Refrigerating appliance

The invention relates to a Cooling means for a machine tool or the like having a circle circulation system in which circulates a cooling medium, said cooling medium of a Tempering the machine tool is supplied, wherein the circuit system having a buffer tank through which the cooling medium is guided and wherein the circulation system is associated with a dosing unit, over a is controller controllable.

Such cooling devices are used, for example, to the machine bed of precision milling machines or to cool. The machine bed is maintained at a temperature by means of the tempering device, which the Surrounding temperature. In this case, the deviation between the must Ambient temperature and the temperature in the tempering very be low, preferably, the deviation 2 / 10-3 / 10 ° C.

Such a cooling device is known from DE 19 32 895 A. These Cooling device has a collecting container, in which a lubricant is stored. The lubricant is by means of a pump to a manifold fed and divided here into two partial streams. One of the two partial streams is passed through a cooling unit. After passing through the cooling unit the two partial streams are recombined by means of a dosing unit. there the partial streams are mixed so that a predetermined temperature value in mixed liquid flow is maintained. Following the dosing unit enters the lubricant in an intermediate container and from there conveyed from a machine tool.

In US 3,729,064, a cooling device is described wherein in a Circulatory system a coolant circulates. The temperature of the cooling medium is chosen so that the temperature control as possible the environment temperature is reached. Now, if the temperature in the circulation system a reaches too high a value, this is detected, a controller. The regulator controls then a metering unit via the cooling medium in the lead, before the Machine tool is metered into the circulatory system. The external Coolant case has a lower temperature than the in the circulatory system guided cooling medium. With this type of cooling for a short time, massive Temperature discrimination effected in advance, what a sudden drop in temperature in the tempering effect. However, this is undesirable because particular in precision turning or milling temperature jumps to manufacturing inaccuracies lead.

The object of the invention to provide a cooling device of the preamble of to provide patent claim 1 mentioned kind, with a reliable kept permanently constant temperature level in the tempering can be.

This issue is solved by external means of a metering unit is the cooling medium circulating in the circulatory system cooling medium metered, that the dosing unit, the external cooling medium in the tempering university next return and before the buffer tank into the circulatory system metered that the cooling device has a refrigeration cycle, to whose evaporator is coupled, a cooling circuit, in which the external Cooling medium is passed, and that by means of dosing a compound is produced between the cooling circuit and the circulatory system.

So according to the invention is next to the circulatory system nor a cooling circuit ready made, in which the external cooling medium is guided. This is to effectively air conditioned in the refrigerator.

To create a self-sufficient, self-contained system provides a possible Invention embodiment provides that the buffer tank is assigned a part tank, the buffer tank is connected to the sub-tank via an overflow, and in that by the sub tank, a cooling circuit is performed, the dosing unit in conjunction with the above the circulatory system is. When using a refrigeration circuit for cooling the external cooling medium, it may be provided that the temperature of the external Cooling medium is monitored in the cooling circuit by means of a temperature sensor, and that the temperature sensor is part of a control circuit of the compressor Refrigeration circuit is activated at a temperature pressure is below a target value and switches off when exceeding a preset value. This control circuit causing an energy-saving operation of the refrigeration circuit.

Preferably, the circulatory system of a heat exchanger, by means of the a consumer can be cooled. As a consumer, for example, a machine controller be used, which is to be cooled eventually to control the Machine tool used. In this way, by means of a single cooling means a complete cooling of the entire machine tool available posed.

A preferred embodiment of the invention can be characterized in that at the knobs on the temperature control device associated ambient temperature sensor and is arranged in the cooling medium of the buffer tank buffer tank temperature sensor is connected, that the regulator has a control circuit which Temperature difference between the ambient and the buffer temperature sensor forms and in dependence of the obtained difference value controls the metering unit. The ambient temperature sensor can be arranged so that it in the immediate vicinity of Temperierungsein-direction is arranged and there the Ambient air temperature measures.

Preferably, the dosing unit is designed as a solenoid valve which, starting clocked by the controller can be opened or be closed.

To reduce the expense parts, it is provided that the buffer tank and the Part tank are formed from a common tank and through a bulkhead are divided from one another, wherein the partition wall forms the overflow.

In the present arrangement of the regulator to reduce the parts should are expenses used to the temperature of the external cooling medium to located at a lower temperature than the temperature of the circulatory system regulate cooling medium.

For reasons of operational safety in a possible configuration of the invention the flow in the cooling circuit by means of a flow switch monitors.

The invention will in the following with reference to an illustrated in the drawings explained embodiment example. The drawing shows a schematic plan a cooling device.

The cooling device has essentially three cycles. Firstly, this is a refrigeration cycle <b>10</b>, On the other hand, a cooling circuit <b>20</b> and further a Circulatory system <b>40</b>,

The refrigerant circuit <b>10</b> has the usual components, among other things, a compressor <b>11</b>, A condenser <b>12</b>, A collector <b>13</b>, An evaporator <b>14</b> and a fan <b>15</b> on. The operation of such a refrigeration circuit commonly known, so there is no need to be examined more closely. The refrigeration cycle is over the evaporator <b>14</b> in connection with the cooling circulation <b>20</b>, Over the evaporator<b>14</b> is thus in the refrigeration cycle <b>10</b> generated energy to the cooling in the cooling circuit <b>20</b> circulating coolant transfer. Below this cooling medium is external cooling medium called. Starting from the evaporator<b>14</b> flows to the external cooling medium a flow switch <b>21</b> over, the permanent flow of the cooling circuit barrel <b>20</b> monitored. Following the flow switch<b>21</b> reaches the external cooling medium in a sub-tank <b>22.1</b> a memory <b>22</b>, The memory<b>22</b> is formed as a plastic tank. Following the subtank<b>22.1</b> is the external cooling medium via a pump <b>28</b> pumped into a flow and a consumer <b>29</b> supplied. In the present case, the consumer is<b>29</b> a precision milling machine. Here, the provided by the cooling circuit Cooling capacity in the control circuit of the machine tool needs. After this consumer <b>29</b> the external cooling medium flows back through the return to the vaporizer <b>14</b> to, thereby, the cooling circuit <b>20</b> would be closed. The memory <b>22</b> has in addition to the sub-tank <b>22.1</b> also a buffer tank <b>22.2</b> on. to Forming the part tank <b>22.1</b> and the buffer tank <b>22.2</b> is the memory <b>22</b> by means of a bulkhead <b>22.4</b> divided into two sub-chambers. The bulkhead<b>22.4</b> is dimensioned so that they overflow <b>22.3</b> between the part tank <b>22.1</b> and the buffer tank <b>22.2</b> forms. is to fill the memory a filling unit <b>22.8</b> used. If the memory<b>22</b> to be emptied, Thus, a drain valve <b>22.5</b> used.

The above-mentioned circulation system <b>40</b> passes through the buffer tank <b>22.2</b>, Starting from the buffer tank <b>22.2</b> is the in the buffer tank <b>22.2</b> stockpiled Cooling medium via a pump <b>25</b> conveyed in a flow. About this Flow flowing the cooling medium of a temperature of above said machine tool. The tempering can the be assigned to the machine bed of the machine tool. It serves the to keep the machine bed in exactly the ambient temperature level. in the Connection to the tempering <b>26</b> the cooling medium flowing over again to return the buffer tank <b>22.2</b> to. Thus, the circulatory system<b>40</b> closed.

Between the cooling circuit <b>20</b> and the circulatory system <b>40</b> is a Dosierein ness <b>27</b> incorporated in the form of a solenoid valve. This dosing<b>27</b> verbin det the flow of the cooling circuit <b>20</b> with the return of Kreislaufsyste mes.

The cooling device also includes a controller <b>23</b> on, the different has functions. For one thing it serves a differential value temperature control perform. This differential value temperature control would under the aid of a buffer tank temperature sensor <b>22.7</b> and an ambient Tempe ture sensor <b>24</b> performed. The buffer tank temperature sensor<b>22.7</b> is in Cooling medium of the buffer tank <b>22.2</b> arranged. The ambient temperature ture sensor <b>24</b> is assigned to the machine tool. The regulator<b>23</b> forms the Temperature difference between the two temperature sensors <b>22.7</b> and <b>24</b>, In the event that the difference is formed of the two temperature values ​​a Nominal value exceeds, is via a control line <b>30</b> the metering <b>27</b> driven. The case emitted control pulse causes the dosing<b>27</b> to a spatial connection between the cooling circuit <b>20</b> and the Circulatory system <b>40</b> produce. It then passes the external cooling medium Cooling circuit <b>20</b> in the return of the circulatory system <b>40</b>, The metered external cooling medium together with the cooling medium of the Kreislaufsyste mes <b>40</b> into the buffer tank <b>22.2</b> promoted. You have the two cooling media mingle and create a temperature balance with each other. Characterized in that a temperature compensation in the buffer tank <b>22.2</b> takes place, a continuous cooling of the temperature <b>26</b> be achieved. If the differential temperature measurement shows that the measured Differential temperature is again below the set value, the dosing is unit <b>27</b> again caused to close.

Thus, the refrigerant circuit <b>10</b> not maintained at a steady-state operation must be, the controller <b>23</b> not shown, through a, in the drawing Control line to the compressor <b>11</b> connected. Under the aid of an the external cooling medium of the sub tank <b>22.1</b> arranged temperature sensor <b>22.6</b> is carried out a fixed set point control. In this case, the temperature of the measured external cooling medium and compared with a desired value. at Exceeding this target value, the compressor <b>11</b> by the controller <b>23</b> switched. The refrigerant circuit<b>10</b> then generated so long cooling capacity until the the temperature sensor <b>22.6</b> pending temperature again a default value below.