WO2022234089A1

WO2022234089A1 - Apparatus for compressing gas and method for filling a tank using said apparatus

Info

Publication number: WO2022234089A1
Application number: PCT/EP2022/062290
Authority: WO
Inventors: Leo Caspers
Original assignee: Van Halteren Technologies Boxtel B.V.
Priority date: 2021-05-06
Filing date: 2022-05-06
Publication date: 2022-11-10
Also published as: WO2022234087A1; DE102021204586A1; EP4334591A1

Abstract

The invention relates to an apparatus for compressing a gas suitable for a drive and to a method for filling a tank using said apparatus, the filling process taking place via a plurality of compression stages. During filling via a compression stage a compressor of the subsequent compression stage is also preliminarily filled.

Description

Device for compressing a gas and method for filling a tank with such a device

description

The invention relates to a device for compressing a gas that is preferably suitable for a drive, for example hydrogen, and a device for filling a tank, preferably a land vehicle, water vehicle or aircraft, with such a device.

In the course of increasing emission limit values, there has been a trend for several years towards replacing conventional internal combustion engines that run on petrol or diesel fuel with alternative drives. Last but not least, due to tax incentives and subsidies, electric drives have become widely accepted as an alternative, which are almost emission-free during use and can thus reduce environmental pollution in densely populated areas. The problem with these electric drives, however, is that when the costs and emissions associated with the production of the batteries are taken into account, the overall energy/pollutant balance is not significantly better than with conventional diesel concepts. Another disadvantage is that there are still few viable solutions that enable the environmentally friendly disposal/reprocessing of defective batteries.

There is therefore a need for further alternative drive technologies, with the use of hydrogen as an energy carrier being one of the most promising concepts. For example, hydrogen can be used as a fuel to power a hydrogen internal combustion engine (hydrogen engine) that operates in the manner of a conventional internal combustion engine. Because with this combustion only a small amount of, for example, by lubricants introduced carbon occurs, such hydrogen engines are superior to conventional internal combustion engines in terms of emissions of carbon-containing pollutants. Nevertheless, not inconsiderable amounts of nitrogen oxides are emitted. A further disadvantage of such solutions is that the complex structure of the internal combustion engine is maintained and, moreover, increased expenditure is required for storing the fuel.

Developments based on a drive system with a hydrogen-oxygen fuel cell and an electric motor that is supplied with energy by the fuel cell are therefore more promising. Of course, in addition to hydrogen, other fuels, for example methanol, butane, natural gas or the like, can also be used.

A problem with such concepts is that the fuel, referred to below as gas, is stored in a tank at a comparatively high pressure, so that the tank station for filling the tank must be designed accordingly.

In the publication DE 298 16811 U1, a system for the compression/storage of such fuels/gases is described, in which the gas is accommodated in a variable-volume accumulator, which is formed, for example, by a piston or bladder accumulator acting as a compressor, with the piston or the bubble is the gas separated from a driving medium, such as hydraulic fluid. A so-called booster to further increase the pressure of the gas can be provided between the tank of the vehicle and the compressor (also called accumulator). A so-called 3-bank method is also described, in which three accumulators with different pressure levels are connected in cascade during refueling. In this known solution, the gas pressure in the respective reservoir is kept hydraulically constant in each case. US Pat. No. 10,753,539 B2 describes a tank station in which the gas is also accommodated in a variable-volume accumulator, for example a bladder accumulator, with the pressurization also taking place hydraulically. In this known solution, the hydraulic pressure medium is sucked out of a tank and brought to the desired pressure by a pump, the outlet connection of the pump being connected to the space of the accumulator, which is filled with the hydraulic pressure medium. In order to increase the storage capacity of the store, US Pat. No. 10,753,539 B2 proposes connecting three such variable-volume stores in parallel.

The publication WO 2006/034748 A1 describes a device for compressing a gaseous medium, in which the compression of the gas also takes place in a compressor/accumulator, in which the gas to be compressed and an ionic liquid are accommodated, the latter via a hydraulic pump pressurized to compress the gas. In the known solution, the ionic liquid is designed in such a way that it has a very low vapor pressure, so that the ionic liquid is not carried over into the medium to be compressed, in this case the fuel gas, only to a very small extent, so that the both components can be separated from each other with comparatively little effort.

A disadvantage of these solutions is that the respective compressor/accumulator has to be charged before each refueling, so that depending on the design capacity of the installed compressor, a considerable time can elapse before the next refueling process can be started. This is particularly problematic when a vehicle has to be refueled with a comparatively large tank whose capacity is greater than the remaining capacity of the compressor/accumulator.

In contrast, the invention is based on the object of creating a device for compressing a gas, for example hydrogen, which also makes it possible to fill up tanks with a large capacity or several tanks in parallel. Of the The invention is also based on the object of providing a corresponding method for filling a tank.

This object is achieved with regard to the device by the combination of features of patent claim 1 and with regard to the method by the combination of features of the independent patent claim 14 .

Advantageous developments of the invention are the subject matter of the dependent claims.

The device according to the invention is designed in particular for compressing a gas suitable for a drive, for example hydrogen, and has a supply pressure source or is connected to such a pressure source that provides the gas subjected to a supply pressure. The device also has at least two compression stages, each having at least one (linear) compressor, in particular in the form of an accumulator and/or in the form of a booster, for the gas, with the term “accumulator” being understood to mean a compressor/storage device, which is designed to receive the gas and, for filling, for example a tank, to apply a pressure via a hydraulic drive that is above the supply pressure or outlet pressure. Accordingly, the gas within the compressors can be pressurized with the predetermined pressure via a hydraulic fluid. According to the invention, a valve logic (valve circuit) is provided on the gas side, which is designed in such a way that one or more gas connections of the compressors can be connected to a tank, for example a vehicle tank, and/or a gas connection of a compressor of a downstream stage.

The valve logic is also designed in such a way that the pressure source can also be connected directly to the tank to be filled and/or the gas connection of a compressor. The term “valve logic” is to be understood as meaning a suitable valve circuit, preferably with a pressure control valve assigned to a tank, with the assigned control/regulation by means of a control device.

Such a device makes it possible, according to the method according to the invention, to selectively apply the supply pressure to a compressor of a first compression stage on the gas side and to initially fill the tank with gas from the pressure source (at the supply pressure). In a subsequent step, the gas received in the first compressor is then compressed via the hydraulic drive and the tank is subjected to a corresponding pressure from the first compressor. At the same time, a compressor of a following compression stage is prestressed/precharged, so that it is prestressed to the outlet pressure of the first compression stage. The gas is then hydraulically compressed in the compressor of the second compression stage, so that the gas in the tank is compressed to the outlet pressure of the second compression stage. The term “compression” is understood to mean compression/compression of the gas in the tank, with the tank also being refilled during this compression to compensate for the change in volume of the gas caused by the compression.

This procedure can be continued accordingly with further compression stages until the desired target pressure of, for example, about 1000 bar or 480 bar is reached in order to refuel systems with 700 bar or 350 bar tank pressure.

This procedure makes it possible to carry out refueling with minimal energy losses and also with minimal pressure loss via a pressure control valve connected upstream of the respective tank. Furthermore, even with comparatively small volumes of the compressors, the storage volumes and thus the dead volume can be kept to a minimum by mutual pre-filling during refueling. Due to the pressurization of the downstream compression stage during filling of the tank with the outlet pressure lower compression stage, the next refueling process can also be initiated without time-consuming loading/unloading of the compressors.

In the present invention, the compressor is a linear compressor in the form of an accumulator and/or in the form of a booster. Accordingly, embodiments are also conceivable where both accumulators and boosters are used as compressors. In this case, two boosters can be used for one accumulator, in particular, with the (total) compression volume of the compression stage being intended to be unchanged compared to the use of one accumulator.

In the event that the compressor is a booster/intensifier, the booster ratios may differ between compression stages. Preferably, all boosters can be operated with an identical hydraulic pressure/drive pressure (e.g. 350 bar) and the boosters can act as a kind of pressure reducer in lower compression stages, based on a pressure ratio between hydraulic pressure and pressure of the gas to be compressed, and in the upper compression stages as one Type of pressure booster, based on a pressure ratio between the hydraulic pressure and the pressure of the gas to be compressed. In other words, a transmission ratio of the booster between the hydraulic pressure and the pressure of the gas to be compressed can be either greater than 1 or less than 1, depending on the location and/or purpose of use of the booster.

The booster can be either a two-chamber booster or a three-chamber booster. A pressure increase in the pressure ratio between the hydraulic pressure and the pressure of the gas to be compressed can preferably be a two-chamber booster, and a pressure reduction in the pressure ratio between the hydraulic pressure and the pressure of the gas to be compressed can preferably be a three-chamber booster act. An extension movement of the piston/stamp (compression of the gas) is caused by the hydraulic pressure or caused by an increase in hydraulic pressure. A retracting movement of the piston is caused by the pressure of the gas to be compressed. Optionally, the retraction movement of the piston can be supported by hydraulic pressure, which is preferably applied to the circumference of the piston.

By using boosters as compressors, it can be achieved that no or only small amounts of liquid occur in the vicinity of a dynamic rod sealing system (gas seal) or that another liquid can be used to lubricate the rod sealing system of the booster. In this case, the properties of the first (driving) and second (lubricating) liquid can be chosen differently, which makes it possible to choose an inexpensive driving liquid while using a high-quality sealing liquid. Furthermore, for example when using a small hydraulic auxiliary drive system for lubricating the rod seal, hydrogen escaping via the rod seal cannot get into a hydraulic main drive system, but can be drained off separately.

Another advantage of using boosters as compressors is that costs can be reduced for the hydraulic pumps and other hydraulic components for the compression stages that require gas pressures above 350 bar. Hydraulic components rated under 350 bar are considered standard equipment that is widely available.

If three chamber boosters are used for the lower pressure stages, hydraulic pumps with a lower flow or lower flow capacity can be selected for these compression stages, which leads to a cost reduction in the hydraulic pumps that also work with a more efficient working pressure.

Replacing the rod seal system does not require the linear compressors (in this case the boosters) to be placed horizontally (as with the Replacing the piston seals of large accumulators), which reduces space requirements.

Monitoring of the stationary rod sealing system is feasible, while the movable sealing system of accumulators is very difficult or impossible to monitor.

One design of the booster does not require a bolted or riveted removable cover on the high pressure side to access the sealing system, allowing for a more cost effective design.

In an exemplary embodiment of the invention, it is preferred to provide two sets of compressors with different compression stages, with each compression stage having at least two approximately identical compressors. The valve logic is then designed to connect the gas connection of the compressor of a compression stage to the gas connection of a compressor of the following compression stage in order to carry out the pre-filling without loss of time.

Depending on the number of sets, several vehicles can then be refueled essentially at the same time or a large tank can be refueled, with the preloading of compressors in the higher compression stages taking place via compressors in the lower compression stage.

It is particularly advantageous if, in an initial position, a compressor of a first compression stage is preloaded/prefilled with the supply pressure and a compressor of a subsequent compression stage with a gas pressure corresponding to the outlet pressure of the preceding compression stage. During the subsequent operation, this pre-filling is then carried out by the preceding compression stage in parallel with the pressurization of the tank.

In one embodiment of the invention, it is provided that, with the gas-side preload described above, the compressor of the first compression stage is preloaded on the fluid side with low pressure, preferably ambient pressure, and the compressor of the following compression stage is preloaded on the fluid side with a pressure corresponding to the outlet pressure of the preceding compression stage. Such hydraulic logic contains all the necessary valves and units, such as pumps for pressurizing the hydraulic side of the respective compressor. This hydraulic logic is also controlled via the control unit or a separate hydraulic control unit, which of course has a data and signal connection with the gas-side control unit.

The invention is not limited to an embodiment with two compression stages, but almost any number of compression stages can be connected in series to bring the gas to the predetermined pressure, with these compression stages, as explained above, being in operative connection with the tank one after the other be brought, wherein the output pressure of a compression stage is in each case a pre-filling of the following compression stage.

In an alternative solution, all compressors of one or all sets are primed/pre-compressed to their maximum outlet pressure so that the total internal storage capacity of the system is maximized. The filling of the tank can then be controlled via the valve logic, in particular via a pressure control valve, so that the pressure in the tank is controlled according to the control characteristics of this pressure control valve (or the like). It is particularly preferred if each compression stage is designed with at least two compressors, so that a corresponding number of compressor sets is provided to form the compression stages.

As mentioned above, the compressors, in particular in the form of accumulators, can be pressurized on the fluid side via the hydraulic logic and at least one pump and optionally via a booster in order to set the desired pressure on the gas side.

It is particularly preferred if each compression stage of one or more sets is optionally assigned a hydraulic pump or motor-pump unit. Of course, these pumps can also be connected in parallel in order to supply the respective compressors with pressure medium. In one embodiment, the motor-pump unit is designed in such a way that a large number of hydraulic pumps are driven by a common motor. The drive can take place directly via the motor shaft or an interposed gear or the like.

In one embodiment, the gas-side valve logic is designed in such a way that the gas connections of the respective sets of compressors can be connected to a corresponding number of tanks or to a larger tank, so that simultaneous refueling of several vehicles/tanks or a large tank is possible in a short time is.

It is particularly preferred if the compressors of each compression stage have approximately the same structure. It is particularly advantageous if the outlet pressure of each compression stage is approximately twice the respective inlet pressure. When designed as an accumulator, the compressors can be in the form of piston accumulators, bladder accumulators, membrane accumulators or can be operated with an ionic fluid.

In a particularly preferred exemplary embodiment of the invention, the device according to the invention is designed with two or four compression stages. Some or all of the compression stages can be biased/driven via a booster.

In one exemplary embodiment of the invention, provision is made for controlling or regulating the delivery of the gas to the tank via a pressure control valve or the like.

To improve the thermodynamic efficiency, the gas flow can be cooled between the compressors or towards the tank. Alternatively, the compressors per se can be designed with cooling.

To avoid contamination, a separator can also be provided downstream of the last compression stage, via which fluid components in the gas or—particularly in the case of a piston accumulator—parts introduced into the gas side by evaporated lubricants can be separated.

The pumps for driving the hydraulic side of the compressor can preferably be variable displacement pumps or constant pumps with a variable-speed drive or a motor-pump unit, so that different APRR characteristics (average pressure ramp rate profiles) can be set according to the control of the pump(s).

The pumps can be adjustable hydraulic pumps, which can be controlled in their flow rate and from a conventional one Electric motor can be driven. All pump shafts of the pumps can be driven by an electric motor. The electric motors can be controlled by an engine controller, with energy recovery being enabled via the engine controller.

To fill up large tank volumes, storage buffer capacities can also be assigned to the compressors, through which further APRR variants can be set.

In an alternative procedure, the gas side of the compressors can be pre-compressed/pre-charged before connection to the tank, in which case the above-described APRR characteristic is then controlled via a suitable valve arrangement, for example a pressure directional valve, after connection to the tank. This compression of the gas within the compressor can continue if the pressure difference across the pressure control valve falls below a minimum. This situation can be relevant, for example, when the refueling process is stopped or interrupted (e.g. by the user) before the gas is compressed within the compressor. Accordingly, according to this procedure, the compressors are controlled in such a way that their maximum capacity for filling the tank(s) can be utilized at any time.

In a preferred embodiment of the invention, each tank is preceded by a pressure control valve or another valve of a suitable type for pressure control, whereby the controller can be designed in such a way that if the pressure drop across this valve falls below a predetermined level, the compressor from which the tank is supplied is compressed .

The applicant reserves the right to make his own claims to these features. Preferred exemplary embodiments of the invention are explained in more detail below using schematic drawings. Show it:

FIG. 1 shows a hydraulic circuit of a device according to the invention for refueling/filling vehicle tanks;

FIG. 2 shows a detailed illustration of a subsystem of the circuit according to FIG. 1;

FIG. 3 shows a diagram in which the pressure in compressors of the circuit according to FIGS. 1 and 2 is shown over time;

FIG. 4 shows a hydraulic circuit of a device according to the invention for refueling/filling vehicle tanks in an alternative embodiment.

Figure 5 shows a booster according to a first embodiment and

FIG. 6 shows a booster according to a second embodiment.

Figure 1 shows an example of a circuit diagram of a tank station 1, which is designed for filling up tanks 2, 4 of two vehicles and which is designed with a device 6 according to the invention for compressing/compressing hydrogen or another gas.

However, the invention is in no way limited to an application for filling up vehicle tanks, but can also be used, for example, to fill up other tanks, for example tanks arranged on trailers or containers, for example with a capacity of 1200 kg. The inventive system can also be used to smaller tanks, for example with a Capacity of 2 x 40 kg or 1 x 80 kg to be refueled simultaneously or across all sets.

The device 6 is connected to a supply network, referred to below as supply pressure source 8 , hydrogen being provided at a supply pressure pO of, for example, 60 bar via this pressure source 8 . This pressure is of course too low to fill tanks 2, 4 with the required tank pressure, for example 350 bar or 700 bar, so that a compressor/accumulator arrangement 10 is provided accordingly in order to build up the required tank pressure. In the illustrated embodiment, the accumulator arrangement has four compression stages 12, 14, 16, 18, each compression stage having a set (subsystem) with two identical accumulators 20a, 20b; 22a, 22b; 24a, 24b and 26a, 26b.

Via the first set of accumulators (compression stage 12), the gas is compressed from the supply pressure pO to an intermediate pressure p1, which is approximately 120 bar, for example. In the second compression stage 14, this intermediate pressure p1 is compressed to a higher pressure p2, which is approximately 240 bar, for example. Via the two further compression stages 16, 18, the gas is then compressed from the further pressure p2 to a first tank pressure p3 of approximately 480 bar and via the set 18 from this first tank pressure p3 to a high tank pressure p4 of approximately 1000 bar. For example, vehicles that require a tank pressure of approximately 350 bar can then be refueled via the compression stage 16 with the first tank pressure p3, while the compression stage 18 is used to refuel vehicles that require a tank pressure of approximately 700 bar. Of course, other pressure ratios can also be realized by designing the accumulators accordingly. As described in more detail below, the accumulators are each designed as a piston accumulator, with the piston in each case separating a gas chamber that absorbs the hydrogen from a fluid chamber filled with hydraulic fluid, which is connected to the pressure connection of a hydraulic pump or to a Tank can be connected in order to apply pressure to the gas-side pressure chamber or to relieve pressure.

In the illustrated embodiment, four such hydraulic pumps 28, 30, 32, 34 are provided, whose pressure port 36 (only one pressure port is provided with a reference number in Figure 1) via hydraulic logic 38 and via working lines 40a, 40b, 42a, 42b, 44 and 46 can be connected to the respective set. Accordingly, the sets each form compression stages 12, 14, 16, 18, so that in the exemplary embodiment shown, four compression stages are provided in order to compress the gas, starting from the supply pressure p0, to the high pressure p4. In the illustrated embodiment, the gas is compressed from the comparatively low pressure p2 to the comparatively high pressures p3 and p4 with the aid of a booster 48, 50, which is connected to the working lines 44, 46 and their outlet connection 52, 54 via a Booster logic 56 is connected to the compression stages 16, 18. In principle, these boosters 48, 50 can also be dispensed with, so that the compression/increase takes place essentially with the aid of the accumulators 20, 22, 24, 26 and the hydraulic pumps 28, 30, 32, 34. In principle, boosters can also be used for support in the low-pressure range (compression stages 12, 14), so that the hydraulic pumps 28, 30,

32, 34 can be designed with a lower maximum pressure.

These hydraulic pumps 28, 30, 32, 34 can be designed, for example, as variable displacement pumps or as constant pumps with a variable-speed drive.

The valves of the hydraulic logic 38 and the booster logic 56 are activated via one or more control units 58.

A special feature of the concept according to the invention is that in the individual compression stages 12, 14, 16, 18 the outlet pressure (p1, p2, p3) of an accumulator 20, 22, 24 is used to compress the hydrogen in the tank 2, 4 and on the other hand for prestressing/orfilling the accumulator of the following compression stage 14, 16, 18, so that no separate pressure accumulator or at most pressure accumulators with a minimum storage capacity are required for this prestressing.

Depending on the control of the hydraulic side, the pressure source 8 and gas connections 60a, 60b, 62a, 62b, 64a, 64b, 66a, 66b of the accumulators 20, 22,

24, 26 are cascadingly connected to the tanks 2, 4 via a gas-side valve logic 68, so that these are pre-filled with gas and this is successively compressed to the required tank pressure, this compression with the outlet pressure (p1, p2, p3, p4) of the respective Compression stages 12, 14, 16, 18 takes place. As explained above, the pre-filling of the following compression stages 14, 16, 18 takes place via the outlet pressure of the preceding compression stage. The pressure is controlled via a pressure control valve (not shown) connected upstream of the tank 2, 4.

As indicated in FIG. 1, the valve logic 68 with the pressure control valves for the tanks 2, 4 is also controlled via the central control device 58 or via a further control device. According to the invention, this control is carried out in such a way that accumulators 20a, 22a, 24a, 26a are used to fill tank 2, depending on the desired tank pressure, and accumulators 20b, 22b, 24b, 26b are used to fill tank 4, so that the Accumulators marked "a" and "b" each form a subsystem / set. The above-described pre-filling is controlled in such a way that the outlet/gas pressure of the first-mentioned subsystem (“a”) is used to preload/pre-fill the compression stages of the second sub-system (“b”). This means that both tanks 2, 4 can be filled in parallel, but slightly offset in time, with several compression stages being able to be implemented.

FIG. 2 shows in a detailed view that part of the circuit according to FIG. 1 with which the tanks 2, 4 can be filled with gas which has a maximum pressure p2, which is 240 bar, for example. As explained above, form it the accumulators 20a, 22a and 20b, 22b each have a subsystem ("a", "b"), the subsystem "a" being designed for filling the tank 2 and the subsystem "b" for filling the tank 4. Of course, a large tank can also be filled via the two subsystems "a" and "b", in which case both subsystems are then alternately actively connected to the tank.

In the illustrated embodiment, the accumulators 20, 22 are designed as piston accumulators, with the pistons each separating a gas space 70a, 70b, 72a, 72b of the accumulator sets from a fluid space 74a, 74b or 76a, 76b. According to the illustration in FIG. 2, the fluid spaces 74, 76 are pressurized via the hydraulic logic 38, which is connected to the fluid spaces 74, 76 via the working lines 40a, 40b, 42a, 42b. The gas connections 60a, 60b, 62a, 62b can be optionally connected to the tank 2 and/or 4 via the valve logic 68 indicated by dashed lines.

In the illustrated embodiment, the valve logic 68 is essentially formed by check valves (check valve), which allow a flow of pressure medium in one direction and block it in the other direction, and by pilot-controlled check valves, which allow a flow of pressure medium in one direction in the manner of a non-pilot-controlled check valve and which can be opened in the other direction via the pilot control.

Accordingly, the pressure source 8, which provides a supply pressure pO, is connected to two supply lines 78, 80, which lead to the tanks 2 and 4, respectively. The supply line 78 is connected to the gas connection 60a via a gas line 82a and to the gas connection 62a of the accumulator 22a of the second compression stage 14 via a further gas line 84a. Correspondingly, the further supply line 80 is connected to the gas connection 60b of the accumulator 20b via a gas line 82b and to the gas connection 62b of the accumulator 22b of the second compression stage 14 via a further gas line 84b. The two gas lines 82a and 84b are connected to one another via a prestressing line 86a and, correspondingly, the two gas lines 82b and 84a are connected to one another via a prestressing line 86b tied together. Check valves 88a, 88b, 90a, 90b and 92a, 92b are provided before and after the branches of the gas lines 82, 84 from the supply lines 78, 80, which open in the direction of the tank 2, 4. Pilot-controlled check valves 96a, 96b, 98a, 98b are arranged in the gas lines 82a, 82b, 84a, 84b branching off from the supply lines 78, 80, the pilot control not being shown for the sake of simplicity.

A check valve 100a, 100b is also provided in each of the two preload lines 86a, 86b, which opens in the direction of the compression stage with the higher pressure and closes in the opposite direction. In a corresponding manner, a return flow from the tank 2, 4 in the direction of the pressure source 8 is blocked via the check valves 88, 90, 92.

Not shown in FIG. 2 are pressure control valves, via which the APRR characteristic can be additionally influenced and which are arranged on the outlet side upstream of the tanks 2, 4.

Before the start of the refueling process, subsystem “a” is pre-filled with hydrogen, with the supply pressure being present in gas space 70a and the mean pressure, i.e. pressure p1 (e.g. 120 bar), being present in gas space 72a. The subsystem “b” is acted upon via the hydraulic side, the ambient pressure being present in the fluid chamber 74b and a fluid pressure corresponding to the pressure p1 being present in the fluid chamber 76b.

In a first compression stage 12, the tank 2 of the first vehicle is filled with hydrogen via the pressure control valve (not shown), this being supplied at the pressure p0 via the valves 88a, 90a and 92a. In the subsystem "b", the gas chamber 70b is acted upon by the supply pressure pO via the valves 88b and 96b, so that the hydraulic fluid is displaced from the fluid chamber 74b. In a second step, the hydraulic logic 38 and the associated hydraulic pump 28, 30, 32 or 34 pressurize the fluid chamber 74a with pressure medium, so that the hydrogen in the gas chamber 70a is compressed from the pressure p0 to the pressure p1 and via the valves 96a, 90a and 92a to the tank 2, so that the hydrogen in the tank 2 is compressed from the supply pressure pO to the pressure p1. This gradual compression ensures that the pressure drop across the pressure control valve and the associated losses are minimal.

According to the invention, a partial flow of the hydrogen is conducted via the valve 100a to the gas space 72b of the accumulator 22b of the second compression stage 14, so that a pre-filling with the pressure p1 takes place.

At the same time, hydrogen is compressed from pressure p1 to pressure p2 via the hydraulic-side drive of accumulator 22a, and the hydrogen in tank 2 is compressed to pressure p2 via valves 98a and 92a in the third step.

After the refueling process, the tank 2 is then completely filled, with the pressure p2 being present in it.

Parallel to this refueling, the tank 4 of the second vehicle is first filled in a corresponding manner in the first step with the supply pressure pO, this filling taking place via the valves 88b, 90b, 92b and possibly the pressure control valve (not shown). As a result, the compression of the hydrogen in the tank 4 then takes place in accordance with the above statements in stages according to the above-described steps 2 and 3 (stage compression of the hydrogen in the tank, which is first pressurized with the pressure p1 and then with the pressure p2), with the The subsystems “a” and “b” are controlled in the opposite way to the filling of the tank 2 described above. This means that the pressure p1 is applied to the gas space 70b of the accumulator 20b via the hydraulic drive and the hydraulic logic 38 and the hydrogen in the tank 4 is then compressed via the valves 96b, 90b and 92b. A partial stream of Hydrogen is branched off via the preload line 36b and the check valve 100b, so that the accumulator 22a of the subsystem “a” is prefilled with the pressure p1 accordingly. In the third step, as described above, the hydrogen in the gas space 72b of the accumulator 22b is then compressed to the pressure p2 via the hydraulic drive and the hydrogen in the tank 4 is compressed to the pressure p2 via the valves 98b, 92b.

In the case where more than two stages (see Figure 2) are provided, the gradual compression of the hydrogen in the tanks 2 and 4 takes place in a corresponding manner, with the outlet pressure of an accumulator in each case being of a lower compression stage of a subsystem for priming an accumulator a higher compression level of the further subsystem is used.

The check valves described above can also be replaced by conventional direct or pilot-operated directional control valves or other valves. As explained above, before the pressure medium connection to the tank 2, 4 of the respective vehicles is established, accumulators can be preloaded with the aid of a pressure control valve, via which the filling process is controlled.

As mentioned at the outset, the hydraulic logic 38, the valve logic 68 and the booster logic 56 are activated via the control unit 58, for example as a function of a predetermined APRR characteristic that is stored in the control unit or is specified by the vehicle when it is connected. The function of the pilot-controlled valves 96, 98 and the boosters 48, 50 or the flydraulic pumps 28, 30, 32, 34 is then controlled in a suitable manner via this control unit 58.

In the case in which the accumulators are driven via the boosters 48, 50, the pressure medium flowing back from the boosters 48, 50 can also be fed directly to a fluid tank or used in another area of the hydraulic system. The same applies to the pressurized pressure medium during of the refueling process is displaced by the hydrogen during compression stages 2, 3 and the following from the respective accumulator.

In the diagram according to FIG. 3, the pressure curve in the above-described compressors, here by way of example in the form of accumulators (see FIG. 1), is shown over time. The two diagonals 104, 106 represent the APRR characteristics, which are generated in the manner described above by appropriate activation of the hydraulic logic 38, the booster logic 56 and the valve logic 68 as well as the flydro pumps 28, 30, 32, 34 and the pressure control valves (or the like) is adjustable.

In FIG. 3, the pressure curves are shown for clarification such that the pressure difference between the tank 2, 4 and the respectively connected accumulator is zero. As can be seen from the individual pressure curves, the accumulators 20a, 20b, 22a, 22b, 24a, 24b of the first three compression stages 12, 14, 16 each have a compression which is characterized by a pressure rise above the current level. These three compression stages also have an active fill phase where the outlet pressure is constant to prime the accumulator of the next compression stage of the second subsystem. Furthermore, each accumulator of the three compression stages 12, 14, 16 has a passive filling phase, which is carried out at a constant inlet pressure. The accumulators of the last compression stage, in the present case the fourth compression stage 18, have no active filling phase since no accumulator of a higher compression stage is connected downstream. As mentioned at the outset, the compression ratios between the individual compression stages are selected in such a way that the compression ratio is 1:2, so that the pressure at the outlet of a compression stage is twice as high as the outlet pressure of the previous compression stage. This compression ratio enables efficient cooling of the hydrogen between the compression stages, since the heat of compression released within the individual compression stages is then approximately the same and also for the Compression in each compression stage approximately the same compression work and thus power is required.

As mentioned above, the hydraulic logic 38, the booster logic 56 and the valve logic 68 as well as the control unit 58 are designed in such a way that the tanks 2, 4 of several vehicles are supplied via the supply system (pressure source 8) and via each accumulator of the compression stages 12, 14, 16, 18 can be charged. According to the pressure curves in Figure 3, the supply pressure, i.e. the pressure of the pressure source 8, is approximately 60 bar, with a maximum pressure of approximately 1000 bar being reached in order to fill vehicles with a 700 bar system. For clarification, it should be pointed out that the pressure curves in FIG. 3 are shown in a greatly simplified manner. In reality, there may be a significant drop in pressure between the compressor and the tank during the refueling process. This is particularly the case when the tank is not completely empty or is subjected to a relatively high internal pressure, so that the pressure from the pressure source 8 is not sufficient to fill the tank 2, 4. In vehicles with a 350 bar system, the fourth compression stage 18 is not required, so that the tanks 2, 4 are filled via the compression stages 12, 14 and 16, the latter delivering the hydrogen or the gas at a pressure of over 480 applied bar, so that filling the tanks 2, 4 is made possible by 350-bar vehicles.

FIG. 4 shows the filling station 1 in an alternative embodiment. A renewed description of assemblies and elements already described in FIG. 1 will be dispensed with at this point and differences from the tank station 1 of FIG. 1 will be explicitly discussed. The tank station 1 shown in FIG. 4 is designed with the compressor arrangement 10 . The embodiment shown includes four compression stages 12, 14, 16, 18, each compression stage containing a set (subsystem) with two identical booster assemblies 108a, 108b, 110a, 110b, 112a, 112b, 114a, 114b. A booster module contains at least one booster (see FIG. 5 or FIG. 6). A booster module preferably contains two boosters of the same construction, which are connected in parallel. The booster assemblies can be made up of several hydraulic pumps from a pump group 28, 30, 32, 34 are driven. Alternatively, each booster assembly can be driven by an individual hydraulic pump, or each booster can be driven by a hydraulic pump/pump group. Another alternative is to operate all booster assemblies with a hydraulic pump.

FIG. 5 shows the booster 116 in a first embodiment. The booster 116 is a three-chamber booster 116 . In other words, the booster 116 of the first embodiment is a three-chamber hydraulic cylinder. The booster 116 contains a (hydraulic) fluid chamber 118, which is connected to the working line 40a, 40b, 42a, 42b, 44a, 44b, 46a, 46b and is provided and configured via the working line 40a, 40b, 42a, 42b, 44a , 44b, 46a, 46b to be fed with the hydraulic fluid and pressurized. As shown in FIG. 4, the application of pressure is controlled via the hydraulic logic 38 . The fluid space 118 is delimited by a hollow shaft 120 and a hollow-cylindrical plunger 122 . The plunger 122 is guided on a lateral surface of the shank 120 and can move linearly relative to the shank 120 . Fluid space 118 is separated from a gas space 126 by a plunger base 124 . By pressurizing the fluid space 118 , the plunger 122 moves and compresses the gas contained in the gas space 126 . In the embodiment shown here, the pressure of the gas in the gas chamber 126 is lower than the pressure in the fluid chamber 118. A further chamber 128 is formed adjacent to a lateral surface of the plunger 122 and can be filled with cooling liquid for cooling the booster 116 or alternatively with the Hydraulic fluid can be filled to support retraction of the ram.

FIG. 6 shows the booster 130 in a second embodiment. The booster 130 in FIG. 6 is a two-chamber booster. The booster 130 includes a (hydraulic) fluid chamber 118, which is connected to the working line 40a, 40b, 42a, 42b, 44a, 44b, 46a, 46b and is provided and configured via the working line 40a, 40b, 42a, 42b, 44a , 44b, 46a, 46b to be fed with the hydraulic fluid and pressurized. As shown in FIG. 4, the application of pressure is controlled via the hydraulic logic 38 . Unlike that three chamber booster 116 in FIG. Due to the pressurization of the fluid space 118 , the plunger 132 moves and compresses the gas contained in the gas space 126 . In the embodiment shown here, the pressure of the gas in the gas chamber 126 is higher than the pressure in the fluid chamber 118. A further chamber 128 is formed adjacent to a lateral surface of the plunger 122 and can be filled with cooling liquid for cooling the booster 130 or alternatively with the Hydraulic fluid can be filled to support retraction of the ram.

Disclosed are a device for compressing a gas that is particularly suitable for a drive and a method for filling a tank with such a device, with the filling taking place over several compression stages, with the filling over a compression stage also pre-filling an accumulator of the following compression stage taking place.

Reference list:

1 gas station

2 tanks

4 tanks

6 device

9 pressure source

10 compressor arrangement

12 compression stage 14 compression stage 16 compression stage 18 compression stage 20 accumulator

22 accumulator

24 accumulator

26 accumulator

28 hydraulic pump

30 hydro pump

32 hydraulic pump

34 hydraulic pump

36 Pressure connection 38 Hydraulic logic 40 Working line 42 Working line 44 Working line 46 Working line 48 Booster

50 boosters

52 output terminal 54 output terminal 56 booster logic

58 control unit

60 gas connection 62 gas connection gas connection

gas connection

valve logic

gas space

fluid space

supply line

Gas line further gas line

priming line

check valve

Check valve pilot operated check valve pilot operated check valve

check valve

diagonal

booster assembly

booster

fluid space

shaft

Rubber stamp

stamp bottom

gas space

chamber 130 boosters 132 stamps

Claims

patent claims

1 . Device for compressing a gas that is preferably suitable for a drive, for example hydrogen, with a supply pressure source (8), which provides the gas to which a supply pressure has been applied, and with at least two compressors (20, 22, 24, 26), each at least one, for compression stages (12, 14, 16, 18) having the gas, wherein the gas can be hydraulically pressurized to fill a tank (2,4) via a hydraulic fluid within each compressor (20, 22, 24, 26), characterized by a Gas-side valve logic (68), which is designed to optionally connect one or more gas connections (60, 62) of the compressors (20, 22, 24, 26) to the tank (2, 4) and/or to the compressor (20, 22 , 24, 26) of a downstream compression stage (12, 14, 16, 18) or the pressure source (8) with the tank (2, 4) and/or the gas connection (60, 62).

2. Device according to claim 1, wherein at least two sets of compressors (20a, 20b; 22a, 22b; 24a, 24b; 26a, 26b) are provided to form compression stages (12, 14, 16, 18), the valve logic ( 68) is designed to connect the gas connection (60a, 60b, 62a, 62b, 64a, 64b) of the compressors (20, 22, 24, 26) of a first set to the gas connection (62a, 62b, 64a, 64b, 66a, 66b) the following compression stage (12, 14, 16, 18) of the first or further set.

3. Device according to patent claim 1 or 2, wherein in an initial state a compressor (20) of a compression stage (12) with the supply pressure (pO) and a compressor (20, 22, 24, 26) of the following compression stages (12, 14, 16, 18) is preloaded with a gas pressure corresponding to the outlet pressure of the preceding compression stage (12, 14, 16, 18).

4. Device according to claim 2, wherein one or both sets are pre-filled according to claim 3 and the compressor (20b) of the first Compression stage of the second set via a hydraulic logic (38) on the fluid side with low pressure (pO), preferably ambient pressure and an outlet pressure and the compressor (22a, 24a, 26a) of the following compression stage (12, 14, 16, 18) with an outlet pressure (p1, p2, p3) of the preceding compression stage (12, 14, 16, 18) corresponding pressure.

5. Apparatus according to claim 1 or 2, wherein the compressors (20, 22, 24, 26) of each set are pressurized/primed to their predetermined outlet pressure.

6. Device according to one of claims 2 to 5, with further compression stages (12, 14, 16, 18), in each of which two or more compressors (20a, 20b, 22a, 22b, 24a, 24b, 26a, 26b) are arranged .

7. Device according to one of the preceding claims, wherein the compressor (20, 22, 24, 26) on the fluid side via a hydraulic logic (38) and at least one hydraulic pump (28, 30, 32, 34) or a motor-pump unit and optionally via a Booster (48, 50) are pressurized.

8. Device according to one of claims 2 to 7, wherein each compression stage of one or more sets is assigned a hydraulic pump or motor pump unit (28, 30, 32, 34).

9. Device according to one of claims 2 to 8, wherein the gas-side valve logic (68) is designed, gas connections (62, 64, 66) of the sets, in particular gas connections of the last compression stage (14, 16, 18) with a corresponding number of tanks (2, 4) or to connect to a tank.

10. Device according to one of the preceding claims, wherein the outlet pressure of each compression stage (12, 14, 16, 18) is approximately twice the respective inlet pressure.

11. Device according to one of the preceding claims, wherein the compressors (20, 22, 24, 26) are designed as piston accumulators, bladder accumulators, diaphragm accumulators or are operated with an ionic fluid.

12. Device according to one of the preceding claims, wherein two or four compression stages (12, 14, 16, 18) are provided.

13. Device according to one of the preceding patent claims, wherein the valve logic (68) has a pressure control valve or the like connected upstream of the tank (2, 4).

14. Method for filling a tank (2, 4) with a device according to one of the preceding claims, with the steps: a) gas-side pre-filling of a compressor (20) of a first compression stage (12) or of all compressors (20, 22, 24, 26) with a supply pressure; b) filling the tank (2, 4) with the gas subjected to the supply pressure (pO); c) Compressing the gas in a compression stage (12, 14, 16, 18) and preferably simultaneously compressing the gas in the tank (2, 4) with the gas from the compression stage (12, 14, 16, 18) and preloading/priming a compressor (20, 22, 24, 26) of a following compression stage (12, 14, 16, 18) to the outlet pressure of the preceding compression stage (12, 14, 16, 18) and d) compression of the gas by means of the following compression stage (12, 14, 16, 18) and compression of the gas in the tank (2, 4) with the gas compressed to the outlet pressure of this compression stage (12, 14, 16, 18).

Repeating steps c), d) until a predetermined tank pressure is reached.

15. The method according to claim 13, wherein at least two sets of compressors (20a, 20b, 22a, 22b, 24a, 24b, 26a, 26b) are provided to form compression stages (12, 14, 16, 18), wherein during the compression of the gas in the tank (2, 4) with the gas from the first compression stage (12, 14, 16) of a set, a pre-filling of the compressor (20, 22, 24, 26) of a following compression stage (14, 16, 18) of same or second sets.

16. The method according to claim 15, wherein one or at least two tanks (2, 4) are supplied with gas during temporally overlapping periods via the sets.

17. The method according to any one of claims 14 to 16, wherein the compression of the gas via further compression stages (12, 14, 16, 18) each with at least one compressor (22a, 22b, 24a, 24b, 26a, 26b), wherein the Compression stages (12, 14, 16, 18) are successively brought into operative connection with the tank (2, 4) to be filled.

18. The method according to any one of claims 13 to 17, wherein the gas-side compression of the compressor (20, 22, 24, 26) can also take place without a connection to the tank (2, 4).