SE538407C2 - Arrangements in a vehicle comprising a retarder and a WHHR system - Google Patents

Description

BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relates to an arrangement in a vehicle according to the preamble of claim 1.

Hydrodynamic retarders are often used as auxiliary brakes in heavy vehicles. Thus, the load and wear on the vehicle's wheel brakes can be reduced. A hydrodynamic retarder typically includes a stator and a rotor that define a toroidal space for receiving a working medium. The stator and rotor comprise a plurality of vanes which are arranged at uniform intervals in the toroidal space. The stator is fixedly mounted on a stationary surface of the vehicle while the rotor is connected to the vehicle's driveline via a motion transmitting mechanism. When the retarder is activated, a working medium is added to the toroidal space. The working medium is guided through the toroidal space in contact with the blades so that it counteracts the rotation of the rotor relative to the stator, which results in the vehicle being braked. The kinetic energy of the working medium in the toroidal space is converted during the braking process into heat energy. The working medium is passed relatively quickly through the toroidal shape so that it does not obtain too high a temperature. In a certain type of hydraulic retarder, coolant is used both as a working medium.

WHR (Waste Heat Recovery) system is being developed for use in vehicles and converting heat energy into mechanical energy. A WHR system includes a pump that pressurizes and circulates a medium in a line circuit. The line circuit comprises one or more evaporators where the medium is heated and evaporated by means of one or more heat sources. The vaporized medium thus provides an elevated temperature and an elevated pressure. The heated and pressurized medium is then passed to an expander such as a turbine where it expands so that mechanical energy is generated. The mechanical energy can be used directly for operation of various kinds or converted and stored as electrical energy. After the medium has expanded in the turbine, it is led to a condenser where it cools down so that it condenses and again turns into a liquid form. The liquid medium is then pressurized again by the pump. With the help of a WHR system, heat energy can, for example, be recovered from the exhaust gases from an internal combustion engine and used for the operation of a vehicle. A WHR system is complex and includes a large number of components. Equipping a vehicle with a WHR system is therefore relatively expensive.

DE 102011017762 shows a part of a driveline of a heavy vehicle. The vehicle is equipped with a WHR system that extracts heat energy and transfers it to mechanical energy for operation of the vehicle. The WHR system includes an expansion machine driven by the medium circulated in the WHR system. The rotational movements of the expansion machine are transmitted to the driveline of the vehicle via a first motion-transmitting mechanism. The vehicle is also equipped with a hydrodynamic retarder. The hydrodynamic retarder is connected to the vehicle's driveline via a second motion transmission mechanism.

SUMMARY OF THE INVENTION The object of the present invention is to provide an arrangement in a vehicle which comprises a hydrodynamic retarder system and a WHR system where the number of components can be reduced and thus the total cost of the two systems.

This object is achieved with the arrangement of the kind mentioned in the introduction, which is characterized by the features stated in the characterizing part of claim 1. A hydrodynamic retarder system includes a retarder that is in constant engagement with the vehicle's driveline via a motion transmitting mechanism. When the hydrodynamic retarder is activated, a working medium is supplied with a space between a rotor unit and a stator unit of the retarder, which counteracts the rotational movement of the rotor unit and thus the rotational movement of the driveline. When the retarder is activated, it applies a braking torque to the driveline and the vehicle. A WHR system comprises a circulating medium which is heated and evaporated after which it expands in a turbine. The turbine thus provides a rotational movement which is transmitted to the vehicle's driveline via a motion transmitting mechanism. The WHR system thus adds a driving torque to the driveline. It can be stated that the retarder system retarder and the WHR system turbine are connected to the driveline at different operating times. It is thus possible to use the same motion-transmitting mechanism between the retarder system retarder and the WHR system turbine. As a result, one motion transmitting mechanism can be excluded in a vehicle that includes both systems. Thus, the number of components can be reduced and thus the total cost of the two systems.

According to an embodiment of the present invention, the motion transmitting mechanism comprises a rotatable shaft which is rotatably connected to the retarder and the turbine. The shaft thus rotates at a speed that is related to the deceleration speed and the turbine speed. The retarder can thus transmit a braking torque, via said shaft, to the driveline when the retarder is activated and the turbine can supply a driving torque, via said shaft, to the driveline when the WHR system is activated.

According to an embodiment of the present invention, the common shaft has a parallel stretch with a shaft of the vehicle driveline which is in contact with the motion transmitting mechanism. With such a design, the motion transmitting mechanism can be made fairly uncomplicated and with a few components included. The motion transmitting mechanism may comprise a first gear attached to the common shaft, which, via a second intermediate gear, is connected to a third gear attached to said shaft of the driveline. Such a motion transmitting mechanism is relatively straightforward and provides a reliable mechanical transmission that transmits rotational motions between the retarder / turbine and the driveline. The motion transmitting mechanism may, of course, include motion transmitting components other than gears.

The motion transmitting mechanism may be connected to the vehicle's driveline via an output shaft of a gearbox. Thus, both the retarder and the turbine can be arranged in the vicinity of the vehicle's gearbox.

According to an embodiment of the present invention, the vehicle comprises a cooling system with a conduction circuit comprising a circulating medium, wherein the conduction circuit of the retarder system is connected to the conduction circuit of the cooling system and that they use a common medium. Most conventional hydrodynamic retarder systems use oil as the working medium. After the oil has been used as a medium in the retarder, it is led to a heat exchanger where it is cooled by coolant circulating in a cooling system. In this embodiment, a retarder system is used where coolant is used both as a medium to supply a braking torque when it is led to the retarder and to cool the retarder. Such a retarder system does not need to be equipped with a separate heat exchanger which transfers heat between the medium in the retarder and the coolant in a cooling system. Such a hydrodynamic retarder system has thus been designed with fewer components than a conventional hydrodynamic retarder system. However, it is possible that the arrangement comprises a conventional retarder system which has a common motion transmitting mechanism with a WHR system.

According to an embodiment of the present invention, the conductor circuit of the cooling system and the conductor circuit of the WHR system comprise at least one common conduit portion and one common medium. In this case, the same medium is thus used in the cooling system as in the WHR system. In this case, the medium must have the property that it evaporates at the pressures and temperatures which arise in the evaporator and that it condenses at the temperatures and pressures which arise in the condenser.

According to an embodiment of the present invention, the control circuit of the retarder system and the control circuit of the WHR system comprise at least one common conduit portion and one common medium. As a result, the retarder system and the WHR system can receive common wires, which further reduces the number of components. The common medium in the WHR system and in the retarder may be an alcohol which has suitable properties. It is possible to use the same medium in all three systems, namely in the cooling system, in the retarder system and in the WHR system.

According to the invention, the retarder of the retarder system and the turbine of the WHR system consist of one and the same component. Since the retarder system retarder and the WHR system turbine have a similar structure and since they never need to be used at the same time, it is possible to use one and the same component both as a retarder and a turbine. Thus, the arrangement can be reduced by an additional component.

According to an embodiment of the present invention, the medium in the WHR system is adapted to be heated in the evaporator by exhaust gases discharged from an internal combustion engine in the vehicle. Exhaust gases from an internal combustion engine contain a lot of heat energy that is normally emitted to the environment. With the help of a WHR system, this heat energy can be utilized and used for operation of the vehicle. Even when the exhaust gases are used to drive a turbocharger, they usually have a sufficiently high temperature downstream of the turbocharger to provide a heating of a medium in a WHR system so that it evaporates.

According to one embodiment of the present invention, the WHR system has an air-cooled condenser. The condenser can be arranged at a front part of a vehicle adjacent to a radiator where the coolant is cooled which cools the internal combustion engine of the vehicle. Conveniently, the condenser is arranged in a position so that it is cooled by air at ambient temperature. Alternatively, the medium in the condenser can be cooled by coolant from the cooling system that cools the internal combustion engine or a low temperature cooling system.

BRIEF DESCRIPTION OF THE DRAWING In the following, as an example, a preferred embodiment of the invention is described with reference to the accompanying drawing, in which Fig. 1 shows an arrangement according to a first embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Fig. 1 shows a supercharged internal combustion engine 1 which may be an otto engine or a diesel engine. The internal combustion engine 1 may, for example, be the drive engine for a vehicle 2 which may be a heavy vehicle. The vehicle comprises a gearbox 3 which is arranged in connection with the internal combustion engine 1. The gearbox 3 has an output shaft 4a which forms part of the vehicle's driveline 4. The exhaust gases from the internal combustion engine 1 are led out via an exhaust line 5. The exhaust line 5 comprises a turbine 6 of a turbocharger . The turbine 6 then provides a driving force which is transmitted, via a connection, to a compressor 7 of the turbocharger. The compressor 7 compresses air which is led, via an inlet line 8, to a charge air cooler 9 for cooling before the compressed air is led to the internal combustion engine 1.

The internal combustion engine 1 comprises a cooling system with a circulating medium. The medium is circulated in the cooling system by means of a pump 10 which is arranged in an inlet line II to the internal combustion engine 1. After the medium has cooled the internal combustion engine, it is led, via an outlet line 12, to a first valve means 13. During normal operation of the vehicle when not braking the valve means 13 in a first position in which it conducts the medium from the first valve means 13, via a line 14, to a return line 15. The return line 15 leads the medium to a thermostat 16. When the medium has a lower temperature than the control temperature of the thermostat 16 it is set in a closed the position in which it leads the medium to a bypass line 17 and back to the pump 10 and the internal combustion engine 1 without cooling. When the medium has a higher temperature than the control temperature, the thermostat device 16 is placed in an open position in which the coolant is led, via a line 18, to a cooler 19 to be cooled. The medium is cooled in the radiator 19 by air which is forced through the radiator 19 by means of a radiator fan (not shown) and the speed wind of the vehicle. The cooled medium leaving the cooler 19 is led, via a return line 20, back to the inlet line 11 and the coolant pump 10 for re-circulation in the cooling system.

The vehicle 2 is equipped with a hydrodynamic retarder system which comprises a retarder 21, a motion transmitting mechanism 22 which connects the retarder 21 to the vehicle driveline 4 and a line circuit for supplying said medium to the retarder 21 when it is activated. The retarder 21 consists of a rotor unit 21a and a stator unit 21b. The rotor unit 21a and the stator unit 21b define a toroidal space for receiving said medium. The rotor unit 21a and the stator unit 21b comprise a plurality of vanes arranged in the toroidal space. The stator unit 21b is stationary mounted in the vehicle while the rotor unit 21a is rotatably mounted on a shaft 22a included in said motion transmitting mechanism 22 which connects the retarder 21 to the vehicle driveline 4. The motion transmitting mechanism 22 also includes a first gear 22b mounted on said shaft 22a . The first gear 22b is, via a second gear 22c, connected to a third gear 22d which is arranged on the output shaft 4a of the gearbox which thus forms a component of the vehicle driveline 4. The shaft 22a has a parallel stretch with the output shaft 4a of the gearbox. A control unit 23 is adapted to activate the retarder 21 by means of information from a brake control 24.

When the control unit 23 receives information from the brake control 24 indicating that the retarder is to be activated, the control unit 23 places the first valve means 13 in a second position so that the medium is led from the line 12 to a line 25. The line 25 leads the medium to a second valve means 26. The control unit 23 has at the same time placing the second valve means 26 in a first position in which it leads the medium to a line 27 and the retarder 21. Since the rotor unit 21a is connected to the vehicle driveline 4 via said motion transmitting mechanism 22, it rotates continuously at a speed related to the driveline speed. The supply of the medium to the toroidal space results in it coming into contact with the vanes of the rotor unit 21a and the stator unit 21b which are designed so that together with the supplied medium they provide a braking torque which counteracts the rotational movement of the rotor unit 21a. Since the rotor unit 21a is connected to the vehicle driveline 4 via the motion transmitting mechanism 22, the supply of the medium to the toroidal space results in the vehicle 2 being braked. The kinetic energy of the medium in the toroidal space is converted during the braking process into heat energy. The medium is passed relatively quickly through the toroidal shape so that it does not obtain too high a temperature. The medium is led from the toroidal space, via a line 28, to a third valve member 29. When the retarder 21 is activated, the control unit 23 places the third valve member 29 in a first position so that the medium is led to the return line 15 and the thermostat 16. The medium essentially always has a higher temperature than the control temperature of the thermostat 16 when the retarder is activated. Thus, the medium is generally led from the thermostat 16 to the cooler 19 for cooling before it is led back to the pump 10 and the internal combustion engine 1.

Vehicle 2 is also equipped with a WHR system for heat recovery. The WHR system includes a control circuit that contains the same medium used in the cooling system and in the retarder system. The medium is circulated and pressurized in the line circuit by means of a pump 30. The medium is led from the pump 30, via a line 31, to an evaporator 32. The medium is heated in the evaporator 32 by exhaust gases in the exhaust line 5 so that it evaporates. The evaporated medium is led, via the second valve means 26, which the control unit 23 places in a second position when the WHR system is activated, to the line 27 and a turbine 21 which in this case consists of the same component as the retarder 21. The turbine 21 thus comprises in in this case a rotor unit 21a and stator unit 21b. The rotor unit 21a is connected to the vehicle driveline 4 via one and the same motion transmitting mechanism 22 which connects the retarder 21 to the vehicle driveline 4. When the gaseous pressurized medium is led to the toroidal space defined by the rotor unit 21a and the stator unit 21b, a driving force is provided 21a receives an increased speed. The increased speed of the rotor unit 21a is transmitted, via the motion transmitting mechanism 22, to the driveline 4 of the vehicle, which thereby obtains an extra driving force.

After the gaseous medium has expanded through the turbine 21, it is led, via the line 28, to the third valve means 29. When the WHR system is activated, the control unit 23 places the third valve means 29 in a second position in which the gaseous medium is led, via a line 33 to a condenser 34 which is arranged at a front part of the vehicle 2. The condenser 34 is in this case arranged in front of the charge air cooler 9 and the cooler 19 at the front part of the vehicle. The gaseous medium is thus cooled in the condenser 34 by air at ambient temperature. The gaseous medium is cooled to a temperature at which it condenses. The medium is thus again in liquid form as it is led from the condenser 34, via a line 35, to the pump 30 for recirculation in the WHR system. The WHR system may, of course, also include additional components such as, for example, a recuperator and a heater located upstream of the evaporator 32 which ensures that all medium in the WHR system is evaporated before it reaches the turbine 21.

The retarder system and the WHR system in this case use a common hydrodynamic component 21 which when the retarder system is activated functions as a retarder and when the WHR system is activated acts as a turbine. The retarder system and the WHR system also utilize a common motion transmitting mechanism 22 which connects a rotor unit 21a of the retarder / turbine to the vehicle driveline 4. This motion transmitting mechanism 22 transmits a braking torque to the driveline 4 when the retarder system is activated and a torque to the driveline when the WHR system is activated. Since the retarder system and the WHR system are never activated simultaneously, it is possible that they include the above-mentioned common components. In this case, the cooling system, the retarder system and the WHR system also use a common circulating medium. Thus, these systems may include a number of common lines. The medium should have the property that it is in liquid form as it circulates in the cooling system and in the retarder system. It should also have the property of evaporating at the temperature and pressure created in the evaporator 32 as it circulates in the WHR system. The medium can be an arbitrary kind but that it has the above mentioned properties. The medium may be a suitable alcohol.

The invention is in no way limited to the embodiment described in the drawing but can be varied freely within the scope of the claims.

Claims (10)

An arrangement in a vehicle, the arrangement comprising a hydrodynamic retarder system comprising retarder (21) in the form of a rotor unit (21a) and a stator unit (21b), a conduction circuit adapted to conduct a medium to and from the retarder (21) when activated and a WHR system comprising a line circuit, a pump (30) pressurizing and circulating a medium in the line circuit, at least one evaporator (32) where the medium is heated so that it evaporates, a turbine (21) where it the evaporated medium expands, and a condenser (34) where the medium is cooled so that it condenses, the retarder system retarder (21) and the WHR system turbine (21) being rotatably connected to a driveline (4) of the vehicle (2) via a common motion transmission mechanism (22), characterized in that the retarder system retarder (21) and the WHR system turbine (21) consist of one and the same component. Arrangement according to claim 1, characterized in that the motion transmitting mechanism (22) comprises a rotatable shaft (22a) which is rotatably connected to the retarder (21) and the turbine (21). Arrangement according to claim 2, characterized in that the common shaft (22a) has a parallel stretch with a shaft (4a) of the vehicle driveline (4) which is in contact with the motion transmitting mechanism (22). Arrangement according to claim 3, characterized in that the motion transmitting mechanism (22) comprises a first gear (22b) arranged on the common shaft (22a), which, via an intermediate second gear (22c), is connected to a third gear (22d) attached to said shaft of the driveline (4a). Arrangement according to one of the preceding claims, characterized in that the motion-transmitting mechanism is connected to the vehicle's driveline (4) via an output shaft (4a) of a gearbox (3). Arrangement according to any one of the preceding claims, characterized in that the vehicle comprises a cooling system with a conduction circuit comprising a circulating medium, wherein the retarder system conduction circuit is connected to the conduction circuit of the cooling system and that said conduction circuits are adapted to conduct a common medium. Arrangement according to claim 6, characterized in that the control circuit of the cooling system and the control circuit of the WHR system comprise at least one common conduit portion and that said control circuits are adapted to conduct a common medium. Arrangement according to one of the preceding claims, characterized in that the retardation system circuit and the WHR system circuit comprise at least one common conduit portion and one common medium. Arrangement according to one of the preceding claims, characterized in that the medium in the WHR system is adapted to be heated in the evaporator (32) by exhaust gases discharged from an internal combustion engine (1) in the vehicle. Arrangement according to one of the preceding claims, characterized in that the condenser (34) of the WHR system is air-cooled.