FR3055364A1 - DEVICE FOR RECOVERING THERMAL ENERGY OF A MOTOR VEHICLE ENGINE - Google Patents

Abstract

Energy recovery device arranged to recover energy produced by a motor vehicle heat engine (41), comprising: - a radial turbine (11), - a current generator (12), coupled to the radial turbine ( 11) for producing an electric current, characterized in that the energy recovery device comprises a heat recovery circuit (10) arranged to recover heat generated by the heat engine (41) with a phase change fluid and in that the radial turbine (11) is arranged to be rotated by the phase change fluid upon expansion of the phase change fluid when in the gas phase.

Description

Holder (s): PEUGEOT CITROEN AUTOMOBILES SA Société anonyme.

Extension request (s)

Agent (s): PEUGEOT CITROEN AUTOMOBILES SA Public limited company.

DEVICE FOR RECOVERING THERMAL ENERGY FROM A MOTOR VEHICLE ENGINE.

FR 3 055 364 - A1

Energy recovery device arranged to recover energy produced by a heat engine (41) of a motor vehicle, comprising:

- a radial turbine (11),

- a current generator (12), coupled to the radial turbine (11) to produce an electric current, characterized in that the energy recovery device comprises a heat recovery circuit (10) arranged to recover heat produced by the heat engine (41) with a phase change fluid, and in that the radial turbine (11) is arranged to be driven in rotation by the phase change fluid, during expansion of the change fluid phase, when it is in the gas phase.

THERMAL ENERGY RECOVERY DEVICE OF A MOTOR VEHICLE ENGINE [0001] The present invention relates generally to an energy recovery device mounted on a motor vehicle, and in particular, the invention relates to a device for recovering energy arranged to recover part of the thermal energy generated and lost by a heat engine fitted to a motor vehicle. The invention also relates to the integration of such a device in a vehicle of the hybrid type, that is to say comprising a motor source of thermal origin, and a motor source of electrical origin.

It is known in the prior art energy recovery devices arranged to recover energy from the exhaust gases by expansion of the latter. In particular, document EP0223419 describes a turbocharged engine to which a turbine has been added to the exhaust line, downstream of the turbocharger, in order to drive a current generator. On the other hand, this system has in particular the drawback of being complex due to the numerous components added and thermal stresses, and not very effective because the rotation of the turbine depends on the characteristics of the flow of exhaust gas, which is obviously not not constant.

An object of the present invention is to overcome the drawbacks of the documents of the prior art mentioned above and in particular, first of all, to propose an energy recovery device for a heat engine which is simple in terms of mechanical parts, and which has good performance.

For this, a first aspect of the invention relates to an energy recovery device arranged to recover energy produced by a heat engine of a motor vehicle, comprising:

- a radial turbine,

- a current generator, coupled to the radial turbine to produce an electric current, characterized in that the energy recovery device comprises a heat recovery circuit arranged to recover the heat produced by the heat engine with a fluid to phase change, and in that the radial turbine is arranged to be driven in rotation by the phase change fluid, during expansion of the phase change fluid, when it is in the gas phase.

The electrical energy recovery device according to the above implementation is simple since the current generator is directly coupled to the radial turbine, and the latter is driven by the expansion of a phase change fluid , when it is in the gas phase. The radial turbine is therefore less thermally stressed than if it is driven by exhaust gases. In addition, the flow rate of the phase change fluid in a heat recovery circuit varies less strongly than the exhaust gas flow rate, which allows better overall operation of the installation.

Advantageously, the radial turbine rotates the direct line current generator. The radial turbine and the current generator are coaxial and directly coupled to each other.

Advantageously, the radial turbine rotates the current generator with a reduction ratio of 1: 1. The current generator is therefore a rotating machine directly coupled to the radial turbine, and rotates at the same speed of rotation. Rotational speeds of between 200,000 and 300,000 revolutions per minute can be envisaged.

Advantageously, the current generator is a current generator with permanent magnets, in particular of the synchronous type, and without brushes. We can consider a current generator

-3 power between 1 kW and 3kW, delivering current in three-phase mode.

Advantageously, the energy recovery device comprises current conversion means, connected to the current generator and arranged to supply the vehicle with direct current at a voltage of 12V. This makes it possible to directly supply a vehicle on-board network or electricity storage means. In other words, the invention proposes means for recovering thermal energy or heat, which directly deliver electrical energy under a standardized voltage and compatible with the on-board network of the vehicle.

Advantageously, the current conversion means further comprises an alternating-direct current converter arranged to convert direct current into alternating current, to supply a traction machine of the vehicle. In other words, there is no need to store high voltage electricity, since the current necessary for the electric traction machine is converted from the 12V on-board network on demand. The electrical network remains simple.

Advantageously, the alternating current converter arranged to convert direct current into alternating current, to supply a traction machine of the vehicle, can operate in a reversible manner. Thus, the electric traction machine used to propel the vehicle during driving phases, can be transformed into an energy recovery device during braking phases: the alternating current produced is then transformed by the reversible alternating-current current converter into direct current. We combine the functions, which further simplifies the system.

Advantageously, the energy recovery device comprises a starter arranged to start the heat engine, in which the starter is arranged is arranged to form the vehicle traction machine and participate in the propulsion of the vehicle. We can therefore consider using the electric starter machine to participate in

-4 traction of the vehicle, and supply this machine directly with the electricity produced by the current generator.

Advantageously, the energy recovery device comprises means for recovering kinetic energy.

Advantageously, the kinetic energy recovery means are a current generator coupled to a wheel of the vehicle and the alternating current-to-DC converter arranged to convert direct current into alternating current is arranged to operate in a reversible manner and transform from alternating current to direct current.

Advantageously, the radial turbine comprises at least one air bearing. Such bearings make it possible to obtain a high rotational speed, with low friction losses. Alternatively, one can consider ball bearings.

Advantageously, the heat recovery circuit with the phase change fluid is arranged to operate according to a Rankine cycle. Such a cycle is well suited for recovering thermal energy.

Advantageously, the phase change fluid is an organic fluid. The phase change temperatures are well suited to the operation of a heat engine.

Advantageously, the heat recovery circuit with the phase change fluid comprises a heat exchanger arranged to recover heat from an engine cooling circuit, and / or engine exhaust gas.

A second aspect of the invention is a motor vehicle, comprising an energy recovery device according to the first aspect of the invention.

Other characteristics and advantages of the present invention will appear more clearly on reading the following detailed description of an embodiment of the invention given by way of non-limiting example and illustrated by the appended drawing, in which :

FIG. 1 represents an architectural diagram of a vehicle equipped with a heat engine and an energy recovery device according to the present invention.

Figure 1 shows a device for recovering thermal energy 5 according to the invention fitted to a heat engine 41 of a motor vehicle.

The heat engine 41 is coupled to a gearbox 44 and a differential 45, to transmit engine torque to a transmission line and to the drive wheels 51.

Conventionally, the heat engine 41 includes a cooling circuit with a radiator 43, and an exhaust line 42. There is also a starter 33, which can be provided to provide an automated start function, after an automatic shutdown of the engine, for example at a red light.

The heat engine 41, during its operation, therefore produces heat which is removed by the radiator 43, and with the exhaust gases.

The invention proposes to recover at least part of this waste heat, by equipping the vehicle with an energy recovery device which in particular comprises a heat recovery circuit 10, which operates according to a Rankine cycle.

In fact, pipes 16 and 17 are provided between the radiator 43 and / or the exhaust line 42 to circulate a heat transfer fluid to an evaporator 15 of the heat recovery circuit 10.

Furthermore, this evaporator 15 is supplied by a pump 14 with working fluid (an organic fluid or otherwise called phase change fluid) in the liquid phase, and supplies the working fluid in the gaseous phase under pressure (thanks to the heat recovered from the heat engine 41), to supply a radial turbine 11, which performs an expansion. After expansion, the working fluid passes through a condenser 13 before returning to the pump 14 to be pressurized again.

We can provide other architectures that the pipes 16 and 17 to heat the evaporator 15. It can pass directly the coolant of the engine 41, or its exhaust gases.

The radial turbine 11 is therefore driven by the working fluid, at high speed (between 200,000 and 300,000 revolutions per minute), and is directly coupled with a current generator 12, which is for example a synchronous rotating electric machine with permanent magnets and brushless. The rotor of this current generator 12 is therefore a permanent magnet, and it allows high speeds of rotation, because there are no brushes or sliding contacts.

Such a current generator is very compact (for a nominal power between 1 kW and 3 kW, a machine with an outside diameter of less than 30 mm and a length of less than 60 mm can be chosen. Bearings can be provided air or ball bearings to withstand the very high speed of rotation Typically, such a current generator 12 produces three-phase current, at a voltage greater than 12V.

Due to the heat supply which is done relatively constantly, the radial turbine 11 rotates more regularly than if it were driven by the exhaust gas for example. The yield is therefore improved.

The invention also proposes to convert the current produced directly into direct current, at a voltage of 12V. Consequently, current conversion means 20 are provided with a current converter 21 which transforms the high-voltage three-phase alternating current into direct current at 12V.

It is then possible to directly supply electricity consumers 31 i, 31 ii, ... which are part of an on-board network 30 of the vehicle. It is also then possible to directly supply electrical energy storage means, such as a battery 32.

The invention also proposes to provide the means for converting current with another current converter 22 which transforms direct current at 12V into alternating current at a voltage greater than 12V, to supply for example the starter 33, in order to participate directly in the traction of the vehicle.

One can consider feeding any type of electric motor with the other current converter 22, such as for example an electric motor coupled to the gearbox 44, or directly housed in a drive wheel 51.

One can also provide that the other current converter 22 operates reversibly, to operate the electric motor which it supplies in the traction phase, in current generator during the braking phases. This combines functions and for example avoids having to equip the vehicle with high voltage current storage means. Indeed, the current converters 21 and 22 guarantee that only a battery 32 is necessary to store electrical energy.

It will be understood that various modifications and / or improvements obvious to those skilled in the art can be made to the various embodiments of the invention described in the present description without departing from the scope of the invention defined by the appended claims. In particular, mention is made of a heat engine, it is possible for example to provide a 4-stroke or 2-stroke engine, petrol or diesel, with a number of cylinders between 1 and 12.

Claims (10)

1. An energy recovery device arranged to recover energy produced by a heat engine (41) of a motor vehicle, comprising: - a radial turbine (11), - a current generator (12), coupled to the radial turbine (11) to produce an electric current, characterized in that the energy recovery device comprises a heat recovery circuit (10) arranged to recover heat produced by the heat engine (41) with a phase change fluid, and in that the radial turbine (11) is arranged to be driven in rotation by the phase change fluid, during expansion of the change fluid phase, when it is in the gas phase. 2. Energy recovery device according to the preceding claim, wherein the radial turbine (11) rotates the current generator (12) with a reduction ratio of 1: 1. 3. Energy recovery device according to one of the preceding claims, in which the energy recovery device comprises current conversion means (20), connected to the current generator (12) and arranged to supply the vehicle direct current at a voltage of 12V. 4. Energy recovery device according to the preceding claim, wherein the current conversion means (20) further comprises a current-converter (22) ac-dc arranged to convert direct current into alternating current, to supply a vehicle traction machine. -95. Energy recovery device according to the preceding claim, comprising a starter (33) arranged to start the heat engine (41), in which the starter (33) is arranged to form the traction machine of the vehicle and participate in the propulsion of the vehicle. 5 6. Energy recovery device according to one of the preceding claims, comprising means for recovering kinetic energy. 7. An energy recovery device according to claim 6 and claim 4, wherein the energy recovery means 10 kinetics are a current generator coupled to a wheel (51) of the vehicle, and in which the AC converter (22) arranged to convert direct current into alternating current is arranged to operate reversibly and transform current alternating in direct current. 15 8. Energy recovery device according to one of the preceding claims, wherein the heat recovery circuit (10) with the phase change fluid is arranged to operate according to a Rankine cycle. 9. Energy recovery device according to one of 20 previous claims, wherein the heat recovery circuit (10) with the phase change fluid comprises a heat exchanger arranged to recover heat from an engine cooling circuit, and / or exhaust gas from the engine. 10. Motor vehicle, comprising a recovery device 25 of energy according to one of the preceding claims. 1/1