WO2015193456A1

WO2015193456A1 - Improved vaporizer and vaporizing method

Info

Publication number: WO2015193456A1
Application number: PCT/EP2015/063756
Authority: WO
Inventors: Ciaran Oglesby
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-06-19
Filing date: 2015-06-18
Publication date: 2015-12-23
Anticipated expiration: 2016-12-19
Also published as: GB2527349A; GB201410970D0

Abstract

The present application is directed at vaporizers, which are employed to allow a user inhale volatiles obtained from plant matter heated within an oven of the vaporizer. The application provides improvements generally with respect to the construction of the oven and associated heating element and methods of controlling the heating element.

Description

Improved Vaporizer and Vaporizing Method

Field

The present application relates to vaporizers and methods of controlling same. Background

It is well known that a number of different plant materials contain volatiles which can be extracted for use.

Historically, the two main ways of extracting volatiles from plant material was through the use of solvents or by smoking the plant material. The process of smoking involves burning plant material (thereby vaporizing the volatiles in the plant material) and inhaling or tasting the resulting smoke. Inhaling the vaporized form of the volatiles into the lungs is a quick and very effective way of delivering the volatiles. However, burning plant material also leads to the release of unwanted carcinogens in smoke. As a result, the use of vaporizers is increasing. Accordingly, one approach is that provided generally by electronic cigarettes (e- cigarettes). These devices are battery-powered vaporizers that simulate the feeling of smoking. The user inhales an aerosol, commonly called vapor, rather than cigarette smoke. E-cigarettes typically have a heating element that atomizes a liquid solution known as e-liquid. E-liquids usually contain propylene glycol, glycerin, nicotine, and flavourings. It will be appreciated that this approach uses an e-liquid rather than the original organic plant (e.g. tobacco) material.

The present application is not directed to e-cigarettes but rather to vaporisers for use with plant material. A vaporizer is a device that it used to extract volatiles from plant material without burning the plant material. Typically this is done by heating the plant material to a point hot enough so that the volatiles undergo a phase change from a liquid state to a gaseous state, but not to a point hot enough to cause plant material to combust. As a result, the number of carcinogens inhaled can be reduced, reducing the health risks to the user. Vaporizers employ an oven heating the organic material. As the organic material is solid in nature rather than a liquid such as an e-liquid. There is no reservoir for storing the e-liquid. Instead, the vaporizer comprises an oven. Typically, the oven will have a door which may be slid, swung or otherwise opened to allow the solid plant material to be introduced and removed from the oven.

Typically, a vaporizer has one or more pre-set temperature settings in the region of 190° C, 210° C and 230° C. However, a vaporizer limited solely to this type of course control has a number of disadvantages. In particular, plant materials can contain a number of different volatiles, each volatile having a different vaporization point to the remaining volatiles. As a result, the use of a course setting can cause a particular volatile to be overheated and degraded. There is therefore a need for an improved vaporizer which addresses this problem and other issues with existing vaporizers. Summary

In a first aspect, an inhalation device is provided for vaporizing the volatiles in organic material. The inhalation device suitably comprises:

an oven for heating organic material, the oven having a chamber for holding the organic material and having a door to allow access to the chamber for inserting or removing of organic material; and

a controller for controlling the actual temperature of the oven, wherein:

the controller is adapted to adjust the actual temperature of the oven towards a desired temperature for the oven; and

the controller is further adapted to automatically adjust the desired temperature for the oven.

The device preferably further comprises a temperature sensor coupled to the controller for monitoring the actual temperature of the oven.

The desired temperature preferably has an initial value and a final value and is automatically increased from the initial value to the final value in a plurality of steps. Preferably, the initial value is 185°C, the final value is 220°C and the desired temperature is increased in steps of 3°C

Preferably, the desired temperature is ramped from the initial value to the final value over a predefined period of time.

Preferably, the predefined time is 20 minutes, and the steps are evenly spaced apart across the predefined time. Optionally, the controller is further configured to monitor for a drop in the actual temperature in the oven and wherein detection of an actual temperature drop is used by the controller to determine that inhalation from the device has occurred.

The controller may automatically increases the desired temperature when controller determines that inhalation from the device has occurred.

Preferably, the desired temperature has an initial value and the controller is configured to increase the desired temperature in incremental steps each time inhalation is detected.

Preferably, the initial value is 185°C, the incremental steps have a value of 3°C, and the desired temperature has a cap of 220°C.

The device may further comprise a timer wherein the timer is used to shut down the device after a predefined shut-down time.

The timer is preferably connected to the controller and the controller is configured to reset the timer when the controller determines that inhalation from the device has occurred.

The timer preferably is started when the actual temperature of the device matches the desired temperature and the predefined shut-down time is 15 minutes. Other aspects will be appreciated from the description and claims which follow.

Brief Description of the Figures The invention will be more clearly understood from the following description with reference to the accompanying figures in which:

Figure 1 is an exploded view of the device, with the cover and internal frame removed to better show elements of the device;

Figure 2 is a second exploded view of the device from another angle;

Figure 3 is a view of the device, showing the elements of figure 1 as assembled; Figure 4 is a second view of the device, showing the elements of figure 1 as assembled from another angle;

Figure 5 is an exploded view of the device showing the internal components of the device shown in figure 1 in combination with power and control components;

Figure 6 is a view of the internal components of the device shown in figure 5 as assembled; and

Figure 7 is an exploded view of the internal components of the device including the internal frame.

Detailed Description

As shown in the figures, the vaporizer device 100 has a bottom frame 101 which comprises a door 102. The bottom frame 101 comprises a fastening means which is used to attach the bottom frame 101 to an internal frame 130. The fastening means preferably comprises clips 121 , 122, 123. Each clip 121 , 122, and 123 mates with a corresponding portion 131 , 132, 133 of the internal frame 130. The internal frame 130 is used to mount elements of the device securely. The device is relatively small portable. It may be held comfortably within a person's hand in use or placed in a pocket for carrying.

The door 102 comprises a number of ventilation ports to allow air to easily enter the device 100. The door 102 has a fastening means 103 which is used to hold the door 102 shut. The fastening means 103 is preferably a sliding clip in the door which engages with a slot in the bottom frame 101 . The clip is preferably biased towards the slot to prevent the clip accidentally disengaging from the slot in use. A spring 104 is positioned between the bottom frame 101 and the door 102 to provide a biasing force which pushes the door 102 away from bottom frame 101 . This biasing force allows the door 102 to be easily opened once the sliding clip is disengaged from the slot. Preferably, the spring 104 is made of a resilient material such as silicone.

The door 102 is opened to introduce material into an oven 105. The oven 105 is a cylindrical chamber. The oven 105 can be made from a ceramic material or from metal. However, metal is preferred because it is more responsive to controlled temperature change. The oven 105 has a screen 106 which has at least one opening. The screen can be a baffle or alternatively a mesh screen. In use, the screen 106 prevents plant material being drawn into tube 1 10. The screen 106 is located in the oven 105. As shown in figure 6, the screen 106 is positioned in the oven 105. Preferably, the screen 106 is positioned in the oven 105, proximate tube 1 10.

The oven 105 can be any size. However, the oven is preferably of a shape and size where the plant material is in constant contact with the oven and also not further than 5mm from a heating surface. The oven 105 has two ports. An input port is provided for receiving organic material. The input port can be accessed by opening the door 102. Organic material can then be placed in the oven 105 between the door 102 and the screen 106. When the door 102 is closed, the ventilation ports allow air to be drawn into the oven 105. The ventilation ports may be in the door or frame. The oven 105 also has an output port. The output port allows a mix of air and vaporized volatiles extracted from the organic material to be drawn from the oven 105. The output port is preferably located at the end of the oven 105 remote from the door 102. The screen 106 comprises a number of ventilation ports. Preferably, the screen 106 has a flat sieve like structure which allows air and vaporized chemicals to easily pass through the screen while at the same time preventing solid organic materials passing through the screen. As a result, the screen 106 prevents organic material reaching and clogging the output port. The oven may be provided with a central pillar. The central pillar improves the performance of the device by providing an additional heat transfer surface in the oven for heating the organic material.

At the end of the oven 105 proximate to the output port, a heater 107 is provided. In operation, heat is transferred from the heater through the base of the oven in which the output port is provided. The pillar is supported on and thus receives heat directly from the base. The walls of the oven also receive heat from the heater which in turn heats the organic material inside. Although many different types of heaters can be used, preferably the heater 107 is an electric heating element. A metal heating element is preferred because of its responsiveness to control signals. Resistance wire can be used and has the advantage of being an inexpensive type of heating element. As a person skilled in the art will recognise, resistance wire is a term typically used to refer to metallic resistance heating elements which may be wire or ribbon, straight or coiled. They are used in common heating devices like toasters and hair dryers, furnaces for industrial heating, floor heating, roof heating, pathway heating to melt snow, dryers, etc. The most common classes of materials used include Kanthal (FeCrAI) wires, alloys of nickel and chromium - commonly referred to as Nichrome (preferably Nichrome 80/20, which comprises 80% nickel and 20% chromium) wire and strip, and Cupronickel (CuNi) alloys for low temperature heating. Alternatively, an etched foil and / or laser cut heating element can be used and has the advantage of being highly suitable for precision temperature control. As a person skilled in the art will recognise, etched foil elements are generally made from the same alloys as resistance wire elements, but are produced with a subtractive photo-etching process that starts with a continuous sheet of metal foil and ends with a complex resistance pattern. The heater 107 is secured proximate to the oven 105 using a clamp plate 108. Preferably, the heater 107 is a heating element. Preferably, the oven 105 and the plate 108 are hard anodized. Hard anodizing, also known as hardcoating or Type III anodizing, is a process well known in the art that is used to create a hard wearing, corrosion resistant coating on a variety of metals. In the present case, hard anodizing is used to provide electrical insulation in order to prevent short circuiting the heating element. The heating element is preferably clamped onto the base of the oven 105 without air gap or insulating material located between the heating element and the base of the oven 105. This provides good thermal conductivity and improves the efficiency of the device 100. In contrast, the walls of the oven may be insulated with a suitable thermal insulator to retain heat within the oven.

A temperature sensor 109 also secured to the clamp plate 108. The temperature sensor 109 is located proximate to the heater 107. The temperature sensor 109 is preferably a thermistor. The thermistor is preferable because of its sensitivity, the ease of obtaining an electronic reading and its lack of expense. The temperature sensor 109 is used to monitor the temperature of the heater 107 and the oven 105.

A spacing tube 1 10 is used to connect the output port of the oven 105 to a mouthpiece 1 1 1 . The mouthpiece 1 1 1 is located on a top frame 1 12. The spacing tube 1 10 is connected to the oven 105 using a first connector 1 13. The spacing tube 1 10 is connected to the mouthpiece 1 1 1 using a second connector 1 14. Preferably, the spacing tube 1 10 is stainless steel. Preferably, the connectors 1 13, 1 14 are food grade silicone. The top frame 1 12 is mounted on the internal frame 130.

Vapour leaving the oven 105 enters a first end of the spacing tube 1 10 proximate the oven 105 and exits a second end of the spacing tube 1 10 proximate the mouthpiece 1 1 1 . The spacing tube 1 10 is dimensioned with a length which allows the vapour entering a first end of the spacing tube 1 10 to cool sufficiently for comfortable inhalation by a user by the time the vapour exits the second end of the spacing tube 1 10. Suitably, the vapour is less than 50°C when exiting the second end of the spacing tube. A battery 1 15 is used to power the heater 107 and control circuitry (described below in more detail). Preferably the battery 1 15 is rechargeable battery. Most preferably, a rechargeable lithium ion 18650 battery is used. The device 100 also has an external cover 140 which is used to protect the internal elements of the device.

A controller 1 1 6 for the oven 105 is connected to the heater 107 and the temperature sensor 109. The controller is preferably provided by a mix of hardware and software components comprising control circuitry, for example a processor. Most preferably, the controller comprises a PIC^® Microcontroller manufactured by Microchip Technology. Ideally, software uses the controller to control the oven. The controller

1 1 6 is also connected to an interface 1 17 on the top frame 1 12. The user interface

1 17 allows a user to select an operation mode for the device 100. The controller 1 1 6 provides energy from the battery 1 15 to the heater 107 to heat the oven 105. The controller 1 1 6 also receives feedback from the temperature sensor 109 which can be used by the controller 1 16 to determine the actual temperature of the oven 105.

Using this feedback, the controller 1 1 6 can control the temperature of the oven 105. In particular, the controller 1 1 6 can be programed to heat the oven 105 to a desired temperature. For example, a user input pre-set temperature settings. Using the feedback from the temperature sensor 109, the controller adjusts the power provided to the heater 107 such that the actual temperature of the oven 105 reaches and is then maintained at the desired temperature.

The controller 1 16 also comprises a charging socket 1 18 which is used to connect the device 100 to a power source (for example the mains) in order to re-charge the battery 1 15. In one operating mode, the interface 1 17 can comprise a control knob which a user can adjust to select a set desired temperature for the oven 105.

An important aspect of the present invention is that it also provides additional operating modes which provide a number of inventive automatic and semi-automatic temperature control programs which can be selected from the interface by a user. These automatic programs allow the user to experience over a period of time the release of the volatiles, each volatile having a different vaporization points to the remaining volatiles, as they each reach their boiling points vaporization points. These automatic programs can be selected by the user using the interface 1 17.

In a first program, the controller 1 16 automatically increases the desired temperature from an initial desired temperature to a final desired temperature over a period of time using a timer. Initially, the controller 1 16 controls the power provided to the heater 107 using feedback from temperature sensor 109 such that the actual temperature of the oven 105 reaches the initial desired temperature.

It will be appreciated that different volatiles will vaporize at different temperatures and that the initial temperature should be set at the lower point at which vaporizing occurs for the volatile of used. Thus the initial temperature may vary on the volatile of interest or the plant material. Accordingly, the initial temperature may be as low as 100°C.

However for some of the more commonly employed plant materials and volatiles of interest, the temperature at which volatiles start to be volatised is closer to 185°C. Accordingly, for such an example, the initial desired temperature can be set at 185°C. The desired temperature can be gradually ramped up by the controller to a final desired temperature over a predefined period of time.

At the same time, the maximum temperature is again dictated by the nature of the plant material and volatiles of interest. Thus for certain volatiles the maximum temperature may be relatively low, for example 150°C.

However for some of the more commonly employed plant materials and volatiles of interest, the temperature may be closer to 220°C and in which case preferably, the final desired temperature is 220°C.

The predefined period of time is preferably between 5 - 30 minutes and most preferably 20 minutes. The control circuitry can gradually increase the desired temperature. The desired temperature can be increased incrementally in steps of a value of between 1 ° C and 10° C, but preferably the desired temperature is increased in incremental steps of 3°C from the initial desired temperature to the final desired temperature. After each incremental step, the controller 1 1 6 controls the power provided to the heater 107 using feedback from temperature sensor 109 such that the actual temperature of the oven 105 reaches the incremented desired temperature.

The incremental steps are preferably evenly distributed over the predefined period of time, such that the time between each step is the same. In this way, each volatile having a different vaporization point can be vaporized in turn, minimizing the loss of the volatiles. Alternatively, the incremental steps can have an exponential distribution such that the desired temperature rises gradually close to the initial desired temperature and steeply close to the final desired temperature or visa-versa. When the desired temperature reaches the final desired temperature, it is capped at the final desired temperature. To put it differently, when the desired temperature reaches the final desired temperature, the desired temperature is not adjusted further. Thus, in this case, the desired temperature is kept at the final desired temperature.

Preferably, the user can reset the device to exit the program using the interface 1 17, for example by turning the control knob to the off position. Alternatively, the user can select another program and the device 100 will switch to this program and stay running.

As noted above, during the program, the actual temperature of the oven 105 is determined using the temperature sensor 109, and the power provided by the controller 1 1 6 to the heater 107 is adjusted to match the actual temperature in the oven 105 to the desired temperature specified by the controller 1 1 6.

The temperature in the oven 105 can also be adjusted on 'a puff by puff basis. When a user inhales from the mouthpiece 1 1 1 of the device 100, air is drawn from the ventilation ports in the door 102 into the oven 105. This causes the actual temperature of the oven 105 to drop from the desired temperature set by the control circuitry 1 1 6. The oven 105 has a low mass, typically of 2 grams, and the drop in the actual temperature of the oven can drop by 1 °C to 50° C.

When the user stops inhalation, the flow of air through the device 100 stops and the actual temperature of the oven 105 will rise again under the influence of the heater 107 and controller 1 1 6 to match the desired temperature. The change in the actual temperature of the oven 105 can be detected by the controller 1 1 6 using the temperature sensor 109. This information can then be used by the controller 1 16 to control the temperature of the oven 105.

For example, the controller 1 1 6 can use this information to determine when a user has inhaled (i.e. taken a 'puff') from the mouthpiece 1 1 1 of the device 100. This determination can then be used by the controller 1 1 6 to adjust the desired temperature of the oven 105. The power provided by the controller 1 1 6 to the heater 107 is then adjusted to cause the actual temperature in the oven 105 to match the adjusted desired temperature.

Optionally, to help with puff detection, a predetermined time can be monitored for the 'puff duration and can also be taken into account by the controller to help with 'puff detection. This predetermined time could be between 0.5 second to 20 seconds. When the controller 1 1 6 detects a 'puff as set out above, the controller 1 16 starts a timer running. While the timer is running, it is assumed that the user is inhaling from the device, or is between inhalations. When the timer reaches the predetermined time, it is assumed that the user may be taking a further inhalation from the device 100.

Thus, the use of a timer to monitor a 'puff time can be used prevent 'false' positives caused by oscillations in the temperature of the oven 105. This prevents the controller detecting multiple 'puffs' when the user has only taken a single inhalation from the device by ignoring any 'puffs' detected when the timer is running.

In a second program, the controller 1 16 automatically increases the desired temperature over on a 'puff by puff basis. For example, at the start of the program, the initial desired temperature, as explained above, and can optionally be set at 185°C. This can then be gradually ramped up to a final desired temperature, as explained above, (preferably 220°C). When the controller 1 1 6 determines that a user has inhaled from the device 100, the controller 1 1 6 increases the desired temperature. The desired temperature can be increased in incremental steps. The incremental steps may have a value of between 1 ° C and 10° C, but preferably the desired temperature is increased by incremental steps of 3° C. Thus, the desired temperature is increased in incremental steps every time a user inhales from the device 100. After each incremental step, the controller 1 1 6 controls the power provided to the heater 107 using feedback from temperature sensor 109 such that the actual temperature of the oven 105 reaches the incremented desired temperature. The desired temperature is increased until it reaches the final desired temperature. In this way, each volatile having a different vaporization point can be vaporized in turn, minimizing the loss of the volatiles. When the desired temperature reaches the final desired temperature, it is capped at the final desired temperature. To put it differently, if the controller 1 1 6 determines that a user has inhaled from the device 100, and the desired temperature has already reached the final desired temperature, the desired temperature is not adjusted further. Thus, in this case, the desired temperature is kept at the final desired temperature.

A third program which can be used in combination with any of the programs or set temperature operating modes of the device 100 described above. In one version of the third program, when the actual temperature of the oven 105 is determined by the controller 1 16 to have reached the initial desired temperature of a mode of operation, a timer starts. The timer runs for a predefined period of time. The predefined period of time is preferably between 15 - 30 minutes and most preferably 20 minutes. After the end of the predefined time period a shut-down program is activated. In the third program, the oven 105 is controlled on 'a puff by puff basis. In particular, once activated, the third program starts a timer which runs for a predefined period. This period can be between 20 seconds and 20 minutes but is more suitably between 1 - 10 minutes and is preferably 3 minutes. At the end of the predefined period, the device 100 is shut down. However, if the controller 1 16 determines that a user has inhaled (i.e taken a 'puff') from the mouthpiece 1 1 1 of the device 100, the timer is reset and starts to run again. In this way, the controller will shut the device down (for example, the controller can put the device into a sleep mode or turn the device off) if it does not detect a puff within 3 minutes or a puff within every 3 minutes thereafter.

In another version of the third program, a modified shut-down program is activated when the device 100 is switched on. The modified shut-down program is the same as the shut-down program above, except that the predefined period is longer. In the modified shut-down program, the predefined period can be anywhere between 30 seconds and 30 minutes but is more suitably in the range 5 - 30 minutes and is preferably 15 minutes. In this way, the device 100 is shut down if no puff is detected within any given 15 minute period regardless of the program or mode of operation selected.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

While the present teaching has been described with reference to some exemplary arrangements it will be understood that it is not intended to limit the present teaching to such arrangements as modifications can be made without departing from the spirit and scope of the present teaching. In this way it will be understood that the invention is to be limited only insofar as is deemed necessary in the light of the appended claims.

Claims

1 . An inhalation device for vaporizing volatiles in solid organic material, the inhalation device comprising:

an oven for heating organic material to release volatiles, the oven situated at a first end of the inhalation device, the oven comprising: a chamber for holding the solid organic material,

a door to allow access to the chamber for inserting or removing of the solid organic material,

one or more ventilation ports to allow air to be drawn into the oven; an output port

a screen preventing plant material being drawn through the output port;

a mouthpiece provided at a second end of the inhalation device opposite the first end;

a spacing tube providing a fluid connection between the output port and the mouthpiece and wherein the screen prevents plant material being drawn into the spacing tube; and

an electrical heater proximate to the oven, wherein the heater comprises an etched or laser cut foil heating element.

2. An inhalation device according to claim 1 , further comprising at least one rechargeable battery for powering the electrical heater.

3. An inhalation device according to claim 2 wherein the at least one rechargeable battery is positioned along the spacing tube and oven between the respective first and second ends.

4. An inhalation device according to any preceding claim, wherein the oven is formed from a metal which is anodised.

5. An inhalation device according to claim 4, wherein the oven metal is hard anodised.

6. An inhalation device according to claim 4 or claim 5, wherein the heating element is in direct contact with the oven.

7. An inhalation device according to any preceding claim, wherein the spacing tube is dimensioned with a length which allows the vapour exiting the output port to cool sufficiently for comfortable inhalation by a user by the time the vapour exits the mouthpiece.

8. An inhalation device according to any preceding claim, further comprising a controller wherein the controller is configured to turn off the heating element if an inhalation is not detected within a predefined period.

9. An inhalation device according to claim 8, wherein the predefined period is between 1 and 10 minutes.

10. An inhalation device according to claim 8 or claim 9, wherein an inhalation is detected using a temperature sensor.

1 1 . An inhalation device according to any preceding claim, wherein the inhalation device further comprises a clamp plate for securing the heating element to the oven.

12. An inhalation device according to claim 1 1 , wherein the clamp plate is anodised.

13. An inhalation device according to claim 1 1 or claim 12, wherein the clamp plate clamps the heating element to the base of the oven, where the base is at the end opposite the door of the oven.

14. An inhalation device for vaporizing volatiles in solid organic material, the inhalation device comprising:

an oven for heating organic material, the oven having a chamber for holding the solid organic material and having a door to allow access to the chamber for inserting or removing of the solid organic material; a controller for controlling the actual temperature of the oven, a temperature sensor coupled to the controller for monitoring the temperature of the oven, wherein:

the controller is further adapted to automatically adjust the desired temperature for the oven, where the desired temperature has an initial value and a final value and is increased from the initial value to the final value.

15. The device of claim 14, wherein the initial value is 185°C, the final value is 220°C and the desired temperature is increased in steps of 3°C

1 6. The device of claim 14 or 15, wherein the desired temperature is ramped from the initial value to the final value over a predefined period of time.

17. The device of claim 1 6, wherein the predefined time is 20 minutes, and the steps are evenly spaced apart across the predefined time.

18. The device of claim 14, wherein the controller is configured to monitor for a drop in the actual temperature in the oven and wherein detection of an actual temperature drop is used by the controller to determine that inhalation from the device has occurred.

19. The device of claim 18, wherein the controller automatically increases the desired temperature when controller determines that inhalation from the device has occurred.

20. The device of claim 19, wherein the initial value is 185°C, the incremental steps have a value of 3°C, and the desired temperature has a cap of 220°C.

21 . The device of any one of claims 14 to 20, further comprising a timer wherein the timer is used to shut down the device after a predefined shut-down time.

22. The device of claim 21 wherein the predefined shut-down time is in the range 1 to 30 minutes and optionally is 15 minutes.

23. The device of claim 21 or claim 22, wherein the timer is connected to the controller and the controller is configured to reset the timer when the controller determines that inhalation from the device has occurred.

24. The device of any one of claims 21 to 23, wherein the timer is started when the actual temperature of the device matches the desired temperature.

25. An inhalation device for vaporizing volatiles in solid organic material, the inhalation device comprising:

a screen preventing plant material being drawn through the output port;

a spacing tube providing a fluid connection between the output port and the mouthpiece and wherein the screen prevents plant material being drawn into the spacing tube;

an electrical heater comprising a hearing element for providing heat to the oven, and

a clamp for holding the heating element in direct contact with a surface of the oven; wherein the clamp plate or oven surface is anodised to electrically insulate the clamp or oven from the heating element.

26. An inhalation device according to claim 25, further comprising at least one rechargeable battery for powering the electrical heater.

27. An inhalation device according to claim 25 or claim 26, wherein the oven or clamp plate is hard anodised.

28. An inhalation device according to any one of claims 25 to 27, wherein the surface is the base of the oven, where the base is opposite the input port.

29. An inhalation device according to any one of claims 25 to 28, wherein the spacing tube is dimensioned with a length which allows the vapour exiting the output port to cool sufficiently for comfortable inhalation by a user by the time the vapour exits the mouthpiece.

30. An inhalation device according to any one of claims 25 to 29, further comprising a controller wherein the controller is configured to turn off the heating element if an inhalation is not detected within a predefined period.

31 . An inhalation device according to claim 30, wherein the predefined period is between 1 and 10 minutes.

32. An inhalation device according to claim 30 or claim 31 , wherein an inhalation is detected using a temperature sensor. 31 . An inhalation device according to claim 32 wherein the at least one rechargeable battery is positioned along the spacing tube and oven between the respective first and second ends.