WO1992003641A1

WO1992003641A1 - Device for cleaning a fuel supply system

Info

Publication number: WO1992003641A1
Application number: PCT/BE1991/000057
Authority: WO
Inventors: Roger Braem
Original assignee: Wynn's Belgium N.V.
Priority date: 1990-08-17
Filing date: 1991-08-13
Publication date: 1992-03-05
Also published as: BE1004545A3; AU8291691A

Abstract

Device for cleaning (9) at least a part of a fuel supply system (1-8; 26-36) for supplying fuel in fluid form to at least one combustion chamber, which device (9) comprises a reservoir (10) for liquid cleaning fuel and a supply pipe (11) for connecting this reservoir (10) to at least a part of the fuel supply system (1-8; 26-36) during the cleaning, characterised in that it comprises a pump (12) which is mounted in the supply pipe (11) and a return pipe (23) which connects with one extremity to the supply pipe (11)on the pressure side of the pump (12) and during the cleaning is connected by its other extremity to the reservoir (10) for cleaning fuel, in which return pipe (23) a flow regulator (24) is mounted which regulates the flow in the return pipe (23) and therefore the pressure in the supply pipe (11).

Description

Device for cleaning a fuel supply system.

The invention relates to a device for cleaning at least a part of a fuel supply system for supplying fuel in fluid form to at least one combustion chamber, which device comprises a reservoir for liquid cleaning fuel and a supply pipe for connecting this reservoir to at least a part of the fuel supply system during the cleaning.

Fuel supply systems for the supply of fuel in fluid form usually comprise a fuel tank, and one or more fuel pipes by which the fuel tank can be connected to one or more combustion chambers. A pump is mounted in the fuel pipe. Through the atomization of fuel, and/ r the burning of this fuel a precipitation occurs on the atomizers, the valves and in the combustion chamber, which precipitation can influence the ideal combustion process.

This is especially the case with injection systems for liquid fuel whereby the fuel pipes connect by means of ne or several injectors to one or several combust_._.on chambers. Such in ection systems are often applied with combustion engines such as an Otto-cycle internal combustion engine with petrol injection or a diesel engine with diesel injection.

Injection systems for combustion engines normally consist of a number of injectors, a fuel distributor, pipes between the fuel distributor and each of the injectors, ^~ fuel pipe which connects the fuel tank to the fuel distributor, a fuel pump mounted in the fuel pipe and a return pipe which connects the fuel distributor to the fuel tank. In the case of a petrol engine a pressure regulator is mounted in the return pipe. The pressure regulator regulates the pressure of the fuel which is sent to the injectors by regulating the flow of the fuel which is returned through the return pipe to the fuel tank. In the case of a diesel engine the fuel distributor is formed by the injection pump.

With the atomization of the fuel a precipitation among others of carbon occurs on the injectors and the valves. In order to clean these injectors these are temporarily fed with cleaning fuel, this is a product that removes precipitation but at bhe same time serves as fuel so that the engine can run during the cleaning.

A known device which is used for cleaning injection systems of petrol engines consists of a spray can with cleaning fuel of which the exit is connected to a part of the fuel pipe on the pressure side of the fuel pump. The fuel pipe is of course interrupted or closed at the location of the connection. The fuel pump is disconnected.

The pressure with which this cleaning fuel is supplied must of course be greater than the pressure necessary for the injectors since via the pressure regulator a part of this fuel must be able to be returned via the return pipe. Recently injection systems with very high operating pressures, even up to 6.5 bars, have been available on the market. With a spray can sufficient pressure can no longer be supplied so that cleaning is not possible.

Sufficient pressure can be supplied with devices for cleaning which, in place of a spray can, comprise a container for the cleaning fuel and a compressed air device with which compressed air can be applied in the container. This latter devices for cleaning usually require an external source of compressed air. Both aforementioned known devices for cleaning furthermore also have the disadvantage that a part of the cleaning fuel which is supplied is not used for cleaning. This part is namely the part that i;^; returned through the return pipe by the pressure regulator and arrives in the fuel tank or, with interrupted return pipe, simply flows away or in the most favourable case is caught in a container.

The purpose of the invention is to remedy these disadvantages and to provide a device for cleaning a fuel supply system which is of simple construction, permits a proper cleaning, is also usable with high operating pressure of the fuel supply system and limits the loss of cleaning fuel for cleaning.

For this purpose the device for cleaning comprises an electrically driven pump which is mounted in the supply pipe and a return pipe which connects with one extremity to the supply pipe on the pressure side of the pump and during the cleaning is connected by its other extremity to the reservoir for cleaning fuel, in which return pipe a flow regulator is mounted which regulates the flow in the return pipe and therefore the pressure in the supply pipe.

In an advantageous embodiment of the invention the device comprises means for also connecting a return pipe of the fuel supply system to the reservoir of the cleaning fuel during the cleaning.

In a particular embodiment of the invention, the puir ^~ is a pump which works on the current of the battery of the vehicle in which the cor.oustion engine is mounted.

In a notable embodiment of the invention, the device comprises an electric circuit to which the pump is connected, a relay with a solenoid and a contact switch. of which the contact switch is connected in series to the pump in the electric circuit, a first parallel line which runs in parallel to the pump and the contact switch and in which the solenoid is connected, and a starting switch which is connected to the solenoid in series to the parallel line.

The control of the motor of the pump by means of a relay offers the possibility of producing the control circuit itself light and compact in view of the small current which is necessary. A much strong current is necessary for the pump motor.

In a preferably applied embodiment of the invention, the device comprises a float switch with a float which floats on the cleaning fuel and indicates the level of this fuel in the reservoir and with a contact switch that controls the pump.

Suitably the device furthermore comprises a second relay with a solenoid and a contact switch, of which the contact switch is connected in series to the solenoid of the first relay in the first parallel line, and a second parallel line, in which the solenoid of the second relay and the contact switch of the float switch are connected to each other in series.

Other details and advantages of the invention will appear from the following description of a device for cleaning a fuel supply system according to the invention. This description is only given as example and does not restrict the invention. The reference figures refer to the enclosed drawings, in which:

Figure 1 schematically shows an injection system of a petrol engine with fuel injection without the device for cleaning according to the invention; figure 2 schematically shows the injection system from figure 1 on which however the device for cleaning according to the invention is mounted;

figure 3 schematically shows an injection system of a diesel engine with fuel injection without the device for cleaning according to the invention;

figure 4 schematically shows the injection system from figure 3 on which however the device for cleaning according to the invention is mounted;

figure 5 schematically shows another embodiment of the device for cleaning from figures 2 and 4, but vrithout electric circuit;

figures 6 to 9 show a variant of the electric circuit of the device for cleaning from figure 2 and 4, respectively in four different positions, namely at rest, during normal operation, with a shortage of cleaning liquid and during purging.

The known injection system of a so-called Otto-cycle internal combustion engine with petrol injection according to figure 1 , that therefore does not comprise the invention, comprises a petrol tank 1 , and petrol distributor 2, injectors 3, namely one in each cylinder of the petrol engine with fuel injection to which the injection system belongs, pipes 4 which connect the petrol distributor 2 to respectively each of the injectors 3, a petrol pipe 5 which connects the petrol tank 1 to the petrol distributor 2, an electric petrol pump 6 in this petrol pipe 5, a return pipe 7 which connects the petrol distributor 2 back to the petrol tank 1 and a pressure regulator 8 which is mounted in the return pipe 7.

The motor of the pump 6 operates from the battery of the vehicle in v/hich the system is mounted. With a running engine this petrol pump 6 pumps petrol through the petrol pipe 5 to the petrol distributor 2 which allows the greater part of the petrol through the pipes 4 to the injectors 3. The remaining part of the petrol is returned by the pressure regulator δ through the return pipe 7 to the petrol tank 1. This pressure regulator 3 is a membrane regulator. The maximum flow that the pump 6 can deliver is greater than the flow necessary for building up the pressure for the injectors 3. By returning a part of the petrol to the tank 1 the pressure regulator 8 ensures that the petrol is supplied to the injectors 3 with the correct operating pressure.

In order to clean this injection system and more specifically the injectors since a precipitation of carbon occurs there, the petrol pipe 5 is uncoupled on the pressure side of the petrol pump 6 and the part connecting to the petrol distributor 2 is connected to a device for cleaning 9 as represented in figure 2. The uncoupling of the petrol pipe 5 can occur at the location of one or other coupling of parts of the petrol pipe if this consists of parts, which coupling must be located on the pressure side of the petrol pump 6.

In analogue manner the return pipe 7, between the pressure regulator 8 and the petrol tank 1 is also uncoupled and the part of this return pipe connecting to the pressure regulator 3 is connected to the aforementioned device for cleaning 9. The uncoupling can occur between the tank 1 and the pressure distributor 3. For this the fuel pump 6 should either be electrically disconnected, which can occur through the removal of a fuse or a relay, or be connected through to the fuel tank 1 which can occur by coupling the uncoupled part of the pipe 5 that is still connected to the pump 6 to the uncoupled part of the return pipe 7 that is still secured to the petrol tank 1 , as represented in dashed line in figure 2.

The injection system represented in figure 2 is thus obtained that comprises a device for cleaning according to the invention. The device for cleaning 9 according to the invention comprises, as represented in this figure 2, a reservoir 10 with cleaning fuel. This cleaning fuel is to be found on the market. It consists for example of petrol to which a cleaning agent is added that among others can remove the carbon precipitation in the injectors. The cleaning occurs after all while the engine provided with the injection system is running.

To the reservoir 10 connects a supply pipe 11 which during the cleaning is connected to the part of the petrol pipe 5 that connects to the petrol distributor 2. An electrically driven pump 12 and a pressure gauge 13, seen in this sequence from the reservoir 10, are mounted in this supply pipe 11.

The pump 12 has a maximum pressure for example 650 kPa (6.5 bars) at 210 1/h, which is higher that the operating pressure of the injectors 3. This pump 12 can constructively be identical to the petrol pump 6. This pump 12, and in fact its electric motor, is electrically connected by means of an electric circuit 14 to two terminals on the two terminals of the battery of the vehicle provided with the injection system. The solenoid 15 of a relay 15, 16 of which the contact switch 16 is connected in series to the pump 12 is installed in this electric circuit 14. This solenoid 15 is on a parallel line 17 in which the starting switch 18 is installed. The solenoid 15 is bridged by a cable 19 on which a lamp 20 is connected while the whole parallel line 17 is bridged by a parallel line 21 on which a second lamp 22 is installed. When connected to the battery of the vehicle the control lamp 22 will burn. 3y closing the starting switch 18 the lamp 20 will burn and the solenoid 15 is excited. This solenoid then closes the contact switch 16 through which the motor of the pump 12 receives current. The pump 12 then pumps cleaning petrol out of the reservoir 10 through the supply pipe 11 to the injection system and namely the petrol distributor 2.

Between the pump 12 and the pressure gauge 13 one extremity of a return pipe 23, of which the other extremity connects to the reservoir 10, connects to the supply pipe 11. A regulating cock 24 is mounted in this return pipe 23 and more especially in the connection thereof to the pipe 11. This regulating cock is so regulated that the pressure of the cleaning fuel which is supplied to the petrol distributor 2 almost corresponds to the operating pressure of the injectors 3 which operating pressure at normal operation of the petrol engine is regulated by the pressure regulator 8 which returns a part of the fuel through the return pipe 7 to the petrol tank 1. During the cleaning the pressure regulator 8 returns a part of the cleaning fuel through this return pipe 7 to the reservoir 10. Since the maximum pressure of the pump 12 even with the presence of the aforementioned pressure regulator is still higher than the operating pressure the regulating cock 24 returns a part of the cleaning fuel to the reservoir 10. This occurs through a return pipe 23. The part of the return pipe 7 that, as already mentioned, is connected to the device for cleaning 9 is connected to the return pipe 23 which has a connection 25 for that purpose. The part that is returned through the return pipe 7 returns into the reservoir 10 via the return pipe 23 so that no cleaning fuel is lost. The pressure distributor 8 in fact performs a rough pressure regulation and the regulating cock 24 for an additional fine pressure regulation.

After cleaning the device 9 is removed and the petrol pipe 5 and the return pipe 7 are returned to their original - 9 - position.

In analogue manner the fuel injection system of diesel engines equipped with line or rotary pumps can be cleaned with the above described device for cleaning. The injection system of a diesel engine is schematically shown in figure 3.

This injection system comprises a diesel tank 26, a number of injectors 27, one for each cylinder of the diesel engine, an injection pump 28 which at the same time forms a fuel distributor and comprises a built-in pressure dist. ^'.butor, pipes 29 between this injection pump 28 and each of these injectors 27 and a fuel pipe 30 which connects the injection pump 28 to the diesel tank 26. A mechanical fuel pump 31 and two fuel filters 32 are mounted in this fuel pipe 30 between the tank 26 and the injection pump 28. Return pipes 33 connect to the injectors 27 while a return pipe 34 connects to the built-in pressure distributor of the injection pump 28. All these return pipes 33 and 34 come together and are connected to the diesel tank 26 via the return pipe 35. The mechanical fuel pump 31 is mounted on the injection pump 28 and principally ensures the supply of the fuel. The pressure for the injection is principally built up by the injection pump 28 which pump is mechanically driven by the diesel engine itself via the coupling 36.

With the atomization of the diesel oil which occurs under a much higher pressure than with the so-called Otto-cycle internal combustion petrol engines, namely at 11 000 up to 90 000 kPa (110 up to 900 bars) expending upon the engine type, a pollution of the injectors 27 and the injection pump 28 can occur. This pollution can cause a bad atomization and an incomplete combustion of the fuel, through which the engine delivers less power, runs irregularly and consumes more fuel. The cleaning of these injectors 27 and this injector pump 28 can occur with the above described device for cleaning 9, with the understanding that as liquid a cleaning fuel is utilised which is suitable for diesel engines, for example a mixture of diesel oil and a suitable cleaning agent.

Constructively the device for cleaning 9 is identical to the above described device 9 for cleaning a petrol engine but, as is shown in figure 4 in which the injection system of a diesel engine is shown during the cleaning and therefore with the device 9 mounted thereon, the connection of the device 9 to the injection system is effected in another manner. The connection is effected between the fuel pipe 30 and a return pipe 35 but, because of the fact that the injection system comprises no electric pump but itself builds up the injection pressure through a mechanical injection pump 28, only the fuel pipe 30 and the return pipe 35 of the diesel tank 26 need to be uncoupled and be connected respectively to the supply pipe 11 and the connection 25 of the device for cleaning 9. The cleaning occurs in analogue manner with running engine whereby cleaning fuel is atomized by the injectors 7 and is burned in the cylinders. The supply pressure is also built up by the injection pump 28 during the cleaning. The pressure of the device for cleaning 9 is regulated by means of the adjustment of the regulating cock 24 at approximately 100 kPa (1 bar). The flow from the electric pump 12 of the device 9 is sufficient for cleaning the injection system of even heavy-duty diesel engines.

The embodiment of the device for cleaning 9 shown in figure 5 principally differs from the device 9 shown in figures 2 and 4 because of the fact that the regulating cock 24 is not mounted in the return pipe 23 at the location of the connection of this return pipe to the supply pipe 11 but is situated between the extremities of this return pipe 23 which apart from that is completely separated from the connection 25 for the return pipe 7 of the petrol engine from figures 1 and 2 or the return pipe of the diesel engine from figures 3 and 4. This connection 25, in which a filter 37 is mounted, therefore does not connect to the return pipe 23, but itself forms a separate return pipe which connects directly to the top of the reservoir 10. This excludes that cleaning fuel which flows back through the return pipe 23 via the connection 25 gives a counter pressure to the cleaning fuel, which flows back from the injectors 3 through the return pipe 7. Through this counter pressure the pressure in the fuel distributor 2 could become too high and damage the pressure regulator 8.

Between the reservoir 10 and the pump 12 a filter 38 is also mounted in the supply pipe 11, which connects to the bottom of this reservoir 10. This filter 38 prevents particles of dirt from the reservoir 10 from entering the pump 12 or the injection system to be cleaned. The aforementioned filter 37 prevents dislodged particles of dirt from this injection system from entering the reservoir 10 and being sent round through the pipe 11 , through which the filter 38 would become dirty too quickly.

The operation of this embodiment is entirely analogue to that of the above embodiments. Through the regulating cock 24 in the return pipe 23 the pressure for cleaning can be very accurately regulated, for example per 100 millibars, over a wide range, for example between 1 and 7 bars.

The embodiment of the electric circuit of the device for cleaning 9 shown in figures 6 to 9 principally differs from the embodiment shown in figures 2 and 4, because of the fact that the solenoid 15 of the relay 15, 16 is not only connected in series to the starting switch 18 between the terminals which must be connected to the terminals of a battery, but at the same time is connected in series to the contact switch 40 of a second relay 39, 40, of which the solenoid 39 is furthermore connected in series both to the starting switch 18 and to a contact switch 42, between the aforementioned terminals connections, controlled by a float 41 in the reservoir 10.

The supply of power to the solenoid 15 and therefore the activation of the pump 12, therefore depends not only upon the position of the starting switch 18, but also under influence of the second relay 39, 40 and the float switch 41 , 42 upon the level of the cleaning fuel in the reservoir 10.

The solenoid 39 and the contact switch 42 are consequently switched to a second parallel line 43, which is parallel to the pump 12 and at the same time to a part of the first parallel line 17, namely the part that comprises the solenoid 15 and the contact switch 40 of the second relay 39, 40. In fact the second parallel line 43 is connected by one extremity to the first parallel line 17 between the solenoid 15 and the starting switch 18 connected to the positive terminal and connected by its other extremity to the negative terminal.

In contrast to the contact switch 16 of the first relay 15, 16 which is a simple on/off switch and with excitation of the solenoid 15 closes the circuit 14 between the terminals but when not excited opens this circuit 14, the contact switch 40 is a two position contact that always opens one line and closes another. With non excitation of the solenoid 39 the contact switch 40 is in a first position in which the first parallel line 17 closes. With excitation of the solenoid 39 the contact switch 40 is in a second position in which this line 17 opens and closes a shunt 44. This shunt 44 bridges the solenoid 15 and the contact switch 40 in its first position. An alarm signal emitter 45 is mounted in this shunt 44.

The shunt 44 is, on the side of the positive terminal in relation to the contact switch 40 in its second position, still connected by a line 46 to the first parallel line 17, between the solenoid 15 and the contact switch 40 in its first position, and by a line 47 connected to the second parallel circuit 43, on the side of the positive terminal in relation to the contact switch 42. A switch for purging 48 is mounted on the line 46.

The operation of the electric circuit is as follows:

In the off position shown in figure 6 the starting switch 18 is in open position and because of that the solenoid 15 is not excited. The contact switch 16 then interrupts the circuit 14 and the pump 12 is inoperative. Only the lamp 22 burns insofar the circuit 14 is connected to the battery of the vehicle.

As soon as the starting switch 18 is brought into closed position, the lamp 20 will burn. The solenoid 39 of the second relay is excited on condition that the second parallel line 43 is not interrupted. This line 43 is closed by the float switch 41 , 42 when there is no or too little cleaning fuel present in the reservoir 10.

Through the excitation of the solenoid 39 the contact switch 40 will interrupt the parallel line 17 and close the shunt 44. The alarm signal emitter 45 receives current and gives an alarm signal. Because of ':he fact that the parallel line 17 is interrupted the solenoid 15 remains unexcited and the contact switch 16 remains open. The pump 12 remains inoperative. This position is shown in figure 8. When, prior to the starting switch 13 being closed, the reservoir 10 is filled with cleaning fuel, the float 41 will rise and the contact switch 42 will open. If the starting switch 18 is now closed, the solenoid 39 will not be excited, since the second parallel line 43 is interrupted. The contact switch 40 of the second relay 39, 40 does not interrupt the parallel line 17, so that the solenoid 15 of the first relay 15, 16 is excited. The contact switch 16 closes the circuit 14, the electric motor of the pump 12 is supplied with power and this pump 12 pumps cleaning fuel out of the reservoir 10 to the fuel supply system to be cleaned. This position is shown in figure 7.

When the level of the cleaning fuel in the reservoir 10 descends below a certain level, the float 41 commands the closing of the contact switch 42. Through that the solenoid 39 of the second relay 39, 40 is excited and the contact switch 40 jumps from its first to its second position. Because of that the first parallel line 17 is interrupted, the excitation of the solenoid 15 of the first relay 15, 16 ceases and consequently the contact switch 16 of this first relay interrupts the circuit 14 through which the pump 12 automatically stops and the dry pumping of the pump 12 is avoided. The circuit is then in the position shown in figure 8.

Because of the fact that the contact switch 40 in its second position closes the shunt 44, the alarm signal emitter receives current and it gives an alarm signal. If through fluctuations in the level or return of the cleaning fuel in the reservoir 10, the level would again rise above the aforementioned level, the pump 12 can nevertheless not start again as long as the starting switch 18 has not been opened and closed again. Even if the contact switch 42 is opened, the solenoid 39 of the second relay 39, 40 remains excited because of the fact that it is connected to the negative terminal via a part of the second parallel line 43, the line 47, the contact switch 40 and a part of the first parallel line 17 and the parallel line 17 remains uninterrupted. Only when the connection of the solenoid 39 over parts of the second and the first parallel lines 43 and 17, is interrupted at the positive terminal by the opening of the starting switch 18, this excitation ceases, so that after the re-closing of this starting switch the normal operation of the device can again be started.

Since, as already described above, the device can be utilised both for cleaning the injectors of a petrol engine and for cleaning the injectors of a diesel engine, and in both cases obviously another cleaning fuel must be used, it is necessary, .nor to changing over fr i one type of engine to another type, to purge the devic, this means to pump away as much as possible of the cleaning fuel which, after the pump 12 has been automatically switched off in the above described manner, because of the fact that the level of the cleaning fuel in the reservoir

10 has become too low, is still in the reservoir 10, the pump 12, the pipes 11 and 23 and the connection 25. This is preferably effected after the uncoupling of the device, through which the cleaning fuel pumped away via the pipe

11 can be collected in a recipient.

This purging is started by pressing the button of the switch for purging 48. In figure 9 the position is shown which is achieved after pressing the button of the switch for purging 48 after the position shown in figure 8 has already been achieved. The cleaning fuel is therefore under the minimum level and the contact switch 42 of the float switch 41 , 42 is therefore closed. The starting switch 18 is also in closed position. By pressing the button of the switch 48 the solenoid 15 of the first relay 15, 16 is excited notwithstanding the contact switch 40 is in its second position and the parallel line 17 is missing. Since the solenoid 15 nevertheless connects over the now closed line 46, a part of the shunt 44 and, both a part of the parallel line 17 and a part of the parallel line 43, to the negative terminal. Through that the contact switch 16 is closed and the pump 12 is in operation.

There is however no longer any protection against the pump 12 running dry, but this presents no danger since with the purging, which for that matter is of short duration compared to the cleaning, the operator is normally speaking present with the device and can himself determine when no more fuel is being pumped. By releasing the push button of the switch 48, the line 46 ^• is interrupted, through which the excitation of the solenoid 15 ceases, the contact switch opens and the pump 12 ceases to operate.

Apart from that during the purging the alarm signal emitter 45 will also receive current and give a signal. This warns the operator that he is busy with a short interim operation and that the reservoir 10 is empty. Even after the button of the switch 48 has been released, the alarm signal continues since the contact switch 42 is closed, until the starting switch 18 is brought into open position. 3ecause of that it will not be forgotten to bring the starting switch 18 into this open position after the purging, through which the off position is again obtained as shown in figure 6.

Trπhe above described devices for cleaning 9 are of simple construction. Subject to the correct choice of the pump 12 they can be utilised for practically any operating pressure of the injectors both with petrol engines and with diesel engines. Subject to use of the suitable cleaning fuel the cleaning is effected very efficiently. In particular with the embodiment of the electric circuit according to figures 6 to 9 the operation is very simple and safe, without danger of damage to the pump.

No cleaning fuel which is not used for the cleaning, is lost. By returning the cleaning fuel to the reservoir 10 the original operation of the engine can be approached as closely as possible. Without this, when for example with the Bosch KΞ-Jetronic injection system the return pipe 7 is closed off in order to prevent to a large extend the cleaning fuel from flowing to the fuel tank 1 of the vehicle, after a short time the supply of this cleaning fuel in the fuel distributor 2 will be blocked by internal adjustment typical of this injection system. The engine will then stop without an effective cleaning having taken place. If the return pipe 7 of the engine remains connected to the fuel tank 1 of the vehicle, then about 80% of the cleaning fuel will be pumped into this fuel tank and only 20% will actually be used for cleaning. Through the return according to the invention through the connection 25 and a part of the return pipe 23 or according to the connection 25 alone if this connects directly to the reservoir 10, he cleaning fuel can be used 100%.

The above described devices also permit a very accurate adjustment of the pressure between wide ranges. Such an adjustment would not be possible if the regulating cock were not mounted in a return pipe 23 but in series between the pump 12 and the connection to the fuel pipe 5 or 30 of the device. Instead of progressively the pressure would increase abruptly. Furthermore by turning off the regulating cock 24 the flow of cleaning fuel going to the injection system would decrease and at the same time the pump 12 be more strongly loaded by the counter pressure. In the extreme case, with closed regulating cock 24 the pump would pump continually in a closed circuit and become overloaded, while no cleaning fuel would flow to the ^{O 92 03}*⁴¹ PCr/BEM/OM-ST

- 1 8 - injection system. By placing the regulating cock 24 as shown in figure 5 in a separate return pipe 23 which directly connects the pipe 11 to the reservoir 10, the pump 12 experiences no counter pressure. The pressure is regulated in function of the flow of the liquid which is pumped to the fuel pipe 5 or 30. The higher this flow, the higher the pressure. This is also necessary for a good operation of the engine. If the regulating cock 24 is completely turned open, then more than half the pumped cleaning fuel will be pumped to the engine and the rest flow back to the reservoir 10. If the regulating cock 24 is completely shut, then all cleaning fuel is pumped to the engine. In this manner the pressure is very accurately and progressively adjustable between 1 and 7 bars. Furthermore the pressure created remains constant from the first to the last drop of cleaning fuel.

Through the adjustment of pressure over a wide range the described devices can be utilised on all engines, both with diesel engines with for example an operating pressure of 1 bar and petrol engines, and with any injection system for example with a monopoint injection (operating pressure 1 bar), an electronic multipoint injection (pressure approximately 3 bars), a mechanical multipoint injection (pressure 4 to 6 bars) or a carburetor provided with a return pipe (pressure 1 bar). Known cleaning devices only exist for petrol engines and then again principally for multipoint injection systems.

The present invention is in no way restricted to the embodiments thereof described above, and within the scope of the patent application many changes can be applied to these described embodiments.

In particular the applications of the device for cleaning as described above are not necessarily restricted to the cleaning of injector systems of combustion engines. Other fuel supply systems in general can also be cleaned with it such as among others fuel supply systems of turbines, of heating installations etc., regardless of the fuel, with the exception of solid fuel.

The flow regulator in the return pipe which connects to the supply pipe need not necessarily be a true regulating cock. Other flow regulators are possible.

Claims

Claims.

1.- Device for cleaning (9) at least a part of a fuel supply system (1-8; 26-36) for supplying fuel in fluid form to at least one combustion chamber, which device (9) comprises a reservoir (10) for liquid cleaning fuel and a supply pipe for connecting this reservoir (10) to at least a part of the fuel supply system (1-3; 26-36) during the cleaning, characterised in that it comprises an electrically driven pump (12) which is mounted in the supply pipe (11) and a return pipe (23) which connects with one extremity to the supply pipe (11) on the pressure side of the pump (12) and during the cleaning is connected by its other extremity to the reservoir (10) for cleaning fuel, in which return pipe (23) a flow regulator (24) is mounted which regulates the flow in the return pipe (23) and therefore the pressure in the supply pipe (23).

2.- Device according to the preceding claim, characterised in that it comprises means (25) for also connecting a return pipe (7, 33-35) of the fuel supply system (1-8; 26-36) to the reservoir (10) for the cleaning fuel during the cleaning.

3.- Device according to the preceding claim, characterised in that these means (25) comprise a connection to the return pipe (23) of the device (9) through which the return pipe (7, 33-35) of the fuel supply system (1-8; 26-36) can be connected to the first mentioned return pipe (23).

4.- Device according to claim 2, characterised in that the means (25) comprise a return pipe which connects to the reservoir (10) completely separately from the aforementioned return pipe (23) connecting to the supply pipe (11).

5.- Device according to any of the claims 2 to 4, characterised in that it comprises a filter (38) in the supply pipe (11), between the pump (12) and the reservoir (10) and a second filter (37) in the means (25) for connecting a return pipe (7, 33-35) of the fuel supply system (1-8; 26-36) to the reservoir (10).

6.- Device according to any of the preceding claims, characterised in that the pump (12) is a pump with a maximum flow higher than the flow necessary for building up the operating pressure of the fuel supply system.

7.- Device according to any of the preceding claims, characterised in that it is mounted in a fuel supply system (1-8; 26-36) that comprises a fuel tank (1 or 26), at least one combustion chamber, an inlet (3 or 27) which exits in this chamber, a fue, pipe (5 or 30) which connects the fuel tank (1 or 26) to this inlet (3 or 27) and a fuel pump (6 or 31) which is mounted in the fuel pipe (5 or 30), whereby the fuel pipe (5 or 30) is interrupted and the part uncoupled from the fuel tank (1 or 26) is connected to the supply pipe (23) of the device (9) according to one of the preceding claims.

8.- Device according to the preceding claim, characterised in that the combustion engine is a so-called Otto-cycle internal combustion petrol engine with fuel injection which comprises a fuel distributor (2) between the injectors (3) and the el pipe (5) and a number of pipes (4) which connect t._is distributor (2) to each of the injectors (3), which injectors each exit in a cylinder which forms the combustion chamber and the pump (12) is a pump with a maximum pressure higher than the operating pressure of the fuel supply system (1-3).

9.- Device according to claim 7, characterised in that the combustion engine is a diesel engine with fuel injection which comprises an injection pump (23) between the injectors (27) and the fuel pipe (30) and pipes (29) between this injection pump (23) and each of the injectors (27), which injectors each exit in a cylinder which forms the combustion chamber.

10.- Device according to either of the claims 8 and 9, characterised in that the pump (12) is a pump which works on the current of the battery of the vehicle in which the combustion engine is mounted.

11.- Device according to claim 2 and any of the claims 7 to 10, characterised in that the return pipe (7 or 33-35) of the fuel supply system (1-8; 26-36) was also interrupted and the part thereof uncoupled from the fuel tank (1 or 26) is connected via the return pipe (23) of the device (9) or directly to the reservoir (10) of the device (9).

12.- Device according to any of the preceding claims, characterised in that it comprises an electric circuit (14) in which the pump (12) is connected, a first relay (15, 16) with a solenoid (15) and a contact switch (16), of which the contact switch (16) is connected in series to the pump (12) in the electric circuit (14), a first parallel line (17) which runs in parallel to the pump (12) and the contact switch (16) and in which the solenoid (15) is connected, and a starting switch (18) which is connected to the solenoid (15) in series to the parallel line (17).

13.- Device according to any of the preceding claims, characterised in that it comprises a float switch (41, 42) with a float (41) which floats on the cleaning fuel and indicates the level of this fuel in the reservoir (10) and with a contact switch (42) that commands the pump (12).

14.- Device according to any of the preceding claims, characterised in that it comprises a second relay (39, 40) with a solenoid (39) and a contact switch (40), of which the contact switch is connected in series to the solenoid (15) of the first relay (15, 16) in the first parallel line (17), and a second parallel line (43), in which the solenoid (39) of the second relay (39, 40) and the contact switch (42) of the float switch (41, 42) are connected to each other in series.

15.- Device according to the preceding claim, characterised in that it comprises a shunt (44) which bridges the solenoid (15) of the first relay (15, 16) and connects to the second relay (39, 40), of which second relay (39, 40) the contact switch (40) is a contact with at least two positions that commands at least the first parallel line (17) and the shunt (44) and in one position closes the first pε ilel line (17) and opens the shunt (44) and in anotner position closes the shunt (44) and opens the first parallel line (17), and that it comprises an alarm signal emitter (45) which is connected in the shunt (44).

16.- Device according to either of the claims 14 and 15, characterised in that it comprises a bridging (17, 47) of the contact switch (42) of the float switch (41, 42), the contact switch (40) of the second relay (39, 40) is a contact with at least two positions that commands at least the first parallel line (17) and the bridging (17, 47) and in one position closes the first parallel line (17) and opens the bridging (17, 47) and in another position clo-.-ss the bridging (17, 47) and opens the first parallel line (17).

17.- Device according to claims 15 and 16, characterised in that both bridgings (44 and 17, 47) coincide and at least at the location of the contact switch (40) of the second relay (39, 40) and the bridging (17, 47) of the contact switch (42) of the float switch (41, 42) comprises a line (47) which connects the second parallel line (43) between the contact switch (42) and the solenoid (39) of the second relay (39, 40) to the shunt (44) of the solenoid (15) of the first relay (15, 16).

18.- Device according to any of the claims 14 to 17, characterised in that it comprises a line (46) and a switch for purging (48) which is connected there to, by which line (46), with a certain position of the switch (48) and with closed position of the starting switch (18), the solenoid (15) of the first relay (15, 16) is brought into the position whereby the contact switch (16) of the first relay (15, 16) closes the circuit (14).

19.- Device according to the preceding claim, characterised in that the cable (46) with the switch for purging (48) on the one hand connects to the first parallel line (17) between the solenoid (15) of the first relay (15, 16) and the contact switch (40) of the second relay (39, 40) and on the other hand to the second parallel switch (43), between the solenoid (39) of the second relay (39, 40) and the contact switch (42) of the float switch (41 , 42).

20.- Device according to claim 15 and either of the claims 18 and 19, characterised in that the cable (46) with the switch for purging (48) on the one hand connects to the first parallel line (17) between the solenoid (15) of the first relay (15, 16) and the contact switch (40) of the second relay (39, 40) and on the other hand connects to the shunt (44) in which the alarm signal emitter (45) is connected.