1. A fuel cell system comprising:
a fuel cell operated to generate power by reaction of a fuel gas supplied to a fuel gas flow field and an oxygen-containing gas supplied to an oxygen-containing gas flow field;
scavenging means for scavenging in at least one of said fuel gas flow field where the fuel gas flows and said oxygen-containing gas flow field where the oxygen-containing gas flows, using a scavenging gas when power generation by said fuel cell is stopped; and
water amount detection means for detecting an amount of water produced in said fuel gas flow field as a result of power generation of said fuel cell when operation of said fuel cell is stopped, wherein
when the amount of water in said fuel gas flow field is at or below a predetermined value, said scavenging means performs:
a first scavenging process for scavenging in said oxygen-containing gas flow field using the scavenging gas at a large flow rate in order to remove liquid droplets in said oxygen-containing gas flow field;
a second scavenging process for scavenging in said fuel gas flow field using the scavenging gas at a large flow rate in order to remove liquid droplets in said fuel gas flow field; and
a third scavenging process for scavenging in said oxygen-containing gas flow field after the first scavenging process using a scavenging gas at a small flow rate, which is smaller than the large flow rate.
2. A fuel cell system according to claim 1, wherein said water amount detection means detects the water amount based on a moisture state at the time of starting operation of said fuel cell, as well as a moisture state at the time of stopping operation of said fuel cell.
3. A scavenging method for a fuel cell system, comprising a fuel cell operated to generate power by reaction of a fuel gas supplied to a fuel gas flow field and an oxygen-containing gas supplied to an oxygen-containing gas flow field, wherein when power generation is stopped, scavenging is performed using a scavenging gas, so as to conduct scavenging in at least one of said fuel gas flow field where the fuel gas flows and said oxygen-containing gas flow field where the oxygen-containing gas flows, the method comprising the step of:
detecting an amount of water produced in said fuel gas flow field by power generation of said fuel cell, at a time when operation of said fuel cell is stopped,
wherein, when the amount of water in said fuel gas flow field is at or below a predetermined value, the method further comprises the steps of:
performing a first scavenging process for scavenging in said oxygen-containing gas flow field using the scavenging gas at a large flow rate in order to remove liquid droplets in said oxygen-containing gas flow field;
performing a second scavenging process for scavenging in said fuel gas flow field using the scavenging gas at the large flow rate in order to remove liquid droplets in said fuel gas flow field; and
performing a third scavenging process after the first scavenging process has been performed, for scavenging in said oxygen-containing gas flow field using the scavenging gas at a small flow rate, which is smaller than the large flow rate.
4. A scavenging method according to claim 3, wherein in the water amount detection step, the water amount is detected based on a moisture state at the time of starting operation of said fuel cell, as well as a moisture state at the time of stopping operation of said fuel cell.
5. A fuel cell system comprising:
a fuel cell operated to generate power by reaction of a fuel gas supplied to a fuel gas flow field and an oxygen-containing gas supplied to an oxygen-containing gas flow field; and
scavenging means for scavenging in at least one of said fuel gas flow field where the fuel gas flows and said oxygen-containing gas flow field where the oxygen-containing gas flows, using a scavenging gas when power generation by said fuel cell is stopped, wherein said scavenging means performs:
a first scavenging process for scavenging in said oxygen-containing gas flow field using the scavenging gas at a large flow rate in order to remove liquid droplets in said oxygen-containing gas flow field;
a second scavenging process for scavenging in said fuel gas flow field using the scavenging gas at the large flow rate in order to remove liquid droplets in said fuel gas flow field; and
a third scavenging process for scavenging in said oxygen-containing gas flow field using the scavenging gas at a small flow rate, which is smaller than the large flow rate, and wherein
the second and third scavenging processes are performed after the first scavenging process in order of the second scavenging process followed by the third scavenging process, or in order of the third scavenging process followed by the second scavenging process; and
the fuel gas in said fuel gas flow field is diluted and discharged at the same time in the first scavenging process or in the second scavenging process.
6. A fuel cell system according to claim 5, wherein the third scavenging process is performed after the first scavenging process, and after a predetermined condition has been satisfied.
7. A fuel cell system according to claim 5, further comprising a system temperature detection means for detecting a temperature of said fuel cell system during a soaking period after stopping power generation, wherein
said scavenging means performs the third scavenging process when the system temperature decreases to a preset temperature during the soaking period.
8. A fuel cell system according to claim 5, further comprising:
system temperature detection means for detecting a temperature of said fuel cell system at the time of stopping power generation; and
time counting means having a preset wait time from the time of stopping power generation until the time for performing the third scavenging process, wherein
the wait time is set at the time of stopping power generation, based on a relationship between the soaking period from the time of stopping power generation and the system temperature during the soaking period.
9. A fuel cell system according to claim 7, wherein the preset temperature is set at or above a minimum temperature, the minimum temperature being determined based on the relationship between the soaking period from the time of stopping power generation and the system temperature during the soaking period, so as to achieve a predetermined start up performance when a restarting operation is conducted at low temperature.
10. A fuel cell system according to claim 8, wherein the wait time is within a maximum period, which is determined based on the relationship between the soaking period from the time of stopping power generation and the system temperature during the soaking period, so as to achieve a predetermined start up performance when the restarting operation is conducted at low temperature.
11. A scavenging method for a fuel cell system, comprising a fuel cell operated to generate power by reaction of a fuel gas supplied to a fuel gas flow field and an oxygen-containing gas supplied to an oxygen-containing gas flow field, wherein when power generation is stopped, scavenging is performed using a scavenging gas, so as to conduct scavenging in at least one of said fuel gas flow field where the fuel gas flows and said oxygen-containing gas flow field where the oxygen-containing gas flows, the method comprising the steps of:
performing a first scavenging process in said oxygen-containing gas flow field for scavenging using the scavenging gas at a large flow rate in order to remove liquid droplets in said oxygen-containing gas flow field;
performing a second scavenging process in said fuel gas flow field for scavenging using the scavenging gas at the large flow rate in order to remove liquid droplets in said fuel gas flow field; and
performing a third scavenging process for scavenging in said oxygen-containing gas flow field using the scavenging gas at a small flow rate, which is smaller than the large flow rate, and wherein
the second and third scavenging processes are performed after the first scavenging process in no particular order; and
the fuel gas in said fuel gas flow field is diluted and discharged at the same time in the first scavenging process or in the second scavenging process.
12. A scavenging method according to claim 11, wherein the third scavenging process is performed after the first scavenging process, and after a predetermined condition has been satisfied.
13. A scavenging method according to claim 11, wherein said third scavenging process is performed when a system temperature of said fuel cell system decreases to a preset temperature during a soaking period after stopping power generation.
14. A scavenging method according to claim 11, further comprising the step of setting a wait time from the time of stopping power generation until the time for performing the third scavenging process,
wherein the wait time is set at the time of stopping power generation, based on a relationship between the soaking period from the time of stopping power generation and the system temperature during the soaking period.
15. A scavenging method according to claim 13, wherein the preset temperature is set at or above a minimum temperature, the minimum temperature being determined based on the relationship between the soaking period from the time of stopping power generation and the system temperature during the soaking period, so as to achieve a predetermined start up performance when a restarting operation is conducted at low temperature.
16. A scavenging method according to claim 14, wherein the wait time is within a maximum period which is determined based on the relationship between the soaking period from the time of stopping power generation and the system temperature during the soaking period, so as to achieve a predetermined start up performance when the restarting operation is conducted at low temperature.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A drug delivery device for dispensing of a dose of a medicinal product, comprising:
a holder for a product-containing cartridge, the cartridge having a piston slidably arranged therein in an axial direction, and
a piston rod to be operably engaged with the cartridge’s piston for dispensing of a dose of the medicinal product,
characterized in that
at least one spacer selected according to a relative distance between piston and piston rod is disposed between the piston rod and the piston for eliminating axial clearance between piston and piston rod.
2. The drug delivery device according to claim 1, wherein the at least one spacer is selected from a set of spacers having different axial dimensions and wherein the at least one spacer is selected according to an actually measured andor determined andor estimated gap size between piston rod and piston in the device’s final assembly configuration.
3. The drug delivery device according to claim, wherein in a pre-assembly configuration, the at least one spacer is disposed at a distal end face of the piston rod andor at a proximal end face of the piston of the cartridge.
4. The drug delivery device according to claim 3, wherein the at least one spacer is adhesively attached to the piston rod andor to the piston of the cartridge.
5. The drug delivery device, wherein the axial dimension of the at least one spacer is smaller than or equal to 1 mm, 0.8 mm, 0.6 mm, 0.4 mm or 0.2 mm.
6. A method of assembly of a drug delivery device being adapted for dispensing of a dose of a medicinal product, comprising the steps of:
determining an axial position of a proximal end face of a piston of a cartridge pre-assembled in a cartridge holder,
determining an axial position of a distal end face of a piston rod of a drive mechanism pre-assembled in a housing,
determining or estimating the size of axial clearance between the piston and the piston rod if cartridge holder and housing were assembled,
selecting at least one spacer from a set of differently sized spacers with respect to the determined size of axial clearance and arranging the selected spacer between the piston and the piston rod.
7. The method according to claim 6, wherein the spacer is attached to the distal end face of the piston rod andor to the proximal end face of the piston.
8. The method according to claim 6, wherein the axial position of the distal end face of the piston rod is determined with respect to a selected reference point of the housing andor wherein the axial position of the proximal end face of the piston is determined with respect to a selected reference point of the cartridge holder.
9. The method according to claim 8, wherein selected reference points of housing andor cartridge holder substantially coincide with the axial position of fastening means adapted to mutually interconnect housing and cartridge holder.
10. The method according to claim 6, wherein the axial position of the piston andor of the piston rod is determined by means of a tactile probe or by means of an optical sensor arrangement.
11. The method according to claim 6, wherein the cartridge is disposed in the cartridge holder to form a cartridge holder sub-assembly and wherein a drive mechanism with its piston rod is disposed in the housing to form a housing sub-assembly before axial positions of piston andor piston rod are determined.
12. The method according to claim 6, wherein the cartridge holder and the housing are undetachably interconnected by means of welding or bonding or by means of friction- or positive locking fastening means.
13. The method according to claim 10, wherein a cartridge holder sub-assembly andor a housing sub-assembly are selected from a set of respective sub-assemblies for minimizing axial clearance between piston and piston rod.