WO2017215839A1

WO2017215839A1 - Feed-supply pump for cryogenic fuels and fuel supply system

Info

Publication number: WO2017215839A1
Application number: PCT/EP2017/060873
Authority: WO
Inventors: Andreas Kellner; Falko Bredow; Frank Zehnder; Dirk SCHNITTGER; Andreas Beiter; Marc Oliver Roehner
Original assignee: Robert Bosch Gmbh
Priority date: 2016-06-16
Filing date: 2017-05-08
Publication date: 2017-12-21
Also published as: DE102016210752A1

Abstract

The invention relates to a feed-supply pump (10) for cryogenic fuels (1), comprising an intake port (22) which can be connected at least directly to a tank container (2) for the fuel (1), a pressurized connection (23) which can be connected to a heating device (15), a pump element (28) which can be actuated by a drive (38) for compressing the fuel (1) in a pump chamber (40). The pump chamber (40) can be connected via an inlet (58) to the intake port (22) and via an outlet (59) to the pressurised connection (23).

Description

description

The invention relates to a feed pump for cryogenic fuels after the

Preamble of claim 1. Furthermore, the invention relates to a

Fuel delivery system for a gas powered vehicle with a

inventive feed pump. A feed pump for cryogenic fuels according to the preamble of the claim

1 is known from EP 2 541 062 A1. The known feed pump serves to convey fuel from a tank container in the direction of

Heating device of the fuel conveyor system. For this purpose, the known

Feed pump to a hydraulic, electrical, pneumatic or mechanical drive, which is located in a pump room of the

Feed pump arranged, reciprocating piston acts. In addition, a check valve is arranged on the pressure-side outlet of the pump chamber of the feed pump, which ensures that the funded via the output or the pressure port in the direction of the heater at each stroke by the piston fuel can not then flow back into the pump chamber. The known delivery pump is at a constant

Conveyance or designed for a maximum flow rate of fuel that is so large that thus the maximum demand for gas at a

Internal combustion engine can be covered. If a lower flow rate is required, then an adaptation when using an electric motor than

Drive for the feed pump by a speed reduction simply possible. However, if such a delivery pump is rigidly coupled to an internal combustion engine or an internal combustion engine for driving, the delivery rate of the delivery pump depends on the rotational speed of the internal combustion engine. However, there are operating conditions that despite the relatively high speed of the engine require a relatively small amount of fuel, for example, during overrun operation of a motor vehicle.

Disclosure of the invention

The feed pump for cryogenic fuels having the features of claim 1 has the advantage that in a relatively simple manner, the delivery rate of the feed pump to the actual fuel demand even with a rigid coupling of the feed pump, especially when the feed pump is connected to an internal combustion engine, adjusted can. Under a rigid coupling is understood that a variable speed of the drive in a possibly with the interposition of a reduction gear

corresponding speed or frequency of a pump element is converted.

The invention is based on the idea of influencing the flow rate at the inlet of the pump chamber by means of an electrically operable valve. Thereby, it is possible to control the amount of fuel flowing into the pump space during the movement of the pump element during the suction movement. Also, a delayed closing of the valve acting as a check valve can be made possible to reduce the flow rate or to allow a time-limited backflow in the direction of the suction side. As a result, for example, with a low requirement for fuel, the possibility is opened up to leave the valve at least temporarily in an open position. This has the consequence that when a movement of the pump element in the pump chamber previously infused fuel is ejected again at least partially via the suction port from the pump chamber. The

The use of an electrically operable valve has the particular advantage that it can be implemented with little device complexity and works quickly or reliably with a high clock frequency.

Advantageous developments of the feed pump according to the invention for cryogenic fuels are listed in the dependent claims. A mechanically particularly simple construction of a pump element and a pump chamber is made possible when the pump element is designed as a pump piston which can be moved back and forth between two end positions along a longitudinal axis of the pump chamber.

The inventive principle of promoting fuel from the

Pump chamber also makes it possible, the inlet and the outlet of the pump chamber in a common portion of the pump chamber

to be located, which is outside the movement path of the pump element.

This results in a particularly simple sealing of the pump element to the compressor chamber.

In order to ensure that fuel is conveyed only when a corresponding requirement of the internal combustion engine is present, it is provided that the valve closes the inlet of the pump chamber

Has closing element, the force applied by means of a spring element in the de-energized state of the electric valve, the closing element in the position releasing the inlet.

In a further development of the last-mentioned concept of the invention, it is provided in a structurally preferred embodiment that the closing element is arranged within the pump chamber in register with the inlet and is connected via a coupling rod in operative connection with an armature. In this case, the closing element and the coupling rod are formed as separate elements, i. that there is only a contact between the two components, such that the coupling rod, the closing element only in the direction of his

Can press opening position, but not active in its closed position.

In particular, in connection with a compressor element which is driven at the speed of the internal combustion engine proportional frequency, it is provided for adjusting the delivery rate per delivery stroke that the electrically actuated valve is adapted to the inlet during movement of the pump element in the direction of the inlet in the opening direction to press. In other words, this means that the valve is the inlet during a compression phase or the compression movement of the

Pump element keeps open, as long as this is its electromagnetic drive allows. As long as the valve has not yet closed the inlet, it is possible that fuel flows out of the inlet during a movement of the pump element in the direction of the inlet and does not reach the pressure port or in the direction of a heating device. The sooner the closing movement of the valve begins, the greater is the amount of fuel delivered per delivery stroke in the direction of the pressure connection of the delivery pump.

The invention also includes a fuel delivery system for a gas powered vehicle using a feed pump of the invention. The feed pump is used to compress the fuel to the required system pressure, for example, to a pressure of the fuel, which is several hundred bar. The fuel delivery system is characterized in that the feed pump is preceded by a prefeed pump, which compresses the fuel at the suction port of the feed pump to a prefeed pressure at which the fuel is not yet evaporated. Such a training of

Fuel feed system has the advantage that the (high-pressure) feed pump according to the invention can be arranged in a region relatively far away from the tank container, for example at an interface on the internal combustion engine for driving the feed pump. In addition, this reduces a transmission of the heat of the drive of the feed pump in the fuel in the tank container.

A particularly simple drive of the feed pump is made possible when the fuel feed system has a mechanical coupling with an internal combustion engine, which serves to drive the feed pump.

In this case, it can also be provided, in particular, that in order to optimize the rotational speed or the speed of the pump element of the feed pump, the coupling between the feed pump and the internal combustion engine below

Interposition of a transmission takes place, for example, increases or decreases the speed of the internal combustion engine.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. This shows in:

Fig. 1 is a simplified representation of a fuel delivery system for a

gas powered vehicle and

Fig. 2 shows a detail of a feed pump, as in the

Fuel supply system of FIG. 1 is used, in an enlarged view.

The same elements or elements with the same function are provided in the figures with the same reference numerals.

1, a fuel delivery system 100 for cryogenic fuel 1 is shown. By way of example and not limitation, the fuel 1 is natural gas or hydrogen which has been cooled down in a tank container 2 to a temperature of, for example, -10 ° C. or less so that it is below a filling level 3 in liquid form. On the other hand, above the filling level 3, the fuel 1 is in a gaseous state. The tank container 2 preferably consists of an inner tank accommodating the fuel 1, which is evacuated from an outer shell to form an evacuated tank

Interspace is enclosed. Since such a tank container 2 of the prior art is known per se and is not essential to the invention, a further description of the tank 2 is dispensed with at this position.

Within the tank 2 is a low-pressure pump 4 as

Pre-feed pump, preferably below the filling level 3, arranged. Also, the drive 5 of the low pressure pump 4 is disposed within the tank 2. On the pressure side of the low-pressure pump 4 are a

Shut-off valve 6 and a pressure relief valve 7 is arranged. The shut-off valve 6 is closed in the de-energized state, and the pressure limiting valve 7 serves to prevent damage to the low-pressure delivery pump 4 in the event of a defective shut-off valve 6.

The pressure side of the low-pressure feed pump 4 delivers the fuel 1 (with the shut-off valve 6 open) into a supply line 8. Spatially separated from the tank container 2, a feed pump 10 is arranged as a high-pressure pump. The feed pump 10 is supplied on the suction side of the fuel 1 of the low-pressure feed pump 4 and is connected on the pressure side to a particular designed in the form of a heat exchanger heater 15, in turn, on the side facing away from the feed pump 10

Intermediate circuit of a buffer memory 17 and a pressure control valve 18 is connected by way of example with a rail 16. The rail 16 is connected, by way of example, to a plurality of gas valves 20, which serve to convey the fuel initially conveyed by the feed pump 10 into the heating device 15, which is heated by the heating device 15, into the combustion chamber of a not-shown fuel

Inject internal combustion engine. In particular, the internal combustion engine is part of a gas-powered vehicle.

For example, while the pressure of the fuel 1 in the tank container 2 is approximately between 3 bar and 15 bar, the pressure on the suction side of the feed pump 10 is caused by the pressure increase by the

Low pressure feed pump 4, approximately between 10bar and 20bar, while the pressure of the fuel 1 at the pressure side of the feed pump 10 may be up to 60bar, for example.

The feed pump 10 has a systemic limit 21 shown only symbolically. The fuel 1 passes through a suction port 22 via the

System boundary 21 and flows in the region of a pressure port 23 from the system boundary 21 in the direction of the heater 15 from. Within the

System boundary 21 is under formation of a fuel 1 filled

Interspace 25 a cylinder 26 arranged or formed. Within the cylinder 26, a longitudinal bore 27 is formed, in which a pump element 28 in the form of a high-pressure pump piston 29 in the direction of the double arrow 31 along a longitudinal axis of the longitudinal bore 37 is arranged back and forth. The high-pressure pump piston 29 is connected via a piston rod 32 and a connecting rod 33 connected to the piston rod 32 with a crankshaft 35, which in turn is coupled to a drive 38 arranged with an example outside the system boundary 21 arranged transmission 37. The drive 38 is in particular the internal combustion engine whose crankshaft, for example, also for driving the crankshaft 35 of the Feed pump 10 is used. The crankshaft 35, together with the connecting rod 33, that the rotational movement of the crankshaft 35 in the direction of the arrow 39 in the above-mentioned reciprocating motion of the connecting rod 32 and the

High-pressure pump piston 29 is transmitted in the direction of the double arrow 31.

The longitudinal bore 27 forms within the cylinder 26 u.a. a cylindrical pump chamber 40, which has on the side facing away from the piston rod 32 side of the high-pressure pump piston 29 via a longitudinal bore 41 connection to a transverse bore 42. The transverse bore 42 is at least indirectly connected to the suction port 22. The longitudinal bore 41 is of a

Coupling rod 44 interspersed with radial spacing, which within the

Pumping space 40 by abutting contact, i. is arranged in operative connection with a plate-shaped closing element 45 designed as a separate component of the coupling rod 44. The acting as a check valve

Closing element 45 is part of an electrically actuatable valve 50. The

Coupling rod 44 is connected on the side facing away from the closing element 45 with an armature 51 which cooperates with a magnet 51 radially surrounding the armature 51. Furthermore, the armature 51 is arranged in operative connection with a compression spring 53, the armature 51 and thus also the closing element 45 in the direction of the high-pressure pump piston 29th

with force.

When energized solenoid 32, the armature 51 is moved against the spring force of the compression spring 53 in the direction away from the high-pressure pump piston 29, so that the closing element 45 with its underside 56 on

Transition region of the longitudinal bore 27 to the longitudinal bore 41 (which has a smaller diameter than the longitudinal bore 27) can bear sealingly. This concern or sealing can take place even when energized solenoid 32 when the pressure prevailing in the pump chamber 40 hydraulic pressure is greater than the opening force of the compression spring 53 (together with the pressure prevailing in the longitudinal bore 41 hydraulic pressure).

In a state in which the solenoid 52 is not operated or with a relatively low current, the compression spring 53 causes that

Closing element 45 is moved by abutting contact with the coupling rod 44 in the direction of the high pressure pump piston 29 and thus on the longitudinal bore 41st

Fuel 1 can flow into the pump chamber 40. The longitudinal bore 41 forms thus on the pump chamber 40 side facing an inlet 58 from. On the side of the inlet 58, an outlet 59 with a high-pressure valve 60 is formed in the pump chamber 40. The high pressure valve 60 is as

Non-return valve formed and prevents backflow of fuel 1 in the direction of the pump chamber 40. Furthermore, it is preferably provided that the high pressure valve 60 opens only when a certain minimum pressure is exceeded. The fuel 1 reaches the pressure connection 23 at least indirectly via the outlet 59. Both the inlet 58 and the outlet 59 are arranged in a partial region 61 of the pump chamber 40, into which the

High-pressure pump piston 29 does not get in his reciprocation.

The operation of the valve 50 within the feed pump 10 is explained as follows: When not actuated valve 50 and not energized solenoid 52, the closing element 45 is pressed by the spring force of the compression spring 53 in the inlet 58 releasing position. As a result, in a (suction) movement of the high-pressure pump piston 29 from the right in FIG. 1 side in the direction of the left side reaches up to the reversal point of the

High-pressure pump piston 29 fuel 1 via the longitudinal bore 41 in the pump chamber 40. During the movement of the high-pressure pump piston 29 from the left in Figure 1 in the direction of the inlet 58 is a closing of the inlet 58 is prevented by the compression spring 53, so that fuel 1 from the inlet 58 can flow back in the direction of the suction port 22, since at the same time the high pressure valve 60 does not open due to the low pressure increase. When the valve 50 is not actuated or the solenoid coil 52 is not energized, no fuel 1 is thus conveyed in the direction of the pressure connection 23 or the heating device 15.

If, however, the valve 50 or the solenoid 52 in the region of

Reversing point of the high-pressure pump piston 29 is activated or energized after the suction of fuel 1 in the pump chamber 40, the closing element 45 can move against the spring force of the compression spring 53 in its closing the inlet 58 position so that it acts as a check valve. This will fuel 1 in the subsequent movement of the

High-pressure pump piston 29 compressed in the direction of the inlet 58 and via the outlet 59 with the high-pressure valve 60 open in the direction of

Pressure port 23 and thus promoted in the direction of the heater 15. An actuation of the valve 50 in the region of the inlet 58 facing away from the reversal point of the high-pressure pump piston 29 thus causes per delivery stroke a maximum flow of fuel 1 in the direction of the pressure port 23 of the feed pump 10th

If, however, the magnetic coil 52 of the valve 50 in a modification of the last described fact only during the movement of the

High-pressure pump piston 29 is energized from the side facing away from the inlet 58 in the direction of the inlet 58, so first fuel 1 during the movement of the high-pressure pump piston 29 in the direction of the inlet 58 from the inlet 58 is conveyed out until the closure member 45 closes or seals the inlet 58 , From this point on, the fuel 1 is conveyed via the outlet 59 in the direction of the pressure connection 23 or the heating device 15.

Depending on the time when the valve 50 is energized or actuated in the direction of the inlet 58 during the movement of the high-pressure pump piston 29, the delivery quantity of the fuel 1 during a working stroke of the high-pressure pump piston 29 can thus be adjusted as needed.

The delivery pump 10 described so far can be modified or modified in many ways, without departing from the spirit. So it is particularly conceivable to form the valve 50 with reverse direction of action. In this case, the inlet 58 is kept open in the energized state of the solenoid coil 52 and closed in the de-energized state by the compression spring 53, the inlet 58 by the closing element 45.

Claims

claims

1 . Feed pump (10) for cryogenic fuels (1), with a suction port (22) which is at least indirectly connectable to a tank container (2) for the fuel (1), with a pressure port (23), preferably with a heating device (15 ) is connectable, with one of a drive (38) operable pump element (28) for compressing the fuel (1) in a pump chamber (40), wherein the pump chamber (40) via an inlet (58) with the suction port (22) and is connected via an outlet (59) to the pressure port (23), characterized in that an electrically operable valve (50) for influencing the

Flow rate of fuel (1) between the pump chamber (40) and the inlet (58) is provided.

2. Feed pump according to claim 1,

characterized,

that the drive (38) of the pump element (28) via a

Internal combustion engine takes place, which is at least indirectly rigidly coupled to the pump element (28).

3. Feed pump according to claim 1 or 2,

characterized,

in that the pump element (28) is designed as a pump piston (29) which can be moved back and forth between two end positions.

4. Feed pump according to one of claims 1 to 3,

characterized,

that the inlet (58) and the outlet (59) in a common

Part region (61) of the pump chamber (40) are arranged, which is arranged outside the movement path of the pump element (28). Feed pump according to one of claims 1 to 4,

characterized,

in that the valve (50) has a closing element (45) which, by means of a spring element (53) in the de-energized state of the valve (50), has the

Closing element (45) in the position releasing the inlet (58) force applied.

Feed pump according to claim 5,

characterized,

that the closing element (45) within the pump chamber (40) in

Cover is arranged with the inlet (58) and connected via a coupling rod (44) in operative connection with an armature (51), wherein the coupling rod (44) and the closing element (45) are formed as separate, non-interconnected components.

Feed pump according to one of claims 3 to 6,

characterized,

in that the valve (50) is designed to close the inlet (58) during a movement of the pump element (28) in the direction of the inlet (58).

Feed pump according to one of claims 1 to 7,

characterized,

in that a high-pressure valve (60) is associated with the outlet (59), which prevents a backflow of fuel (1) into the pump chamber (40) and an outflow of fuel (1) from the pump chamber (40) only at

Exceeding a minimum pressure in the pump chamber (40) permits.

A fuel delivery system (100) for a gas powered vehicle, comprising a delivery pump (10) according to any one of claims 1 to 8, characterized

in that the feed pump (10) is preceded by a prefeed pump (4) which is designed to compress the fuel (1) at the suction port (22) of the feed pump (10) to a pre-demand pressure at which the fuel (1) does not yet evaporated.

10. Fuel supply system according to claim 9,

characterized,

in that the prefeed pump (4) is arranged inside the tank container (2).

1 1. Fuel feed system according to claim 9 or 10,

characterized,

that the drive (38) of the feed pump (10) via a mechanical

Coupling is done by an internal combustion engine.

12. Fuel feed system according to claim 1 1,

characterized,

in that the coupling has a transmission gear (37).