Especially with regard to vessels and trucks, it is undesirable for a generator or a main motor to consume energy and produce exhaust fumes and/or noise when stationary.

The Applicant already brings equipment onto the market--that can be connected at battery voltages of 48,42, 24 or 12 volt and can also'operate on solar cells in motor homes, pleasure craft, trucks and the like for cooling purposes.

The present invention provides a device for the cooling of air, comprising; - a direct current motor to be connected to an electrical source; - a rotation compressor connected to the direct current motor; and - at least one direct current ventilator connected to the electrical source.

The combination of a direct current motor, rotation compressor and direct current ventilator renders a, total effective yield of approximately 80% feasible, which is at least 60% more than that made possible by previously available systems. Owing to the higher yield a back-up generator can be dispensed with, for instance in the case of housings for telecommunication equipment. An extra generator

for supplying power is unnecessary in the case of electric vehicles.

It has furthermore been shown in practice that, in particular, the yield increases when the compressor operates at relatively low revolutions and/or by overdimensioning one or more heat exchangers (i. e. condenser, vaporizer) connected to the compressor, for example by approximately 50%.

Additional advantages, features and details of the present invention will be clarified on the basis of the following description of a preferred embodiment of same, with reference to the enclosed figures, in which: fig. 1 shows a cut-away perspective view of a device according to the present invention in a first preferred embodiment- ; fig. 2 shows an exploded perspective view of a second preferred embodiment; fig. 3 shows a third preferred embodiment of a device according to the present invention; and fig. 4 shows a chamber of the compressor in cross- section.

A cooling device 10 according to the present invention comprises a direct current motor 11 which is connected in a manner not illustrated to an accumulator of 12,24, 42 or 48 Volt or to any other direct current source.

A rotary-compressor 12 is connected to the output'shaft of the direct current motor. Direct current motor 11 and rotary- compressor 12 have been installed as much as possible in line and non-vibrating relative to a groove. Preferably, both are arranged on a common shaft in the same housing in order to reduce sealing problems at the shaft as much as possible. The direct current motor can be embodied with or without brushes (fig. 1).

A condenser 16 and a vaporizer 17 are connected in series to the compressor 12 via pipes 13,14 and 15, respectively. Using a ventilator 18, that has been connected to the accumulator in a manner not illustrated, an airflow as indicated by arrows A, B and C is forced along vaporizer 17 and brought into the space to be cooled. The order of ventilator 18 and vaporizer 17 can also be reversed.

Opposite ventilator 18 a second direct current ventilator 20 has been installed onto frame 19 of a housing that has not been illustrated further, which forces the airflow according to arrows D en E alongside condenser 16, thus bringing hot air to the environment according to arrow F. The medium, preferably the environmentally-friendly coolant R134A, which likewise improves the yield and is available on the market, is hereby condensed once again.

For a greater flexibility when building in the cooling device according to the invention, the device is manufactured in different variants. The above described first variant extends substantially in vertical direction, while a second preferred embodiment (fig. 2) extends in mainly horizontal direction. This is advantageous for instance in vehicles wherein the air-conditioning is mounted on the roof.

The cooling device 40 comprises a housing which consists of parts 42,44 and in which, similarly to the first embodiment, a direct current motor 48 is arranged with an output shaft to which a rotary-compressor 46 is connected.

Motor 48 and compressor 46 are arranged in non-vibrating manner on an elongate holder 50 and connected via pipes to heat exchangers 56 and 58. Heat exchanger 56 is the vaporizer and heat exchanger 58 the condenser as according to the above described first embodiment. Two ventilators 60,62 arranged close to vaporizer 56 draw air for cooling through the

vaporizer. Two ventilators 64,66 arranged adjacently of each other draw air through the condenser for discharge of heat.

In a third preferred embodiment the device is divided into two parts 70 and 72 which are mutually connected by pipes 74,76 for the cooling medium. The vaporizer with associated ventilator, among other components, are arranged in part 72 in order to blow out cooled air, while the condenser with associated ventilator 78 are arranged in part 70 for blowing out heated air to the environment. This embodiment is advantageous for instance in trucks, where as much space as possible in the cab is taken up by all kinds of equipment. It is thus possible to mount part 70 on the front of the cab, while part 72, which is mounted in the cab, is relatively-flat.

In practical implementations of the above described preferred embodiments, a direct current motor with a yield of about 85% is used. In the case of an accumulator producing 12V, the yield of the motor is about 65%. The shaft of the direct current motor which drives the compressor is set to relatively low revolutions of less than 2000 rpm. Higher yields were achieved at revolutions of less than 1500 rpm.

The speed of revolution preferably lies between 500 and 1000 rpm. The compressor used has a yield of about 95% and the ventilators have a yield of about 90%. The compressor comprises an impeller movable in a cylinder. Such a construction is referred to as a rotary vane or sliding vane.

The low revolutions of the compressor are elucidated with reference to fig. 4. A compressor comprises a chamber 90 of oval cross-section in which a cylinder 92 provided with a number of radially exensible vanes 94-104 is arranged rotatably. In the shown position gaseous cooling medium is drawn into chamber part 106 between vane 102 and the wall of chamber 90. In use the cylinder 92 rotates in the direction

of the arrow, so that a determined maximum quantity of gaseous cooling medium is first drawn into chamber part 106, which medium is then compressed. In chamber part 108 the cooling medium, which has meanwhile become liquid, is pressed out of chamber 90. At low revolutions the cooling medium has sufficient time to completely fill chamber part 106. At higher revolutions the chamber part 106 will however fill insufficiently, so that the yield becomes lower.

The vaporizer and/or the condenser are preferably over-dimensioned, preferably in the order of 50%. That is, they have a relatively high power compared to the cooling power of the device.

In a practical embodiment the device has for instance a cooling power of 3 kW. The installed vaporizer then has an electrical power of 1. 5 x 3 kW = 4.5 kW. If a compressor of 500 W is used, the condenser must be able to discharge 3.5 kW of heat. In the device according to the present invention a condenser with an electrical power of 1.5 x 3.5 kW = 4.75 kW is used.

The above stated powers are guidelines, and concessions and modifications required for instance due to lack of space are possible. This will however reduce the yield.

The power of the condenser or of the vaporizer can also be increased by applying a stronger ventilator which can cause a greater airflow along the heat exchangers.

For a further increase in the yield of the cooling device, it is advantageous to keep the difference in temperature between the condenser and the vaporizer as small as possible. The pressure difference in the pipes for the cooling liquid is then also as low as possible, so that the compressor has to do less work.

The present invention is not limited to the above described preferred embodiments thereof. The requested rights are determined by the following claims, within the scope of which many modifications are conceivable.