FIELD OF THE INVENTION

The present invention relates to an apparatus for drying granular material in a granular material accommodating tank in a vehicle, such as grain in a grain tank in a combine harvester having a combustion engine using surplus heat from the combustion engine for the drying, wherein the apparatus comprises a dryer box adapted for being fitted in a grain tank of a combine harvester or the like, wherein said dryer box comprises a heat exchange system for feeding air heated into the dryer box, and conditioning means for conditioning the granular material in the granular material accommodating tank. The invention further relates to a method for drying granular material and a combine harvester with such apparatus.

BACKGROUND OF THE INVENTION

An apparatus of the above-mentioned kind is known from US 3,581,407. The grain conditioner disclosed therein receives the exhaust gas from the engine of the combine harvester which is fed into a how shaft of the auger. The shaft has a perforated lowermost end. The hot exhaust gas emanates through the perforations and are transmitted upwards with the movement of the grain as the auger is rotated. However, this solution is not desirable as the exhaust gas contaminates the grain with the impurities in the hot exhaust gas, and also because the temperature that the grain is exposed to cannot be controlled very well.

In DE 36 27 267 Al a method and device for drying of grain in the grain storage tank of a combine harvester is known, where surplus heat from the exhaust gas and/or the cooling liquid of the engine of the combine harvester.

In DE 197 00 646 Cl there is disclosed a combine harvester with a grain drying device for drying the grain in the grain tank using the heat from the cooling liquid of the engine of the combine harvester. Also from GB 696,228 there is known a grain drying device for use in combination with a combine harvester. The drying device comprises a series of trays inside the grain storage tank on the combine harvester and a supply of hot air from the engine.

When harvesting a crop, the grain contains some moisture and often it is necessary to dry the harvested grain before processing the grain further. This is done in silos or the like. This can be quite expensive so as the three examples show, it is found advantageous to reuse the heat of the combustion engine on the combine harvester to dry the harvested grain before it is unloaded. This - if not eliminates - then at least reduces the need for drying of the grain in a silo or the like.

However, common to these known grain drying apparatuses on board a combine harvester is that the drying temperature is difficult to control. Hence, it is an object of the present invention to provide an on-board grain drying apparatus on a combine harvester or the like, where it is possible to control the drying temperature and to ensure that the grain is dried at a relatively uniform temperature.

SUMMARY OF THE INVENTION

This object is achieved by an apparatus of the initially mentioned kind, wherein the conditioning means comprises a plurality of raising augers, and wherein said heat exchange system comprising a heat exchange volume encompassing said plurality of raising augers, and wherein the dryer box is provided a bottom inlet for receiving granular material from the tank, so that said raising augers are raising said granular material in the dryer box, whilst subjecting the granular material with heat from the encompassing heat exchange volume, and an open top outlet, whereby the granular material is conditioned and heated inside the tank.

By an apparatus according to the invention it is found advantageous to circulate the granular material, in particular grain inside the grain tank by entering the grain into a dryer box and condition the grain therein and as the dryer box fills and the grain is lifted, the grain will re-enter the tank outside the dryer box due to overflow inside the dryer box. At the same time, a flow of exhaust gas is provided around the augers in the dryer box, where the temperature can be pre-set by controlling the amount of hot exhaust gas which is directed into the heat exchange volume. Moreover, the grain is not in direct contact with the exhaust gas. By the present disclosure, it is found advantageous that the grain in the grain tank on-board the combine harvester can be both pre-dried and conditioned so that the grain temperature is kept uniform in the grain tank. The temperature can be regulated in accordance with the specific crop being harvested or the like. It is found that the pre-drying on-board the combine harvester can achieve a decrease in the humidity of the grain on as much as 4 % depending on the amount of heated air is supplied. This improves the quality of the grain and results in significant cost savings for drying during storage as well as utilising the otherwise surplus heat generated by the engine of the combine harvester.

By the invention, it is surprisingly found that by heating the grain in the grain tank on-board the combine harvester immediately after the crop is harvested, the amount of fungi growing in the grain is reduced if not even eliminated. This further increases the quality of the harvested grain.

It is furthermore found advantageous to provide a plurality of raising augers, and in particular provided in parallel. This increases the capacity and ensures a more even heating as the time the grain is subjected to heating in the raiser augers in the dryer box is more precisely controlled.

In the present disclosure, the term "grain" refers to any kind of seeds of plants of the grass family, such as wheat, corn, and rice, as well as seeds of non-edible grass species, such as seed grass.

Depending on the type of grain it is important to control the temperature of the drying process. For instance seed grass should not be heated above a certain temperature where the seeds start to spire, whereas wheat, rye or the like, may be heated at a higher temperature. In the preferred embodiment of the invention, the heat exchange system comprises a heat exchange canal extracting heat from the exhaust gas from the engine and feeding said exhaust gas through the heat exchange volume and returning the exhaust gas to the exhaust system of the engine.

In a preferred embodiment, a second airflow is provided as a fresh air flow, which is achieved by a blower for feeding the air into the axial shaft of the at least one auger, said shaft being perforated so that granular material while being raised in the auger is subjected to an airflow from said air outlets in the auger shaft. The fresh air may be drawn from the warm end of the cooler of the combustion engine of the combine harvester and into the dryer box.

In an embodiment of the disclosure, a bottom manifold is provided expanding underneath the plurality of augers for providing the conditioning air flow for the auger shafts. This allows for a uniform distribution of fresh conditioning air to all of the augers. In a particular embodiment, the manifold is provided with one or more air flow regulators for adjusting the amount of conditioning air which is distributed to the augers. Hereby, the amount of conditioning air can be regulated.

In order to regulate the temperature a control valve is provided in the heat exchange canal for controlling the temperature of the air supplied to the dryer box. Hereby, the control valve can control the amount of air, which is fed into the dryer box.

The one or more raising augers in the dryer box according to the invention are driven by a hydraulic motor, an electric motor and/or by a mechanical drive.

A control system is advantageously provided for controlling the predetermined drying temperature in the dryer box. Based on inputs from sensors, the amount of heated air from the exhaust system passing through the control valve is controlled by the control system. The sensors providing input signals may include a heat sensor and a humidity sensor are provided in the grain tank, a thermometer is provided in the grain tank, an outside temperature sensor and the like. In a preferred embodiment, the control system is provided with inputs from one or more of said heat sensor, the humidity sensor and the thermometer in the grain tank and an exterior thermometer for controlling the control valve to adjust the airflow in the heat exchange canal for maintaining the predetermined temperature.

Preferably, the control system comprises a user control panel provided in the driver cabin of the combine harvester so that the user can select a predetermined drying temperature and monitor the drying process. Hereby, the user/driver can provide input to the on-board drying of the grain so that the drying temperature can be adjusted and monitored with respect to the specific crop which is being harvested.

In a second aspect of the invention, there is provided a method of drying granular material in a granular material accommodating tank in a vehicle, such as grain in a grain tank in a combine harvester having a combustion engine using surplus heat from the combustion engine, wherein the method comprises the steps of

- providing a dryer box in the granular material accommodating tank, preferably fitted in the grain tank of a combine harvester or the like;

- feeding granular material into the tank;

- raising granular material in the dryer box by a plurality of raising augers with a bottom inlet for receiving granular material from the tank and raising said granular material in the augers to an open top outlet where the granular material re-enters the tank outside the dryer box; and

- feeding air heated to a predetermined temperature into a heat exchange system having a volume encompassing the plurality of augers in the dryer box, whereby the granular material is conditioned and heated inside the tank.

As explained above in relation to the first aspect of the invention, it is found advantageous to circulate the grain inside the grain tank by entering the grain into a dryer box and condition the grain therein and as the dryer box fills, the grain will re-enter the tank outside the dryer box due to overflow inside the dryer box. At the same time, a flow of preheated air is provided, where the temperature can be pre-set. Hereby, the grain in the grain tank on-board the combine harvester can be both pre-dried and conditioned so that the grain temperature is kept uniform in the grain tank. It is found that the pre-drying on-board the combine harvester can achieve a decrease in the humidity of the grain on as much as 4 % depending on the amount of heated air is supplied. This improves the quality of the grain and results in significant cost savings for drying during storage as well as utilising the otherwise surplus heat generated by the engine of the combine harvester.

Advantageously, heat from the exhaust gas from the engine is extracted by feeding said exhaust gas through the heat exchange volume and returning the exhaust gas to the exhaust system of the engine. This utilise the heat in the exhaust gas which otherwise would be emitted into the air.

In a preferred embodiment of the invention, a second air stream is provided where the step of feeding of fresh air into the axial auger shaft of the at least one auger is provided, and whereby said axial auger shaft is perforated so that granular material while being raised in the auger is subjected to an airflow from said air outlets in the axial auger shaft. This fresh air flow is preferably provided by a blower creating an airflow from the warm side of the cooler of the combustion engine. Hereby, the granular material, in particular the grain, is subjected to heated air during the raising in the auger(s) both from the heat exchange volume surrounding the auger(s) as well as from the shaft of the auger(s). This ensures an even heating of the grain.

As explained above, the temperature of the heated air is regulated by a control valve, by which the amount of air from exhaust system which is fed into the heat exchange system is regulated.

In a third aspect of the invention, there is provided a combine harvester having a combustion engine, wherein surplus heat from the combustion engine is used for drying granular material in a granular material accommodating tank in a vehicle, such as grain in a grain tank in the combine harvester, wherein an apparatus as described above is provided.

DETAILED DESCRIPTION In the following, the invention is described in more detail with reference to the accompanying drawings, in which:

Figure 1 is a schematic side view of a combine harvester with an apparatus according to the invention, fig. 2 is a schematic perspective view of a grain drying apparatus according to the invention; fig. 3 is a schematic side view of a dryer box according to an embodiment of the invention; fig. 4 is a schematic top view of same; fig. 5 is a schematic side view of a second embodiment, figures 6 and 7 are perspective views of an apparatus according to a third embodiment of the invention; and fig. 8 is a detailed side view of the raiser auger according to a preferred embodiment of the invention.

With reference to fig. 1, there is shown a combine harvester where a crop is harvested by being cut at a reel 2 and then threshed and the grain is then collected in a grain tank 4 on-board the combine harvester. The combine harvester is provided with an engine room 8 with an internal combustion engine 10 driving the combine harvester. A cooler 12 is provided in connection with this combustion engine 10. The combine harvester is also provided with a driver's cabin 14.

As shown in fig. 1, a grain drying apparatus 6 is provided in the grain tank 4. The grain drying apparatus 6 is shown in more detail in fig. 2.

As schematically shown in fig. 2, the combustion engine 10 drives the combine harvester as indicated in fig. 1. The heat from exhaust gas and the coolant is fed into the drying apparatus 6 in the grain tank (see fig. 1). The drying apparatus 6 comprises a dryer box 16 in which a first raiser auger 20 and a second raiser auger 22. The grain is fed into the bottom of the dryer box 16 and raised by the first auger 20 and falls into the dryer box 16 as it exits the top of the first auger 20. The grain in the dryer box 16 is then conditioned by being raised from the bottom to the top of the dryer box 16 by the second raise auger 22. Hereby, the dryer box is being filled up with grain, which continuously is conditioned so that the temperature is kept uniform. The grain will re-enter the grain tank 4 outside the grain drying apparatus 6 (see fig. 1).

The exhaust air is led through a heat exchange canal 24. In this canal, the exhaust gas from the engine 10 is forwarded in a first tube 26 to a heat exchange volume 25 and returned in a second tube 28 and exits at the exhaust outlet 32. The temperature of the heated air drawn in around the exhaust gas tubes 26, 28 is regulated by a control valve 30, by which the amount of air from exhaust system, which is fed into the heat exchange system (24, 26, 28), is regulated. Heated air is also drawn into the dryer box by a blower 18 creating an airflow from the engine compartment 8, in particular the warm section of the cooler 12, i.e. a second, "fresh" airflow as opposed to above mentioned first, exhaust gas flow. This fresh air flow is used for conditioning the granular material while it is being raised in the augers 20, 21, 22.

A control system is provided for controlling the predetermined drying temperature in the dryer box. Based on inputs from sensors, the amount of heated air from the exhaust system passing through the control valve 30 is controlled by the control system. The sensors providing input signals may include a heat sensor and a humidity sensor are provided in the grain tank, a thermometer is provided in the grain tank, an outside temperature sensor and the like.

In figures 3 and 4, the embodiment shown comprises three augers 20, 21, 22 in the dryer box 16 inside the grain tank 4. The augers 20, 21, 22 are driven by drive means 19, which in a currently preferred embodiment is a hydraulic drive using the hydraulic oil system on the combine harvester, but could alternatively be mechanically driven, e.g. by a belt, or electrically driven. The grain 40 is entered into the grain tank 4 via an inlet 36 and from the bottom of the tank 4 the grain is raised in the augers 20, 21, 22. The auger shafts 201 are hollow and perforated with small air holes 23 (see figures 4 and 8) and the fresh air supply 38 provides an airflow out of said air holes 23 and into the grain which is being lifted up in the augers 20, 21, 22. The grain is simultaneously also being subjected to heat from the surrounding heat exchange volume 25, which encompasses the augers 20, 21, 22. The heat exchange volume 25 is - as described above - accommodating a first airflow of exhaust gas in the incoming tube 26 and the outgoing tube 28. The grain 40 exits the augers 20, 21, 22 in the top of the dryer box and re-enters the grain tank 4 as indicated by the arrows.

The control system is provided with inputs from one or more of said heat sensor, the humidity sensor and the thermometer in the grain tank and an exterior thermometer for controlling the control valve to adjust the airflow in the heat exchange canal for maintaining the predetermined temperature.

The control system comprises a user control panel provided in the driver cabin 14 of the combine harvester so that the user can select the type of grain being harvested, a predetermined drying temperature, and the like, and monitor the drying process. Hereby, the user/driver can provide input to the on-board drying of the grain so that the drying temperature can be adjusted and monitored with respect to the specific crop which is being harvested.

In the figures 6 and 7, a third embodiment of the apparatus for drying grain is shown. In this embodiment, four raising augers 20, 21, 22 are provided in a row and with a heat exchange volume 25 formed around the augers 20, 21, 22. The heated exhaust gas is fed into this volume 25 by the exhaust gas inlet tube 26 and exits the volume 25 by the exhaust gas outlet tube 28. The temperature of the exhaust gas drawn in around the heat exchange volume 25 may be 200- 300°C upon entry and radiates the heat from the volume and thereby heats the grain being raised in the augers. The temperature can be controlled as described above. The exit temperature may be approx. 75°C as the exhaust gas exits the volume 25 in the outlet tube 28 and returns to the engine exhaust system (as shown in fig. 2).

At one end, the grain inlet 36 is provided. Through this inlet 36, the grain flows from the grain tank 4 of the combine harvester and into the dryer box 16 for being conditioned and dried.

At the bottom of the apparatus, a manifold 34 is provided. By this manifold the air for the auger shafts 201 is provided so that the airflow of fresh air can be regulated and supplied evenly to the shafts 201 of all the augers 20, 21, 22. In order to regulate the airflow in the manifold 34, the manifold may be provided with shutters 39 along the lowermost side that can be opened or closed to regulate the amount of air in the airflow to each of the auger shafts above.

In fig. 8 there is shown a detailed side view of the raiser auger according to a preferred embodiment of the invention. The auger 20 comprises a shaft 201 which is provided with a helically formed raiser wing 202. In the shown embodiment, it is one wing 202 helically formed around the shaft 201, but in an alternative embodiment, the raiser wing 202 can be made up by a plurality of separate wing sections. The shaft 201 is provided with perforations 23 for the provision of the conditioning air to the grain which is being lifted up by the auger wing 202.

Above the invention is described with reference to some currently preferred embodiments. In the present disclosure, the term "grain" refers to any kind of seeds of plants of the grass family, such as wheat, corn, and rice, as well as seeds of non-edible grass species such as seed grass. It is realised that variations to the above described may be provided without departing from the invention as defined in the accompanying claims.