FR2795138A1 - FUEL SUPPLY INSTALLATION OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Installation for supplying fuel (5) from a tank (1), comprising a pump unit (2, 3) and at least one injector (4) supplied by a pressure line (6). A discharge installation (7) is fitted to the pressure line (6) in order to lower the pressure therein according to the operating conditions of the engine. The installation (7) comprises an artificial user connected or cut by mechanical-hydraulic means.

Description

State of the art: The present invention relates to an installation

  fuel supply to provide fuel to a

  internal combustion engine, comprising a tank of

  a fuel pump unit, at least one injector, the pump unit taking fuel from the tank to supply the injector through a pressure line.

  to supply the fuel at least indirectly to a room

  the combustion engine of the internal combustion engine, and an

  discharge system which makes it possible to reduce the pressure of the fuel in the pressure line according to a condition of

  operation of the internal combustion engine.

  Such a fuel supply installation is known according to the state of the art, for example according to DE 195 39 883 Ai. The fuel supply system described in this document comprises a fuel pump unit with a first pump and a second pump: the first pump transfers the fuel from the tank to the second pump and the latter supplies the fuel through the pump.

  pressure line to the injector. The food installation

  The fuel system shall have a dump facility

  allows to lower the fuel pressure in the pipe.

  Without this discharge facility, it would not be possible

  to draw the pressure in the pressure line only by the quantity injected (quantity of fuel that the injector

  distributes in the combustion chamber of the combustion engine

  internal control), the amount of control (amount of fuel used to control the injectors) and the amount of leakage

  (amount of fuel passing through the injector

  it is closed). But, as a result, under certain operating conditions of the internal combustion engine,

  that the decrease in pressure would be too slow.

  A condition of operation of the engine with

  internal combustion in which the pressure decrease too slow in the pressure line becomes noticeable, is for example that of the internal combustion engine operating in a partial load range, particularly in thrust mode. In the thrust range, the injected quantity is equal to zero and the pressure decrease in the pressure line can only be done by the leaks, for example at

  level of the injector, if there is no installation of de-

  charge. When the load operating mode is resumed after the push operation mode, under certain conditions, the actual pressure in the driving direction

  pressure can be significantly higher than the pres-

  setpoint; by respecting the quantities to be injected, this can lead to very short injection times. But this again translates into a short, beat sound

  internal combustion engine, perceived as extremely

  both by the driver and the passengers of the vehicle.

  as well as by people outside.

  The discharge installation of the food installation

  fuel pressure, allows to reduce the pressure in the pressure line much more quickly if necessary, which results in certain conditions to a considerable reduction of the engine combustion noise to

internal combustion.

  The discharge installation equipping the installation

  The fuel supply, known from DE 195 39 883 A1, is for example constituted by an electromagnetically controlled discharge valve connected to the pressure line. When the internal combustion engine is in an operating situation in which the pressure in the pressure line must be rapidly reduced, the discharge valve is electrically controlled by a control device to open at least until the necessary pressure decrease is made in the pressure line. The control device must not only include the relief valve, but it must also control a large number of sensors and actuators, for example made in the form of injectors. In general, the control apparatus constitutes the central control unit of the entire internal combustion engine. In the known fuel supply system, the apparatus

  The control unit also ensures the control of the

  charge. This additional function concerns both the

  computing power of the control unit, and the power supply

  electrical energy supply of the relief valve. In addition to operation of the electromagnetically controlled discharge valve, too high thermal stresses of the relief valve may be present. Now, the installation

  known fuel supply system, does not include

  positive cooling for the relief valve. In-

  end, the electromagnetically controlled discharge valves used in fuel supply facilities,

known, are very expensive.

  The present invention aims to develop a fuel supply system corresponding to the

  type defined above, to have an installation of

  simple, robust, inexpensive and also operating load

  independently of the electrical control apparatus.

  For this purpose, the present invention relates to a

  fuel supply installation of the type defined above.

  characterized in that the discharge device is connected to the pressure line and comprises a user

  which can be connected and cut by mechanical means.

  Picnic / hydraulic. According to the invention, the pressure prevailing in the pressure line can be advantageously reduced by

  an artificial user connected to the pressure line.

  This user is sized so that the decrease of

  pressure in the pressure line for certain conditions

  operating conditions of the internal combustion engine, for example

  example when the motor is in its load range par-

  tive, and in particular when the engine is in thrust, is done quickly enough so that the recovery of the operating mode under load for the actual pressure in the pressure line is substantially equal to the pressure of

  set for not having any burning noise of bat-

  internal combustion engine. On the other hand, for the

  dimensioning of the artificial user, it is also necessary to

  make sure to always establish in the pressure line,

  sufficient pressure for the internal combustion engine

  dull can operate without difficulty in its range of

full charge.

  For the fuel supply system to

  according to the invention can establish as quickly as possible a certain limit pressure, for example the idle pressure, in the pressure line, and can maintain it in a guaranteed way, the artificial user can

  be connected or cut mechanically / hydraulically.

  The user stays cut preferably until the

  limit pressure is reached. Only after the

  limit pressure that the user is again

  connected and produces a decrease in pressure in the con-

  pressure drop due to continuous consumption of fuel

in the pressure line.

  One can also envisage a cut /

  staggered step of the artificial user according to

  operating conditions of the internal combustion engine, and under these conditions, the user consumes more or less fuel from the pressure line according to the conditions of the

  operation of the internal combustion engine.

  The fuel supply installation according to the invention offers the advantage of being of a simple construction

  and robust. The mechanically-controlled discharge system

  that / hydraulic fuel supply system

  of the invention is much less cumbersome than the

  Electrically controlled discharge discharges of known fuel supply installations. Finally, the discharge facility of the fuel supply system

  the invention operates independently of the communication apparatus

  control of the internal combustion engine, so that this

  Control wire has no additional charge.

  According to an advantageous development of the invention, the artificial user comprises a return of the pressure line to the fuel tank and this return is

  equipped with a throttle. When the user

  If the cable is plugged in, it can be passed through the return, a quantity of fuel depending on the throttle section

  from the pressure line back to the tank.

  To cut and connect mechanically / -

  hydraulically the artificial user, the discharge installation according to a preferred embodiment of the invention comprises a valve controlled by pressure. This valve may be a slide valve or a seat valve. The valve is closed in the rest position, that is to say when the internal combustion engine is shut down and when the artificial user is cut, that is to say when the

  connection between the latter and the pressure line is

broken.

  According to a preferred embodiment of

  the invention, the valve is solicited by an element with

  fate acting against the pressure prevailing in the conduct of

  pressure so that the artificial user remains cut off

  that a limit pressure is exceeded. The pressure

  mite is advantageously regulated by the choice of a suitable spring. Limit pressure can be adjusted by choosing a spring with a desired spring constant or by

  a spring which is under a desired prestressing. The pressure

  limiting pressure is preferably the idling pressure prevailing in the pressure line when the combustion engine

internal idle.

  According to an advantageous development of the invention, the flow characteristic of the discharge installation

  present a hysteresis loop, and the artificial user

  sky, connected, is cut off only after the limit pressure has been exceeded. During the increasing passage of the curve

  flow characteristic, the flow rate increases from the

  passing the limit pressure with increasing pressure

  in the pressure line. In the case of a passage

  increasing, the characteristic curve of flow has, for the same pressures, a higher flow rate than for the path in the increasing direction. The artificial user is thus connected only after exceeding the limit pressure, preferably the idle pressure. This quickly establishes the idle pressure and maintains it in a guaranteed way. After exceeding the idle pressure, the artificial user remains connected until the fuel pressure in the pressure line drops below the limit pressure. This makes it possible, if necessary, to ensure a rapid decrease in the pressure prevailing in

the pressure chamber.

  According to a preferred embodiment of the invention, the valve of the discharge installation is a

  pressure controlled slide valve. Compartment slide valve

  takes a piston loaded by a spring; he is at equilibrium

  between the force of the spring and the force depending on the

  the fuel in the pressure line. If the pressure

  in the pressure line is less than or equal to the limit pressure, the piston is closed. Only the leakage goes into the closed position through the gap between the housing and the slide valve piston. The pressure rise in the pressure line on the basis of this leakage current is very low. When the pressure in the pressure line exceeds the limit pressure, the piston is moved against the spring force to release a control end channel to the artificial user. In this position, the artificial user produces a decrease in

  much faster pressure. Thus, the decrease in

  in this position the valve corresponds to the curve

  flow characteristic of the artificial user,

  to say of the throttle.

  As soon as the pressure prevailing in the conduct of

  pressure falls again below a fixed level,

  at the limit pressure, the spring element moves the

  piston of the slide valve to bring it into a closed position

  ture. The end of command channel is closed and the user

artificial is cut.

  In a variant, according to a preferred embodiment

  the discharge valve is actually

  sée as pressure-controlled seat flap. The seat flap comprises a shutter member pushed by an element

  spring against the force developed by the pressure of the car-

  burst in the pressure line against the seat of the

  fart. In this operating range, there is only a pressure decrease in the pressure line produced by the leakage current passing between the sealing member

  and the seat when the valve is in the closed position. The di-

  pressure loss due to the leakage current is very low.

  corn. The closure element is subjected to the force developed by the pressure in the pressure line against the force developed by the spring element. The seat valve is designed so that the closure member lifts from its seat against the force of the spring member as soon as the pressure of the fuel in the pressure line exceeds the

  limit pressure. In this operating state, the decrease

  pressure is first of all due to the size of the sur-

  passageway between the valve seat and the element

  shutter. As soon as this surface is greater than

  face of the section of an artificial user downstream of the seat valve in the direction of the passage, the pressure decrease responds to the flow characteristic curve of this

artificial user.

  According to an advantageous development of the invention,

  the return of the fuel pump unit as a flow of

  cooling through the discharge facility, passes into the fuel tank. The cooling flow

  allows the cooling of the fuel discharge

  to evacuate the hydraulic losses that have been

  in heat. Cooling flow reduces

  decisively the thermal load applied to the installation

  discharge during operation, and to increase the

to bring reliability.

  According to a particularly embodiment

  of the invention, the fuel pump unit

  takes a first pump and a second pump; the first pump takes the fuel into the tank to feed the

  second pump and the latter feeds the injector through

  to the accumulator volume of a pressure pipe in the form of a common rail. The first fuel pump is a low pressure pump and the second pump is a high pump

  pressure. The fuel valve through which the fuel

  edge in the combustion chamber of the internal combustion engine

  dull, is performed as an injector. When using the fuel supply system according to the invention in a common rail injection system, the advantages of

  the invention appear in a very particular way.

  In particular, the construction of the ramp injection system com-

  mune can be simplified and so the cost of this system can

to be lowered.

  The present invention will be described hereinafter

  in more detail using two examples of

  FIG. 1 is a diagrammatic view of a fuel supply installation according to the invention;

  * Figure 2 shows a discharge installation of a

  fuel supply system according to the invention IS corresponding to a first embodiment; FIG. 3 shows the flow characteristic of the discharge installation according to FIG. 2; and FIG. 4 shows a second embodiment of a discharge installation of a feed installation

in fuel according to the invention.

  FIG. 1 shows a first embodiment of a fuel supply installation according to the invention. The fuel supply system serves

  to the fuel supply of an internal combustion engine

  dull. This installation is in the form of common rail injection system. The fuel supply installation comprises a tank 1, a first fuel pump 2, a second fuel pump 3 and four injectors 4. The

  first pump 2 is a pre-feed pump and the se-

  Pump 3 is a high-pressure transfer pump.

  The fuel injection valves 4 are injectors. The

  first fuel pump 2 takes fuel 5 from the fuel tank

  see 1 for supplying the second pump 3. This second pump 3 transfers the fuel 5, via a pressure line 6, to the injectors 4 which inject at least a portion of the fuel 5 into a combustion chamber, not shown,

of the internal combustion engine.

  Between the first pump 2 and the second pump 4 is a fuel filter 7. The pressure line 6 is formed as accumulator volume of the common rail injection system. The fuel supply installation is connected by the pressure line 6 to a discharge installation 7 which makes it possible to lower the fuel pressure.

  prevailing in the pressure line 6 as a function of a

  operating condition of the internal combustion engine.

  For example, it is necessary, for example, to reduce the pressure in the pipe as quickly as possible.

  pressure 6 when the internal combustion engine

  in partial load mode or in push mode, to reduce the combustion noise of the engine during

resume charging mode.

  The discharge installation 7 comprises a user

  artificial battery which connects mechanically / -

  hydraulic. The artificial user comprises a return 11 of the pressure line 6 to the tank 1. A throttling member 8 equips the return line 11. When

  the artificial user is plugged in, the fuel can not-

  the pressure line 6 through the return 11 and the throttle 8 to return to the tank of

fuel 1.

  To connect and cut mechanically / hydraulically

  the artificial user 8, the installation of de-

  load 7 comprises a valve controlled by pressure 9. The valve 9 is urged on the one hand by the force of a spring element 10 and on the other hand by the force developed by the

  fuel pressure in the pressure line 6.

  The artificial user remains cut as long as the pressure in the pressure line 6 does not exceed a certain limit pressure. As soon as the force developed by

  fuel in the pressure line 6 exceeds the force de-

  expanded by the spring element 10, the pressure-controlled valve 9 is put in a position in which the artificial user is connected. In the position of the valve 9 of the discharge installation 7 which is shown

  in Figure 1, the artificial user is connected.

  A return 10 of the second fuel pump 3

  is returned back to the tank 1 as a flow of re-

  The cooling flow enables the discharge plant 7 to be cooled by converting the lost hydraulic power of the discharge installation 7 which is largely converted into steam. The return 10 opens into the return 11 by which, when the artificial user is connected,

  the fuel passes from the pressure line 6 into the

  supply tank 1. Another return 12 from the injectors 4 also returns to the return line 11; this

  return takes again the leakage flow of injectors 4.

  FIG. 2 shows a first preferred embodiment of a discharge installation 7. The valve 9 of the discharge installation 7 is a slide valve 13

  pressure controlled, mechanically closed

  as / hydraulic. The slide valve 13 comprises a piston 14 loaded by a spring slidably housed in a body 16. The piston 14 is in equilibrium being subjected on the one hand to the force developed by the spring element 10, and on the other hand to the force developed by the fuel pressure in the pressure line 6 as a function of the pressure prevailing in the common rail. If the pressure in the line 6 is less than or equal to a limit pressure, the piston 14 is in the closed position (see Figure 2). When the piston 14 is in the closed position, there is only a leakage current that passes

  by the gap 15 between the body 16 and the piston 14 of the

  pet to drawer 13 escaping from the pressure line 6.

  In this position, the pressure decrease of the pipe

pressure 6 is very slow.

  As a limiting pressure, the idle pressure p LL which prevails in the driving of

  pressure 6 when the engine is idling. In the

  common-rail injection plants, present, this

  idle pressure p_LL is of the order of 250 bars.

  If the fuel pressure in the line of

  pressure 6 exceeds the limit pressure, the piston 14 is de-

  place against the force of the spring member 10 and descends it until it releases a control end channel 17 to the throttle member 8. In this position of the slide valve 13, the fall of pressure in the pressure line 6 is set according to the flow characteristic in the throttle 8. FIG. 3 shows the flow characteristic curve in the throttle member 8. It can be seen that this flow at

  through the throttle 8 is practically zero when

  that the idle pressure pLL is reached. Only the current of

  QL leakage through the gap 15 of the slide valve 13 com-

  pressure. As soon as the pressure p increases and reaches a value greater than the idle value pLL, the slide valve 13 releases the control end channel 17 of the throttling member 8. A certain flow of fuel can then escape of the pressure line 6 through the organ

  throttling 8 and return 11 to return to the tanker

see fuel 1.

  Figure 3 clearly shows that the characteris-

  flow rate of the throttling element 8 has a

  key to hysteresis. If one goes through the characteristic curve in the increasing direction, it gives lower flow values for the same pressures p than in the case of the downward passage on the characteristic curve. In addition, the artificial user remains connected when the pressure

  decreases in the pressure line 6, beyond the pres-

  boundary limit p_LL, so that when we cross the characteristic curve in the downward direction, we will have flow rates

  limited even for pressures below the

mite pLL.

  For the nominal operating pressure p_B in the pressure line 6, in a current common-rail injection installation, with a discharge installation 7 according to FIG. 2, there will be a flow rate of approximately

  12 1 / h. The nominal operating pressure is

Viron 1300 bars.

  Figure 4 shows a second embodiment

  of a discharge installation 7 according to the invention. The sou-

  Pope 9 is made here in the form of a seat valve 18.

  The valve 18 comprises a seat 19 against which is supported a closure member 20 loaded by a spring member 10. The closure member 20 is a ball. As soon as

  the force developed by the fuel pressure in the

  pressure drop 6 exceeds the force of the spring element, the closure member 20 rises from the seat 19 against the force of the spring element 10. Between the closure member 20 and the seat 19, we will have a passage having a

  certain surface area by which a certain amount of

  rant can escape from the pressure line 6 through the throttle 8 and the return 11 back into the fuel tank 1. When the seat valve 18 is

  completely open, the decrease in pressure is

  the characteristic curve of the flow of the organ

throttling 8.

R E V E N DI C A T IONS

* 1) A fuel supply installation for supplying fuel (5) to an internal combustion engine, comprising: * a fuel tank (1), e a fuel pump unit, * at least one injector (4) ,

  * the pump unit taking fuel (5) into the fuel tank

  see (1) to feed the injector (4) through a

  pressure device (6) for supplying the fuel (5) at least indirectly to a combustion chamber of the internal combustion engine, * a discharge device (7) which makes it possible to reduce the

  fuel pressure in the pressure line (6) se-

  an operating condition of the internal combustion engine, characterized in that the discharge device (7) is connected to the pressure line (6) and comprises an artificial user which can

  be connected and cut by mechanical / hydraulic means.

  2) Installation according to claim 1, characterized in that

  the artificial user comprises a return (11) of the

  pressure drop (6) to the fuel tank (1), this

  return (11) being equipped with a throttling member (8).

  3) Installation according to claim 1 or 2, characterized in that

  the discharge device (7) comprises a valve (9) comprising

  pressure, which allows the user to be switched on and off. 4) Installation according to claim 3, characterized in that the valve (9) is biased by a spring element (10)

  acting against the pressure in the pressure line

  sion (6) so that the artificial user remains cut off

  that a limit pressure is exceeded.

   ) Installation according to claim 4, characterized in that

  the limiting pressure is regulated by the choice of a suitable resort element (10).

  6) Installation according to any one of claims 4

  or 5, characterized in that the limiting pressure is the idling pressure (p_LL) prevailing

  in the pressure line (6) when the combustion engine

internally is idling.

  7) Installation according to any one of claims 4

at 6, characterized in that

  the flow characteristic curve of the plant of de-

  charge (7) has a hysteresis loop, the user

  artificial, in the plugged state, being cut only after

  Passing down the limit pressure.

  8) Installation according to any one of claims 3

at 7, characterized in that

  the valve (9) of the discharge installation (7) is a

  pet to drawer (13) controlled under pressure.

  9) Installation according to any one of claims 3

  7, characterized in that the valve (9) of the discharge device (7) is

  as a seat valve (18) controlled under pressure.

   ) Installation according to any one of claims 1

  9, characterized in that a return (10) of the pump unit passes through the installation of

  discharge (7) to return to the fuel tank (1).

  11) Installation according to any one of claims 1

  at 10, characterized in that * the pump unit comprises a first fuel pump (2) and a second fuel pump (3),

  the first pump (2) transfers the fuel (5) from the reservoir

  see (1) to the second pump (3) and the latter transfers the fuel (5) through the pressure line (6) produced by the storage capacity of an injection plant

  common rail, for supplying the injector (4).