DE102018211924A1 - Fuel delivery device for cryogenic fuels - Google Patents

Abstract

Fuel delivery device (100) for cryogenic fuels with a tank (8), a high-pressure delivery pump (2) and an inlet line (9) via which inlet line (9) to the high-pressure delivery pump (2) cryogenic fuel can be supplied from the tank (8). A compression chamber (4) is formed in the high-pressure feed pump (2), which compression chamber (4) can be connected to a control line (60). A cold run valve (6) is arranged in the control line (60), which cold run valve (6) comprises a main valve (44) and a control valve (23), the main valve (44) being controllable by the control valve (23) and thus the connection can be opened or closed between the compression space (4) and the control line (60).

Description

The invention relates to a fuel delivery device for cryogenic fuels. This fuel delivery device is used, for example, in internal combustion engines of motor vehicles with a cryogenic fuel drive, in particular with natural gas.

State of the art

In the unpublished script DE 10 2017 219 784 A1 describes a fuel delivery device for cryogenic fuels. The fuel delivery device comprises a prefeed pump and a high pressure pump. Furthermore, the high pressure pump has a pump head in which a compression space is formed, which is delimited by a reciprocating piston. In addition, a cold run valve is integrated into the high pressure pump, via which the compression space and / or a low pressure space of the high pressure pump can be connected to a tank.

If the high pressure pump is put back into operation after a break in operation, it typically has an ambient temperature. However, the cryogenic fuel from the tank has a storage temperature of, for example, -160 ° C., so that it evaporates immediately when the cryogenic fuel is conveyed into the pump head of the high-pressure pump. Therefore, in the high pressure pump DE 10 2017 219 784 a cold travel valve is integrated, whereby the compression space and / or the low pressure space can be connected to the tank, so that the pump head of the high pressure pump is flushed with cryogenic fuel before start-up in order to cool it for operation.

Proceeding from this, the present invention is based on the object of specifying an alternative cooling method.

Advantages of the invention

The fuel delivery device according to the invention with the characterizing features of claim 1 has the advantage that by dividing the cold travel valve into a main valve and a control valve controlling the main valve, the cold travel valve is arranged efficiently in the high-pressure delivery pump and the efficiency of the fuel delivery device is increased.

For this purpose, the fuel delivery device for cryogenic fuels has a tank, a high-pressure delivery pump and an inlet line, via which inlet line the cryogenic fuel can be fed from the tank to the high-pressure delivery pump. A compression chamber is formed in the high-pressure feed pump and can be connected to a control line. Furthermore, a cold travel valve is arranged in the control line, which cold travel valve comprises a main valve and a control valve. The main valve can be controlled by the control valve, whereby the connection between the compression space and the control line can be opened or closed.

By dividing the cold run valve into a main valve and a control valve that controls the main valve, the respective valve can be adapted accordingly to the installation position in the high-pressure feed pump and the conditions there. Furthermore, the dead volume, which is additionally generated by a cold travel valve connected directly to the compression chamber, is minimized and the optimal functioning of the high-pressure feed pump is achieved.

In a first advantageous embodiment, it is provided that the control valve is designed as a 2/2 way valve. The control valve can thus be integrated into the high-pressure feed pump in a space-saving manner.

In a further embodiment of the invention, it is advantageously provided that the main valve has a sleeve element and a longitudinally movable valve element, the valve element being at least partially surrounded and accommodated by the sleeve element and the valve element and the sleeve element delimiting an inner annular space. Advantageously, the valve element projects into the compression space with a mushroom-shaped end, this mushroom-shaped end cooperating with a sealing seat formed on the sleeve element, and a connection between the inner annular space and the compression space can thus be opened or closed.

In an advantageous development, the sleeve element comprises a transverse bore through which the inner annular space is connected to an outer annular space, the outer annular space being delimited by the main valve and the pump housing and being formed in the control line. The control line is advantageously connected to a return line, the return line opening into the outer annular space and cryogenic fuel being able to be discharged from the outer annular space into the tank via the return line. In this way, cryogenic fuel can be discharged from the inner annulus into the tank via the return line.

In an advantageous development, it is provided that a further control valve is arranged in a connecting channel between the return line and the control line, which further control valve with that in the control line arranged control valve is operatively connected. The further control valve is advantageously designed as a 2/2 way valve. The control valve and the further control valve can also advantageously be designed as a one-piece 3/2 way valve. The control valves can thus be arranged in a space-saving manner in the control line of the high-pressure feed pump.

In an advantageous development, it is provided that the valve element is at least partially received in a recess of the control piston and a valve spring is supported on the control piston, which valve spring acts on the valve element with a force in the direction of the sealing seat. As a result, a connection between the inner annular space and the compression space can be opened or closed.

In a further embodiment of the invention, it is advantageously provided that the valve element has a shoulder on which a valve spring is supported, which valve spring acts on the valve element with a force in the direction of the sealing seat. In this way, a connection between the inner annular space and the compression space can be opened or closed.

In an advantageous development, a longitudinally movable control piston is arranged in the control line, which control piston is pressed against the valve element by means of a piston spring and is thus operatively connected to the valve element. Thus, the valve element can be carried along by the control piston during a longitudinal movement of the latter.

In a further embodiment of the invention, it is advantageously provided that the control piston is arranged in a control space, which control space is connected to the transverse bore by a longitudinal bore formed in the sleeve element. The control room can thus be connected to the return line and thus to the tank.

In an advantageous embodiment, the control chamber is divided by the control piston into a first control sub-chamber and a second control sub-chamber, the first control sub-chamber and the second control sub-chamber being hydraulically connectable to one another by a throttle formed in the control piston. An annular gap is advantageously formed between the control piston and the pump housing, through which annular gap fuel leakage flows from the first control part space into the second control part space, the fuel leakage being interrupted by an axial seal between the control piston and a screw element when the sealing seat is open.

In an advantageous development, it is provided that a pre-feed pump is arranged in the tank, which pumps fuel from the tank via the feed line into the compression chamber of the high-pressure feed pump. This enables a variable arrangement of the high-pressure feed pump, so that it can be arranged, for example, relatively close to the tank or relatively close to an internal combustion engine.

list of figures

• 1 eine Kraftstofffördereinrichtung im Längsschnitt,
• 2a ein erstes Ausführungsbeispiel einer erfindungsgemäßen Kraftstofffördereinrichtung im Bereich des Pumpenkopfs im Längsschnitt,
• 2b ein zweites Ausführungsbeispiel der erfindungsgemäßen Kraftstofffördereinrichtung im Bereich des Pumpenkopfs im Längsschnitt,
• 3a ein drittes Ausführungsbeispiel der erfindungsgemäßen Kraftstofffördereinrichtung im Bereich des Pumpenkopfs im Längsschnitt,
• 3b ein viertes Ausführungsbeispiel der erfindungsgemäßen Kraftstofffördereinrichtung im Bereich des Pumpenkopfs im Längsschnitt.

The drawing shows exemplary embodiments of a fuel delivery device according to the invention, only the essential areas being shown. It shows in

• 1 a fuel delivery device in longitudinal section,
• 2a a first embodiment of a fuel delivery device according to the invention in the region of the pump head in longitudinal section,
• 2 B 2 shows a second exemplary embodiment of the fuel delivery device according to the invention in the region of the pump head in longitudinal section,
• 3a A third embodiment of the fuel delivery device according to the invention in the region of the pump head in longitudinal section,
• 3b a fourth embodiment of the fuel delivery device according to the invention in the region of the pump head in longitudinal section.

Description of the embodiments

1 shows a fuel delivery device 100 for cryogenic fuel, for example natural gas, in longitudinal section. The fuel delivery system 100 includes a pre-feed pump 1 and a high pressure feed pump 2 , in the present case the prefeed pump 1 in the bottom area of a tank 8th is net for storing a cryogenic fuel. There is a liquid phase there 13 of fuel from a gas phase 11 of the fuel is covered.

The arrangement of the pre-feed pump 1 in the tank 8th has the advantage that to connect the pre-feed pump 1 with the high pressure feed pump 2 only one inlet pipe 9 from the tank 8th must be brought out. The pre-feed pump 1 can be designed in particular as a side channel or centrifugal pump. The Tank 8th serves to store the fuel cooled down to a temperature of, for example, -110 ° C. or less.

The high pressure feed pump 2 has a pump housing 32 with a pump head 3 on, in the pump housing 32 a step-shaped longitudinal bore 46 is trained. In the longitudinal bore 46 is a longitudinally moving pump piston 5 arranged, which in the longitudinal bore 46 is guided and together with the pump housing 32 a leakage gap 51 having. With one end 41 the pump piston limits 5 a compression room 4 which with a high pressure channel 14 by means of an exhaust valve 15 is connectable, the high pressure channel 14 with a high pressure accumulator 45 connected is. Furthermore, the compression room 4 with a control line 60 connectable in which a cold run valve 6 is arranged.

Furthermore, the control line 60 by means of a return line 10 with the tank 8th connectable.

The pump piston 5 is from a seal 21 , here formed as piston rings, surround, whereby the compression space 4 to the leakage gap 51 is sealed off. The leakage from the leakage gap 51 can over a channel 17 from the high pressure feed pump 2 be dissipated.

Furthermore is in the longitudinal bore 46 a low pressure room 7 trained, which with the inlet line 9 is connected and from which connection channels 47 in the compression room 4 lead. In the low pressure room 7 is a longitudinally movable suction valve element 12 arranged, which with a plate-shaped end 48 in the compression room 4 protrudes. The suction valve element 12 acts to open and close the connection channels 47 with one on the pump housing 32 trained sealing seat 50 together and forms a suction valve 120 out.

Furthermore, the suction valve element 12 a paragraph 49 on which there is a spring 54 which supports the suction valve element 12 with a force in the direction of the sealing seat 50 acted on, so that the suction valve element 12 with its plate-shaped end 48 the connection channels 47 locks.

With its the compression space 4 the pump piston delimits the opposite end 5 together with the pump housing 32 a spring chamber 19 in which a spring 18 is arranged, the pump piston 5 towards an opening 20 with force. The opening 20 is with a hydraulic system, not shown, for driving the high-pressure feed pump 2 connected.

The operation of the fuel delivery system 100 is the following: When the fuel delivery device is operating 100 feeds the pre-feed pump 1 Fuel from the tank 8th via the feed line 9 towards the low pressure room 7 the high pressure feed pump 2 , By longitudinal movements of the suction valve element 12 and the pump piston 5 the fuel is pumped into the high pressure feed pump 2 sucked. The pump piston moves 5 towards the opening 20 , causing in the compression space 4 the pressure drops so that the suction valve element 12 the connection channels 47 releases and cryogenic fuel from the low pressure chamber 7 in the compression room 4 can flow. After the pressure equalization, the suction valve element locks 12 the connection channels 47 again. The pump piston 5 moves back towards the compression space 4 , so that the cryogenic fuel is compressed to a system pressure of 500 bar, for example, and via the exhaust valve 15 in the high pressure duct 14 is pressed. The compressed fuel can then be fed to an internal combustion engine, for example.

When operating or restarting the fuel delivery system for the first time 100 becomes the high pressure feed pump 2 flushed with cryogenic fuel to cool it and evaporation of the cryogenic fuel immediately after entering the high pressure feed pump 2 to prevent and prevent possible losses. The cold run valve is for this 6 in the control line 60 arranged.

2a shows a first embodiment of the fuel delivery device according to the invention 100 in the area of the pump head 3 , Components with the same function have been given the same reference number.

The compression room 4 is here with the control line 60 connectable in the cold run valve 6 is arranged, the control line 60 also with the inlet pipe 9 is connectable. The cold run valve 6 includes a main valve 44 and a control valve 23 that controls the cold run valve 6 has and is designed here as a 2/2 way valve.

The main valve 44 has a sleeve member 30 and a longitudinally movable valve element 31 on which in the sleeve member 30 is recorded and managed. The sleeve element 30 is for example by means of a sealing washer element 35 in the control line 60 arranged and by means of a screw element 25 in the pump housing 32 clamped. The compression room 4 faces the valve element 31 a mushroom-shaped end 43 on which with a on the sleeve member 30 trained conical sealing seat 42 interacts. At the mushroom-shaped end 43 opposite end has the valve element 31 a paragraph 36 on which a valve spring 28 is arranged. The valve spring 28 surrounds the valve element 31 and leans between the paragraph 36 and the sleeve member 30 from. This is how the valve spring acts 28 the valve element 31 with a force in the direction of the sealing seat 42 ,

The valve element 31 and the sleeve member 30 delimit an inner annulus 37 which by opening and closing the sealing seat 42 with the compression space 4 is connectable. Furthermore is in the sleeve element 30 a cross hole 34 trained which in the inner annulus 37 empties. The main valve 44 forms together with the pump housing 32 in the control line 60 an outer annulus 38 from the return line 10 with the tank 8th connected is. The cross hole 34 connects the inner annulus 37 with the outer annulus 38 ,

The sealing disc element described above 35 also seals the outer annulus 38 against the compression space 4 so that a single hydraulic connection between the outer annulus 38 and the compression space 4 over the sealing seat 42 is available. Furthermore, the sealing washer element 35 preferably made of a metallic material.

The cross hole 34 is with one in the sleeve element 30 trained longitudinal bore 33 hydraulically connected, the longitudinal bore 33 in a control room 24 empties.

The sleeve element 30 and the control line 60 limit the control room 24 , In this control room 24 this also protrudes from the mushroom-shaped end 43 opposite end of the valve element 31 into the valve spring 28 is arranged in it. One in the control room 24 arranged longitudinally movable control piston 27 divides the control room 24 in a first control compartment 240 and a second control compartment 241 and has a throttle 22 on which is the first control compartment 240 with the second control compartment 241 combines.

In the first control room 240 is a piston spring 26 arranged, which is between the control piston 27 and a closure element 61 supported. Here is the piston spring 26 in a recess 52 of the closure element 61 guided and acted on the control piston 27 with a force towards the compression space 4 so that the valve element 31 on the control piston 27 is present and is operatively connected to it. The force of the piston spring 26 can be adjusted by appropriate preload. The force of the valve spring 28 here is greater than the force of the piston spring 26 so the main valve 44 is closed without pressure difference.

The functionality of the cold run valve 6 is as follows: The control valve 23 is designed, for example, as an electromagnetic valve and opens a connection between the supply line when the electromagnet is energized 9 and the first control compartment 240 via the control line 60 , Cryogenic fuel, which comes from the pre-feed pump 1 brought to a certain inlet pressure and in the direction of the first control compartment 240 is promoted, achieved in the control room 24 a stroke movement of the control piston 27 , since in the second control compartment 241 Cryogenic fuel with lower pressure is present: the second control compartment 241 is over the longitudinal bore 33 with the cross hole 34 and thus with the return line 10 to the tank 8th connected so that in the second control compartment 241 Tank pressure and thus a lower pressure than in the first control compartment 240 is present. The hydraulic and pneumatic force of the cryogenic fuel exceeds the force of the piston spring 26 and the valve spring 28 and the control piston 27 moves towards the compression space 4 - here in the 2a up. Due to the active connection of the valve element 31 with the control piston 27 the valve element also moves 31 towards the compression space 4 and thus gives the sealing seat 42 free.

Cryogenic fuel now flows in a circuit from the tank 8th via the suction valve 120 in the compression room 4 and on over the approved sealing seat 42 in the return line 10 back into the tank 8th , By means of the throttle 22 cryogenic fuel flows out of the first control compartment 240 in the second control compartment 241 , Due to a larger cross-sectional dimension in the control valve 23 compared to the throttle 22 and the gap leakage on the control piston 27 , remains a positive pressure difference from the first control compartment 240 to the second control compartment 241 received as long as the control valve 23 open. The control valve 23 The pneumatic and hydraulic force on the control piston is no longer energized 27 through the fuel drain from the first control compartment 240 to the second control compartment 241 reduced. Since the pressure difference is now eliminated, the control piston moves 27 due to the difference in force between valve spring 28 and piston spring 26 again from the compression room 4 gone - here in the 2a down - and takes the valve element 31 due to the active connection, so that the sealing seat 42 through the valve element 31 is closed again.

So the high pressure feed pump 2 when operating or restarting the fuel delivery system for the first time 100 are cooled to operating temperature by flushing with cryogenic fuel and there are no losses during commissioning, for example due to evaporation of the cryogenic fuel immediately after entering the high-pressure feed pump 2 ,

As described above, the compression space 4 also with the return line 10 be connected when system pressure in the high pressure duct 14 is available.

In an alternative embodiment, the control valve 23 the connection between the supply line even when energized 9 and the first control compartment 240 via the control line 60 close so that the connection is de-energized in an open state.

2 B shows a second embodiment of a fuel delivery device according to the invention 100 in the area of the pump head 3 in longitudinal section. The function and structure of the second exemplary embodiment largely correspond to the first exemplary embodiment. Components with the same function are identified by the same reference number.

The valve element 31 is in a recess here 63 of the control piston 27 recorded in sections. Here is the control piston 27 on the valve element 31 pressed on and firmly connected to it. Because the valve element 31 in the sleeve element 30 is guided, the control piston 27 via the connection to the valve element 31 guided. On the outside diameter of the control piston 27 sufficient play is therefore provided to avoid overrule.

Alternatively, the control piston 27 against a shoulder of the valve element 31 with the screw element 25 biased and thus firmly connected to this. The piston spring 26 omitted here and the valve spring 28 is supported directly on the control piston 27 off, causing the valve element 31 against the sealing seat 42 is pressed.

Next to the throttle 22 can through an annular gap 62 between the control piston 27 and the pump housing 32 additional leakage of cryogenic fuel from the first control compartment 240 in the second control compartment 241 stream. This leakage occurs when the cold run valve is operated 6 through an axial seal between the control piston 27 and the screw element 25 minimized so that cryogenic fuel is only via the throttle 22 flows. For the closing process of the cold run valve 6 can the throttle 22 have a small geometry because the low flow rate is only the beginning of the closing movement of the main valve 44 certainly. If the axial seal is no longer effective, the leakage through the annular gap 62 between the control piston 27 and the pump housing 32 the closing process of the main valve 44 accelerated.

3a shows a third embodiment of a fuel delivery device according to the invention 100 , with only the essential area around the pump head 3 is shown. Components with the same function are identified by the same reference number.

The third exemplary embodiment largely corresponds in function and structure to the first exemplary embodiment. In addition, here is the control valve 23 in a connecting channel 53 between the return line 10 and the control line 60 another control valve 39 arranged. The further control valve 39 is also designed as a 2/2 way valve. The throttle is also omitted 22 in the control piston 27 ,

By arranging a further control valve 39 becomes a higher opening speed of the main valve 44 achieved because during the opening process, ie during the lifting movement of the control piston 27 no cryogenic fuel via the throttle 22 from the first control compartment 240 in the second control compartment 241 can flow off. In addition, it is preferable for the opening process of the main valve 44 when using another control valve 39 a lower pressure difference between the first control compartment 240 and the second control compartment 241 required than with throttle 22 , In addition, the pressure conditions in the first control compartment 240 through the further control valve 39 can be controlled so that a faster closing of the main valve 44 can be achieved.

In an alternative embodiment, the control valve 23 and the further control valve 39 as a one-piece pilot valve 40 be carried out. The pilot valve 40 is then like in 3b shown as a 3/2 way valve between the return line 10 and the control line 60 educated.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102017219784 A1 [0002]
• DE 102017219784 [0003]

Claims (15)

Fuel delivery device (100) for cryogenic fuels with a tank (8), a high-pressure delivery pump (2) and an inlet line (9) via which inlet line (9) to the high-pressure delivery pump (2) cryogenic fuel can be supplied from the tank (8) the high-pressure feed pump (2) has a compression chamber (4), which compression chamber (4) can be connected to a control line (60), in which control line (60) a cold travel valve (6) is arranged, which cold travel valve (6) is a main valve (44 ) and a control valve (23), wherein the main valve (44) can be controlled by the control valve (23) and thus the connection between the compression space (4) and the control line (60) can be opened or closed. Fuel delivery device (100) after Claim 1 , characterized in that the control valve (23) is designed as a 2/2 way valve. Fuel delivery device (100) after Claim 1 or 2 , characterized in that the main valve (44) has a sleeve element (30) and a longitudinally movable valve element (31), the valve element (31) being at least partially surrounded by the sleeve element (30) and accommodated therein and the valve element (31) and the sleeve element (30) delimit an inner annular space (37). Fuel delivery device (100) after Claim 3 , characterized in that the valve element (31) projects into the compression space (4) with a mushroom-shaped end (43) and this mushroom-shaped end (43) interacts with a sealing seat (42) formed on the sleeve element (30) and thus a connection between the inner annular space (37) and the compression space (4) can be opened or closed. Fuel delivery device (100) after Claim 4 characterized in that the sleeve element (30) comprises a transverse bore (34) through which transverse bore (34) the inner annular space (37) is connected to an outer annular space (38), the outer annular space (38) through the main valve ( 44) and a pump housing (32) and is formed in the control line (60). Fuel delivery device (100) after Claim 5 , characterized in that the control line (60) is connected to a return line (10), the return line (10) opening into the outer annular space (38) and thus cryogenic fuel from the outer annular space (38) via the return line (10) can be discharged into the tank (8). Fuel delivery device (100) after Claim 6 , characterized in that a further control valve (39) is arranged in a connecting channel (53) between the return line (10) and the control line (60), which further control valve (39) with the control valve (39) arranged in the control line (60) ) is connected. Fuel delivery device (100) after Claim 7 , characterized in that the further control valve (39) is designed as a 2/2 way valve. Fuel delivery device (100) after Claim 7 , characterized in that the control valve (23) and the further control valve (39) are designed as a one-piece 3/2 way valve. Fuel delivery device (100) after Claim 4 characterized in that the valve element (31) is at least partially received in a recess (63) of the control piston (27) and a valve spring (28) is supported on the control piston (27), which valve spring (28) controls the valve element (31) applied with a force in the direction of the sealing seat (42). Fuel delivery device (100) after Claim 4 , characterized in that the valve element (31) has a shoulder (36) on which a valve spring (28) is supported, which valve spring (28) acts on the valve element (31) with a force in the direction of the sealing seat (42). Fuel delivery device (100) after Claim 5 , characterized in that a longitudinally movable control piston (27) is arranged in the control line (60), the control piston (27) being pressed against the valve element (31) by means of a piston spring (26) and thus being operatively connected to the valve element (31) , Fuel delivery device (100) after Claim 12 , characterized in that the control piston (27) is arranged in a control chamber (24), which control chamber (24) is connected to the transverse bore (34) by a longitudinal bore (33) formed in the sleeve element (30). Fuel delivery device (100) after Claim 13 , characterized in that the control chamber (24) is divided by the control piston (27) into a first control sub-chamber (240) and a second control sub-chamber (241), the first control sub-chamber (240) and the second control sub-chamber (241) being divided by a The throttle (22) configured to the control piston (27) can be hydraulically connected to one another, an annular gap (62) being formed between the control piston (27) and the pump housing (32), through which annular gap (62) fuel leakage from the first control sub-chamber ( 240) flows into the second control compartment (241), which fuel leakage occurs when the sealing seat (42) is open an axial seal between the control piston (27) and a screw element (25) is interrupted. Fuel delivery device (100) according to one of the preceding claims, characterized in that a prefeed pump (1) is arranged in the tank (8), which delivers fuel from the tank (8) via the inlet line (9) in the direction of the compression space (4) High-pressure feed pump (2) delivers.

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