simple manner by the use of an electrically driven coolant pump when the combustion engine is not in operation. The second coolant pump may also be used as a complement to the first coolant pump in the engine circuit of the cooling system when the combustion engine is in operation.

According to an embodiment of the invention, the second coolant pump and a check valve are arranged in parallel lines in the cab heating circuit. The existence of the check valve allows a coolant flow past the second coolant pump when the first coolant pump circulates the coolant flow in the cooling system. Furthermore, the check valve prevents a coolant flow in an incorrect direction in the cab heating circuit.

According to an embodiment of the invention, the coolant heater has at least two different heating capacities. During occasions when the combustion engine is not in operation, the heating demand is usually significantly higher during the case when the cab and the combustion engine are to be heated compared to the case when only the cab is to be heated. Thus, it is an advantage to use a coolant heater having a variable heating capacity during said two different modes. The coolant heater may produce heat by burning diesel. Alternatively, it is possible to use an electric coolant heater.

According to an embodiment of the invention, the cooling system comprises a manual control member configured to control the valve device when the combustion engine is not in operation. By means of such a manual control member, the driver is able to set the cooling system in a cab heating mode or in a cab and engine heating mode when the combustion engine is not in operation According to an embodiment of the invention, the cooling system comprises a control unit configured to control the valve device when the combustion engine is in operation. The control unit may automatically set the valve device in the cab heating mode when the combustion engine starts. The control unit may also receive information indicating if there is a heating demand of the cab. In case there is no heating demand of the cab, the control unit may initiate a movement of the valve device to a position in which it blocks the coolant flow to the cab heating circuit. In case the control unit receives information indicating there is possible to receive a sufficient coolant flow from a position downstream of the engine to the cab heating circuit, it is possible for the control unit to move the valve device to a position in which it directs coolant, via the first inlet line, to the cab heating circuit. In this case, it is possible to use the heat from the combustion engine to heat the cab.

According to an embodiment of the invention, the control unit is configured to control the power of the coolant heater. The control unit may, for example, control the power of the coolant heater by means of information about at least one parameter related to the heating demand of the coolant. Such a parameter may be the coolant temperature in a suitable position of the cab heating circuit, the air temperature in the cab etc. The control unit may also be configured to control the second coolant pump. In case the first coolant pump circulates a too small coolant flow to the cab heating circuit when the combustion engine is in operation, the control unit may start the second coolant pump in order to increase the coolant flow to the cab heating circuit. Furthermore, the control unit may control the speed of the second coolant pump when the combustion engine not is in operation in order to provide a sufficient coolant flow in cab heating circuit which fulfills the heating demand of the cab. Furthermore, the control unit may be configured to control a fan forcing air through the heat exchanger. The heating effect of the air in the cab is related to the temperature of the coolant and the air flow rate through the heat exchanger. The control unit may control the speed of the fan by means of information about parameters related to the heating demand of the cab.

According to an embodiment of the invention, the valve device may be placed on the combustion engine. In this case, it is possible to provide the cooling system with relatively short lines. Alternatively, the valve device is placed close to the components in the cab heating circuit.

BRIEF DESCRIPTION OF THE DRAWINGS In the following preferred embodiments of the invention is described, as examples, with reference to the attached drawings, in which: Fig. 1 shows a cooling system according to a first embodiment of the invention, Fig. 2 shows a cooling system according to a second embodiment of the invention and Fig. 3 shows a cooling system according to a third embodiment of the invention.

DETAIFED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Fig. 1 shows a schematically indicated vehicle 1 powered by a combustion engine 2. The combustion engine 2 may be a diesel engine. The vehicle 1 comprises a cooling system 3. The cooling system comprises an engine circuit 4 for cooling of the combustion engine 2 and a retarder cooler 5. The engine circuit comprises a first coolant pump 6 arranged in an engine inlet line 4a. In this case, the first coolant pump 6 is driven by the combustion engine 2. The coolant leaves the combustion engine 2 via an engine outlet line 4b. The engine outlet line 4b directs the coolant to the retarder cooler 5 in which the coolant cools an oil or the like used in a hydrodynamic retarder. The coolant leaving the retarder cooler 5 is directed, via a retarder cooler outlet line 4c, to a thermostat 7. The thermostat 7 directs the coolant to a radiator bypass line 4d when the coolant has a lower temperature than a regulating temperature of the thermostat 7. The bypass line 4d directs the coolant to the first coolant pump 6 and the engine inlet line 4a. The thermostat 7 directs the coolant to a radiator 8, via a radiator inlet line 4e when the coolant has a higher temperature than the regulating temperature. The radiator 8 is arranged at a front portion of the vehicle 1. A radiator fan 9 and the ram air provide a cooling air stream through the radiator 8 during operation of the vehicle 1. A radiator outlet line 4f directs the cooled coolant to the engine inlet line 4a.

The cooling system comprises a cab heating circuit 10 for heating of a schematically indicated cab 11 in the vehicle 1. The cab heating circuit 10 comprises a first inlet line 10a receiving coolant from the engine outlet line 4a in the engine circuit 4 in a position downstream of the combustion engine 2. The cab heating circuit 10 comprises a second inlet line 10b receiving coolant from the engine circuit 4 in the engine inlet line 4a in a position upstream of the combustion engine 2 and downstream of the first coolant pump 8. The cab heating circuit comprises a three way 12 valve having a first inlet connected to the first inlet line 10a and a second inlet connected to the second inlet line 10b and an outlet directing the coolant from the first inlet line 10a or the second inlet line 10b towards two parallel lines 10c, 10d in the cab heating circuit 10.

One of the parallel lines 10c comprises a second coolant pump 13 and the other parallel line 10d comprises a check valve 14. The second coolant pump 13 is electrically driven. The coolant leaving the second coolant pump 13 or the check valve 14 is directed to a diesel coolant heater 15. The diesel coolant heater 15 produces heat by burning diesel. The coolant is directed from the diesel coolant heater 15 to a heat exchanger 16. A fan 17 circulates air through the heat exchanger 16. The air, which is heated by the coolant in the heat exchanger 16, is directed into the cab 11. The coolant is directed from the heat exchanger 16 back to the engine circuit 4 in a position upstream of the first coolant pump 6 in the engine inlet line 4a. A control unit 18 controls the second coolant pump 13, the coolant heater 15 and the fan 17 by means of information about parameters 20 related to the heating demand of the cab. The parameter 20 may be the coolant temperature in a suitable position of the cab heating circuit and/or the air temperature in the cab 11. The control unit 18 also control the three way valve 12 during operation of the combustion engine 2. A manual control member 19 is used to control the three way valve 12 when the combustion engine 2 is not in operation. The driver may indicate one of said two heating modes by means of the manual control member 19 when the combustion engine is not in operation.

When ambient temperature is low and a driver of the vehicle wants to rest or sleep in the cab 11 , the driver sets the cooling system in a cab heating mode by the manual control member 19. Furthermore, the driver may indicate a desired temperature in the cab 11 by means of the temperature control member 21. In view of this information, the control unit 18 starts the second coolant pump 13 and the circulation of coolant through the cab heating circuit 10 and a part of the engine circuit 4. The control unit 18 sets the three way valve 12 in the second position such that coolant is directed from an upstream position of the combustion engine, via the second inlet line 10b, to the three way valve 12 and the diesel coolant heater 15. The control unit 18 starts the diesel coolant heater 15 such that it heats the coolant before it is directed to the heat exchanger 16. The control unit 18 controls the fan 17 such that it forces a suitable air stream through the heat exchanger 16 such that the air is heated by the coolant in the heat exchanger 16 to a suitable temperature. The control unit 18 controls the diesel coolant heater 15 in order to equalize the difference between the desired air temperature 21 and the air temperature sensed by the temperature sensor 20 in the cab 1 1. The coolant leaving the heat exchanger 16 is directed to the engine inlet line 4a in the engine circuit 4 in a position upstream the first coolant pump 6. The coolant leaves substantially immediately the engine circuit 4 and enters the engine circuit 10 via the second inlet line 10b. In this mode, the diesel coolant heater 15 supplies a relatively small amounts of heat energy to the coolant since there is no heating demand of the combustion engine 2. Furthermore, the coolant flow resistance is low since the coolant does not need to flow through the combustion engine 2. Consequently, the energy consumption for heating and circulation of the coolant is low in the cab heating mode.

A suitable period before it is time to start the combustion engine, the driver sets the cooling system in a cab and engine heating mode by the manual control member 19. The control unit 18 sets the three way valve 12 in the first position such that coolant is directed from a downstream position of the combustion engine 2, via the first inlet line 10a, to the three way valve 12 and the diesel coolant heater 15. The control unit 18 increases the power of the diesel coolant heater 15. The coolant leaving the heat exchanger 16 is directed through the combustion engine 2 in the engine circuit 4 before it is directed back to the cab heating circuit via the first inlet line 10a. In this mode, the diesel coolant heater 15 supplies an increased amounts of heat energy to the coolant in order to heat the air in the cab 11 and the combustion engine 2. The combustion engine 2 is heated to a relatively high temperature. Thus, it is possible to avoid a cold start of the combustion engine 2.

When the combustion engine 2 is started, the control unit 18 sets the cooling system in an engine operation mode. The second cooling pump 13 is switched off and the first coolant pump 6 starts and takes over the circulation of the coolant in the cooling system. The control unit 18 moves the three way valve 12 to the second position such that a part of the coolant flow is directed to the cab heating circuit 10 via the second inlet line 10b and a remaining part of the coolant flow is directed through the combustion engine 2. In the engine operation mode, the control unit 18 controls the coolant heater, and the fan 17 such that the cab receives a demanded heating. The remaining part of the coolant flow cools the combustion engine 2. In case, the coolant flow through the cooling system or the cab heating circuit is to low, the control unit starts the second coolant pump 13 such that it provides an increased coolant flow.

Fig. 2 shows an alternative embodiment of the cooling system. In this case, the valve device has been formed as a first two way valve 22a arranged in the first inlet line 10a and a second two way valve 22b arranged in the second inlet line 10b. The control unit 18 controls the valves 22a, 22b when the combustion engine 2 is in operation. The driver controls the valves 22a, 22b by the manual control member 19 when the combustion engine 2 is not in operation. Furthermore, the valves 22a, 22b are arranged on the combustion engine 2 while the three way valve 12 in the first embodiment is arranged in a more protected position at a distance from the combustion engine 2.

Fig. 3 shows a further alternative embodiment of the cooling system. In this case, the valve device comprises a check valve 23 a arranged in the first inlet line 10a and a two way valve 23b arranged in the second inlet line 10b. The control unit 18 controls the two way valve 23b when the combustion engine 2 is in operation. The driver controls the two way valves 23b by the manual control member 19 when the combustion engine 2 is not in operation. When the two way valve 23b is closed, coolant flows through the first inlet line 10a to the coolant heater 15. When the two way valve 23b is open, coolant flows through the second inlet line 10b to the coolant heater 15. In this case, the check valve 23 a prevents a coolant flow through the first inlet line 10a since the coolant pressure is lower in a downstream position than in an upstream position of the combustion engine 2.

The invention is not restricted to the described embodiment but may be varied freely within the scope of the claims.

Claims

1. A cooling system for a vehicle, wherein the cooling system (3) comprises an engine circuit (4) comprising a first coolant pump (6) which is driven by the combustion engine (2), an engine inlet line (4a) configured to direct coolant to a combustion engine (2) and an engine outlet line (4b) configured to receive coolant from the combustion engine (2), and a cab heating circuit (10) comprising a first inlet line (10a) configured to receive coolant from the engine outlet line (4b) in the engine circuit (4), a second coolant pump (13) configured to circulate coolant in the cab heating circuit (10), a coolant heater (15) configured to heat the coolant in the cab heating circuit (10) and a heat exchanger (16) enabling heat transfer from the coolant to air in a cab (11) of the vehicle (1), characterized in that the cab heating circuit (10) comprises a second inlet line (10b) receiving coolant from the engine inlet line (4a) in a downstream position of the first coolant pump (6) and an upstream position of the combustion engine (2), a valve device (12, 22a, 22b, 23a, 23b) configured to direct coolant from a selected one of the first inlet line (10a) or the second inlet line (10b) to the coolant heater (15) and that the valve device (12, 22a, 22b, 23a, 23b) is configured to direct a coolant flow by the first coolant pump (6) from the second inlet line (10b) to the coolant heater (15) and the heat exchanger (16) during operation of the combustion engine (2).

2. A cooling system according to claim 1, characterized in that the valve device comprises a three way valve (12).

3. A cooling system according to claim 1, characterized in that the valve device comprises a first two way valve (22a) arranged in the first inlet line (10a) and a second two way valve (22b) arranged in the second inlet line (10b).

4. A cooling system according to claim 1, characterized in that the valve device comprises a check valve (23 a) arranged in the first inlet line (10a) and a two way valve (23b) arranged in the second inlet line (10b).

5. A cooling system according to any one of the preceding claims, characterized in that the cab heating circuit (10) configured to ct coolant back to the engine inlet line (4a) in a position upstream of the first coolant pump (6).

6. A cooling system according to any one of the preceding claims, characterized in that the second coolant pump (13) is electrically driven.

7. A cooling system according to claim 6, characterized in that the second coolant pump (13) is arranged in a parallel line (10c) to a line (10d) with a check valve (14) in the cab heating circuit (10).

8. A cooling system according to any one of the preceding claims, characterized in that the coolant heater (15) produces heat by burning diesel.

9. A cooling system according to any one of the preceding claims, characterized in that the cooling system comprises a manual control member (19) configured to control the valve device (12, 22a, 22b, 23a, 23b) when the combustion engine is not in operation.

10. A cooling system according to any one of the preceding claims, characterized in that the cooling system comprises a control unit (18) configured to control the valve device (12, 22a, 22b, 23a, 23b) when the combustion engine (2) is in operation.

11. 1 1. A cooling system according to claim 10, characterized in that the control unit (18) is configured to control the coolant heater (15).

12. A cooling system according to claims 10 or 11, characterized in that that the control unit (18) is configured to control the second coolant pump (13).

13. A cooling system according to any one of the claims 10 to 12, characterized in that the control unit (18) is configured to control a fan forcing air through the heat exchanger (16).

14. A cooling system according to any one of the preceding claims, characterized in that the valve device (12, 22a, 22b, 23a, 23b) is placed on the combustion engine (2).