WO2017215818A1

WO2017215818A1 - Feed pump for cryogenic fuels and fuel delivery system

Info

Publication number: WO2017215818A1
Application number: PCT/EP2017/059639
Authority: WO
Inventors: Andreas Kellner; Falko Bredow; Dirk SCHNITTGER; Andreas Beiter
Original assignee: Robert Bosch Gmbh
Priority date: 2016-06-16
Filing date: 2017-04-24
Publication date: 2017-12-21
Also published as: DE102016210728A1

Abstract

The invention relates to a feed pump (10; 10a) for cryogenic fuels (1), comprising a suction inlet (32) which is at least indirectly connectable to a tank container (2; 2a) for the fuel (1), a pressure outlet (33) which is preferably connectable to an evaporator (15), and a compression element (29) that can be actuated by a drive (65) for compressing the fuel (1) in a compressor chamber (25).

Description

description

Feed pump for cryogenic fuels and fuel feed systems

State of the art

The invention relates to a feed pump for cryogenic fuels according to 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 claim 1 is known from EP 2 541 062 A1. The known feed pump is the

Promote fuel from a tank container in the direction of a

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, an adaptation in the use of an electric motor as a drive for the feed pump by a speed reduction is easily 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 require a relatively low fuel consumption despite relatively high engine speed, for example when

Pushing operation of a motor vehicle. DISCLOSURE OF THE INVENTION The feed pump for cryogenic fuels with 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 if the feed pump is connected to an internal combustion engine , can be adjusted. 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, the pump element or the

High pressure pump piston with its drive not directly, i. rigidly connected, but via a coupler space filled with a pressure medium, wherein the pressure prevailing there can be influenced by a blocking of the coupler space during a movement of a drive plunger projecting into the coupler space in such a way that a controllable transmission of the

Drive movement is made possible on the pump element. In other words, this means that one of the pump element

(High-pressure pump piston) independent movement of the drive element or the drive plunger is made possible. In particular, the invention provides that the pump element via a filled with a pressure medium

Coupler space in operative connection with the drive (internal combustion engine) is connected, and that the coupler chamber via a valve with a

Buffer memory for the pressure medium is connected, wherein the valve for controlling the flow of pressure medium between the coupler space and the

Buffer memory is formed. Such a construction according to the invention makes it possible, with an open valve to the buffer memory, a back and forth promotion of the pressure medium between the coupler space and the

Cause buffer without causing the force acting on the pump element (high-pressure pump piston) via the coupler space force is so large that the pump element (high-pressure pump piston) moves. If, on the other hand, the valve is closed, the coupler space is the only one Volume on which the drive acts on its movement. As a result, a transfer of the hydraulic pressure to the pump element (high pressure pump piston) is effected in a compression of the pressure medium in the coupler space.

As a suitable pressure medium is particularly intended to a hydraulic medium, in particular oil. This has the advantage that the medium used can simultaneously serve for the lubrication of components of the feed pump. Advantageous developments of the feed pump according to the invention for cryogenic

Fuels are listed in the subclaims.

In a structurally preferred embodiment, which allows a particularly simple construction of the pump element and a coupling of the pump element to the drive, it is proposed that the pump element along a

Longitudinal axis of the pump chamber reciprocally trained piston is that a connected to the piston piston plunger protrudes with an end region facing away from the piston in the coupler space, and that the drive is connected to a drive plunger, which faces away from the drive end portion protrudes into the coupler space. Thus protrude two piston-like

Elements (piston plunger and drive plunger) on opposite, opposite end faces in the coupler space inside.

In order to position both the piston tappet and the drive tappet in a defined initial position, for example, when the coupler space is depressurized and, moreover, to assist the suction movement of the piston element, it is provided that the piston tappet and the drive tappet each have a spring element in a direction away from the coupler space

are charged with force.

In a first basic structural design or arrangement, it is provided that the coupler space are arranged together with the piston plunger and the drive plunger in a common housing. This makes it possible to use the feed pump in particular using a

Pre-feed pump in a relatively distant from the tank container area to be able to order. Furthermore, a particularly compact construction of the feed pump is made possible.

The particularly compact construction of such a feed pump is favored when the piston tappet, the drive tappet and the piston are arranged along two aligned longitudinal axes, and when the piston tappet and the drive tappet protrude from opposite sides into the coupler space. In a second basic structural design or arrangement, it is provided that the coupler space consists of two sub-coupler spaces in

is formed from separate housings, the two

Teilkopplerräume are interconnected by means of a hydraulic line. Such a structure has the advantage that it is possible to dispense with a prefeed pump when the compressor element (high-pressure pump piston) accommodating housing, for example, relatively close to the tank container or partially disposed in the tank container.

The invention also includes a fuel delivery system for a gas powered vehicle using a delivery pump heretofore described in accordance with a first basic configuration of the coupler space in a single housing. 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 is a transmission of the heat of the drive of the feed pump in the fuel in the

Tank container reduced. In order to allow a particularly simple interface in the wall of the tank, which only requires the implementation of a (pressure) line required, it is provided that the prefeed pump is disposed within the tank. Such an arrangement is so far as regards the heat transfer of the drive of the prefeed pump possibly uncritical or advantageous, since the power requirement of the pre-feed pump, in relation to the (high-pressure) feed pump, is relatively low.

Preferably, the drive of the feed pump via a mechanical coupling with an internal combustion engine, wherein the coupling is also a

Translation gear with constant gear ratio may have, for example, the speed of a crankshaft better to one for the

Frequency or speed of the drive plunger to adjust.

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 system view of a fuel delivery system, in which one of

Power transmission is arranged on a piston serving coupler space in a feed pump and

2 shows a fuel delivery system in which the two-part coupler space is provided in different areas of the fuel delivery system, wherein the two Teilkopplerräume are connected to each other via a hydraulic line.

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, the fuel 1 is, and is not limited to, natural gas which is 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 a fuel tank 1 receiving the inner tank, which is enclosed by an outer shell to form an evacuated gap. Since such a tank container 2 known from the prior art per se and is not essential to the invention, is omitted at this point to a more detailed description of the tank 2.

By way of example, a low-pressure delivery pump 4 is arranged within the tank container 2 as a prefetching pump, preferably below the filling level 3. 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 check valve 6 is closed in the de-energized state, wherein the pressure relief valve 7 serves to damage the faulty shut-off valve 6

Low-pressure pump 4 to prevent.

The pressure side of the low-pressure delivery pump 4 conveys the fuel 1 (in the case of an energized and thus open shut-off valve 6) into a supply line 8 which is connected to the suction side of a (high-pressure) delivery pump 10. The

Pressure side of the feed pump 10 is in turn connected via a pressure line 9 with a heater 15. The heating device 15, which is designed in particular in the form of a heat exchanger, has a heating element, not shown in detail, which is designed to heat the liquid fuel 1 conveyed by the feed pump 10 and via a further line 16 with the interposition of a buffer 14 and a pressure regulating valve 19 a storage volume, in particular a rail 17, supply. From the rail 17 turn lines 18, which are each connected to a gas valve 20. The gas valves 20 are each a not shown

Combined combustion chamber of an internal combustion engine of a motor vehicle, and serve to the gaseous fuel 1, for example, under a

System pressure of some 100bar, in the respective combustion chamber of the

Inject internal combustion engine. The feed pump 10 has a housing 21, the example of two, on a

Front side axially interconnected housing parts 22, 23 has. In the first housing part 22, a longitudinal bore 24 is formed with sections with different bore diameters as a through hole. The longitudinal bore 24 forms in the section in which it has its largest diameter, a cylindrically shaped pump chamber 25. In the pump chamber 25 is along a longitudinal axis 26 in the direction of the double arrow 27 back and herbeweglichen high-pressure pump piston 28 is arranged. The high-pressure pump piston 28 acts as a compressor or pump element 29, which is designed to compress the fuel 1 flowing into the feed pump 10 from a suction-side feed pressure of, for example, up to 60 bar, prevailing on account of the low-pressure feed pump 4 to a system pressure of a few 100 bars and the heating device 15 feed.

In a portion 31 of the pump chamber 25, outside the

Movement path of the pump element 29 is located, a suction inlet 32 and a pressure outlet 33 of the pump chamber 25 are formed. The suction inlet 32 has a portion 34 of the longitudinal bore 24 connection with a surrounding the first housing part 22 storage space 35 for the fuel 1, which is filled via the suction side of the feed pump 10 from the supply line 8 with fuel 1. In the region of the suction inlet 32, a check valve is arranged, which allows only an inflow of fuel 1 into the pump chamber 25, but not an outflow of fuel 1 via the suction inlet 32 into the storage space 35th

On the side facing away from the suction inlet 32 of the pump element 29, a transverse bore 36 is formed, the connection with the storage space 35 has, and the inflow and outflow of fuel 1 in the suction inlet 32 and the pressure outlet 33 opposite side of the pump chamber 25 allows. Furthermore, in the first housing part 22, a high pressure line 37 is formed, which connects the pressure outlet 33 with the pressure line 9. In the area of

Pressure outlet 33 is also arranged in detail, also not shown in detail, high-pressure valve, on the one hand prevents backflow of fuel 1 from the high pressure line 37 into the pump chamber 25, and on the other hand, a spill of fuel 1 from the pump chamber 25 into the high-pressure line 37 allows. In the simplest case, the high pressure valve is thus designed as a check valve. However, it can also be provided that the high-pressure valve opens only at a certain overpressure in the pump chamber 25 in the direction of the high-pressure line 37.

The pump element 29 or the high-pressure pump piston 28 is connected to a side facing away from the portion 31 of the pump chamber 25 with a piston rod 39. The piston rod 39 protrudes from the second housing part 23 facing out end of the first housing part 22 and is connected on the side remote from the pump element 29 side with a piston plunger 40. The piston plunger 40 projects into a section of a bore formed as a blind hole 41 in the second housing part 23 bore. On the

Pump element 29 facing side is supported on an end face of the

Piston plunger 40 from a compression spring 43, whose the piston plunger 40th

remote end is supported on the end face of the first housing part 22. As a result, a spring force is generated by the compression spring 43 on the piston tappet 40 and the pump element 29, which forces the high-pressure pump piston 28 in the direction of the second housing part 23.

The piston rod 39 facing away from the end of the piston rod 40 protrudes into an end face in a portion of the blind hole 41 into it, the one

Coupler space 45 forms, wherein a longitudinal axis 46 of the blind hole 41 is aligned with the longitudinal bore 24 on the first housing part 22.

On the side facing away from the piston plunger 40 side of the coupler space 45 projects into this a drive plunger 50 into it. The end of the drive tappet 50 facing away from the coupler space 45 cooperates within a section 51 of the blind bore 41 with a cam 52, which is connected to a camshaft 53.

Furthermore, a further compression spring 55 is supported between a collar 54 of the drive plunger 50 and an end-side boundary of the section 51, which forces the drive plunger 50 in a direction away from the first housing part 22 direction.

Upon rotation of the camshaft 53 in the direction of arrow 57 is the

Rotation of the camshaft 53 via the cam 52 in a linear outward and

Herbewegung the drive ram 50 in the direction of the double arrow 58 transmitted. An outstanding from the second housing part 23 end of the camshaft 53 is connected by way of example with a fixed gear ratio having transmission 60. The transmission 60 is in turn connected via a mechanical coupling 61 to a drive 65 of the feed pump 10. The drive 65 is, in particular, the internal combustion engine or its crankshaft or a device for decoupling a drive (power take-off) connected to the internal combustion engine. The coupler chamber 45 is connected via a transverse bore 66, an electrically actuated switching valve 68 for adjusting the stroke of the piston plunger 40 and a

Switching valve 68 bridging bypass line 69 with integrated

Check valve 71 connected to a buffer memory 75. The spring-loaded buffer memory 75 is in turn connected via a check valve 76 to the pressure side of a motor oil pump 77. The Motorolpumpe 77 delivers engine oil, which serves as a pressure medium 47 in the coupler space 45 and at the same time the lubrication of components, in particular the drive plunger 50 and the piston plunger 40. In particular, can be compensated with the Motorolpumpe 77 and leakage losses. Furthermore, the portion 51 in the blind hole 41 and the spring chamber 78 of the buffer memory 75 are connected to an oil tank 79, from which the motor oil pump 77 sucks the pressure medium 47. About another line 81 which has 53 different areas of the blind hole 41 and the camshaft connection is from these areas

escaping pressure medium 47 and oil also discharged into the oil tank 79.

The operation of the delivery pump 10 described so far is explained as follows: In a movement of the drive ram 50 in the direction of

In a locked position of the switching valve 68 and no oil or pressure medium 47 can flow out of the coupler chamber 45 via the bypass line 69 into the buffer memory 75, since the check valve 71 in. In the buffer space 75, the drive plunger 50 of the

Bypass line 69 locks. This causes the piston rod 40, and thus also the piston rod 39 and the high-pressure pump piston 28, to move in the same direction as the drive rod 50

High pressure pump piston 28 causes due to previously sucked into the pump chamber 25 fuel 1, that the fuel 1 is compressed in the pump chamber 25 and conveyed through the high pressure line 37 to the heater 15. When locked switching valve 68 is thus the maximum

Flow rate per stroke of the drive plunger 50 and the high-pressure pump piston

28 scored. During a movement of the drive plunger 50 in the direction of the cam 52, the further compression spring 55 prevents the drive plunger 50 from lifting off the camshaft 53 or the cam 52. Furthermore, the plunger 40 is moved by the compression spring 43 in the direction of the coupler space 45. This movement simultaneously causes a corresponding movement of the High pressure pump piston 28 and thus a suction of fuel 1 via the suction inlet 32 into the pump chamber 25th

If, however, the switching valve 68 is switched to the passage position shown in FIG. 1, can in a movement of the drive plunger 50 in the coupler space

45 escape from the drive plunger 50 pressure fluid 47 and oil via the switching valve 68 in the buffer memory 75. The pressure in the coupler chamber 45 is then not sufficient to move the plunger 40 against the spring force of the compression spring 43 in the direction of the pump chamber 25. As a result, no fuel 1 is displaced or conveyed in the direction of the pressure outlet 33 in the pump chamber 25 by the high-pressure pump piston 28. At a

Movement of the drive plunger 50 in the direction of the camshaft 53 flows the previously pumped into the buffer memory 45 pressure fluid 47 or oil via the bypass line 69 and / or not switched switching valve 68 in the

Coupler chamber 45 back.

Finally, it is also possible to set a demand-based flow rate of fuel 1 to the feed pump 10. In this case, the drive ram 50 moves in the direction of the coupler space 45, wherein the switching valve 68 initially unconfirmed, i. in open position, stands. As a result, the pressure medium 47 displaced by the drive plunger 50 flows via the switching valve 68 into the buffer memory 75. The piston plunger 40 is therefore not yet moved and no fuel 1 is delivered. Before reaching the first housing part 22 facing the end position of the drive plunger 50, the switching valve 68 is then energized. This means that no pressure fluid 47 or more oil from the coupler 45 in

Direction of the buffer memory 75 escape or can flow. This in turn leads to the fact that the piston rod 40 (together with the drive rod 50) moves in the direction of the pump chamber 25 and thereby compressed in the pump chamber 25 previously sucked fuel 1 and in

Direction of the pressure outlet 33 flows out of the compressor chamber 25.

Depending on the time when the switching valve 68 during its

Movement is energized in the direction of the coupler space 45, the

Flow rate of fuel 1 from the pump chamber 25 are adjusted as needed. In addition, it is mentioned that it is also conceivable to operate the switching valve 68 for stroke adjustment with reverse direction of action. In this case, the switching valve 68 is de-energized in its blocking position, while in the energized state allows a flow of pressure medium 47 from the coupler chamber 45 in the direction of the buffer space 75.

The fuel delivery system 100a shown in FIG. 2 does not have a low-pressure delivery pump 4 in contrast to the fuel delivery system 100. Rather, the (high-pressure) delivery pump 10a protrudes with its suction side into the tank container 2a. The first housing part 22a has via the longitudinal bore 34a and the transverse bore 36 directly connected to the fuel 1 in the

Tank container 2a. In the second housing part 23 a is in a as

Blind hole formed longitudinal bore 82 on the

High-pressure pump piston 28 side facing away from a first Teilkopplerraum 83 is formed, which has a hydraulic line 84 connection with a second Teilkopplerraum 85, which is arranged in a separate housing part 86. The two Teilkopplerräume 83 and 85 thus form together with the

Hydraulic line 84 from the coupler chamber 45a. The further housing part 86 serves in particular for receiving the drive ram 50a. This makes it possible, the further housing part 86 and the drive 65 in one of the

To arrange delivery pump 10 a and its housing parts 22 a, 23 a relatively widely spaced area.

In addition, it is mentioned that, in addition to the representation of FIG. 2, it is additionally conceivable that the (high-pressure) delivery pump 10 a is in a

Tank container 2 a close range, but outside the tank 2a to arrange, and to lead a suction line of the feed pump 10 a in the tank container 2 a. The fuel delivery system 100, 100a described so far or the

Feed pump 10, 10a can be modified or modified in many ways, without departing from the spirit.

Claims

Claims 1. Feed pump (10; 10a) for cryogenic fuels (1) with a suction inlet

(32), which is at least indirectly connectable to a tank container (2; 2a) for the fuel (1), with a pressure outlet (33), which is preferably connectable to a heater (15), and with one of a drive (65 ) operable pump element (29) for compressing the fuel (1) in a pump chamber (25), characterized in that the pump element (29) via a with a pressure medium (47) filled coupler space (45; 45a) in operative connection with the drive ( 65) is connected via a valve (68) to a buffer store (75) for the pressure medium (47), the valve (68) being used to regulate the flow of pressure medium (47). between the coupler space (45, 45a) and the buffer memory (75) is formed.

2. Feed pump according to claim 1,

characterized,

the pump element (29) is a piston (28) which is designed to be movable back and forth along a longitudinal axis (26) of the pump chamber (25) such that a piston ram (40) connected to the piston (28) has a piston ram (40)

And the drive (65) is connected to a drive ram (50; 50a) whose end region facing away from the drive (65) is inserted into the coupler space (45; 45a) in the coupler space (45; 45a). protrudes.

3. Feed pump according to claim 2,

characterized,

in that the piston plunger (40) and the drive plunger (50) are each driven by a spring element (43, 55) in the direction of the coupler space (45, 45a)

are charged with force. Feed pump according to one of claims 1 to 3,

characterized,

in that the coupler space (45) together with the piston tappet (40) and the drive tappet (50) are arranged in a common housing (21).

Feed pump according to one of claims 2 to 4,

characterized,

in that the piston tappet (40), the drive tappet (50) and the piston (28) are arranged along two longitudinal axes (26, 46) which are aligned with each other, and in that the piston tappet (40) and the drive tappet (50) are of mutually opposite sides the coupler room (45)

protrude.

Feed pump according to one of claims 1 to 3,

characterized,

in that the coupler space (45a) is formed from two sub-coupler spaces (83, 85) in separate housings (21, 86), wherein the two sub-coupler spaces (83, 85) are interconnected by means of a hydraulic line (84).

A fuel delivery system (100) for a gas powered vehicle, comprising a delivery pump (10) as claimed in any one of claims 1 to 5, characterized

that the feed pump (10) is preceded by a prefeed pump (4), the fuel (1) on the suction side of the feed pump (10) to a

Prepress pressure compressed at which the fuel (1) is not yet evaporated.

A fuel delivery system (100a) for a gas powered vehicle, comprising a delivery pump (10a) as claimed in claim 6,

characterized,

in that the feed pump (10a) with the compressor element (29) is arranged directly in a tank container (2a) or in an area near the tank container (2a).

9. fuel delivery system (100, 100a) according to claim 7 or 8,

the drive (65) of the feed pump (10, 10a) is an internal combustion engine.

10. Fuel supply system according to claim 9,

characterized,

a mechanical clutch (61) and possibly a transmission (60) are arranged between the internal combustion engine and the delivery pump (10; 10a).