FR2983524A1 - COOLING SYSTEM OF HANDLING TROLLEY - Google Patents

Abstract

Cooling system of a truck (1) equipped with a heat engine (10) and a power electronics (16). A circuit (33) cools the heat engine (10) and a circuit (41) cools the power electronics (16). A suction line (39) connects a circulation pump (34) of the circuit (33) to a rebreathing branch (38) of the expansion vessel (37). A purge line is connected to the compensation tank (37). A re-suction line of the circuit (43) connects the suction side of a circulation pump to the re-suction connection (38) of the expansion vessel (37) and a bleed line (44) connects the circuit (41) to the vessel. Expansion (37). At least one of the lines (39, 40, 43) has a throttling device (46) for limiting the coolant volume flow rate.

Description

Field of the invention The present invention relates to a cooling system of a handling truck equipped with a heat engine and at least one power electronics, a cooling circuit cooling the heat engine and a circuit cooling of the electronics cooling power electronics as well as an expansion tank for the coolant, a motor exhaust line connecting the suction side of a motor cooling circuit circulation pump to a rebreathing connection of the expansion tank and at least one bleed line of the engine cooling circuit is connected to the expansion tank. State of the art Forklift trucks, such as forklift trucks, use an electric drive from a combustion engine. The combustion engine, in particular a diesel engine or a gas engine drives a generator that supplies electric power. The electric current feeds an intermediate circuit, in general an intermediate circuit with DC voltage and one or more electric motors for driving as well as other means for driving the carrier carriage, for example the electric motor of the pump supplying liquid. hydraulic handling truck.

The heat engine gives off heat in the form of lost heat and that is why it must be cooled. Current engines use cooling of the coolant which is a liquid supplemented with an antifreeze agent. In this circuit, a pump circulates the cooling liquid and the heat released is exchanged with the ambient air via a radiator. According to the state of the art, for the control of electric motors such as rolling motors or the motor driving the hydraulic operating pumps, but also the generators, power electronics are used, in particular inverters which transform the motor. dc direct current to a polyphase alternating current or in the case of a generator, the inverse transformation is carried out. These power electronics, use power semiconductors to switch very high currents but which give a high power lost. It is known to provide cooling also by cooling with a liquid. Power semiconductors require a temperature level of about 70 ° C for optimum and efficient operation. On the other hand, for thermal engines, in particular for the behavior of the exhaust gases and the fuel consumption, in the partial load operation mode, it is typically necessary to have cooling water temperatures which are optimal around 100 ° C. This is why there is a separate cooling circuit for the power electronics and for the heat engine. The cooling circuits are pressurized circulation circuits and they each have an expansion tank to compensate for the volume variations related to the expansion caused by the temperature but also to the tolerances of the filling volume. In general, the expansion tanks allow, thanks to a pressure-tight opening, to fill or complete the filling of the system. In addition, an expansion tank separates the air bubbles from the cooling system and could hinder the flow of coolant. For this, a suction line opening into the bottom of the expansion tank is connected to the suction side of the circulation pump of the cooling circuit. But at the same time all the points located at the height of the cooling circuit where the air bubbles can accumulate and hang are generally connected to the expansion tank by the purge lines, for example to the upper side of the heat exchanger or radiator. The air purge lines open into the expansion vessel in a position higher than the suction line which, in the usual embodiments, opens in a position higher than the outlet of the suction line and often above of the liquid level. If the suction pump sucks coolant back into the expansion tank, a mixture of cooling line and any air bubbles will be pushed under the same conditions by the purge line or the purge lines. in the expansion vessel. As the volume of coolant circulating in the expansion vessel is a relatively small volume, the liquid settles in the expansion vessel and the air bubbles are released. The disadvantage of this state of the art is that in the industrial truck such as a forklift, because of the organization in the vehicle, the necessary lengths of the coolant lines and the power consumed by the cooling system requires relatively large volumes and relatively large expansion vessels. In the case of two cooling systems, this results in the disadvantage of a large footprint. In the case of two expansion tanks, especially if these expansion vessels are placed in different places, there is a risk that a cooling system is not taken into account during the daily maintenance of the vehicle. It is also conceivable to combine the expansion vessels of the two cooling circuits in a single expansion vessel into which the bleed pipes of the second cooling circuit, for example the cooling circuit of the electronics, connected to the vessel, open. expansion. But as the coolant in the electronics cooling circuit does not pass through the expansion vessel, there will not be this annoying mixture of hot coolant from the engine cooling system and relatively coolant. cold of the electronics cooling circuit. The air bubbles in the electronics cooling circuit would only be incompletely separated and the first filling or the additional coolant filling of the electronics cooling circuit would be complicated operations because it would be necessary to take special measures to purge the air.

OBJECT OF THE INVENTION The object of the present invention is therefore to develop a cooling system enabling the power electronics and the heat engine of an equipped industrial truck to be cooled as simply and economically as possible. a drive system with electric motor and heat engine, avoiding the bulk and the disadvantages of two expansion tanks. SUMMARY OF THE INVENTION AND ADVANTAGES OF THE INVENTION To this end, the subject of the invention is a cooling system for a handling trolley of the type defined above, characterized in that a cooling circuit re-suction duct is provided. electronics connects the suction side of an electronics cooling circuit circulation pump to the expansion manifold of the expansion vessel and at least one purge line of the electronics cooling circuit connects the cooling circuit of the cooling of the electronics to the expansion tank and at least one pipe comprises a throttling device for limiting the volume flow of coolant, this pipe being one of the following pipes: - engine re-suction pipe, pipe of purge of the engine cooling circuit, liquid recirculation line of the electronics cooling circuit and purge line of the cooling circuit of the el ectroniques.

This system has the advantage of being compact and simple because it only takes one expansion tank. Nevertheless, the system ensures that the cooling circuit will not contain air bubbles, although there is only a restricted flow rate of coolant through the expansion vessel. This ensures the full power capacity of this cooling circuit. At the same time, too much mixing of the two cooling circuits is avoided and thus, for example, a disturbing heating of the coldest cooling circuit. The unique expansion tank simplifies the daily maintenance of the industrial truck and avoids the risk that one of the cooling circuits is not taken into account for checks and small daily maintenance. According to an advantageous development, the throttling device equips the re-suction line of the cooling circuit of the electronics. The throttling device is advantageously installed in the bleed line of the cooling circuit of the electronics. The cooling circuit of the electronics is generally simple, even if several electronic power components have to be cooled. The engine cooling circuit typically has a more complex structure due to the short-circuiting circuit which corresponds to a small cooling circuit used during the reheating phase or by the presence of a heat exchanger. supplement for heating the cabin. This is why the cooling circuit of the electronics is generally easier to purge and avoid air bubbles, so it is particularly advantageous that the cooling liquid of the electronics cooling circuit does not cross the vessel. of expansion with a restricted flow rate. This is sufficient to ensure that the cooling circuit of the electronics does not contain air bubbles. The throttling device can be constituted by a reduction of the section of the pipe, which is a particularly simple and effective solution to apply. According to an advantageous development of the invention, the throttling device is constituted by a diaphragm. The diaphragm makes it possible to precisely adjust the throttling effect of the throttling device, which makes it possible to adapt the cooling system to environmental conditions such as, for example, particular climatic zones or different types of trolleys. Handling. The diaphragm makes it possible to have a throttling effect which is sufficiently large for the volume flow rate so that in each case the annoying heating of the least hot cooling circuit is avoided.

There may be several air exhaust or purge lines of the engine cooling circuit, which allows a more efficient purging of the corresponding circuits in that the potential points of attachment or accumulation of air bubbles will be equipped with a purge line. According to an advantageous development, the heat engine drives a generator which supplies the intermediate electrical circuit, in particular an intermediate DC circuit for supplying the driving motors.

In the case of such a drive with electric and thermal motors, the invention applies in a particularly advantageous manner because the electronic circuits or power components such as, for example, the inverter of the generator or those of the driving motors have high power and thus require cooling adapted to this power. The industrial truck is advantageously a forklift truck. In the case of forklift trucks, it is particularly advantageous that the space requirement is reduced by means of a single expansion vessel. At the same time, in the case of a fork-lift truck, the radiator is generally installed at the rear and will not be cooled by the circulating wind, so that relatively long lines will be available for the liquid. cooling and thus a large volume of coolant requiring an expansion tank of appropriate dimensions; moreover, a routing of the lines, that is to say the air purging lines of the engine cooling circuits and the electronics, will cause the cooling circuit (s) to be free. (s) air bubbles. The solution according to the invention makes it possible precisely in the case of forklifts with cooling circuit of the electronics and cooling circuit of the engine to maintain these circuits without air bubbles. Drawings The present invention will be described in more detail below with the aid of an exemplary trolley cooling system, shown in the accompanying drawings, in which: Figure 1 shows a trolley in the form of a forklift equipped with a cooling system according to the invention, FIG. 2 shows a cooling system according to the state of the art, FIG. 3 shows the cooling system of the industrial truck of the invention represented in FIG. Figure 1.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION FIG. 1 shows a handling trolley 1 equipped with a drive system with thermal and electric motors in the form of a forklift and counterweight 2. The forklift truck and counterweight 2 comprises a lifting mast 3 equipped with a load-receiving means such as a liftable fork 4. The driver's cab 5 has a driver location 6 with a driver seat 7. A counterweight 9 is provided above and behind the rear axle 8 which is steering. A heat engine 10 which, in this example, is a diesel engine 11 is combined with a generator 12 for generating electric current supplied by a DC intermediate circuit, not shown, as an intermediate electric circuit, and an inverter 15, a power electronics 16 connected to at least one electric displacement motor 13 equipping the front axle 14. The electric displacement motor 13 drives the forklift and counterweight 2. The heat released by the diesel engine 11 is taken by the engine coolant coolant to pass through a motor radiator 17 traversed by air as indicated by the arrow, to evacuate the heat to the ambient air. Another cooling circuit of the electronics evacuates the heat generated by the power electronics 16 to the ambient air also via an electronics cooling radiator 18. FIG. a cooling system corresponding to the state of the art for an electric drive truck from a heat engine. The heat engine 10 is cooled by the coolant passing into the cooling circuit 19 of the engine. A motor cooling circulation pump 20 takes the coolant into the engine cooling circuit 19. A thermostatic valve 21 directs the coolant through a short-circuit conduit 22 into a small cooling circuit to return to the engine cooling circuit. coolant circulation pump 20 or to the engine radiator 17 in which the coolant discharges the heat released, recovered in the engine 10 to the ambient air. After a cold start of the engine 10, the thermostatic valve 21 directs the coolant through the small cooling circuit, directly back to the engine coolant pump 20 until the correct temperature is reached. Operating. An expansion vessel 23 is provided in a position quite beneath the rebreathing branch 24 from which a motor re-suction pipe 25 is output at the outlet of the circulation pump of the engine cooling circuit 20. Engine cooling system purge lines 26 depart from the high points of the thermostatic valve 21 of the engine coolant circuit 19 and the engine radiator 17 to open into the expansion vessel. When the circulating pump 20 of the engine cooling circuit circulates the coolant in the engine cooling circuit 19, coolant is sucked into the expansion vessel 23 through the suction branch 24. and the engine exhaust pipe 25. A corresponding amount of coolant is discharged through the bleed lines 26 of the engine cooling circuits to the expansion vessel 23, causing any air bubbles from the high points of the motor cooling circuit 19 where they accumulate, for transfer to the expansion tank 23. In the expansion tank 23, the coolant is calmed and air bubbles are released. Next to the engine cooling circuit 19, the cooling system according to the state of the art comprises another cooling circuit of the electronics 27. In the cooling circuit of the electronics 27, a circulation pump The cooling circuit of the electronics 28 pumps the coolant through a heat exchanger of the power electronics 16 to calm the flow and then to remove the heat to the ambient air through the radiator 18 of the electronic. Another expansion tank 29 with a rebreathing branch 30 installed in the low position is connected to the rebreathing branch 30 via an electronic circuit re-aspiration duct 31 with the suction side of the circulating pump 28 of the cooling circuit. 'electronic. A bleed pipe of the cooling circuits of the electronics 32 is connected to the electronics heater 18 which is the highest point of the cooling circuit of the electronics 27. The disadvantage of this solution according to the state of the The technique is to require two expansion vessels 23, 29 which are bulky. If for reasons of space, these expansion vessels 23, 29 are installed at different locations, this increases the risk of error. FIG. 3 shows the cooling system according to the invention of the industrial truck of FIG. 1. The thermal engine 10 is cooled by the coolant of the engine coolant circuit 33. A circulation pump 34 of the Engine cooling circuit pumps the coolant into the engine cooling circuit 33. A thermostatic valve 35 directs the coolant to either the short-circuit conduit 36 in a short cooling circuit back to the circulating pump coolant 34 or to the engine radiator 17 wherein the coolant discharges heat from the engine 10 to the ambient air. After a cold start of the heat engine 10, the thermostatic valve 35 directs the coolant through the small cooling circuit, directly back to the engine coolant circulation pump 34 until the temperature of the engine is reached. operation. An expansion vessel 37 comprises, in a low position, a rebreathing branch 38 connected to a motor rebreather pipe 39 for the suction side of the circulation pump 34 of the engine cooling circuit. Purge lines 40 of the engine cooling circuits depart from the engine cooling circuit 33 at the high points of the thermostat 35 and the radiator 17 of the engine to pass into the expansion vessel. In the cooling circuit of the electronics 41, a coolant circulation pump of the electronics 42 pumps the coolant through a heat exchanger of the power electronics 16 to cool it and then evacuate. the ambient air heat through an electronic radiator 18. The rebreathing branch 38 of the expansion tank 37 is further connected to an electronic cooling circuit re-suction line 43 whose Another end is connected to the suction side of the circulation pump 42 of the electronics cooling circuit. A purge line 44 of the electronics cooling circuit is connected to the electronics of the electronics 18 at the highest point of the electronics cooling circuit 41 via a diaphragm 45 for the electronics. in the upper zone of the expansion tank 37. When the circulation pump 34 of the engine cooling circuit circulates the coolant in the engine cooling circuit 33, coolant is sucked into the vessel 37, a corresponding volume of coolant is discharged through the cooling circuit bleed lines 40 into the expansion tank 37 and causes the eventual expansion of the expansion vessel 37. air bubbles at the high point of the engine cooling circuit 33 to collect them in the expansion tank and let out air bubbles accumulating in the expansion tank 37. The coolant and the air bubbles separate in this expansion tank 37. Similarly, the suction pipe 43 of the cooling circuit of the electronics sucks liquid. cooling and pushing it back to the highest point of the radiator of the electronics 18 according to a suitable volume of coolant through the bleed line 44 of the exhaust circuit of the radiator of the electronics to discharge this volume of coolant in the expansion tank 37. The volume of coolant is limited by the diaphragm 45 functioning as a throttling device 46 and limiting the flow rate in the bleed line 40 of the cooling circuits of the cooling system. electronics. This prevents too much hot coolant from the engine cooling circuit 33 into the cooling circuit of the electronics 41 colder and warms it unnecessarily.10 NOMENCLATURE 1 Handling cart 2 Forklift and counterweight 3 Lift mast 4 Load receiving fork 5 Driver's cab 6 Driver's location 7 Driver's seat 8 Rear axle 9 Counterweight 10 Engine 11 Diesel engine 12 Generator 13 Electric drive motor 14 Front axle 15 Inverter 16 Power electronics 17 Engine radiator 18 Electronics radiator 19 Engine cooling circuit 20 Circulation pump 21 Thermostatic valve / valve 22 Short-circuit line 23 Expansion vessel 24 Re-suction connection / output connection 25 Engine exhaust line 26 Purge line 27 Electronics cooling circuit 28 Fuel pump circulation 29 Expansion tank 30 Connection connection 31 Re-suction line 32 Drain line 33 Motor cooling circuit 34 Circulating pump 35 Thermostatic valve 36 Short-circuit line 37 Expansion tank 38 Breathing branch 39 Re-suction line 40 Drain line 41 Electronics cooling circuit 42 Circulation pump 43 Suction line 44 Drain line 45 Diaphragm 46 Throttle device15

Claims (1)

CLAIMS 1 °) Cooling system of a truck (1) equipped with a heat engine (10) and at least one power electronics (16), - a cooling circuit (33) cooling the heat engine mate (10) and an electronics cooling circuit (41) cooling the power electronics (16) and an expansion tank (37) for the coolant, a motor exhaust line ( 39) connecting the suction side of a circulating pump (34) of the engine cooling circuit to a rebreathing branch (38) of the expansion vessel (37) and at least one bleed line (40) of the engine cooling circuit (33) is connected to the expansion tank (37), a cooling system characterized in that an electronic cooling circuit re-suction line (43) connects the suction side of a pump circulation circuit (42) of the electronic cooling circuit rebreathing anchor (38) of the expansion vessel (37) and at least one purge line (44) of the electronics cooling circuit connects the cooling circuit of the electronics (41) to the vessel of expansion (37) and at least one pipe has a throttling device (46) for limiting the flow rate of coolant, this pipe being one of the following pipes: - motor re-suction pipe (39) , purge line (40) of the engine cooling circuit, liquid refrigerant recirculation line (43) of the electronics cooling circuit and purge line (44) of the electronic cooling circuit. 2) Cooling system according to claim 1, characterized in thatthe throttling device (46) is installed in the re-suction line (43) of the cooling circuit of the electronics. Cooling system according to claim 1, characterized in that the throttling device (46) is installed in the purge line (44) of the electronic cooling circuit. 4) Cooling system according to one of claims 1 to 3, characterized in that the throttling device (46) is a reduced pipe section. 5 °) cooling system according to one of claims 1 to 4, characterized in that the throttling device (46) is a diaphragm (45) 6 °) cooling system according to one of claims 1 to 5, characterized by a plurality of purge lines (44) of the electronics cooling circuit. 7 °) Cooling system according to one of claims 1 to 6, characterized by a plurality of purge lines (40) of the engine cooling circuits. 8 °) cooling system according to one of claims 1 to 7, characterized in that a generator (12) is driven by the heat engine which feeds the intermediate electrical circuit, including a DC intermediate circuit for powering an engine rolling (13). 9 °) cooling system according to one of claims 1 to 8, characterized in that the carrier carriage is a fork carriage (2).