FR2461101A1 - DEVICE FOR CONTROLLING THE AIR OF DIESEL ENGINE POWER SUPPLY - Google Patents

Abstract

THE INVENTION CONCERNS SUPERCHARGED DIESEL ENGINES. THE BOOST AIR SUPPLIED BY COMPRESSOR 10 PASSES INTO A FIRST HIGH TEMPERATURE R HEAT EXCHANGER THEN IN A SECOND LOW TEMPERATURE R EXCHANGER IN SERIES WITH THE FIRST EXCHANGER. A BYPASS 28 DERIVES AN ADJUSTABLE PART OF THE BOOST AIR FLOW OUTSIDE THE EXCHANGER R. ONE OR MORE FLAPS 30-36 ADJUST THE AIR FLOWS. APPLICATION TO THE REGULATION OF THE TEMPERATURE OF THE BOOSTER AIR AT THE ENGINE INLET.

Description

1.

24 6110 1

  The present invention relates to superheat thermal engines

  compressor-based, in particular diesel engines, and more particularly it relates to a device for regulating the temperature

  of the charge air supplied to the engine by the compressor.

  It is known that, on a diesel engine, it would be desirable for the temperature of the air at the end of compression to vary little, whatever the operating conditions, in order to obtain suitable ignition delays and good combustion. Therefore, not to reach excessive temperatures at full load Io, when the air temperature at the exit of the

  compressor is high, it is customary to mount a sample system

  of heat on the charge air circuit between

  the compressor outlet and the air inlet on the engine.

  Such a heat exchanger system often comprises two heat exchangers. On some engines, these two exchangers are connected in parallel. On other engines, the two heat exchangers are mounted in series, the second heat exchanger being traversed by a coolant (for example water from an external source, or ambient air) colder than the heat transfer fluid browsing the first exchanger. In known manner, the first exchanger can use as heat transfer fluid the water

engine cooling.

  The present invention concerns more precisely the systems of this second type, that is to say with two exchangers in series, the first exchanger being a high temperature exchanger, the

  second exchanger being a low temperature exchanger.

  Known systems of this type normally avoid

  crank the engine, with heavy loads, with surplus air

  temperature too high.

  However, high outside temperatures can

  thermal overloads, while low temperatures

  erations can lead to incomplete combustions.

  causing clogging on the engines with

  normal metrics, or impossibilities of operation in

  the case of engines with reduced volumetric ratio.

2 2461101

  It has been proposed to control the temperature of the air to control the flow or temperature of the heat transfer fluids

  in both exchangers, so that the system can function

  as a cooler or air heater, depending on the load, but this leads to improper use of the exchangers, a complication of the installations, and therefore

  less security of operation.

  Moreover, the control of the flow of the caloporic fluids

  causes a significant hysteresis phenomenon, which can be detrimental-when the motors are

very quickly variable.

  The present invention makes it possible, with a system of two

  heat exchangers in series, to obtain satisfactory regulation

  rapid response, the air temperature of

  Temptation admitted to the engine, this result being obtained thanks to

  simple means, little cogous and safe operation.

  The invention relates to a device with two series exchangers of the aforementioned type in which there is provided a bypass passage of the supercharger ir whose input is

  connected between the two heat exchangers and whose output

  tie is connected between the output of the second heat exchanger and

the air intake of the engine.

  Preferably, there is provided a controlled member for adjusting the charge air flow through at least one of the passages comprising the aforementioned bypass passage and the passage connecting the outlet of the second heat exchanger to the inlet

of engine air.

  Advantageously, the aforementioned controlled member is actuated by a servomechanism under the control of one of the operating parameters of the engine, in particular the air pressure at the

compressor output.

  Preferably, the temperature of the coolant trans-

  pouring the high temperature exchanger is greater than the time

  maximum ambient air temperature, so that reheating

  systematically occurs in empty markets, and,

  their, is substantially lower than the air temperature of

  compressor discharge when the engine is at full

  ge, so that at these regimes, the exchanger can operate

in cooler.

  The invention applies to diesel engines with a volumetric ratio

  but is of particular interest in the

  the so-called "reduced volumetric ratio" motors, that is to say

re less than 12

  The invention will be better understood on reading the detailed description which follows and with the aid of the attached drawing which

  represents, as a non-limitative example, one of the modes of

implementation of the invention.

  The single figure is a schematic representation of a supercharged diesel engine comprising the improvements of the invention. The diesel engine M comprises a supercharger group 2 with a turbo-compressor comprising at least one turbine 4 which is

  supplied by the exhaust gases from the exhaust manifold

  6 of the engine and which is hitched by a shaft 8 to a

  Presser 10. Generally the boost unit is two-stage, but only one floor has been shown to simplify

the drawing.

  The compressor 10 draws atmospheric air to its inlet - 12 and delivers the engine supply air via its outlet pipe 14. The outlet pipe 14 of the turbo-compressor unit

  is connected to the intake manifold 16 of the engine through

  mediate a refrigerant group 18-for the supply air.

  Group 18 comprises two heat exchangers R1 and R2 which are connected in series to the supply air circuit of the

  motor, via lines 20, 22, 23.

  The first exchanger R1 has a circuit 24 in which circulates a relatively hot heat transfer fluid. For example, the circuit 24 can be traversed by the high temperature water of the circuit of

  water cooling (not shown) of the engine. -

  The second exchanger R2 has a circuit 26 in which cir-

  a heat transfer fluid colder than that of the first exchanger, for example ambient air. If the motor M is a

  Marine diesel, the circuit 26 of the second exchanger can be

  If it is a fixed engine, the cir-

  cooked 26 could be connected to a city water circulation.

  According to the invention, a pipe 28 for the air of

  supercharging is provided in bypass on the exchanger R2, that is,

  that is to say that the inlet of this branch pipe is connected to the pipe 20, between the exchangers R1 and R2 while the outlet of this branch pipe is connected to the pipe 22, that is to say between the exit of the R2 exchanger and the entrance

of engine air 16.

  Preferably, an air flow control member, such as a shutter-30, is mounted on the pipe 22 and is controlled by a servo-mechanism 32 slaved to one or more detectors 34, 34 ', 34 "measuring operating parameters such as the charge air pressure, the ambient temperature,

  the temperature or the load of the engine.

  For certain applications, and depending on the temperatures that can be obtained for the hot source and the cold source, it may be advantageous to provide an air flow control member,

  such as a flap 36, in the branch pipe 28, this

  let 36 being also controlled by a servomechanism 38

detectors 34, 34 ', 34 ".

  We will now describe the operation of the device

  according to the different operating conditions of the engine.

  It should first be noted that the high temperature exchanger R2 generally traversed by the engine water (80 to 1000C) operates

  air heater during empty or partial loads

  and refrigerant when, with the increase of the load, the air compressor exceeds the pressure ratio for which the temperature of the compressed air is equal to the temperature of the

  fluid passing through the high temperature exchanger.

  Without any shutters 30 or 36 on the air circuits, the

  flow distribution is done according to the pressure losses.

  At the level of the exchanger bundles, the derivative circuit has a lower pressure drop than the one passing through the two series exchangers. If the bypass duct 28 is very permeable (large diameter) the derived flow can reach 3/4 and even more of the total flow and, at no-load or partial load, the heating effect will be sensitive, without being able to reach the heating obtained by the entire flow of air passing through the branch circuit. If the shutter is mounted only on the high-permeability bypass circuit (flap 36) the reheating effect

  will not be maximum for the open flap, but the cooling effect

  If the load is high, the shutter will be closed. This arrangement may be interesting for engines

  normal volumetric ratios, engines for which

  hate some level of reheating at partial loads, but the greater efficiency of cooling to strong

loads.

  If a diversion pipeline 28 is

  mable (small diameter), the derived flow may be small relative to the total flow (20% fi for example) and, the two circuits fully open, the resulting temperature will approach the minimum temperature possible corresponding to the total flow

  crossing in series the two exchangers.

  With the flap 30 mounted downstream of the low temperature exchanger

  when this shutter is closed, we will obtain, in the

  when empty or at low engine loads, the maximum efficiency

  warming male. This configuration will generally be better suited to reduced volumetric ratio engines for which

  we are looking for maximum warmth at no load and at low temperatures

  ges. If, from this arrangement, we want, for heavy loads, take advantage of the total efficiency of the refrigerants, it will be sufficient to install the second component 36 on the bypass circuit 28

  so that, with heavy loads, this shutter being closed and the

  the main let 30 of course open, the totality of the air flow

  crosses in series the two exchangers RI and R2.

  It must be remembered that the air temperature at the outlet of the compressor depends for an ambient air temperature only on the pressure ratio given by the compressor. It follows that the control of the flap (s) will be preferentially

  linked directly or indirectly to the excess air pressure

  tion (detector 34 controlling servo mechanisms 32 and 38).

  The successive positions of the component (s) will be different

  annuities depending on whether the flaps will control one or the other circuit.

  In the case of installation of the flap 36 on the bypass 28, the flap will be completely open at startup, idling and low engine load. From a boost air pressure level that will depend on the air temperatures that you want to obtain depending on the load (with integration

  possible influence of the ambient temperature), the

  will close gradually, to arrive at a total closure, usually located between the half load and 3/4 load. However

  when the engine will have to run at ambient temperatures

  very low, the correction may be such that the shutter does not

  not completely closed for maximum loads, in order to

  avoid the inconvenience caused by too much air

low at the entrance of the cylinder.

  In the case where the shutter will be installed downstream of the sample

  low temperature R2, this flap 30 will be completely closed to

  starting, for idling and low engine loads.

  From a certain boost air pressure, it will open gradually to reach the full opening for

  a load generally between 1/2 and 3/4.

  As in the previous case, the ambient temperature correction may lead to a partial opening of the shutter at

  fully loaded, when the engine will have to operate in con-

very low mood conditions.

  It should be noted that, for this case of installation, and contrai-

  the previous level, the level of warming will be practically

  depending on the ambient conditions, the temperature of the hot source being practically constant when it comes to the water of

  circulation of the motor, and the air masses to be heated being

  weakly in relation to the heat capacity of the sample.

high temperature generator Rl.

  The third case of installation, where both panels 30 and 36 are used, is only a development of the previous case. When, around the half load for example, the flap 30 has reached the fully open position, the flap 36 of the bypass circuit will begin to close to reach

  the total closure between 3/4 and full load for example.

  Of course, in the case where both flaps 30 and 36 are used, these two flaps can be replaced by

  a three-way air valve distributing the air flow of

  between the exchanger R2 and the bypass 28 and located, for example, between the two exchangers, on the pipe 20 to the

right of diversion 28.

  It follows clearly from the foregoing that the invention makes it possible to obtain a satisfactory regulation of the temperature of the air

  at the inlet of the cylinders, for the engines Die-

  conventional salt and for engines with reduced volumetric ratio,

  with a good use of the capacity of the exchangers.

  With this new arrangement, the high-temperature exchanger with high loads works with refrigerant and can, in the case of very high supercharging, evacuate more than half of the

  amount of heat that you want to extract from the air; exchanged the

  low temperature should only evacuate a fraction of the

  total heat content that is to be extracted, will be

much less important.

  An important advantage provided by the invention is the

  response time of the temperature regulation, in the case of

  rapid changes in engine load.

  By way of example, the operation of a reduced compression ratio engine, for which the desired intake air temperature is of the order of 70 and whose turbo-compressor is at full capacity, will be examined by way of example. charge works with a report of

pressure of 4.

  At the discharge of the compressor, temperatures are recorded

  tures of the order of the ambient temperature, for example 250

  the idling, and about 220 at full load. This temperature

  for a given ambient temperature is only related to the

  pressure port given by the compressor and is established

  without delay in relation to the pressure level. A motor can

  especially in going from running at full load to idling in a fraction of a second, it is clear that the devices

  previously known regulators, which acted

  the flow or temperature of heat transfer fluids, were unable to rapidly restore the temperature at all

  air intake around 70 as a result of the hysteresis-

sis of the entire system.

  On the contrary, according to the invention, it acts on the air flow through the exchangers and, according to the preferred embodiment, the position of the air shutter or slats is directly linked to the boost air pressure, which makes it possible to obtain a very short response time ensuring satisfactory regulation.

  despite rapid changes in load.

  In the case where the shutter (s) is also slaved to another operating parameter of the engine, these parameters

  must introduce a corrective factor to the position of the

  in order not to delay response, the main action

  blade being related to the boost air pressure.

  The invention is in no way limited to the modes of

  described and represented; it is capable of numerous variants accessible to those skilled in the art without departing for that purpose

of the scope of the invention.

Claims (10)

R E V E N D I C A T I 0 N S   l. A device for regulating the temperature of the charge air of a heat engine, in particular a diesel engine, supercharged by a compressor, of the type which comprises, on the supercharging air circuit, a first heat exchanger traversed by a first heat transfer fluid and a second heat exchanger traversed by a second coolant cooler than the first fluid, said two heat exchangers being connected in series between the compressor and the air inlet of the engine, said device being characterized in   what it entails a bypass passage from the overeating air   whose inlet is connected between the two heat exchangers and whose outlet is connected between the outlet of the   second heat exchanger and the air intake of the engine.   2. Device according to claim 1, characterized in that it comprises a controlled member for adjusting the air flow rate   through at least one of the passages comprising   the aforementioned bypass passage and the passage connecting the   output of the second exchanger to the engine air inlet.   3. Device according to one of claims 1 or 2   characterized in that the first heat exchanger is traversed by a heat transfer fluid whose temperature is greater than the maximum temperature of the ambient air and is substantially lower than the temperature of the air at the outlet   compressor when the engine is fully charged.   4. Device according to claim 3 characterized in that the first heat exchanger is an air exchanger   supercharging / engine cooling water.   5. Device according to one of claims 1 to 4   characterized in that the second heat exchanger is a   exchanger charge air / ambient air.   6. Device according to one of claims 1 to 4,   characterized in that the second heat exchanger is a charge air exchanger / cold water from a source external to the engine.   7. Device according to any one of the claims   1 to 6 characterized in that the controlled member for adjusting the charge air flow is constituted by a flap disposed in at least one of the aforementioned passages and actuated by a servomechanism.   8. Device according to claim 7 characterized in that the aforesaid servomechanism is controlled by a   sensor responsive to the charge air pressure.   9. Device according to one of claims 7 or 8   characterized in that the aforementioned servomechanism is under the control of a detector sensitive to at least one of the parameters comprising the ambient temperature, the temperature   engine, engine load, engine speed.   10. Device according to any one of the claims   1 to 9 characterized in that the controlled air flow control member is constituted by a three-way valve of   distribution of air between the above passages.