Compressor system and method for controlling a cooling device of a compressor system

Abstract

The invention relates to a compressor system (1), comprising: a compressor (10), a cooling device (40) and a control device (30), wherein the control device (30) is configured to control the cooling device (40) independently of the operation of the compressor (10) and to dynamically adjust a control variable (T Luft , #imgabs0#) and / or the actuator.

Description

Technical Field

[0001] The invention relates to a compressor system, a method for controlling a cooling device of a compressor system, and a machine-readable carrier designed therefor. Background Art

[0002] Compressors are used in numerous technical applications. Reducing noise emissions in modern rail vehicles is one example of an increasingly important area of ​​application. At the same time, temperature balance must be ensured across the entire temperature range (for example, between -40°C and +50°C in rail vehicles) and within confined installation spaces.

[0003] A conventional compressor system for air compressors in rail vehicles consists of a compressor and, if applicable, an aftercooler or (as in the case of two-stage piston compressors) an intercooler and an aftercooler. The compressor can be designed as a piston engine or a rotary compressor, for example as a screw or scroll compressor, and is usually air-cooled. The air cooling is provided by one or more fans that are operated in accordance with the compressor speed via mechanical or signal coupling.

[0004] However, high ambient temperatures and unfavorable space conditions often lead to compressor overheating. Conversely, this direct coupling, coupled with the resulting high cooling power at low intake air temperatures and short operating times, carries the risk of internal ice formation or condensation accumulation, with attendant operational limitations, increased wear, and increased corrosion. This creates a conflict of objectives that cannot be resolved with conventional cooling systems due to the coupling of the radiator fan speed to the compressor speed.

[0005] Furthermore, the operation of the cooling device can influence the temperature balance of the compressor system in such a way that conditions are optimal for the system components, but overall an unfavorable operating state is achieved. Summary of the Invention

[0006] In view of the above, it is therefore an object of the present invention to provide a compressor system, a method for controlling a cooling device of a compressor system and a computer program product for executing the method, which allow improved cooling of the compressor system.

[0007] This object is achieved by a compressor system, a method for controlling a cooling device of a compressor system, and a machine-readable carrier according to the invention.

[0008] According to the present invention, the compressor system comprises a compressor, a cooling device and a control device, wherein the control device is configured to control the cooling device independently of the operation of the compressor and to dynamically adjust a control variable of an actuator and / or the actuator in order to control the cooling device.

[0009] The cooling device of the compressor system can thus be operated independently of the compressor speed of the compressor, coordinated with the cooling power required for optimal operation. This can be achieved by separate signaling control of the cooling device's independent energy drive and / or, for example, by using a variable transmission ratio even when the cooling device is mechanically coupled to the compressor. Separate signaling control of the cooling device also has the advantage that, in this case, it is independent of whether the compressor is essentially switched on or off. Depending on the control phases / variants to be provided, mechanical coupling may also be no longer easily controllable due to the associated complexity.

[0010] In this context, separate control via signaling does not necessarily mean the use of separate control devices for the compressor and the cooling device. Rather, it refers to independent signal transmission and independent signal content. This independence is not limited to the fact that the compressor operating state is also taken into account when generating the signal for controlling the cooling device. For example, essentially independent control is possible, but at least one basic operation of the cooling device is set from a certain compressor speed.

[0011] The cooling device can also be operated via separate signaling. In operating states where the compressor and cooling device operate in parallel, mechanical coupling to the compressor's speed can support the cooling device's operation. In this sense, the cooling device remains independently controlled, with the coupling serving as an optional drive function or auxiliary drive. In other words, the cooling device can be mechanically coupled to the compressor and thus driven by it in certain operating states, for example, or when a required drive power level corresponds to the compressor's speed, to reduce energy consumption. Nevertheless, the compressor system still offers the possibility of independent control.

[0012] By controlling the cooling device independently of the compressor operation, the cooling device can be switched on and off as needed. This prevents or at least reduces overheating and / or condensate accumulation. In particular, such a cooling device can be used preventively in recurring operating situations.

[0013] However, the control of the cooling device independently of the operation of the compressor may be subject to various, sometimes mutually contradictory, optimization criteria, the weighting of which does not necessarily remain constant depending on the operating state. The control device is accordingly configured to dynamically adjust the control variable of the actuator and / or the actuator itself in order to control the cooling device.

[0014] A controlled variable is understood to be a variable based on which the actuator controls the cooling device or influences the manipulated variable. In this context, "dynamically adjusting the controlled variable of the actuator" means adjusting the control variable by selecting one, another, or both of the at least two available controlled variables. The selection of the controlled variable or variables to be used can be determined by their respective values ​​and / or can be coupled to certain operating states.

[0015] As an alternative or supplement to the dynamic control of the control variable, dynamic control of the actuator involves the actual conversion of the control variable into a manipulated variable. If, for example, only one control variable has been selected beforehand, the manipulated variable can be influenced by actuator control depending on the value of this control variable and / or the corresponding operating state. Dynamic control does not refer to the possibility of changing the manipulated variable in dependence on the control variable according to a specified transfer function, but rather to the control of the transfer function itself.

[0016] For example, multiple variables can be used to control a cooling device, with the control device selecting only one of the variables as the controlled variable, and the transfer function of the actuator remaining constant. In another example, all variables can be used as controlled variables, but the transfer function is adjusted based on the value of at least one of the controlled variables. Also by way of example, a combination of controlled variables and actuator adjustments is also possible.

[0017] The compressor system, in particular the compressor itself, can therefore be operated at an optimal operating point depending on the control variables. This not only has a positive effect on the efficiency and service life of the compressor system, but also avoids overloading of downstream components, thereby also increasing their efficiency and extending their service life.

[0018] The compressor system can be used in particular in an advantageous manner in rail vehicles.

[0019] In one embodiment, the control device is configured to specify a cooling fluid volume flow rate, in particular a cooling air volume flow rate, as the manipulated variable.

[0020] The cooling device therefore has a regulating device that can vary the volume of fluid provided per unit time for cooling. For example, this can be achieved by controlling the fluid flow rate accordingly via a valve position, or by controlling the output via the drive power, such as by controlling the flow rate based on the fan speed. Due to its readily available properties, using air as a cooling medium is a simple and economical solution. Even if air is not the only cooling medium, cooling can still be easily regulated by varying the air flow rate.

[0021] Alternatively or additionally, the cooling fluid temperature and / or the switch-on and switch-off times of the cooling device can also be used as manipulated variables.

[0022] According to the invention, the control device is configured to receive at least two control variables, one of which can be determined as a primary control variable and the other as a secondary control variable, in order to control the cooling device depending on the primary control variable and / or the secondary control variable.

[0023] The controlled variable that should be used first according to the specified control logic of the control device is determined as the primary controlled variable. If such a primary controlled variable does not require actuation according to predetermined conditions, the secondary controlled variable is considered independently and / or again with reference to the primary controlled variable. In other words, the primary controlled variable is always evaluated first, and therefore, the secondary controlled variable must influence actuation only if the primary controlled variable alone does not require actuation.

[0024] This, on the one hand, results in optimized cooling device control for at least two controlled variables. The selection of a primary controlled variable and the first weighting resulting from the associated decision criteria can simplify the control device by eliminating the need to constantly evaluate both variables or requiring the actuator's transfer function to take into account the corresponding evaluation results. Transfer functions can, for example, be cascaded. Furthermore, it is not necessary to constantly monitor both the primary and secondary controlled variables; instead, monitoring can be performed only as needed. For example, monitoring the secondary controlled variable is unnecessary as soon as the primary controlled variable alone has already caused the cooling device to be controlled. This reduces energy requirements and the amount of data to be transmitted.

[0025] According to the invention, the control device is configured to operate the cooling device in accordance with the primary controlled variable when the primary controlled variable is above a predetermined upper primary controlled variable limit value, and / or to operate the cooling device in accordance with the secondary controlled variable when the primary controlled variable is below or equal to a predetermined upper primary controlled variable limit value and at the same time the secondary controlled variable is above a predetermined secondary controlled variable limit value, and / or to operate the cooling device in accordance with the primary controlled variable and the secondary controlled variable when the primary controlled variable is below or equal to the predetermined upper primary controlled variable limit value and the secondary controlled variable is below the predetermined secondary controlled variable limit value.

[0026] Thus, if the cooling device is to be actuated according to the primary controlled variable, the primary controlled variable represents a variable that, regardless of other conditions, requires the cooling device to be actuated when the primary controlled variable exceeds a predetermined upper primary controlled variable limit value. In other words, the variable represented by the primary controlled variable accounts for a situation in which the cooling device cannot be adequately actuated based on other variables.

[0027] If a correspondingly predetermined upper primary manipulated variable limit value is exceeded, the cooling device is actuated as a function of the primary manipulated variable, as already described. To this end, either the actuator or its transfer function can be regulated as a function of the corresponding value of the primary manipulated variable, and / or the primary manipulated variable can be directly incorporated into the transfer function.

[0028] Alternatively or additionally, the control device designed as described above can control the cooling device according to the secondary controlled variable when the primary controlled variable is below or equal to a predetermined upper primary controlled variable limit value and the secondary controlled variable is simultaneously above a predetermined secondary controlled variable limit value.

[0029] The control device thus takes into account both the primary and secondary controlled variables, but the latter are decisive for the actuator or the transfer function. In a supplementary variant, this can involve cascade control of the cooling device, while an alternative variant can be used, for example, in combination with other cooling devices.

[0030] Furthermore, as an alternative or in addition, the control device of the aforementioned design can control the cooling device as a function of the primary manipulated variable and the secondary manipulated variable, i.e., when the primary manipulated variable is below or equal to the predetermined upper primary manipulated variable limit value, and the secondary manipulated variable is also below the predetermined secondary manipulated variable limit value. Thus, the control device also considers both the primary manipulated variable and the secondary manipulated variable, but both manipulated variables have a decisive influence on the actuator or the transfer function.

[0031] In particular, the control device is configured to control the cooling device in such a way that the cooling device is operated at maximum power when the primary manipulated variable is above a critical upper primary manipulated variable limit value, in particular greater than the predetermined upper primary manipulated variable limit value.

[0032] Therefore, the actuator is regulated in such a way that the manipulated variable corresponds to the maximum power of the cooling device. The maximum power of the cooling device can correspond to the maximum power technically available by the cooling device or a specified maximum power. The specified maximum power can, for example, be a power that is lower than the technically available power, but which should nevertheless be preferred for long-term operation or be considered sufficient even in the case of low energy consumption.

[0033] In principle, the critical upper primary manipulated variable limit value can be equal to the predetermined upper primary manipulated variable limit value, wherein the cooling device is always operated at maximum power when the predetermined upper primary manipulated variable limit value is exceeded. However, this is undesirable for reasons of efficiency and due to disadvantages with excessively high cooling power, so that the critical upper limit value is in particular higher than the predetermined upper primary manipulated variable limit value.

[0034] As an alternative or in addition, the control device is configured to control the cooling device in such a way that, when the primary controlled variable lies above the predetermined upper primary controlled variable limit value, the cooling device is operated at a power proportional to the primary controlled variable up to its maximum power (i.e., before its maximum power is exceeded).

[0035] Therefore, the manipulated variable can be derived from the primary controlled variable multiplied by a scaling factor, according to the formula: Manipulated variable = a * primary controlled variable, where a is the primary controlled variable scaling factor. If the manipulated variable corresponds to the power of the cooling system, the applicability of this formula is limited by the maximum power. As the maximum power is reached, the actuator or transfer function can then be adjusted so that the manipulated variable corresponds to the maximum power. However, corresponding logic can also be incorporated into the control path for converting the controlled variable into the variable to be controlled, thereby limiting the power to the maximum power when the manipulated variable exceeds the maximum power.

[0036] According to a particular embodiment, as a supplement, a critical upper primary controlled variable limit value, which is higher than the upper primary controlled variable limit value, is stored in the control system. The cooling device is then operated at a power proportional to the primary parameter until the critical upper primary controlled variable limit value is exceeded, and at maximum power when the critical upper primary controlled variable limit value is exceeded. Consequently, upon exceeding the critical upper primary controlled variable limit value, the actuator is regulated to convert the corresponding controlled variable into a manipulated variable, and the primary controlled variable no longer enters the transfer function.

[0037] Operating the cooling system at a power level lower than its maximum capacity allows for reduced energy consumption and noise emissions. Furthermore, the reduced cooling effort can reduce other adverse effects, such as increased water absorption at lower temperatures and the resulting risk of corrosion. This control thus allows for operation of the cooling system tailored to the operating conditions.

[0038] Also as an alternative or in addition, the control device is configured to control the cooling device in such a way that, when the primary controlled variable is below or equal to the predetermined upper primary controlled variable limit value and the secondary controlled variable is above the predetermined secondary controlled variable limit value, or when the secondary controlled variable is below or equal to the predetermined secondary controlled variable limit value and the primary controlled variable is above or equal to a predetermined lower primary controlled variable limit value, the cooling device is operated at a power proportional to the secondary controlled variable until its maximum power is reached.

[0039] Therefore, the manipulated variable can be obtained by multiplying the secondary controlled variable by a proportional coefficient, that is, according to the formula:

[0040] Manipulated variable = b*secondary controlled variable,

[0041] Here, b is the secondary controlled variable proportionality factor. Here, the maximum power also needs to be taken into account when the power of the cooling device acts as an actuator. If the cooling device is controlled, for example, via the primary controlled variable when the upper primary controlled variable limit value is exceeded, it is conceivable that the control device is designed so that the manipulated variable according to the secondary controlled variable does not exceed the manipulated variable according to the primary controlled variable, so that maximum power is not required when controlling according to the secondary controlled variable. The corresponding design of the control device can then correspond to the condition: b*maximum secondary controlled variable ≤ a*minimum primary controlled variable. However, it is also possible to specify a maximum power for control according to the secondary controlled variable that is different from that for control via the primary controlled variable. Here, a distinction must then be made between a maximum secondary controlled variable power and a maximum primary controlled variable power, which should each apply to the maximum power.

[0042] According to the control described above, in any case, when the primary manipulated variable is below or equal to the predetermined upper primary manipulated variable limit value and the secondary manipulated variable is between the predetermined upper primary manipulated variable limit value and a predetermined secondary manipulated variable limit value, the cooling device is operated at a power proportional to the secondary manipulated variable, up to the point of reaching its maximum power. If the predetermined secondary manipulated variable value is reached or fallen below, the primary manipulated variable value is decisive for the actuator. To provide a power proportional to the secondary manipulated variable, the actuator control presupposes that the primary manipulated variable is above or equal to a predetermined lower primary manipulated variable limit value. Thus, the actuator control takes both the primary and secondary manipulated variables into account.

[0043] Here too, the already explained advantages of controlling the cooling device in accordance with the respective operating conditions result.

[0044] Furthermore, as an alternative or in addition, the control device is configured to operate the cooling device in such a way that the cooling device is switched off when the secondary controlled variable is lower than or equal to the predetermined secondary controlled variable limit value and the primary controlled variable is lower than a predetermined lower primary controlled variable limit value.

[0045] Reaching or falling below a predetermined secondary control variable limit value and falling below the lower primary control variable limit value means that there is no need to operate the cooling device, either with regard to the secondary control variable or with regard to the primary control variable, so that the cooling device can be disconnected or shut down in order to save energy or reduce noise emissions.

[0046] In one construction design, the compressor system includes at least one air temperature detection unit for detecting air temperature and at least one oil temperature detection unit for detecting oil temperature, wherein the air temperature detection unit and the oil temperature detection unit are connected to a control device via signal technology, wherein the control device is configured to determine the detected air temperature as a primary controlled variable and the detected oil temperature as a secondary controlled variable and / or vice versa.

[0047] The air temperature and the oil temperature can be detected directly or indirectly by the air temperature detection unit and the oil temperature detection unit. For example, the air temperature and the oil temperature can be detected indirectly by detecting a temperature of a corresponding component corresponding to the air temperature or the oil temperature.

[0048] Defining air temperature as the primary controlled variable allows it to be considered a critical variable for the primary criterion. Oil temperature serves as a secondary controlled variable, as excessively high oil temperatures cause oil aging, while excessively low oil temperatures lead to increased water absorption. As long as there's no need to manipulate the air temperature as the primary controlled variable, the temperature range for the oil temperature as the secondary controlled variable can be optimized. Overall, this results in controlled cooling systems adapted to the respective operating conditions for the optimal temperature range. This reduces the risk of corrosion and component wear in the compressor system. At the same time, switching on the compressor for short periods of time is less prone to problems.

[0049] Alternatively, however, the oil temperature can be determined as the primary controlled variable and the air temperature as the secondary controlled variable. This can be advantageous if, for example, water absorption by the oil or oil aging is to be specified as a critical variable. The configuration of the oil temperature as the primary controlled variable and the air temperature as the secondary controlled variable, and vice versa, can also be adjusted accordingly, for example, depending on predetermined operating conditions or other specified values ​​or input options.

[0050] The detection or evaluation of the secondary control variable does not necessarily have to be performed simultaneously with the detection or evaluation of the primary control variable. For example, the detection or evaluation of the control variable can be arranged only when the primary control variable is not above an upper primary control variable value.

[0051] In particular, the air temperature detection unit and the oil temperature detection unit are arranged at corresponding output ends of the compressor.

[0052] The air temperature detection unit is therefore located in the area of ​​the compressor's air outlet. The oil temperature unit measures the oil temperature in the oil sump area and is, for example, located in the area of ​​the oil sump's oil outlet. Thus, the detection is performed at the location where the highest air or oil temperatures are expected to occur, respectively. Alternatively or additionally, the air temperature detection unit can also detect the temperature of the air flowing out of an aftercooler located downstream of the compressor. Similarly, the oil temperature detection unit can detect the temperature of the oil flowing through the downstream internal and / or external oil circuit.

[0053] In one embodiment, the compressor system is designed as an oil-lubricated compressor, in particular as an oil-lubricated screw compressor.

[0054] Oil-lubricated compressors must cover a wide range of climatic conditions, for example, operating in temperatures from -40°C to +50°C, and the cooling requirements can vary greatly during operation. The load factor, for example, is also a significant factor here. Process air and oil can be considered as the media to be cooled, but this can lead to optimization conflicts. On the one hand, the oil must reach operating temperature as quickly as possible, while at the same time the air temperature at the cooler outlet must not rise too much. Variable cooling is particularly helpful in ensuring the best possible operation.

[0055] In another aspect, the present invention relates to a method for controlling a cooling device of the above-mentioned compressor system, comprising the following steps:

[0056] - Test at least two control variables and

[0057] - controlling the cooling device based on the detected control variable,

[0058] In order to control the cooling device as a function of the detected control variable, the control variable of the actuator and / or the actuator is dynamically adjusted.

[0059] The features and advantages of the method result in analogy to the description of the compressor system.

[0060] In the method, the control device determines one detected control variable as a primary control variable and another detected control variable as a secondary control variable, and, when the primary control variable is above a predetermined upper primary control variable limit value, the control device operates the cooling device according to the primary control variable, when the primary control variable is below or equal to a predetermined upper primary control variable limit value and the secondary control variable is above a predetermined secondary control variable limit value, the control device operates the cooling device according to the secondary control variable, and / or when the primary control variable is below or equal to the predetermined upper primary control variable limit value and the secondary control variable is below the predetermined secondary control variable limit value, the control device operates the cooling device according to the primary control variable and the secondary control variable.

[0061] Reference is also made here to the corresponding detailed description of the compressor system.

[0062] In particular, the control device actuates the cooling device as follows:

[0063] a) operating the cooling device at maximum power when the primary manipulated variable is above a critical upper primary manipulated variable limit value, in particular above the predetermined upper primary manipulated variable limit value,

[0064] b) operating the cooling device at a power proportional to the primary manipulated variable up to its maximum power when the primary manipulated variable is above the predetermined upper primary manipulated variable limit value,

[0065] c) when the primary controlled variable is below or equal to said predetermined upper primary controlled variable limit and the secondary controlled variable is above said predetermined upper secondary controlled variable limit, or

[0066] When the secondary controlled variable is lower than or equal to the predetermined secondary controlled variable limit and the primary controlled variable is higher than or equal to a predetermined lower primary controlled variable limit,

[0067] operating the cooling device at a power proportional to the secondary controlled variable up to its maximum power, and / or

[0068] d) shutting down the cooling device when the secondary controlled variable is lower than or equal to the predetermined secondary controlled variable limit value and the primary controlled variable is lower than a predetermined lower primary controlled variable limit value.

[0069] The explanations given in this connection for the compressor system also apply to the design of the method described above.

[0070] Furthermore, the present invention relates to a machine-readable carrier on which program code of a computer program product is stored, wherein the program code is designed to cause a data processing device to execute the above-mentioned method when the program code is executed on the data processing device.

[0071] The computer program product makes it possible in particular to retrofit a cooling device of a conventional compressor system that is controlled by signal technology in a simple manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The present invention will be explained in detail below with reference to the accompanying drawings, using an embodiment.

[0073] Figure 1 shows a schematic diagram of a compressor system according to a first embodiment of the present invention;

[0074] Figure 2 Shows a schematic design concept diagram for operating a cooling device, which can be applied to Figure 1 The compressor system shown;

[0075] Figure 3 A flow chart for operating a cooling device is shown, which can be applied to Figure 1 Compressor system shown. DETAILED DESCRIPTION

[0076] Figure 1A schematic diagram of a compressor system 1 is shown, which is designed here as an oil-lubricated screw compressor system by way of example, and includes a compressor 10 (here a screw compressor) and an aftercooler 20. Air to be compressed is first guided through the compressor 10 according to arrows representing process air flow 60, compressed there, and then flows through the aftercooler 20. The compressor system 1 also includes a control device 30, which actuates a cooling device, which in the present embodiment includes a fan 40. During operation, the fans can each generate a cooling air volume flow 41, which is directed primarily to the compressor 10 and / or the compressor outlet via a fan 40, primarily to the aftercooler outlet and / or the aftercooler 20 via a fan 40, and primarily to an oil cooler 21 (described later) and / or its outlet via a fan 40. The control device 30 is designed here to regulate both the switching on and off times of the fan 40 and the cooling air volume flow rate of the fan 40 by controlling the fan speed corresponding to the fan output. The fan output is controlled identically in each case. As an alternative, it is also possible to provide that the manipulated variables of the corresponding fans 40 are set to different, that is, for example, different transfer functions and / or proportionality factors used when necessary are selected. In another structural design, only one fan 40 can be provided as a cooling device.

[0077] The compressor 10 also includes an oil sump 11, in which oil can flow through an internal oil circuit 23 and an external oil circuit 22 that is guided through an oil cooler 21. The guidance of oil through the external oil circuit 22 can be coupled to the operation of a cooling device or a fan 40. For example, the oil is guided through the external oil circuit only when a primary manipulated variable exceeds a predetermined upper primary manipulated variable limit value or a secondary manipulated variable exceeds a predetermined secondary manipulated variable limit value, as will be explained in detail below.

[0078] An air temperature detection unit 50 a is provided at the output end of the process air 60 of the compressor 10 , which detects the air temperature T at the output end of the compressor 10 . Luft As an alternative, the air temperature detection unit may also be provided at the output end of the aftercooler 20. In addition, an oil temperature detection unit 50b is provided at the output end 11a of the oil pan 11, which detects the oil temperature T at the output end of the oil pan 11. Öl As an alternative, the oil temperature detection unit may also be provided at the output end of the oil cooler 21 , for example.

[0079] In the present embodiment, the control device 30 sets the air temperature T Luft Determine as the primary control variable, and the oil temperature TÖl Determined as the secondary control variable to adjust the air temperature T according to the detected air temperature Luft and / or oil temperature T Öl The fan 40 is controlled.

[0080] Figure 2 For this purpose, a schematic design concept sketch of the control fan 40 is shown. In the embodiment shown, the air temperature T currently detected by the air temperature detection unit 50a and the oil temperature detection unit 50b is Luft (as the primary control variable) and the oil temperature T Öl The value of the primary controlled variable (as a secondary controlled variable) is transmitted to the control device 30. The transmission can take place via a cable or wirelessly. Even when both signals are transmitted simultaneously, it is possible, for example, to detect and / or transmit the secondary controlled variable only as required. In one variant, for example, the secondary controlled variable is detected and transmitted only when the primary controlled variable is below or equal to a predetermined upper primary control limit value.

[0081] The control device 30 then selects the control variable or the control variables to be used and / or the applicable transfer function as a function of the value of the primary control variable and / or the value of the secondary control variable. To control the fan 40, the control variables and / or the actuators are dynamically adjusted accordingly.

[0082] With the help of Figure 3 The flow chart shown in FIG. 4 illustrates by way of example the use of actuation of a control variable and / or a dynamically controlled actuator for the control of the fan 40 . For this purpose, the air temperature T is read as the primary control variable. Luft , read the oil temperature T as the secondary control variable Öl As a decision basis for selecting the control variable and transfer function to be used specifically for the control of the actuator, a critical upper air temperature limit value T is stored in the control system. Luft,krit. As the critical upper primary controlled variable limit value, an upper air temperature limit value T is stored. Luft,max. As the upper primary controlled variable limit value, an oil temperature limit value T is stored. Öl,min. As a secondary controlled variable limit value and store a lower air temperature limit value T Luft,aus As the lower primary control variable limit value. The critical upper air temperature limit value T Luft,krit. This corresponds to an air temperature which can indicate a risk to the compressor system, so that maximum cooling is required. The critical upper air temperature limit value T Luft,krit. Higher than the upper air temperature limit value T Luft,max. (This results in a cooling that does not have to be achieved with maximum power). The oil temperature limit value TÖl,min. corresponds to the lowest oil temperature, while the lower air temperature limit value T Luft,aus This corresponds to a maximum air temperature, up to which the fan 40 is allowed to be switched off.

[0083] If the detected air temperature T Luft Above the critical upper air temperature limit value T Luft,krit. , the fan 40 is operated at maximum power. Here, the power P as the manipulated variable is generated by P = 100%, where 100% here refers to the technically specified maximum power. However, 100% may also be another predetermined maximum value that is not specified by the fan 40 itself. In this embodiment, the power P of the fan 40 is related to the fan speed and, therefore, the cooling air volume flow rate provided by the fan 40.

[0084] If the critical upper air temperature limit value T is not exceeded Luft,krit. If so, then ask, air temperature T Luft Is it higher than the upper air temperature limit value T Luft,max. If this is the case, the fans 40 are set to a temperature that is consistent with the air temperature T Luft Proportional power operation. Therefore similar to a P = a * T Luft The corresponding transfer function generates the manipulated variable P. If the fans 40 should be controlled differently, a different proportional coefficient a can be selected for each fan as needed. In addition, the transfer function can also have an additional addend or subtractor, such as P=a*T Luft + Offset, in order to be able to prescribe a base power or a power reduction, for example.

[0085] If the air temperature T Luft The upper air temperature limit T is not exceeded Luft,max. If the oil temperature is T Öl For controlling the fan 40. Öl Higher than the oil temperature limit T Öl,min. , the fans 40 are respectively set to a temperature corresponding to the oil temperature T Öl Proportional power operation. Therefore similar to a P = b * T Öl A corresponding transfer function generates the manipulated variable P. Here, the fan 40 can also be actuated with different powers by selecting the proportionality factor b and / or the transfer function can have an additional addend or subtractor.

[0086] If the oil temperature T Öl Not higher than the oil temperature limit T Öl,min. , then the previously detected air temperature TLuft The control device 30 performs an evaluation. If in such a case the air temperature T Luft Higher than or equal to the lower air temperature limit value T Luft,aus If the oil temperature is higher than the oil temperature limit value T Öl,min. However, if the air temperature T Luft Lower than the lower air temperature limit value T Luft,aus If so, the fan 40 is turned off.

[0087] Although the flowchart shows a serial query, parallel evaluation is also possible by assigning the detected primary and secondary controlled variables to a category that can be assigned via a corresponding query, for example, by measuring the temperature and comparing it with table values. With regard to the control results, parallel evaluation is equivalent to serial evaluation. However, serial querying makes it possible, for example, to read the secondary controlled variables only as needed.

[0088] Furthermore, the present invention is not limited to the described embodiments. Although a cooling device using a fan has been described, other cooling devices may also be used, such as a heat exchanger, through which the air from the compressor system passes and / or through. The cooling capacity of the heat exchanger can be adjusted by the positioning and orientation of the heat exchanger and / or, in the case of a heat transfer medium flowing through the heat exchanger, by the cooling fluid volume flow rate, the cooling fluid volume flow temperature, and / or by changing the heat transfer medium.

[0089] Reference Signs List

[0090] 1. Compressor system

[0091] 10. Compressor

[0092] 10a Output (air)

[0093] 11 Oil pan

[0094] 11a Output (oil)

[0095] 20 Aftercooler

[0096] 21 Oil cooler

[0097] 22 External oil circulation

[0098] 23 Internal oil circulation

[0099] 24 Intercooler

[0100] 30 Control device

[0101] 40 Fan

[0102] 41 Cooling air volume flow

[0103] 50a Air temperature detection unit

[0104] 50b Oil temperature detection unit

[0105] 60 process air flow

[0106] T Luft Air temperature

[0107] T Luft,aus Lower air temperature limit

[0108] T Luft,krit. Critical upper air temperature limit

[0109] T Luft,max. Upper air temperature limit

[0110] T Öl Oil temperature

[0111] T Öl,min. Oil temperature limit

Claims

1. A compressor system (1), comprising: compressor (10), Cooling device (40) and a control device (30), The control device (30) is configured to control the cooling device (40) independently of the operation of the compressor (10) and to dynamically adjust the control variable (T Luft , T Öl ) and / or said actuator, The control device (30) is configured to receive at least two control variables (T Luft , T Öl ), where one of the control variables can be identified as the primary control variable (T Luft ) and another control variable can be determined as a secondary control variable (T Öl ), so that according to the primary control variable (T Luft ) and / or the secondary control variable (T Öl ) operates the cooling device (40), and The control device (30) is configured to, when the primary control variable (T Luft ) is above a predetermined upper primary control variable limit (T Luft,max. ), according to the primary control variable (T Luft ) controls the cooling device (40), and / or when the primary control variable (T Luft ) is lower than or equal to a predetermined upper primary control variable limit value (T Luft,max. ) and the secondary control variable (T Öl ) is higher than a predetermined secondary control variable limit value (T Öl,min. ), according to the secondary control variable (T Öl ) controls the cooling device (40), and / or when the primary control variable (T Luft ) is lower than or equal to the predetermined upper primary control variable limit value (T Luft,max. ) and the secondary control variable (T Öl ) is lower than the predetermined secondary control variable limit value (T Öl,min. ), according to the primary control variable (T Luft ) and the secondary control variable (T Öl ) controls the cooling device (40).

2. The compressor system (1) according to claim 1, wherein The control device (30) is configured to specify a cooling fluid volume flow rate as a manipulated variable.

3. The compressor system (1) according to claim 1 or 2, wherein: The control device (30) is configured to operate the cooling device (40) in the following manner, that is, when the primary control variable (T Luft ) is above a critical upper primary control variable limit (T Luft,krit. ), the cooling device (40) is operated at maximum power.

4. The compressor system (1) according to claim 1 or 2, wherein: The control device (30) is configured to operate the cooling device (40) in the following manner, that is, when the primary control variable (T Luft ) is above the predetermined upper primary control variable limit value (T Luft,max. ), the cooling device (40) is made to reach its maximum power at most to match the primary control variable (T Luft ) operates in proportion to the power.

5. The compressor system (1) according to claim 1 or 2, wherein: The control device (30) is configured to operate the cooling device (40) in the following manner, that is, when the primary control variable (T Luft ) is lower than or equal to the predetermined upper primary control variable limit value (T Luft,max. ) and the secondary control variable (T Öl ) is higher than the predetermined secondary control variable limit value (T Öl,min. ), or when the secondary control variable (T Öl ) is lower than or equal to the predetermined secondary control variable limit value (T Öl,min. ) and the primary control variable (T Luft ) is greater than or equal to a predetermined lower primary control variable limit (T Luft,aus ), the cooling device (40) is made to reach its maximum power at most to match the secondary control variable (T Öl ) operates in proportion to the power.

6. The compressor system (1) according to claim 1 or 2, wherein the control device (30) is configured to operate the cooling device (40) in the following manner, that is, when the secondary control variable (T Öl ) is lower than or equal to the predetermined secondary control variable limit value (T Öl,min. ) and the primary control variable (T Luft ) is below a predetermined lower primary control variable limit (T Luft,aus ), the cooling device (40) is turned off.

7. The compressor system (1) according to claim 1 or 2, wherein: The compressor system (1) comprises at least one air temperature detection unit (50a) for detecting air temperature and at least one oil temperature detection unit (50b) for detecting oil temperature, wherein the air temperature detection unit and the oil temperature detection unit are connected to the control device (30) via signal technology, and the control device (30) is configured to detect the air temperature (T Luft ) is determined as the primary control variable (T Luft ) and the detected oil temperature (T Öl ) is determined as the secondary control variable (T Öl ) and / or vice versa.

8. The compressor system (1) according to claim 7, wherein The air temperature detection unit (50a) and the oil temperature detection unit (50b) are arranged at corresponding output ends (10a, 11a) of the compressor (10).

9. The compressor system (1) according to claim 1 or 2, wherein: The compressor system (1) is designed as an oil-lubricated compressor.

10. The compressor system (1) according to claim 2, wherein The control device (30) is configured to specify the cooling air volume flow rate as a manipulated variable.

11. The compressor system (1) according to claim 3, wherein: The critical upper primary controlled variable limit value is higher than the predetermined upper primary controlled variable limit value (T Luft,max. ).

12. The compressor system (1) according to claim 9, wherein The compressor system (1) is designed as an oil-lubricated screw compressor.

13. A method for controlling a cooling device (40) of a compressor system (1) according to any one of claims 1 to 12, comprising the steps of: - Test at least two control variables (T Luft , T Öl )and - Based on the detected control variables (T Luft , T Öl ) controls the cooling device (40), In order to determine the control variable (T Luft , T Öl ) controls the cooling device (40) and dynamically adjusts the control variable (T Luft , T Öl ) and / or actuator, wherein the control device determines one of the detected control variables as a primary control variable (T Luft ) and determining another detected control variable as a secondary control variable (T Öl ), and when the primary control variable (T Luft ) is above a predetermined upper primary control variable limit (T Luft,max. ), the control device is configured to control the primary control variable (T Luft ) controls the cooling device (40), when the primary control variable (T Luft ) is lower than or equal to a predetermined upper primary control variable limit value (T Luft,max. ) and the secondary control variable (T Öl ) is higher than a predetermined secondary control variable limit value (T Öl,min. ), the control device adjusts the secondary control variable (T Öl ) controls the cooling device (40), and / or when the primary control variable (T Luft ) is lower than or equal to the predetermined upper primary control variable limit value (T Luft,max. ) and the secondary control variable (T Öl ) is lower than the predetermined secondary control variable limit value (T Öl,min. ), the control device is configured to control the primary control variable (T Luft ) and the secondary control variable (T Öl ) controls the cooling device (40).

14. The method according to claim 13, wherein The control device (30) controls the cooling device (40) as follows: a) When the primary control variable (T Luft ) is above a critical upper primary control variable limit (T Luft,krit. ), the cooling device (40) is operated at maximum power, b) When the primary control variable (T Luft ) is above the predetermined upper primary control variable limit value (T Luft,max. ), the cooling device (40) is made to reach its maximum power at most to match the primary control variable (T Luft ) is proportional to the power (P) operation, c) When the primary control variable (T Luft ) is lower than or equal to the predetermined upper primary control variable limit value (T Luft,max. ) and the secondary control variable (T Öl ) is higher than the predetermined secondary control variable limit value (T Öl,min. ) or When the secondary control variable (T Öl ) is lower than or equal to the predetermined secondary control variable limit value (T Öl,min. ) and the primary control variable (T Luft ) is greater than or equal to a predetermined lower primary control variable limit (T Luft,aus )hour, The cooling device (40) is operated until it reaches its maximum power in accordance with the secondary control variable (T Öl ) proportional to power (P), and / or d) When the secondary control variable (T Öl ) is lower than or equal to the predetermined secondary control variable limit value (T Öl,min. ) and the primary control variable (T Luft ) is below a predetermined lower primary control variable limit (T Luft,aus ), the cooling device (40) is turned off.

15. The method according to claim 14, wherein The critical upper primary controlled variable limit value is higher than the predetermined upper primary controlled variable limit value (T Luft,max. ). 16 . A machine-readable carrier on which the program code of a computer program product is stored, the program code being designed such that, when the program code is executed on a data processing device, the data processing device is caused to carry out the method according to claim 13 .

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