Method for managing a pump device for alternative fuels, in particular for methanol or ammonia, as well as a pump device implementing this method

Abstract

TITLE: Method for managing a pump device for alternative fuels, in particular for methanol or ammonia, as well as a pump device implementing this method Method for managing a pump device (10) comprising a pre-charge pump (2) and a high-pressure pump (3). The pre-charge pump (2) supplies fuel to an element (4) of the high-pressure pump (3) via a supply path (5) of a low-pressure circuit (6) and discharging the fuel arriving from the leak in a pump element (4) via a return path (7) of the low-pressure circuit (6). From the supply path (5), downstream of the pre-charging pump (2) and upstream of a metering unit (8) integrated in the supply path (5), fuel is diverted to a cooling path (9) and supplied to a cooling element (10) integrated in a suction chamber (11) and / or a leakage chamber (12) of the high-pressure pump (3). Figure 1

Description

Title of the invention: Method for managing a pump device for alternative fuels, in particular for methanol or ammonia, as well as a pump device implementing this method. FIELD OF THE INVENTION

[0001] The present invention relates to a method for managing a pump device for alternative fuels, in particular methanol or ammonia, comprising a pre-charge pump and a high-pressure pump,

[0002] * the pre-charge or pre-feed pump supplying fuel to an element from the high pressure pump by a supply path of a low pressure circuit and discharging the fuel arriving from the leak in a pump element by a return path of the low pressure circuit.

[0003] The invention also relates to a pump device implementing this method.

[0004] The preferred field of application of the invention is that of engines, in particular large engines powered by an alternative fuel. STATE OF THE ART

[0005] In the field of combustion engines, fuel injection systems are known with pump devices comprising a pre-feed pump and a high-pressure pump. The state of the art includes, for example, common rail injection systems for diesel engines which have a pump device consisting of a pre-feed pump and a high-pressure pump. The high-pressure pump of such a device often comprises a suction throttle member. This means that the high-pressure pump receives the systematically pressurized fuel quantity. Any leakage quantities from the elements of the high-pressure pump are discharged separately and remain in the liquid state without cooling even at operating temperatures. The leakage quantities can thus be returned simply and generally without pressure to the suction side of the high-pressure pump or to the tank.

[0006] A property of alternative fuels such as methanol or ammonia is that they change their state of aggregation at relatively low temperatures and pressures. From a liquid fuel, a fuel in the gaseous state can then be obtained. According to the vapor curve of methanol, this already occurs at a temperature of 65°C and at ambient pressure. As ambient temperature in the area of the engine supplied with active fuel is often greater than this, this can easily translate into the suction area of the high-pressure pump or into a leak path by evacuating the leak quantity. In addition, this constitutes a risk for compliance with safety regulations.

[0007] PURPOSE OF THE INVENTION

[0008] The present invention aims to promote the change in the state of aggregation of active fuels when passing to high pressure in order to thus avoid the corresponding drawbacks.

[0009] DISCLOSURE AND ADVANTAGES OF THE INVENTION

[0010] To this end, the invention relates to a method for managing a pump device for alternative fuels, in particular methanol or ammonia, comprising a pre-charge pump and a high-pressure pump,

[0011] * the precharge pump supplying fuel to at least one element of the pump high pressure through a feed path of a low pressure circuit and discharging the fuel arriving from the leak in at least one pump element through the return path of the low pressure circuit,

[0012] method characterized in that from the supply path, preferably downstream of the precharge pump and upstream of the metering unit integrated in the supply path, fuel is diverted into a cooling path and supplied to at least one cooling element integrated in a suction chamber and / or a leakage chamber of the high pressure pump.

[0013] The fuel in the feed path is at a lower temperature than the fuel pressurized by the high pressure pump. The method according to the invention utilizes this by diverting "fresh" fuel from the feed path to a cooling path and supplying it for cooling to at least one element of the high pressure pump. The cooling avoids a change in the aggregation state of the fuel due to temperature, passing from the liquid state to the gaseous state, which avoids the difficulties described above in drawing fuel into a pump element and / or in returning fuel resulting from leaks.

[0014] Fuel derived from the cooling path is supplied to a cooling element integrated in the suction chamber and / or in a leakage chamber of the high pressure pump.

[0015] Preferably, a respective cooling element is integrated in both the suction chamber and the leakage chamber to enable the high-pressure pump and the leakage quantity to be cooled. The cooling path is, for example, traversed by the fuel only in the cooling element integrated in the suction chamber and then a cooling element integrated in the leakage chamber. The cooled fuel is sucked into the suction chamber to a pump element with the cooling element integrated in the leakage chamber the fuel arriving in at least one pump element through the leakage can be cooled before it is returned through a return path. The leakage chamber can also receive a quantity of fuel discharged from the supply path through a zero-load throttle and be cooled before its return.

[0016] The fuel intended for cooling is preferably diverted downstream of the pre-charging pump and upstream of a metering unit integrated in the supply path from the supply path to the cooling path. A metering unit meters the fuel transferred at high pressure. The fuel to be metered arrives via the metering path into the suction chamber and via the suction chamber into an element of the high-pressure pump.

[0017] According to a development of the invention, the fuel derived from the cooling path is cooled by a cooling installation integrated in the supply path. This makes it possible to optimize the cooling effect by the bypass fuel. The cooling installation is, for example, a heat-conducting element integrated in the cooling circuit swept by the cooling agent of the cooling circuit.

[0018] According to another feature, fuel derived from the cooling path and supplied to a cooling element is returned to the tank or upstream of the precharge pump in the supply path. Fuel derived from the cooling path is not lost under these conditions but remains available to be put under high pressure.

[0019] Preferably, the return path and / or the cooling path is adjusted with a check valve to a minimum pressure level, previously defined. It is higher than the ambient pressure and must guarantee the liquid aggregation state of the fuel at a raised temperature. The minimum pressure level to be adjusted is chosen according to the vapor pressure curve of the respective fuel.

[0020] As a development, the fuel from the cooling path is diverted into a flushing path to be supplied by at least one pump element for discharging the leaking fuel. Flushing the fuel element promotes the discharge of the leaking quantity. In addition, cooling of the pump element can thus be achieved at the same time. The fuel for flushing is preferably diverted between two cooling elements from the cooling path to the flushing path. The diverted quantity in the flushing path is then regulated with a throttle member integrated in the flushing path.

[0021] A pump device is further provided for alternative fuels, in particular for methanol or ammonia. This pump device comprises a pre-charge pump and a high-pressure pump, the pre-charge pump being integrated into a supply path of a low-pressure circuit through which fuel is supplied by an element of the high-pressure pump and the low-pressure circuit of which comprises a return path for discharging fuel which arrives due to leaks in a pump element. According to the invention, a path branches off from the supply path and passes through a cooling element integrated in the suction chamber and / or in a leakage chamber of the high-pressure pump.

[0022] The pump device as proposed is particularly suitable for applying the method described above or operating according to this method so that the advantages resulting therefrom are identical to those already described. In particular, the high-pressure pump and / or the quantities arriving via the return path can be cooled by the fuel in the supply path. The cooling prevents the fuel in the suction zone of the high-pressure pump and / or the return from changing its state of aggregation from the liquid state to the gaseous state depending on whether the cooling element is in the high-pressure pump, the suction chamber and / or in the leakage chamber. Advantageously, a cooling element is integrated in both the suction chamber and the leakage chamber.

[0023] This cooling element is in particular in the form of a pipe or a tube which passes into the suction chamber and / or into the leakage chamber. Preferably, the cooling element is in the suction chamber and / or in the leakage chamber so that the fuel can flow through it on all sides. In this way, a maximum heat transfer surface is obtained. According to another improvement of the heat exchange, at least one thermal element has an outer contour which enlarges the surface and / or is made of a material having good thermal conduction properties.

[0024] The cooling path preferably branches downstream of the pre-charging pump or upstream of a metering unit of the supply path. The pre-supply pump can thus be used to transfer fuel through the cooling path and the metering unit does not influence the quantity of fuel.

[0025] According to a development of the invention, a cooling installation is integrated as a bypass in the supply path, preferably downstream of the pre-charging pump and upstream of the cooling line. The cooling installation makes it possible to cool the fuel before it diverts into the cooling path, which increases the cooling effect. The cooling installation may be a heat-conducting element integrated into the cooling circuit and swept by a cooling agent from the cooling circuit.

[0026] According to a preferred development of the invention, the cooling path opens downstream of at least one cooling element into the tank containing the fuel or upstream of the precharge pump in the fuel path. This way the fuel always remains available.

[0027] According to another preferred feature, a pressure retaining valve is integrated in the return path and / or in the cooling path. The pressure retaining valve makes it possible to maintain a minimum pressure, avoiding, for a rise in fuel temperature, a change in the aggregation state of the fuel which would pass from the liquid state to the gaseous state. Ideally, the fuel is expanded to ambient temperature just before the tank.

[0028] According to another feature, a flushing path branches off from the cooling path and connects at least one pump element to the leak chamber and / or the return path. The fuel thus branched off into the flushing path allows at least one pump element to be flushed, thereby promoting the removal of the leaked quantity. The flushing path branches off, for example, from the cooling path between two cooling elements.

[0029] Preferably, a throttle member is integrated into the rinsing path. This throttle member makes it possible to adjust the rinsing quantity. Brief description of the drawings

[0030] The present invention will be described below in more detail with the aid of the attached drawings in which:

[0031] [Fig-1] diagram of a first pump device according to the invention, and

[0032] [Fig.2] diagram of a second pump device according to the invention.

[0033] DESCRIPTION OF EMBODIMENTS

[0034] [Fig.l] shows a pump device 1 according to the invention for alternative fuels, for example for methanol. The pump device 1 comprises a pre-charging pump 2 and a high-pressure pump 3. The pre-charging pump 2 takes fuel from a tank 14 to supply it via a supply path 5 to at least one pump element 4 of the high-pressure pump 3. The high-pressure pump 3 as shown comprises three pump elements 3; this number is chosen solely as an example. Upstream of the pre-charging pump 2, the supply path 5 integrates a filter 18 which separates harmful particles from the fuel. Downstream of the pre-charging pump 2, a metering unit 8 is integrated in the supply path 5 for metering the fuel.

[0035] The supply of the various pump elements 4 with fuel is done by means of suction valves 19 associated with the pump elements 4. The suction valves 19 connect the pump elements 4 to a suction chamber 11 of the high-pressure pump 3, a chamber into which the supply path 5 opens. The pump elements 4 pass the fuel arriving from the suction valves 19 at high pressure and by the high pressure valves 20 in a high pressure line 21. During the transition to high pressure, the leakage fuel is evacuated by a return path 7 passing through the leak chamber 12 of the high pressure pump 3 and opening into the tank 14. The supply path 5 and the return path 7 together form a low pressure circuit 6. A zero throttling member 23 makes the connection bypassing the pump element 4, between the supply path 5 and the return path 7.

[0036] A cooling path 9 branches off from the supply path 5 downstream of the pre-charging pump 2 and upstream of the metering unit 8 passes for cooling the high-pressure pump 3 and the leakage quantity 8 in a first cooling element 10 integrated in the suction chamber 11 and in a second cooling element 10 integrated in the leakage chamber 12. To increase the cooling effect, downstream of the branched cooling path 9, a cooling installation 13 is integrated in the supply path 5. The cooling path 9 opens upstream of the pre-charging pump 2 again into the supply path 5 so that the fuel branched off for cooling is not lost.

[0037] In the present case, a respective pressure retaining valve 15 is integrated in the return path 7 and in the cooling path 9. This valve or these valves can be in or outside the housing 22 of the high-pressure pump 3. The pressure retaining valves 15 make it possible to maintain a minimum pressure in the return path 7 and in the cooling path 9.

[0038] [Fig. 2] shows another pump device 1 according to the invention with a precharge pump 2 and a high-pressure pump 3. This device differs from that of [Fig. 1] only in that a flushing path 16 is additionally provided for flushing the pump elements 4. The flushing promotes the removal of leakage quantities. The flushing path 16 branches off the cooling path 9 between the two cooling elements 10. A throttle member 17 integrated in the flushing path 16 regulates the flushing quantity. Since the flushing path 16 branches off the cooling path 9, the quantity used for flushing can subsequently be used for cooling at the same time.

[0039] NOMENCLATURE OF MAIN ELEMENTS

[0040] 1 Pump device

[0041] 2 Precharge pump

[0042] 3 High pressure pump

[0043] 4 Pump element

[0044] 5 Power path

[0045] 6 Low pressure circuit

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] 7 Return path 8 Dosing unit 11 Suction chamber 12 Leakage chamber 14 Reservoir 15 Pressure check valve 16 Flushing path 17 Integrated throttle 18 Filter 19 Suction valve 20 High pressure valve 21 High pressure line 22 High pressure pump housing 23 Zero load throttle

Claims

Claims

1. Method for controlling a pump device (10) for alternative fuels, in particular methanol or ammonia, comprising a pre-charging pump (2) and a high-pressure pump (3), * the pre-charging pump (2) supplying fuel to a pump element (4) of the high-pressure pump (3) via a supply path (5) of a low-pressure circuit (6) and discharging fuel arriving from leaks in at least one pump element (4) via a return path (7) of the low-pressure circuit (6), characterized in that from the supply path (5), preferably downstream of the pre-charging pump (2) and upstream of a metering unit (8) integrated in the supply path (5), fuel is diverted to a cooling path (9) and supplied to at least one cooling element (10) integrated in a suction chamber (11) and / or a leakage chamber (12) of the high-pressure pump (3).

2. Method according to claim 1, characterized in that the fuel diverted into the cooling path (9) is pre-cooled with a cooling installation (13) integrated in the supply path (5).

3. Method according to claim 1 or 2, characterized in that the fuel diverted into the cooling path (9) and supplied to at least one cooling element (10) is returned to a fuel tank (14) or upstream of the precharge pump (2) in the supply path (5).

4. Method according to one of the preceding claims, characterized in that by means of a pressure check valve (15) a minimum pressure level is set in advance, defined in the return path (7) and / or in the cooling path (9).

5. Method according to one of the preceding claims, characterized in that from the cooling path (9) preferably between two cooling elements (10) fuel is diverted into a flushing path (16) and it is supplied to at least one pump element (4) for discharging the fuel arriving through the leaks, * preferably the quantity diverted into the flushing path (16) is regulated by means of a throttle (17) integrated in the flushing path (16).

6. Pump device (1) for alternative fuels, in particular for methanol or ammonia, comprising a pre-charging pump (2) and a high-pressure pump (3), * the pre-charging pump (2) being integrated in a supply path (5) of a low-pressure circuit (6) via which fuel is supplied to at least one pump element (4) of the high-pressure pump (3), and * the low-pressure circuit (6) has a return path (7) for discharging fuel, which has leaked into at least one pump element (4), the pump device being characterized in that a cooling path (9) is branched off from the supply path (5) preferably downstream of the pre-charging pump (2) and upstream of a metering unit (8) integrated in the supply path (5), this cooling path passing through at least one cooling element (10) which is integrated in a suction chamber (11) and / or in a leakage chamber of the pump high pressure (3).

7. Pump device (1) according to claim 6, characterized in that a cooling installation (13) is integrated in the supply path (5) preferably downstream of the precharging pump (2) and upstream of the bypass cooling line (9).

8. Pump device (1) according to claim 6 or 7, characterized in that the cooling path opens downstream of at least one cooling element (10) into a tank (14) containing the fuel or upstream of the pre-charging pump (2) into the supply path (5).

9. Pump device (1) according to one of claims 6 to 8, characterized in that a pressure check valve (15) is integrated in the return path (7) and / or in the cooling path (9).

10. Pump device (1) according to one of claims 6 to 9, characterized in that a flushing path (16) branches off from the cooling path (9) preferably between two cooling elements (10), this path being connected by at least one pump element (4) to the leakage chamber (12) and / or to the return path (7), the flushing path (16) preferably incorporating a throttle member (17).

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