Portable device and method for regulating the temperature of a substance
The present invention is related to a portable device and a method for regulating the temperature of a temperature sensitive substance according to the independent patent claims .
There are many substances known which need to be kept at a constant temperature during their entire lifetime. Especially during transport of these substances it is difficult to have the temperature kept within the right range. Therefore it is most important to have portable devices wherein such substances can be carried without leaving the predefined temperature range.
Most common examples for such substances are medicaments, in particular liquid medicaments such as insulin. If the medicament is not kept at the right temperature, it might separate into its components or solidify. As a patient often needs to carry the medicament with him or her, it is of great interest to have a portable device where the medicaments are kept within a clearly defined temperature range.
Such devices have been shown in the state of the art. Examples are given in US 6,260,360, DE 35 03 281, DE 198 38 834 or US 5,029,446. All these devices have some drawbacks. Most of them are rather bulky or energy consuming and thus not adapted to be carried around a whole day long. Further, there occurs a rather strong temperature gradient within the devices . The substances thus might be tempered correctly only in a restricted region of the device.
It is thus an object of the present invention to overcome the drawbacks of the prior art, in particular to provide a portable
device and method for regulating the temperature of temperature sensitive substances which can be carried around easily, and which allows for a reliable control of the temperature of the substance .
These and other objects are solved by a portable device and a method according to the independent patent claims .
The portable device is intended for regulating the temperature of preferably temperature sensitive substances . These substances are provided within receptacles, typically vials and pens, having a predefined size and shape, thus having a predefined length. It is also conceivable to use the device and method for substances which are not temperature sensitive but are preferred to be cooled or heated for other reasons, e.g. beverages which are kept at their optimal consuming temperature.
The term regulating is not necessarily used in the sense of a feed-back control but shall only indicate that the temperature of the substance is set to a predefined value. Of course, a feed-back control can be used in preferred embodiments of the invention, however the invention is not restricted thereto.
The device comprises a main case and a receptacle holding arrangement for receiving at least one receptacle. The receptacle holding arrangement can be arranged within the main case directly or can be provided with an additional casing. It is adapted in size and shape to receive the receptacles with the substance. One or more receptacles may be received. The holding device can be arranged to hold the receptacles firmly, e.g. with clamps. Alternatively, the holding device can only predefine the place or space where to put the receptacle, e.g. being formed as deepening where the receptacle is to be placed.
The device further comprises a temperature regulating arrangement which is connected to a temperature regulating plate. This temperature regulating plate is arranged and formed in such a way that it extends substantially along the entire length of the holding arrangement, such that the substance is tempered substantially uniformly over its entire dimensions . The length of the holding arrangement is given by the shape, number and length of the receptacles to be held. The shape and length of the temperature regulating plate is preferably chosen in such a way, that all receptacles can be brought into contact with the plate over their entire length. Substantially along the entire length means in this context, that the temperature regulating plate extends at least along 75% of the length of the receptacle holding arrangement .
With such an arrangement, the temperature sensitive substance is tempered substantially along its entire dimensions . Temperature gradients within the substance are mostly avoided. Further, the energy consumption of the device reduced, as the temperature is applied exactly where it is used. The size of the device can be reduced as well, because the temperature regulating plate can be arranged in a space-saving manner around the receptacle holding arrangement .
In a preferred embodiment the device further comprises a temperature sensor and a temperature control circuit. With the temperature sensor the temperature is watched while the device is used. If the temperature sensor measures a value out of a predetermined temperature range, the temperature regulating device is activated accordingly by the temperature control circuit. The temperature regulating device may cool or heat the temperature regulating plate. It is also possible, that the temperature
regulating device is switched off until a threshold temperature value is reached. This can be useful, if the temperature range is significantly below room temperature and the temperature sensor measures a value even below the temperature range.
The temperature sensor is preferably placed inside the main case. Most preferably it is placed near the receptacle holding arrangement, as there the temperature of the substance is influenced the most.
In a particularly preferred embodiment, the receptacle holding arrangement is housed within a drawer. To reach the receptacles, simply the drawer has to be opened. This allows a good access to the receptacles .
In this embodiment, the temperature regulating arrangement is preferably comprised in the drawer. Like this it is easy to pose the temperature regulating plate inside the drawer, along the receptacle holding arrangement. Most preferably the temperature regulating arrangement is arranged in the front panel of the drawer. There it can be arranged in a space-saving manner. Further, if air circulation around the temperature regulating arrangement is desired, the front panel can be provided with venting slots and, if necessary, with a fan.
To increase the usability of the device, a user interface can arranged at the front panel of the drawer. This user interface may comprise e.g. an on/off switch for the temperature regulating device, an LED for indicating whether the temperature range is kept or an indication whether the batteries have enough charge. Such an embodiment is particularly preferable as it can be designed small and user-friendly, and thanks to the tempera-
ture regulating plate the cooling or heating takes place exactly where it is needed.
Instead of conventional batteries, rechargeable batteries may be used for powering the temperature regulating device. Thus, the amount of waste material can be reduced.
Preferably, the portable device has further a connecting plug which is connectable to an external power supply. This external power supply is most preferably the mains power supply, but can also be a car battery or the like.
To further reduce the energy consumption of the device, the main case may be provided with at least one thermally insulating wall. Preferably, all the walls of the main casing are thermally insulating. A preferred embodiment of a thermally insulating main case is where the main case is formed as vacuum flask.
In a preferred embodiment, the receptacle holding arrangement is . formed as molded plastic insert. Such an insert is easy to manufacture at a low cost. The plastic insert can be formed in such a way, that the receptacles are held in a tight way. Most simply, the holding arrangement is comprising clamps holding the receptacles .
Preferably, the temperature regulating arrangement contains a Peltier device. With a Peltier device, the temperature regulating arrangement can be designed very small but still efficient. With an appropriate control circuit, the temperature regulating plate can be cooled and heated with the same Peltier device by turning around the sign of the voltage.
For many applications it is useful for the temperature regulating arrangement to be a cooling arrangement and the temperature regulating plate a cold plate. Most often, temperature sensitive substances have to be kept at a temperature below the room temperature. In this case, only cooling but no heating is desired.
The method for regulating the temperature of temperature sensitive substances, which are provided within receptacles having a predefined length, is comprising the following steps : - providing a device having a receptacle holding arrangement for receiving at least one receptacle - providing a temperature regulating arrangement connected to a temperature regulating plate, and - regulating the temperature of the substance by bringing the temperature regulating plate in contact with the at least one receptacle in such a way that the plate extends substantially along the entire length of said receptacle, thereby regulating the temperature of the substance substantially uniformly over its entire dimensions.
With this method, the substance is tempered efficiently, thus the energy consumption is reduced. Further, as the substance is tempered uniformly over its entire dimensions, no undesired temperature gradients occur.
Preferably, the temperature regulating arrangement is powered by a rechargeable battery. Further it is preferred, that the rechargeable battery is recharged by an external power supply. The external power supply is most preferably the mains power supply, but other power sources as car batteries can be useful as well.
It is most preferably to regulate the temperature at the same time as the battery is recharged. The receptacles can therewith
be left inside the device during the recharging. The cold chain is not interrupted. In a preferred embodiment, the temperature regulating arrangement is powered by the external power supply as long as the battery is recharged.
Preferably, the temperature regulating arrangement is controlled by a control circuit. In this way, the temperature is held in a predefined temperature range, such that the substance is never kept at an undesired temperature.
In a further preferred embodiment, the temperature regulating arrangement is automatically switched off as soon as the device is opened. Thereby a high energy consumption is avoided if the device is left open unintentionally. A LED might indicate whether the temperature regulating arrangement is switched on or off.
In the following, preferred embodiments of the invention are illustrated with the help of accompanying drawings, which show:
Fig. 1: a perspective view of a first preferred embodiment of the invention, Fig. 2a-c: the drawer according to the embodiment shown in Fig. 1 in detail, Fig. 3: the front panel of the drawer of Fig. 2 in detail, Fig. 4a,b: the battery casing of the device according to Fig. 1, Fig. 5: an alternative embodiment of the invention, and Fig. 6: a top view of the inner space of the embodiment according to Fig. 5.
The portable device 1 is shown in a perspective view in Fig. 1. The device 1 comprises a main case 2 and a drawer 3 (shown in Fig. 2a) . A battery casing 11 is comprised in the main case. The
front panel 4 of the drawer 3 comprises an user interface consisting of button 5, switch 6 LEDs 8 and 10 and connector plug 9.
The main case 2 is formed as a vacuum flask made of 0.5 mm stainless steel with a 5 mm vacuum gap. This design allows for an optimal thermal insulation of the interior space of the main case 2. For decorative reasons, the vacuum flask is entirely covered by a plastic layer.
By activating button 5 the drawer 3 is released such that it can be opened. Switch 6 is the on/off-switch for the DC power of the batteries . LED 8 is a temperature indicator which changes the color in dependence of the temperature inside the main case 2. As long as the LED 8 is green, the temperature inside the main case is in the allowed range. If the allowed temperature range is left, LED 8 changes its color to red. LED 10 flashes when the battery charge is too low.
The connector plug 9 is designed to receive a connector wire (not shown) with a transformer, such that the device 1 can directly be powered with DC-voltage from the mains power supply, and the batteries can be recharged simultaneously.
Further, there are venting slots 7 to allow the air to circulate inside the front panel 4. As can be seen in Fig. 3 and is described below, the front panel 4 houses a temperature regulating arrangement with a radiating element which needs to be cooled.
As can be seen in Fig. 2a, 2b and 2c, inside the drawer 3 there can be placed several receptacles for the substance. In this embodiment, the drawer is designed to accept two insulin pens 12 and two vials 13 containing the reserve insulin. The pens 12 and
the vials 13 are held in a molded plastic insert 14. This plastic insert 14 is shaped in such a way, that the pen 12 and the vials 13 can be snapped therein and are held tightly. The space within the drawer is about 170mm x 45mm x 20mm.
In Fig. 2b and 2c the drawer 3 is schematically shown cut along its long axis. The cold plate 15 is situated below the molded plastic insert 14 an extends along its entire length, such that the pen 12 and the vials 13 are cooled efficiently.
Insulin has to be kept at a temperature below room temperature, preferably within a temperature range between 6°C and 15°C. Thus, the device 1 is in this embodiment designed for cooling. The maximum temperature of 15°C can be reached if the device is used at an environmental temperature of below 50 °C.
Along the plastic insert 14 a cold plate 15 is extending at the bottom of the drawer 3. Cold plate 15 is arranged in such a way that it is proximate to the pens 12 and to the vials 13 simultaneously. Like this, the insulin in the pens 12 and the reserve insulin in the vials 13 is kept cool substantially uniformly. Cold plate 15 is extending substantially along the whole length of the drawer.
The temperature regulating arrangement is a Peltier device 70 which is sandwiched between a hot plate 17 and the cold plate 15. For better heat insulation the Peltier device 70 and the parts of the hot plate 17 and the cold 15 which are contacting the Peltier device 70 are molded within a Polystyrene insulation. Thus, unnecessary increases in temperature are prevented.
The temperature is measured by temperature sensor 73. The temperature sensor 73 is located in a small hole in the cold plate
15 and measures the current temperature of the cold plate 15. As this, the fastest possible reaction time is given. The air temperature in the drawer 3 is extrapolated from the temperature of the cold plate 15. Of course, it would be possible to locate the temperature sensor 73 in such a way that the air temperature would be measured directly. As well, more than one temperature sensor 73 could be used.
The interior of the front panel is shown in more detail in Fig. 3. Additionally to the externally visible LEDs 8 and 10, release button 5, power switch 6 and connector plug 10 there are a fan 16, the hot plate 17 and two air gaps 18 separated from the hot plate 17 by printed circuit boards (PCBs) 19.
The fan 16 is arranged to dissipate the heat from the hot plate 17 via venting slots 7. This is important to efficiently cool the interior of the drawer, as the Peltier device cools the cold plate 15 with the same efficiency as the hot plate 17 can be heated. The cold plate 15 which is extending into the drawer.3 is attached to the cold side of the Peltier device and thereby cooled.
The PCBs 19 separate the further functional components 6, 8, 9 and 10 from the hot plate 17. The air gap 18 is forming a slight thermal insulation for these components.
In Fig. 4a, the battery case 11 is shown in detail. The batteries 20 do not occupy the whole space within the case 11. The PCBs 21 for controlling the LEDs 8 and 10 and the voltage applied to the Peltier device are arranged next to the batteries 20 and are powered by these batteries. The contacts 22 serve to conduct the power into the front panel 4 to supply all the electrical components with energy.
In Fig. 4b, the battery case 11 is shown as it is actually built into the main case 2. The PCBs 21 and the batteries 20 are covered by cover plate 24. Only the contacts 22 are laid free. The battery case 11 is locked to the main case 2 by locking screw 23.
When the drawer 3 is opened, the contacts 22 are separated from the contacts (not shown) of the front panel 4. Thus, as soon as the drawer 3 is opened, the power supply of the Peltier device and of the LEDs 8 and 10 is interrupted. In this way the device 1 is prevented from consuming energy as long as the drawer 3 is not closed correctly and warm air can enter the interior space of drawer 3 and main case 2.
In the Fig. 5 and 6 a portable device 50 as alternative embodiment of the invention is schematically illustrated. Features having the same function as in the first embodiment are designated with the same reference numbers as before..
The main case 2 is in this embodiment formed as substantially rectangular casket. The bottom part 54 of the casket is separated from the upper part 55 by a separating plate 53. This separation is not visible from outside, but for illustration it is, indicated by dotted line 52 where the separation is generated. Main case 2 can be closed with the cover lid 51. To open the cover lid 51, release button 5 has to be activated.
At the bottom part 54 the control and regulating arrangements are housed. A battery compartment 11 is comprised in the back portion of the casket. Next to it, a connector plug 9 for the connection to an external power source (not shown) is visible. The plug is designed to be fed with DC power by a car battery.
As soon as the device 50 is connected to the car battery, the batteries inside the battery compartment 11 are recharged and the power for driving the device 50 is taken from the car battery.
On the front side of the casket there is a user interface 56. The user interface 56 comprises an on/off-switch 6, a display 7, a set-button 58 and a loudspeaker 59.
During the use of the device 50, the current temperature inside the main case 2 is displayed on display 57. The target temperature value can be set with the set-button 58. If the current temperature inside the main case 2 differs more than 2°C from the target temperature, a beep is issued by the loudspeaker 59. If the battery charge is low, a beep with a different melody is generated.
The device 50 is tempered by a Peltier device (not shown) , which is situated behind the venting slots 7. A fan (not visible) is used to dissipate heat from the Peltier device. A PCB (not visible) behind the user interface controls the voltage applied to the Peltier device. In dependence of the target and the current temperature values the interior space of main case 2 is either heated or cooled by choosing the sign of the voltage applied to the Peltier device.
In Fig. 6 the separating plate 53 is shown from a top view. The separating plate 53 comprises six deepenings 61 to receive receptacles (not shown) of the substance to be tempered. The temperature regulating plate 60 extends along these deepenings in such a way that every deepening is tempered at least from two sides. Thus, the receptacles are tempered very uniformly to the temperature set by set-button 58. Device 50 is not restricted to
a single application but can be subsequently used for different substances. The substances can be cooled down to 5°C, or might be heated to 50°C. Most commonly the substances need to be cooled to a temperature between 5°C and 15°C.