EP0816651B1 - Cooling device of an internal combustion engine - Google Patents

Description

The present invention relates to a device for cooling of an internal combustion engine, two or four stroke, allowing to differentiate the temperature reached by cylinder head and cylinder block of this motor respectively, with a view in particular to reducing gross emissions of pollutants, in particular particular when starting the engine, and to decrease the temperature rise time of a catalyst provided in the gas exhaust line to increase its speed of action.

We know that the constant goal of manufacturers automobiles, to meet pollution control standards for increasingly severe imposed, is to reduce in the as much as possible the time it takes for a catalyst, arranged in the exhaust gas line combustion, reaches the required level of efficiency, this catalyst which achieves a reduction or oxidation of these gases, or even better a double oxidation and reduction action, the products which result from the catalytic treatment thus implemented can be discharged outside without creating a unacceptable environmental pollution.

However, it is known that the catalysis reaction is not triggered and only becomes effective above a certain temperature, variable depending on the type of catalyst used, but which is generally close to 200 ° C, this temperature being reached only after a relatively significant period of time during which gross engine emissions are significant and produce harmful pollution.

However, we know that these raw emissions, with low engine load, can be reduced even more as the walls of it and in particular of the block cylinders and cylinder head, are themselves more hot, hence the interest of a distribution system of the temperature which achieves these two objectives, while ensuring that the means implemented do not cause a corresponding decrease in engine performance at full load.

The invention therefore relates to a device which makes it possible to decrease the line temperature rise time exhaust gas and simultaneously raising quickly and maintain the temperature of the walls of the engine block at low load to a sufficient value, in improving in all cases the conditions of operation of this engine at all speeds.

French patent FR-A-2 594 84 describes a device for cooling for an internal combustion engine according to the preamble of claim 1 comprising a cylinder block and a cylinder head, device comprising a radiator and a circuit provided a pump for the circulation of a cooling between this radiator and the engine block. The circuit is divided into two parts, established respectively in the walls of the cylinder block and in those of the breech, these two parts being put in series, the one that interests the cylinder block being arranged downstream from each other in the direction of circulation of the fluid. A set of valves is provided to control the flow of this fluid, either in one, either in the two parts of the circuit, depending on predetermined valve trip thresholds.

Such a system is however complex to implement, cumbersome to to implement and expensive to manufacture. Furthermore, it aims at a completely different objective which consists in maintaining in constantly coolant temperature in the cylinder head at a level lower than that corresponds to the cylinder block, in order to obtain lower temperatures in the combustion chamber to limit the self-ignition phenomenon, while the higher temperature in the cylinder block lowers the viscosity of the lubricating oil and reduces the friction of the pistons in their shirts.

The invention relates to a device of more simple and which allows a higher temperature rise rapid catalyst combined with optimal reduction of polluting emissions, before it reaches its full efficiency.

For this purpose, the device considered, for a motor with internal combustion comprising a cylinder block and a cylinder head whose walls are arranged to delimit a first and second separate parts of the same circuit for the separate cooling of these walls, a radiator with an input and an output connected to the circuit and a circulation pump for a fluid cooling in it the radiator outlet being connected, by means of the traffic, at the entrance to the first part of the circuit provided in the cylinder head, the exit of this first part being separated in two ways, one of which is connected to the radiator inlet and the other to the inlet of the second part of the circuit planned in the block cylinders, the output of this second part being also connected to the radiator input, is characterized in that the entrance to the first part of the circuit is provided in the side wall fluid swept cylinder head inlet, outlet of this first part being provided on the side exhaust.

According to another characteristic, the entry of the second part of the circuit, connected to the output of the first part, and the output of this second part are one and the other provided in the wall on the exhaust side of the cylinder block.

According to another characteristic, the first part of the circuit has, between its input and its output, transverse connecting conduits, extending in the cylinder head wall between the spark plugs and / or injectors fuel in the engine cylinders.

According to an additional characteristic, the second part of the circuit in the wall of the cylinder block, has a hairpin profile.

Advantageously, the input of the radiator is connected to the outputs of the first and second parts of the circuit by a first thermostatic mixer, the trigger point is set by construction to a setpoint temperature T1. Preferably also, the output of the first mixer is connected to the input of the radiator or directly to the circulation pump by through a bypass line and a second thermostatic mixer with a trigger threshold is set at a set temperature T2, different or nonde T1.

According to another particular characteristic of the device considered, the second thermostatic mixer is placed downstream of the first mixer, in the direction of the circulation of the fluid in the circuit.

In addition and in a preferred embodiment of the invention, the set temperature T1 of the first thermostatic mixer is less than or equal to the setpoint temperature T2 of the second.

Also preferably, one or both thermostatic mixers is associated with a drawer hydraulic adjusting the fluid flow rates cooling delivered to these mixers by the circuit.

Advantageously, each thermostatic mixer comprises a body containing a block of expandable material under the effect of temperature variation and acting on a piston movable in a guide carried by the body. A tampon intermediate is mounted between the material block and the piston, which is joined to a spring of reminder. The block of expandable material acts on the piston to through a waterproof diaphragm or the like.

• La Figure 1 est un schéma de principe illustrant en perspective l'aménagement du circuit de refroidissement dans la culasse et le bloc cylindres du moteur.
• La Figure 2 est également un schéma de principe correspondant à une vue en plan et de dessus du circuit de la Figure 1.
• La Figure 3 est une vue en coupe à plus grande échelle du premier mélangeur thermostatique et du tiroir hydraulique qui lui est associé pour ajuster les sections des sorties des première et seconde parties du circuit.

Other characteristics of a device for cooling an internal combustion engine established in accordance with the invention will become more apparent from the following description of an exemplary embodiment, given by way of non-limiting example, with reference to the drawings annexed on which:

• Figure 1 is a block diagram illustrating in perspective the arrangement of the cooling circuit in the cylinder head and the engine block.
• Figure 2 is also a block diagram corresponding to a plan and top view of the circuit of Figure 1.
• Figure 3 is an enlarged sectional view of the first thermostatic mixer and the hydraulic slide associated therewith to adjust the sections of the outputs of the first and second parts of the circuit.

In Figure 1, the reference 1 designates very schematically an internal combustion engine, the two essential parts consist of a cylinder block 2 and a cylinder head 3. In the example thus illustrated, the block 2 has four parallel cylinders 4, arranged vertically, the cylinder head 3 comprising, in line with these cylinders, intake manifolds such as 5.

Of course, it is clear that the invention is not limited to such an arrangement, block 2 may include a different number of cylinders 4, these being arranged in another orientation, in V for example. Of even, no limitation is imposed as to the nature of engine power or gas ignition, engine considered may be direct injection or indirect, with conventional spark plug ignition or by compression.

Reference 6 designates as a whole a closed circuit for the circulation of a coolant of the motor, this circuit being formed of two parts separate, respectively 7 and 8, in series, one with the other, the first being arranged in the thickness of the wall of the cylinder head 3 and the second in that of the block cylinders 2. This circuit also includes a radiator 9, conventionally associated with a fan 9a (Figure 2), and a circulation pump 10.

The first part 7 of circuit 6 has an input E1 for the fluid delivered by the pump 10 and, after this has circulated in the wall of the cylinder head 3, a output S1. Likewise, the second part 8 of this circuit, arranged downstream from the first in the direction of the circulation of the fluid shown diagrammatically by the arrows and fitted in the wall of the cylinder block 2, comprises also an E2 input and an S2 output, the E2 input being connected to the output Si of the first part.

As we can also see, the output Si of the first part actually subdivides into two separate tracks, S11 and S12 respectively, channel S11 being alone connected to input E2 of the second part 8 of the circuit, while channel S12 is connected, by via a line 11, at the entrance R1 of the radiator 9. The R2 output of this radiator is for its part joined by a line 12, through the pump circulation 10, at the entrance E1 of the first part 7 of circuit.

The second channel S12 at the output S1 of the first part 7 is connected to the pipe 11 via a first thermostatic mixer M1, according to an assembly more particularly illustrated in Figure 3 described below.

Between the input R1 and the output R2 of the radiator 9 is provided a bypass line 13, the connection between this and the pipe 12 downstream of the outlet R2 being produced by a second mixer thermostatic M2.

Note that the first part 7 of circuit 6 is advantageously arranged to include a series of transverse conduits 14, extending between the heads of the cylinders 4, inside the walls of the cylinder head 3.

Figure 3 illustrates more specifically how produced and controlled by the first mixer thermostatic M1, the connection between the S2 output of the second part 8 of the cooling circuit, the outlet S12 of the corresponding channel, coming from the first part 7, and line 11 back to the entrance R1 from radiator 9 or bypass line 13.

As shown, the assembly uses a drawer hydraulic 15, generally cylindrical in shape, suitable for slide inside a hollow guide sleeve 16 into which the outputs S2 and S12 open. These outputs are separated from each other, depending on the direction of the axis of the guide sleeve, by a distance which corresponds substantially to the length of the drawer, so that depending on the position relative of the latter in the folder, the S2 output can be fully closed when the S12 output is fully open or vice versa, the drawer may well heard occupying any intermediate position by adjusting the relative flow rates of the cooling from these two outputs respectively, flowing to return line 11.

The hydraulic slide 15 is controlled by means of a thermostatic element 17, in itself known in the technical, with a fixed body 18 inside which houses a block 19 of an expandable material appropriate.

Depending on the temperature surrounding the body 18, this block expands or retracts and acts through a diaphragm 20 and possibly a thrust pad 21 on a movable piston 22, through a guide 23 provided in the body, this piston 22 resting on its opposite end on a shoulder 24 integral with the drawer 15.

Under these conditions, when under the effect of a temperature increase block 19 expands, this one causes displacement of the piston 22 and consequently that of drawer 15 upwards in the figure, opening gradually output S2 and simultaneously closing the outlet S12, the fluid coming from these outlets, respectively of the cylinder block 2 and of the cylinder head 3, being collected in line 11 and sent to radiator 9 or to the bypass line 13. When the temperature decreases, block 19 retracts, piston 22 being biased against buffer 21 via a spring 25 housed in the body 18 under the guide 23.

A similar arrangement is made for the second thermostatic mixer M2, the fluid that enters the hollow jacket containing the hydraulic drawer respectively coming from line 12 connected to the R2 output from radiator 9 and bypass line 13, this fluid being at the outlet of the mixer taken up by the circulation pump 10.

Element 17 used in either of the two thermostatic mixers is chosen by construction of so as to present a set point corresponding to a predetermined temperature, only above which occurs the displacement of the hydraulic slide. The setpoint thresholds of the first and of the respectively second mixers M1 and M2 are generally different and by convention identified in the following under the references T1 and T2. In addition and preferably, the threshold T1 is less than threshold T2.

Finally, it will be noted that, according to a characteristic essential of the invention, the entry E1 of the fluid in the first part 7 of the circuit is arranged on the side admission into cylinder head 3, outlet Si being on the side exhaust, the opposite sides being joined by the transverse conduits 14, while the inlet E2 and the output S2 of the second part 8 are both provided on the exhaust side, the circuit profile in this second part corresponding substantially to a hair pin.

The operation of the device considered is then next, the fluid used is usually of water, possibly with appropriate additives as is well known in the art of setting work of these circuits for cooling a internal combustion engine.

Water from the radiator and circulated by pump 10 enters the first part 7 of the circuit 6 at the entrance E1 thereof, provided on the admission side in cylinder head 3, preferably one or the other of its ends, on the distribution side as shown in Figures 1 and 2, or if necessary opposite, on the side clutch.

The water thus sweeps the entire wall of the cylinder head in the face of it corresponding to the admission, so longitudinal as well as transverse between the heads cylinders 4 thanks to the transverse conduits 14, in allowing efficient cooling of the usual organs provided at this location, in particular the candles and / or fuel injectors.

At the output S1 of this first part 7, the water can be conveyed, in whole or in part as the case may be, either towards the input E2 of the second part 8 of the circuit 6, either directly to return line 11 through thermostatic mixer M1 via channel S12, whether or not cooling the cylinder block 2 by the hairpin path provided in the wall of this last.

The control of the mixer M1 is carried out by its element thermostatic 17 as mentioned above, in function of the setpoint T1, therefore of the level of the water temperature.

In particular, as long as the temperature at the outlet of the mixer M1 remains below this value of setpoint T1, the water flows exclusively through channel S12 and the return line 11, the cylinder block 2 not being not cooled.

However, when the temperature reaches this value T1, the mixer M1 adapts its opening so that the water flow is distributed between inlet E2 in the second part 8 of the circuit in the wall of the block cylinders and the outlet S12 as before;

In either case, the collected water returns, either to radiator 9, i.e., by-pass line 13 and the second mixer M2, directly to the pump circulation 10 which returns it to entrance E1 of the first part, this depending on the value setpoint T2 set for the triggering of the element thermostat of this second mixer.

In other words, as long as the water temperature of output of mixer M2 remains below the value of setpoint T2, this water does not circulate in the radiator but is completely taken up by the pump and returned to entry E1.

Thanks to these provisions, when the engine is cold and especially when it starts up, all the liquid circulates only in the first part 7 of the circuit, allowing a much faster heating of the block cylinders and therefore a very high temperature rise rapid combustion gases which, by heating the catalyst in the exhaust line, cause the very quick implementation of it by reducing particularly sensitive the level of pollution when rejected outside.

However, as soon as the cylinder block is heated, the thermostatic mixer M1 is controlled to allow the regulated circulation of water in the second part 8 of the circuit, downstream of the first. If, during engine temperature drops to again, the mixer M1 will play in reverse, limiting or even canceling traffic in the second part of the circuit.

In all cases, the device makes it possible to avoid accidental overheating thanks to the second M2 mixer, whose setpoint temperature T2 is preferably chosen higher than the temperature T1 of the first, in according to the case, either direct circulation by pump 10, which is a passage of all or part of the flow by the radiator 9, making it possible to reduce the temperature of this water to below the set value T2 for which the direct circuit is again set up artwork.

However, it would not go beyond the scope of the invention to choosing equal temperatures T1 and T2, for example with two identical mixers for which the opening drawer action occurs at 83 ° C and full opening at 95 ° C.

The device thus produced, because it dissociates the two-part cooling circuit arranged in series, interesting for one the breech always cooled, and for the other the cylinder block whose cooling is continuously adjusted, allows to obtain permanent control of the temperature in this block and, at low loads, reduce very sensitive to polluting emissions of combustion gases.

The cooler water supplied by the pump circulating first in the cylinder head on the intake side, in addition to ensures efficient cooling of sensitive organs arranged in this place such as the injectors fuel, does not heat this cylinder head, since this water is not yet thermally charged. As a result, the mass flow of gases through the admission is favored, that these gases are constituted by clean air, by a mixture of air and burnt gases, or by burnt gases alone.

Of course, it goes without saying that the invention is not limited not to the embodiment more specifically described above with reference to the accompanying drawings; she in on the contrary embraces all variants.

Claims (12)

1. Cooling device for an internal-combustion engine, comprising a cylinder block (2) and a cylinder head (3) of which the walls are arranged so as to define a first distinct portion (7) and a second distinct portion (8) of the same circuit (6) for the separate cooling of these walls, a radiator (9) comprising an inlet (R1) and an outlet (R2) connected to the circuit and a pump (10) for circulating a coolant therein, the radiator outlet being connected via the circulating pump to the inlet (E1) of the first portion of the circuit provided in the cylinder head, the outlet (S1) of this first portion being separated into two channels, of which one (S12) is connected to the inlet of the radiator and the other (S11) to the inlet (E2) of the second portion of the circuit provided in the cylinder block, the outlet (S2) of this second portion also being connected to the inlet of the radiator, characterised in that the inlet (E1) of the first portion (7) of the circuit (6) is provided in the wall disposed on the intake side of the cylinder head (3) swept by the fluid, the outlet (S1) of this first portion being provided on the exhaust side.
2. Device according to claim 1, characterised in that the inlet (E2) of the second portion (8) of the circuit, connected to the outlet (S1) of the first portion, and the outlet (S2) of this second portion are each provided in the wall of the exhaust side of the cylinder block (2).
3. Device according to any of claims 1 or 2, characterised in that the first portion (7) of the circuit (6) comprises, between its inlet (E1) and its outlet (S1), transverse connecting conduits (14) extending in the wall of the cylinder head (3) between the spark plugs and/or fuel injectors in the engine cylinders (4).
4. Device according to any of claims 1 to 3, characterised in that the second portion (8) of the circuit (6) in the wall of the cylinder block (2) has a hairpin-shaped profile.
5. Device according to any of claims 1 to 4, characterised in that the inlet (R1) of the radiator (9) is connected to the outlets (S1, S2) of the first portion (7) and of the second portion (8) of the circuit (6) by a first thermostatic mixer (M1) of which the activation threshold is fixed by design to a reference temperature T1.
6. Device according to any of claims 1 to 5, characterised in that the outlet of the first mixer (M1) is connected to the inlet (R1) of the radiator (9) or directly to the circulating pump (10) via a by-pass conduit (13) and a second thermostatic mixer (M2) of which the activation threshold is fixed at a reference temperature (T2) which may or may not be different from T1.
7. Device according to claim 6, characterised in that the second thermostatic mixer (M2) is placed downstream of the first mixer (M1) in the direction of circulation of coolant in the circuit (6).
8. Device according to any of claims 6 or 7, characterised in that the reference temperature T1 of the first thermostatic mixer (M1) is lower than or equal to the reference temperature T2 of the second mixer (M2).
9. Device according to any of claims 6 to 8, characterised in that one or each of the two thermostatic mixers (M1, M2) is associated with a hydraulic slide valve (15) adjusting the flows of coolant supplied to these mixers by the circuit.
10. Device according to any of claims 5 to 9, characterised in that each thermostatic mixer (M1 or M2) comprises a body (18) containing a block (19) of material which is expandable due to the variation in temperature and acting on a piston (22) moving in a guide (23) carried by the body.
11. Device according to claim 10, characterised in that an intermediate buffer (21) is mounted between the block of expandable material (19) and the piston (22) combined with a restoring spring (25).
12. Device according to any of claims 10 or 11, characterised in that the block of expandable material (19) acts on the piston (22) through an impermeable diaphragm (20) or the like.

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