DE102019002864B4 - Cooling system for an engine and a water retarder - Google Patents

Abstract

Cooling system for an internal combustion engine (2) and a water retarder (6) connected to a power train in a vehicle (1), the cooling system comprising a coolant pump (9) configured to circulate coolant in the cooling system, an expansion tank (22), a static line (23, 23a) which is connected to an inlet of the coolant pump (9), a radiator (21) which is configured to cool the coolant, a retarder circuit (13), a A retarder inlet line (11) configured to direct coolant to the retarder circuit (13) and a retarder outlet line (17) configured to receive coolant from the retarder circuit (13), and wherein the retarder circuit (13) includes a retarder bypass (13a) configured to direct coolant past the water retarder (6), a retarder passage (13b) configured to direct coolant through the water retarder (6 ) to conduct, anda vent il device (12), which is designed as a directional control valve and is configured to be - moved to a retarder-on position when the water retarder (6) is to be activated, in which the valve device (12) the entire coolant flow from directing the retarder inlet line (11) to the retarder passage (13b), while the valve device (12) simultaneously prevents coolant flow through the retarder bypass (13a), and- being moved to a retarder-off position, wherein the valve device (12) in the retarder-off position directs the coolant past the retarder (6) via the retarder bypass (13a); wherein the cooling system includes a pressure relief mechanism (24a-d, 25a-d) configured to prevent the coolant pressure at a specific point (ps) in the cooling system from rising above a maximum allowable pressure level.

Description

BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention relates to a cooling system for an engine and a water retarder, and a vehicle with such a cooling system.

Heavy vehicles are often equipped with one or more auxiliary brakes to reduce wear on the conventional wheel brakes. Such an additional brake can be a hydraulic retarder. One type of hydraulic retarder, commonly referred to as a water retarder, uses coolant as both a cooling medium and a working medium. A water retarder includes a stationarily disposed stator assembly and a rotor assembly that rotates at a speed related to the speed of the vehicle's powertrain. The stator assembly and rotor assembly define an annular space that encloses the stator and rotor blades. The supply of liquid coolant into the annular leads to a braking movement of the drive train and the drive wheel of the vehicle. In addition, the relative movements of the stator blades and the rotor blades ensure a flow of coolant through the retarder and the cooling system. Consequently, a water retarder can be defined as a pump with a high pumping capacity.

U.S. 2010/0 147 641 A1 shows a cooling system that includes a coolant pump, an internal combustion engine and a retarder circuit with a hydrodynamic retarder. The retarder circuit includes a switching valve that directs all coolant flow to the hydrodynamic retarder when the hydrodynamic retarder is engaged while simultaneously preventing coolant flow through a retarder bypass. Such a design of the retarder circuit makes it possible to significantly increase the flow of coolant in the cooling system with the aid of the hydrodynamic retarder, which generally has a higher pump capacity than the conventional coolant pump. However, switching on a hydrodynamic retarder leads to an abrupt acceleration of the coolant flow in the cooling system and switching off the hydrodynamic retarder leads to an abrupt deceleration of the coolant flow in the cooling system. Abrupt changes in coolant flow cause transient pressure spikes in the cooling system, which can shorten the life of components in the cooling system. In addition, there is an obvious risk that negative pressures will arise in the internal combustion engine when the hydrodynamic retarder is switched on.

EP 1 251 050 A2 shows a cooling system with a coolant pump, an internal combustion engine and a retarder circuit. The retarder circuit includes a retarder passage directing coolant to a hydrodynamic retarder, a retarder bypass, and a switching valve allowing coolant flow to the retarder passage when the hydrodynamic retarder is to be engaged. However, the retarder bypass is not blocked when the hydrodynamic retarder is switched on. In view of this fact, a large part of the coolant flow provided by the hydrodynamic retarder is recirculated in the reverse direction via the retarder bypass when the hydrodynamic retarder is switched on. Consequently, it is not possible to increase the coolant flow in the cooling system when the hydrodynamic retarder is switched on.

DE 196 03 184 A1 discloses a cooling system with a cooling circuit, in which an internal combustion engine, a retarder, a coolant pump, an expansion tank, and a cooler are integrated. Furthermore, a non-return valve is provided, which is set up to open onto an inlet side of the cooler. Furthermore, a second check valve is provided, which is set up to open from an outlet side of the cooler to an outlet side of a pressure relief valve.

DE 102 42 736 A1 discloses a further cooling system with a retarder, the retarder comprising means for emptying a residual amount of liquid against the external pressure built up by the cooling system.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a cooling system for an internal combustion engine and a water retarder with a design that allows the coolant flow in the cooling system to be increased when the water retarder is switched on, while at the same time undesired pressures in the cooling system are eliminated.

These objects are solved by the features defined in claim 1. The motor can be any motor that needs to be cooled during operation. The motor can be an internal combustion engine, an electric motor, etc. The cooling system includes a valve device that prevents coolant from flowing through a retarder bypass when the water retarder is on. Thus, no part of the coolant flow provided by the water retarder can be returned via the retarder bypass. As a result, the entire pumping capacity of the water retarder can be used to cool the coolant in the cooling system tem to circulate. A water retarder normally has a significantly higher pump capacity than a coolant pump. It is thus possible to significantly increase the coolant flow in the cooling system and the heat exchange in the radiator when the water retarder is activated.

Since the water retarder has a significantly higher pump capacity than the coolant pump, the coolant flow in the cooling system changes abruptly when the water retarder is switched on and off. There is therefore a great risk that high pressure peaks will occur in the cooling system when the water retarder is switched on and off by the valve device. To avoid such high pressure spikes, the cooling system includes a pressure relief mechanism configured to prevent the coolant pressure from rising above a maximum allowable pressure level at a specific point in the cooling system. The presence of the pressure relief mechanism ensures in a simple and effective way that the coolant pressure in the specific point of the cooling system does not rise above a maximum allowable value. By locating the pressure relief mechanism at a suitable specific point, the risk of high pressure spikes propagating to sensitive components in the cooling system is eliminated.

According to one embodiment, the pressure relief mechanism includes a connection line that extends between the specific point and a reference point in the cooling system, and a pressure relief valve that is configured to open and allow a flow of coolant from the specific point to the reference point via the connection line when the Pressure difference between the specific point and the reference point exceeds a predetermined value. The relief valve opens when there is a certain pressure difference between the specific point and the reference point. In view of this fact, it makes sense to choose a reference point with relatively constant pressure in the cooling system. In such a case it is easy to dimension the pressure relief valve so that it opens when the pressure in the specific point exceeds a maximum allowable pressure level. The pressure relief valve can be of simple design and relatively inexpensive. It is noted that the high pressure spikes are of short duration. In view of this fact, the coolant flow, which is led from the pressure relief point via the connection line to the reference point, is small.

According to one embodiment, the specific point is located in a retarder outlet line that receives coolant from the retarder circuit. During a switch-on process of the water retarder, the water retarder ensures an abrupt acceleration of the flow of coolant taken up in the outlet line of the retarder. The abrupt acceleration of the coolant flow can trigger a high pressure spike that propagates in the intended direction of flow from the retarder circuit to the downstream portions of the cooling system. Because the specific point is located in the retarder inlet line, such high pressure spikes are reduced to an acceptable pressure level substantially instantaneously before reaching downstream parts in the cooling system.

According to one embodiment, the specific point is located in a retarder inlet line that directs the coolant to the retarder circuit. During a water retarder shutdown event, the water retarder abruptly decelerates the flow of coolant in the retarder inlet line. The abrupt deceleration of coolant flow can result in a high pressure spike that propagates in the opposite direction to the intended direction of flow in the cooling system. Because the specific point is located in the retarder inlet line, such high pressure spikes are reduced to an acceptable pressure level substantially instantaneously before reaching upstream components in the cooling system.

According to one embodiment, the reference point is arranged downstream of the coolant pump and upstream of the internal combustion engine in the cooling system. The coolant pump is usually located close to the combustion engine. In this case, the connection line is able to lead a small amount of high-pressure coolant from the specific point to a reference point located between the coolant pump and the internal combustion engine. In this case, the reference point is on the pressure side of the coolant pump.

According to one embodiment, the reference point is a pressure associated with a static line in the refrigeration system. In this case, the reference point is on the suction side of the coolant pump. The pressure at this reference point is relatively constant, making it easy to define an opening pressure of the relief valve to open when the pressure at the specific point exceeds an unacceptable level.

According to one embodiment, the reference point is in the retarder inlet line in the cooling system. The retarder inlet pipe and the retarder outlet pipe are normally arranged in a small distance from each other. If the specific point in the retarder outlet line is arranged, it is possible to connect it to a reference point in the retarder inlet line via a short connecting line. Alternatively, the reference point is in the retarder outlet line in the cooling system. In this case the reference point can be connected to a specific point in the retarder inlet pipe with a short connecting pipe.

According to one embodiment, the internal combustion engine is arranged in a position downstream of the coolant pump and upstream of the water retarder in the cooling system. In view of the fact that the water retarder has a higher pump capacity than the coolant pump, there is a risk that negative pressures will be generated in the internal combustion engine when the water retarder is switched on. To address this problem, the cooling system includes a line connecting the static line to a first point in the cooling system downstream of the engine and upstream of the water retarder such that a pressure related to the pressure in the expansion tank is created downstream of the engine. Since such an overpressure prevails downstream of the engine, the risk of negative pressures occurring in the engine is eliminated.

According to one embodiment, the line is an engine bypass line configured to route coolant to the first point downstream of the engine from a second point in the cooling system that is at a position upstream of the coolant pump and the engine. The pressure drop in the motor bypass line is small. Thus, the presence of the engine bypass creates a pressure related to the overpressure in the expansion tank at the points defined above on opposite sides of the engine. The cooling system may include a check valve that allows coolant flow in only one direction through the engine bypass line. Thus, the check valve allows coolant flow through the engine bypass line to the water retarder when the water retarder is on and prevents coolant flow in the opposite direction through the engine bypass line when the water retarder is off.

According to an alternative embodiment, the line is a first static line portion of the static line connected to the first point downstream of the engine. In a position downstream of the engine, such a static line section generates an overpressure which is related to the pressure in the expansion tank. Since there is excess coolant pressure in a position downstream of the engine, there is no risk of negative pressures occurring in the engine. The static line may include a second static line section connected to a second point located at a position upstream of the coolant pump and the motor, and a check valve configured to restrict only coolant flow in the second static line section in allow a direction towards the second point. The coolant flow through the first static line section is small. In this way, essentially the entire flow of coolant from the water retarder is routed through the engine. This means that the pressure at the inlet of the coolant pump can be so low that there is a risk of cavitation in the coolant pump. However, the check valve is placed in a closed position when the water retarder is turned on by coolant pressure provided by the water retarder. This relatively high coolant pressure at the inlet to the coolant pump eliminates the risk of cavitation in the coolant pump. In this case, the coolant pump is overflown by the coolant flow from the water retarder.

According to the invention, the valve device is a directional valve which is arranged to be adjustable between a retarder switch-on position and a retarder switch-off position. Such a directional control valve may be a solenoid valve located in a connection point between the retarder bypass and the retarder passage. However, it is possible to design the valve device in a different way. The valve device may, for example, comprise a valve element in the retarder bypass and a valve element in the retarder passage.

According to one aspect, a vehicle includes a cooling system according to the above.

The invention also relates to a vehicle according to claim 14.

character list

• 1 ein Kühlsystem gemäß einer ersten und einer zweiten Ausführungsform der Erfindung zeigt,
• 2 ein Kühlsystem gemäß einer dritten Ausführungsform der Erfindung zeigt,
• 3 ein Kühlsystem gemäß einer vierten Ausführungsform der Erfindung zeigt, und
• 4 ein Kühlsystem gemäß einer fünften Ausführungsform der Erfindung zeigt.

Preferred embodiments of the invention are described below by way of example with reference to the accompanying drawing, in which:

• 1 shows a cooling system according to a first and a second embodiment of the invention,
• 2 shows a cooling system according to a third embodiment of the invention,
• 3 shows a cooling system according to a fourth embodiment of the invention, and
• 4 shows a cooling system according to a fifth embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

1 shows a schematically indicated vehicle 1, which can be a heavy vehicle. The vehicle 1 is driven by an internal combustion engine 2 . The internal combustion engine 2 can be an Otto engine or a diesel engine. The vehicle 1 comprises a drive train which, in addition to the internal combustion engine 2 , comprises a clutch mechanism 3 , a transmission 4 and a transmission output shaft 5 . The vehicle 1 is equipped with a water retarder 6 which comprises a stator unit which is arranged in a stationary manner in the vehicle and a rotor unit which is connected to the transmission output shaft 5 via a motion transmission mechanism 7 . Thus, the rotor unit is rotated at a speed defined by the speed of the transmission output shaft 5 and the gear ratio in the motion transmission mechanism 7 . The stator assembly and rotor assembly define an annular space for containing coolant during activation of the water retarder. The stator assembly includes stator blades and the rotor assembly includes rotor blades located in the annular space. A control unit 8 is set up to control the activation of the water retarder 6 by means of information from a brake activation element 8a, which can be a brake pedal.

A cooling system with circulating coolant is used to supply the internal combustion engine 2 and the water retarder 6 with coolant. The coolant is used as a working medium and cooling medium in the water retarder 6 . The cooling system includes a coolant pump 9 which circulates the coolant in the cooling system. The coolant pump 9 is arranged in an engine intake line 10 from where it circulates coolant to the cooling ducts in the internal combustion engine 2 . The coolant leaving the internal combustion engine 1 enters a retarder inlet line 11 . The retarder inlet line 11 is connected to a valve device in the form of a directional control valve 12 . The directional control valve 12 can be switched between two positions, namely a retarder off position and a retarder on position. In the retarder-off position, the directional valve 12 directs the coolant past the retarder 6 via a retarder bypass 13a. In the retarder-on position, the directional control valve 12 directs all coolant to the retarder passage 13b and the water retarder 6. The directional control valve 12 is located in a connection point between the retarder bypass 13a and the retarder passage 13b. In view of this, the directional control valve 12 prevents refrigerant flow through the retarder bypass 13a in the retarder on position. The retarder passage 13b includes a pressure control valve 15 and a check valve 16 which are arranged at a position downstream of the retarder 6. As shown in FIG. The coolant exiting the retarder circuit 13 enters a retarder outlet line 17 via the bypass 13a or the retarder passage 13b. The retarder outlet line 17 directs the coolant to a thermostat 18.

The thermostat 18 directs the coolant to a radiator bypass 19 when the coolant has a temperature lower than a control temperature of the thermostat 18 . The radiator bypass 19 routes the coolant to the engine inlet line 10. When the coolant is at a temperature higher than the regulation temperature, the thermostat 18 routes the coolant to a radiator line 20 which includes a radiator 21. The coolant is cooled in the radiator 21 by a flow of cooling air forced through the radiator 21 by ram air pressure and a radiator fan (not shown). When the coolant in the radiator 21 has cooled, it is directed to the engine inlet pipe 10 . A coolant expansion tank 22 is connected via a static line 23 to the engine intake line 10 at a position upstream of the coolant pump 9 .

The coolant pump 9, which can be a mechanical pump, starts the circulation of coolant in the cooling system as soon as the internal combustion engine 2 is switched on. If, under operating conditions, the control unit 8 receives information from the brake control unit 8a indicating that the retarder 6 should not be switched on, it triggers a movement of the directional control valve 12 into the retarder off position. In this position, the coolant flow in the retarder inlet line 11 is directed to the thermostat 18 via the retarder bypass 13a and the retarder outlet line 17 .

Under operating conditions, when the control unit 8 receives information from the brake control unit 8a indicating that the water retarder 6 is to be switched on, it triggers movement of the directional control valve 12 into the retarder-on position, ie the coolant is fed into the retarder passage 13b and the retarder 6 passed. The water retarder 6 works as a pump and draws in coolant from the retarder inlet line 11 . In the retarder-on position, the directional control valve 12 prevents coolant flow through the retarder bypass 13a. This measure prevents the coolant from flowing back through the retarder bypass 13a when the water retarder is switched on. Thus, the entire coolant flow of the water retarder 6 is directed to the retarder outlet line 17 . Consequently, the entire pumping capacity of the water retar Ders 6 are used to circulate coolant in the cooling system.

Normally, the water retarder 6 has a significantly higher pump capacity than the coolant pump 9. Against this background, the water retarder 6 initiates an abrupt acceleration of the coolant flow in the retarder outlet line 17 during a switch-on process of the water retarder, when the directional control valve is just in the retarder-on position was switched. In this case, a high pressure spike may be introduced in the retarder outlet line 17 in the cooling system. In addition, during a water retarder turn-off event, the coolant flow experiences an abrupt deceleration when the directional control valve 12 has just been switched to the retarder-off position. In this case, a high pressure spike may be initiated in the retarder inlet line 11 in the cooling system. If the directional control valve 12 is frequently switched between the retarder off position and the retarder on position, there is a risk that such high pressure spikes will shorten the life of pressure-sensitive components in the cooling system.

In order to avoid high pressure peaks when the water retarder is switched on, the in 1 The cooling system shown has a first connection line 24a, which extends between a specific point p _s in the retarder outlet line 17 and a reference point p _ref in the engine inlet line 10 located between the coolant pump 9 and the internal combustion engine 2. The first connecting line 24a includes a first pressure relief valve 25a. The first relief valve 25a is designed to open when the pressure difference between the specific point p _s and the reference point p _ref exceeds a predetermined value. It is possible to estimate the pressure at the reference point p _ref with a relatively high level of accuracy during a switch-on process of the water retarder 6 . In view of this fact, it is possible to design the pressure relief valve 25a in such a way that it opens when the pressure exceeds a maximum permissible pressure level in the specific point p _s in the retarder outlet line 17. In this case, part of the coolant flow in the retarder outlet line 17 is directed to the engine inlet line 10 . This measure reduces the size of a high-pressure spike in the retarder outlet line 17 during a switch-on process of the water retarder 6. Thus, the presence of the first connecting line 24a and the pressure relief valve 25a eliminates high-pressure spikes in the retarder outlet line 17 in a simple and reliable manner.

1 FIG. 12 further shows a second alternative connection line 24b, which extends between a high-pressure point p _s in the retarder outlet line 17 and a reference point p _ref in the engine inlet line 10 located upstream of the coolant pump 9. FIG. The pressure at this reference point p _ref relates to the pressure in the static line 23 and the surge tank 22. The pressure at this reference point is relatively constant. It is thus relatively easy to design the second safety valve 25b in such a way that it opens when the pressure at the specific point p _s exceeds a maximum permissible pressure level. The second connecting line 24b is an alternative to the first connecting line 24a which eliminates pressure peaks above a predetermined level in the retarder outlet line 17 in the cooling system. It is therefore sufficient to use one of the connecting lines 24a, 24b.

If the coolant flows through the coolant pump 9, the internal combustion engine 2 and the water retarder 6 one after the other when the water retarder 6 is switched on, there is an obvious risk that a vacuum will develop in the internal combustion engine 2. Negative pressure can reverse the coolant flow in parallel cooling channels in the internal combustion engine 2. In order to eliminate this problem, the cooling system comprises an engine bypass line 28 which is provided with a non-return valve 29. The engine bypass line 28 is connected to a first point p ₁ in a position downstream of the engine 2 and a second point p ₂ in a position upstream of the coolant pump 9 and the engine 2 . The pressure drop in the engine bypass line 28 is negligible. Thus, there is essentially no pressure difference between the first point p ₁ and the second point p ₂ . Since the engine bypass line 28 in a position downstream of the internal combustion engine 2 ensures an overpressure defined by the static line 23 and the expansion tank 22, negative pressure in the internal combustion engine 2 is avoided. The presence of the engine bypass line 28 thus eliminates the risk of negative pressures occurring in the internal combustion engine 2 when the water retarder 6 is switched on. When the water retarder is off, the check valve 29 prevents reverse coolant flow through the engine bypass line 28.

2 shows a cooling system similar to the cooling system in 1 corresponds, with the exception of the positioning of the connecting lines 24c, 24d. In this case the cooling system comprises a third connecting line 24c extending between a specific point p _s in the retarder outlet line 17 and a reference point p _ref in the retarder inlet line 11 . A third pressure relief valve 25c in the third connecting line 24c is designed to open when the pressure exceeds a maximum permissible pressure level at the specific point p _s in the retarder outlet line 17 . That The presence of the third connecting line 24c and the third pressure relief valve 25c eliminates high pressure spikes in the retarder outlet line 17 in the cooling system which may occur during the water retarder 6 start-up process.

A fourth connection line 24d is used in combination with the third connection line 24c. The fourth connection line 24d extends between a certain point p _s in the retarder inlet line 11 and a reference point p _ref in the retarder inlet line 17. The fourth connection line 24d includes a fourth pressure relief valve 25d, which is designed to open when a predetermined pressure difference between the specific point p _s in the retarder inlet line 11 and the reference point p _ref in the retarder outlet line 17 is generated. It is possible to design the fourth pressure relief valve 25d in such a way that it opens when the pressure in the specific point p _s in the retarder inlet line 11 exceeds a maximum permissible pressure level. The presence of the fourth connecting line 24d and the fourth pressure relief valve 25d eliminates high-pressure peaks in the cooling system which can occur during the water retarder 6 switch-off process. The presence of the third connecting line 24c and the fourth connecting line 24d thus reduces the size of the pressure peaks that occur when the water retarder 6 is switched on and when the water retarder 6 is switched off.

3 shows another embodiment of the cooling system. In this case, the coolant exiting the internal combustion engine 2 is routed to the thermostat 18 via an engine outlet line 30 . The retarder inlet line 11 and the retarder outlet line 17 are connected to the engine inlet line 10 . Furthermore, the internal combustion engine 2 is not arranged between the cooling pump 9 and the water retarder 6 . There is thus no risk of negative pressures occurring in the internal combustion engine 2 when the water retarder 6 is switched on. Therefore, a motor bypass line 28 is not required. In this case, a fifth connection line 24e and a fifth overpressure valve 25e are arranged between a high-pressure point p _s in a retarder outlet line 17 and a reference point p _ref in the retarder inlet line 11 . The fifth connection line 24e eliminates high pressure spikes in the retarder outlet line 17 when the directional control valve 12 has been switched to the retarder on position. A sixth connecting line 24f and a sixth overpressure valve 25f are arranged between a specific point p _s in a retarder inlet line 11 and a reference point p _ref in the retarder outlet line 17 . The sixth connecting line 24f eliminates high pressure spikes in the retarder inlet line 11 when the directional control valve 12 has been switched to the retarder off position. Finally, the thermostat 18 is a valve controlled by the control unit 8.

4 shows a cooling system with corresponding third and fourth connecting lines 24c, 24d like the cooling system in FIG 2 . In this case, the static line 23 of the expansion tank 22 is branched into a first static line section 23a and a second static line section 23b. The first static line portion 23a is connected to a first point p ₁ at a position downstream of the engine 2 . This means that a pressure related to the pressure in the expansion tank 22 prevails downstream of the internal combustion engine 2, which eliminates the risk of negative pressures being created in the internal combustion engine 2. The second static line portion 23b is connected to a second point p ₂ located at a position upstream of the coolant pump 9 . In this case, the cooling system does not include an engine bypass line 28. In view of this, when the water retarder 6 is switched on, it draws substantially all of the coolant through the internal combustion engine 2. This means that the pressure at the inlet of the coolant pump 9 can be so low that there is a risk of cavitation in the coolant pump 9 . In order to rule out this risk, the second static line section 23b is provided with a check valve 31. The check valve 31 is brought into a closed position when the water retarder is switched on due to the relatively high coolant flow pressure of the water retarder 6 . This increased pressure at the inlet to the coolant pump 9 eliminates the risk of cavitation. In this case, it is permissible for the coolant flow from the water retarder 6 to flow over the coolant pump 9 .

The invention is not limited to the embodiment described but can be varied freely within the scope of the claims. It is not necessary for the engine to be an internal combustion engine. The motor can be any motor that needs to be cooled during operation.

Reference List

1

vehicle

2

combustion engine

3

clutch mechanism

4

transmission

5

transmission output shaft

6

water retarder

7

motion transmission mechanism

8th

control unit

8a

brake activation element

9

coolant pump

10

engine inlet line

11

retarder inlet line

12

directional valve

13

retarder circuit

13a

retarder bypass

13b

retarder passage

15

pressure control valve

16

check valve

17

retarder outlet line

18

thermostat

19

cooler bypass

20

cooler line

21

cooler

22

surge tank

23

Management

24a

first connection line

24b

second connection line

24c

third connection line

24d

fourth connection line

24e

fifth connection line

24f

sixth connection line

25a

first pressure relief valve

25b

second pressure relief valve

25c

third pressure relief valve

25d

fourth relief valve

25e

fifth relief valve

25f

sixth relief valve

28

engine bypass line

29

check valve

30

engine exhaust line

31

check valve

ps

specific point

pref

reference point

p1

first point

p2

second point

Claims (14)

Cooling system for an internal combustion engine (2) and a water retarder (6) connected to a power train in a vehicle (1), the cooling system comprising a coolant pump (9) configured to circulate coolant in the cooling system, an expansion tank (22), a static line (23, 23a) which is connected to an inlet of the coolant pump (9), a radiator (21) which is configured to cool the coolant, a retarder circuit (13), a A retarder inlet line (11) configured to direct coolant to the retarder circuit (13) and a retarder outlet line (17) configured to receive coolant from the retarder circuit (13), and wherein the retarder circuit (13) includes a retarder bypass (13a) configured to direct coolant past the water retarder (6), a retarder passage (13b) configured to direct coolant through the water retarder (6th ) to conduct, and a V valve device (12) which is designed as a directional control valve and which is configured to - be moved to a retarder-on position when the water retarder (6) is to be activated, in which the valve device (12) controls the entire coolant flow from directing the retarder inlet line (11) to the retarder passage (13b), while at the same time the valve device (12) prevents coolant flow through the retarder bypass (13a), and - being moved to a retarder off position, wherein the valve device (12) in the retarder-off position directs the coolant past the retarder (6) via the retarder bypass (13a); wherein the cooling system includes a pressure relief mechanism (24a-d, 25a- _d ) configured to prevent the coolant pressure at a specific point (ps) in the cooling system from rising above a maximum allowable pressure level. cooling system after claim 1 , characterized in that the pressure relief mechanism comprises a connecting line (24a-f) extending between the specific point (p _s ) and a reference point (p _ref ) in the cooling system, and a pressure relief valve (25a-f) configured thereto is to open and allow coolant flow from the specific point (ps) to the reference point ( _{p ref} ) via the connecting line (25a-f) when the pressure difference between the specific point (ps) and the reference point ( _{p ref} ) exceeds a predetermined value. cooling system after claim 1 or 2 , characterized in that the specific point (p _s ) in the retarder outlet line (17) is arranged, which receives coolant from the retarder circuit (13). cooling system after claim 1 or 2 , characterized in that the specific point (p _s ) is located in the retarder inlet line (11) which conducts the coolant to the retarder circuit (13). Cooling system according to one of the preceding claims, characterized in that the reference point (p _ref ) is located downstream of the coolant pump (9) and upstream of the internal combustion engine (2) in the cooling system. Cooling system according to any of the preceding Claims 1 until 4 , characterized in that the reference point (p _ref ) is connected to a static line in the cooling system. Cooling system according to any of the preceding Claims 1 until 4 , characterized in that the reference point (p _ref ) is in the retarder inlet line (11) in the cooling system. Cooling system according to any of the preceding Claims 1 until 4 , characterized in that the reference point (p _ref ) is in the retarder output line (17) in the cooling system. Cooling system according to one of the preceding claims, characterized in that the internal combustion engine (2) is arranged in a position downstream of the coolant pump (9) and upstream of the water retarder (6) in the cooling system. cooling system after claim 9 , characterized in that the cooling system comprises a line (28, 23a) connecting the static line (23) to a first point (p ₁ ) located downstream of the engine (2) and upstream of the water retarder (6), so that in the first point (p ₁ ) downstream of the motor (2) a pressure related to the pressure in the expansion tank (22) is generated. cooling system after claim 10 , characterized in that the line is an engine bypass line (28) configured to conduct coolant to the first point (p ₁ ) downstream of the engine (2) from a second point (p ₂ ) located in a position upstream of the coolant pump (9) and the engine (2). cooling system after claim 11 , characterized in that the line forms a first static line section (23a) connecting the static line (23) to the first point (p ₁ ) downstream of the engine (2). cooling system after claim 12 , characterized in that the static line comprises a second static line portion (23b) connected to a second point (p ₂ ) located at a position upstream of the coolant pump (9) and the engine (2), and a check valve (31) configured to do so A vehicle (1) comprising a cooling system according to any one of the preceding Claims 1 - 13 .

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