COMPRESSOR SYSTEM FOR A RAIL VEHICLE AND METHOD FOR CONTROLLING A COOLING DEVICE OF A COMPRESSOR SYSTEM

Description

[0001] The invention relates to a compressor system for a rail vehicle, a method for controlling a cooling device of a compressor system, and a computer program product provided for this purpose.

[0002] Compressors are used in a wide variety of technical applications. In modern rail vehicles, for example, reducing noise emissions is becoming increasingly important. At the same time, the compressor's temperature must be maintained across the entire temperature range, for example, between -40°C and +50°C in rail vehicles, and even in confined installation spaces.

[0003] Conventional air compressor systems for rail vehicles comprise a compressor and, optionally, an aftercooler or, as in the case of two-stage piston compressors, an intermediate and an aftercooler. The compressor can be a piston engine or a rotary compressor, such as a screw or scroll compressor, and is predominantly air-cooled. This air cooling is achieved via fans, such as one or more fans or electric fans, which are mechanically or electronically linked to the compressor speed.

[0004] Despite high ambient temperatures and unfavorable room conditions, compressor overheating is a frequent occurrence. Conversely, this direct coupling, with its high cooling capacity at low intake temperatures and short operating times, poses a risk of internal ice formation or condensation accumulation, leading to operational limitations, increased wear, and corrosion. This creates a conflict of objectives that cannot be resolved with conventional cooling systems due to their coupling of the cooling fan speed to the compressor speed.

[0005] In this context, CN 110318983 A relates to an operational control system for preventing icing of an air compressor for a rail vehicle. In this system, a cooling impeller is arranged on a heat radiant heater and can be controlled independently. DE 20 2017 001 925 U1 relates to a control unit for a compressor, wherein a first inverter is configured to control the first variable-speed motor driving the compressor element, and a second inverter is configured to control a second variable-speed motor driving a fan designed to cool the compressor.WO 2015 / 082430 A1 concerns a compressor system for a rail vehicle, comprising a compressor driven by an electric motor via a drive shaft for generating compressed air, wherein the electric motor can be controlled, at least indirectly, via a control device, to operate the electric motor at at least one rated speed between a maximum and a minimum speed. The control device controls, at least indirectly, a cooling unit with a cooling fan located downstream of the compressor, wherein the speed of the cooling fan can be continuously adjusted by the control device.

[0006] In view of the foregoing, it is therefore an object of the invention to provide a compressor system, a method for controlling a cooling device of a compressor system, and a computer program product for carrying out the method, which enables improved cooling of the compressor system.

[0007] The problem is solved by a compressor system, a method for controlling a cooling device of a compressor system, and a computer program product according to the independent claims. Advantageous embodiments of the invention are contained in the dependent claims.

[0008] According to the invention, the compressor system comprises a compressor, a cooling device, and a control device. According to one disclosure, the compressor system has an interface for receiving control signals from a control device. According to the invention, the control device is configured to control the cooling device independently of the operation, in particular the speed, of the compressor.

[0009] The cooling unit of the compressor system can thus be operated independently of the compressor speed, adjusted to the cooling capacity required for optimal operation. This can be implemented via a separate signal-based control of an independent energy drive for the cooling unit and / or, for example, even with a mechanical coupling of the cooling unit to the compressor, through the use of switchable gear ratios. A separate signal-based control of the cooling unit also offers the advantage that, in such a case, the control is independent of whether the compressor is generally switched on or off.

[0010] Separate signal control does not necessarily require separate control devices for the compressor and the cooling unit, but rather aims at independent signal transmission and independent signal content. This independence is not limited by the fact that compressor operating states may also be considered when generating the signal to control the cooling unit. For example, fundamentally independent control is possible, although a basic level of operation of the cooling unit is maintained above a certain compressor speed.

[0011] The cooling unit can be operated via a separate signal control system. In operating states where the compressor is operated in parallel with the cooling unit, a mechanical coupling to the compressor speed can support the operation of the cooling unit. In this sense, the control of the cooling unit remains independent, with the coupling merely representing a selectable drive function or drive support.

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

[0013] This allows the compressor system, and especially the compressor itself, to operate at its optimal operating point. This not only has a positive effect on the efficiency and service life of the compressor system, but can also prevent an overload of a downstream dryer due to excessively high dryer inlet temperatures, thereby also increasing its efficiency and the service life of the desiccant.

[0014] Furthermore, the cooling device is configured to provide a variable cooling fluid volume flow rate, in particular a cooling air volume flow rate, which can be specified as a control variable by the control device.

[0015] In this context, it should be noted that the control device is not limited to simply controlling the cooling system, but, depending on its design, can also be used for regulation. This is the case when a corresponding control variable is monitored and compared. Where the term "control" is used, it can encompass regulation, i.e., it can be extended to include it, for example, if corresponding detection units are provided, or will be provided, provided that these are not mutually exclusive.

[0016] The cooling system thus features an adjustment mechanism that can vary the volume of fluid supplied for cooling per unit of time. For example, the flow rate of a fluid can be controlled via a valve position, or the generated volume can be controlled via a drive power, such as a flow rate corresponding to a fan speed. Due to its widespread availability, the use of air as a coolant represents a simple and cost-effective solution. Even if air is not used exclusively as a coolant, the cooling can be easily adjusted, at least by varying the airflow rate.

[0017] Alternatively or additionally, the cooling fluid temperature and / or the switching on and off times of the cooling device can also be used as control variables.

[0018] The compressor system can be simplified if it does not include its own control device for controlling the cooling unit and / or the compressor, but merely has an interface for receiving a corresponding external control device.

[0019] In one embodiment of the compressor system, the control device is a central control device, in particular an inverter, of the compressor system. According to a disclosure, the compressor system has an interface for receiving control signals from a central control device of the rail vehicle.

[0020] A central control unit for a rail vehicle can take into account additional factors influencing the control of the cooling system and / or the compressor. This central intelligence can also include self-learning functionalities to accelerate, refine, and / or coordinate the response to specific conditions with other functional components of the rail vehicle. Self-learning functionalities of the control unit can prevent unfavorable operating situations, for example, by operating the compressor with a low duty cycle and optimizing the duty cycle and activation behavior of the cooling system to ensure an optimal average temperature across all activation cycles.For example, the cooling system can only be activated once the minimum temperature required for optimal (low-wear) operation of a critical component has been reached, and the cooling capacity is regulated based on one or more key process parameters, such as temperature and / or pressure. The above explanations regarding the central control unit of the rail vehicle can be applied analogously to the central control unit of the compressor system. To account for additional influencing factors not directly provided by the central control unit of the compressor system, appropriate interfaces for receiving corresponding input signals can be provided as needed.

[0021] According to the invention, the compressor system includes a temperature detection unit for detecting air and oil temperatures. Additionally, the compressor system can also include a temperature detection unit for detecting component temperatures. The control device is configured to control the cooling system based on the air and oil temperatures detected by the temperature detection unit, and optionally, the component temperature.

[0022] Accordingly, the manipulated variable is adjusted via a control mechanism based on at least one temperature signal. Temperature measurements allow direct inferences to be drawn about the probability of overheating and / or condensation, enabling, for example, adjustments to the manipulated variable based on limit values ​​stored in the control device or other algorithms. A corresponding temperature detection unit can comprise one or more temperature sensors.

[0023] Measuring component temperature allows not only the detection and mitigation of general overheating and / or condensation risks, but also the monitoring of component temperature with regard to excessive wear and aging, for example, of elastomers, bearing greases, piston rings, or other temperature-sensitive materials. Even if actual overheating does not occur, the component's temperature data can be documented to adjust maintenance intervals accordingly. This also applies to measuring oil temperature.

[0024] Alternatively or additionally, other measured variables that correlate with the probability of overheating and / or condensation can also be used to control the cooling system. For example, a humidity sensor can be used to monitor for condensation or its probability.

[0025] According to the invention, the compressor system comprises an aftercooler and optionally an intercooler, which are located downstream of the compressor in the direction of air flow through the compressor, and the control device is configured to control the cooling device based on an aftercooler outlet temperature and optionally an intercooler outlet temperature of the air and an oil sump temperature.

[0026] By measuring the aftercooler outlet temperature and, optionally, the intercooler outlet temperature of the air, the cooling capacity of the aftercooler and, optionally, the intercooler (which, for example, in two-stage compressors, is located downstream of the first compression stage of the compressor, before the second compression stage and subsequently the aftercooler) is passed through, is taken into account with regard to the probability of overheating and / or condensation. Thus, the control of the cooling system can be independent of the performance data or operating settings of the compressor and the respective cooler; that is, the respective temperature is detected directly and not indirectly derived from other parameters, which would, in principle, be possible.In the case of an indirect derivation, for example, when measuring the compressor outlet temperature of the air, the further cooling by the aftercooler and / or the intercooler would have to be represented in the control device, which increases the complexity of the control algorithms and disregards deviations of the assumed cooling capacity of the aftercooler and / or the intercooler from the actual cooling capacity.

[0027] Furthermore, by additionally measuring the oil sump temperature, the entry of water into the oil at excessively low temperatures and a temperature-related reduction in oil lifespan can be counteracted by adjusting the control of the cooling system accordingly.

[0028] Furthermore, it can be advantageous to measure both the aftercooler outlet temperature and the oil sump temperature in order to control the cooling system in a way that is tailored to both temperatures. Likewise, the failure of one temperature detection unit can be compensated for by the other. In addition to redundant design, the parallel measurements also allow for plausibility checks, which provide valuable insights into malfunctions of the temperature detection units. This also applies to the use of multiple sensors in a single temperature detection unit. These advantages are not limited to the aftercooler outlet temperature of the air and the oil sump temperature, but apply equally to measurements taken by other detection units that measure at least two different parameters.

[0029] In one embodiment, the aforementioned temperature detection unit or a further temperature detection unit is provided in the area of ​​an aftercooler and / or the intercooler of the compressor system, in particular in the airflow on a downstream side of the aftercooler and / or the intercooler.

[0030] As previously explained, considering the temperature in the aftercooler area simplifies the design of the control algorithm and increases the reliability of the control. The acquired measurement signal can be used alone or in conjunction with other measurement signals. In particular, measuring in the airflow downstream of the aftercooler can be advantageous with regard to the placement of a temperature detection unit due to its easy accessibility.

[0031] According to the invention, the control device is configured to take into account a differential adjustment of the aftercooler outlet temperature of the air and the oil sump temperature with a respective predetermined limit value of the aftercooler outlet temperature of the air and the oil sump temperature as an input variable for controlling the cooling device, in particular to use the differential adjustment as a control variable for controlling an internal and external oil circuit at a respective temperature difference above a predetermined limit value.

[0032] Typically, in oil-lubricated compressors, for example, once a predetermined minimum oil sump temperature is reached, the system switches from an internal oil circuit, which bypasses the oil cooler, to an external oil circuit, which does pass through the oil cooler, in order to avoid exceeding a maximum oil sump temperature. However, according to the above configuration, not only the oil sump temperature but also the aftercooler outlet temperature is considered. Therefore, the switch to the external oil circuit cannot occur solely upon reaching the minimum oil sump temperature, but can be delayed as long as the oil sump temperature remains below the maximum oil sump temperature and the aftercooler outlet temperature of the air is below a predetermined limit.In this case, switching to the external oil circuit is only planned if one of the aforementioned criteria is no longer met, i.e., if the maximum limit of the oil sump temperature and / or the predetermined limit of the aftercooler outlet temperature is reached or exceeded.

[0033] In a further development, the control device is configured to take into account temperature losses, in particular temperature losses via a housing, and / or temperature inertias, in particular an inertia of an oil temperature, as disturbance variables for the control of the cooling device, in particular via at least one proportional element.

[0034] Temperature losses, such as those occurring through the compressor or aftercooler housing, and / or thermal inertia can negatively affect a controlled variable. By taking one or more such disturbances into account, the controlled system can adjust the manipulated variable accordingly. Using a proportional link enables a fast response. The proportional link can also be incorporated, for example, into a first-order lag element (PT1), a second-order lag element (PT2), or a PID controller.

[0035] In one embodiment, the cooling device includes at least one fan, in particular at least one electric fan.

[0036] Fans used as cooling devices can be easily integrated and retrofitted into suitable compressor systems. If the cooling system includes multiple fans, cooling can be targeted locally, and the required cooling capacity can be reduced by decreasing the airflow due to shorter distances to the object being cooled and / or the airflow being cooled.

[0037] In particular, at least one fan is provided for each oil circuit of the compressor system and one fan for compressed air after-cooling and / or compressed air inter-cooling.

[0038] Both the oil circuit and the compressed air are crucial control variables with regard to the effects of overheating or undercooling, so targeted local cooling by at least one fan in each circuit offers a rapid response option to prevent overheating. Furthermore, to avoid or at least reduce condensation, it is advantageous if the area of ​​influence of each fan is locally limited through local cooling, especially if they are individually controlled.

[0039] In one embodiment, the control device is configured to perform a run-on operation of the cooling device after the compressor has been switched to intermittent operation, and / or not to activate the cooling device or only partially when the compressor starts up.

[0040] Accordingly, based on operating and / or environmental data, a run-on mode for the cooling system can be implemented, allowing the system to continue operating for a predetermined period and / or until a predefined event occurs. Such a predefined event could be, for example, a decrease in a detected temperature by a predetermined amount, or falling below a predetermined absolute temperature limit or a maximum temperature difference to the intake temperature. After the compressor switches to intermittent operation, the cooling system can continue operating with constant parameters for the specified period, or it can execute a run-on parameter scheme, for example, continuously reducing the fan speed in the case of a fan. The run-on mode allows the heat capacities of various components, such as the compressor block or cylinder, to be utilized.During compressor shutdowns, the heated components can be further cooled. Upon restart, the components' heating curve begins at a lower point than it would without post-cooling. This reduces peak temperatures and the overall temperature level of the components during the intermittent operation typical of rail vehicles. As a result, thermal stresses and the associated thermal aging processes are avoided or at least reduced. Accordingly, materials used in the area to be cooled, as well as temperature histories, can be taken into account during post-run operation. If thermal stresses and associated aging processes cannot be completely avoided, temperature data can be collected for maintenance purposes and / or appropriate maintenance measures can be triggered based on this data.

[0041] If the cooling device is not activated or only partially activated after the compressor starts, the control device can provide a predetermined delay, which depends in particular on the operating parameters of the compressor, or also link the operation of the cooling device to predefined events, such as exceeding a temperature limit.

[0042] In particular, the control device is configured to not activate the cooling device, or to activate it only partially, at least until the compressor has reached its operating temperature.

[0043] This allows the compressor to quickly reach operating temperature without any delay caused by the cooling system. For this purpose, a relevant temperature, such as the compressor component temperature or another temperature representing the compressor's operating temperature, can be detected by the temperature detection unit. Alternatively or additionally, the control device can regulate the cooling based on stored empirical data or an algorithm, depending on the operating conditions or parameters that indicate when the operating temperature is likely to be reached. In this context, it is also possible to operate the compressor at an energy-optimized speed, for example, particularly slowly to overcome the system's inertia.Alternatively, the compressor speed can be increased and subsequently decreased to asymptotically approach the upper pressure point, thus delaying shutdown for as long as possible.

[0044] In another aspect, the invention relates to a method for controlling a cooling device of a compressor system, comprising the steps: Detecting air temperature, oil temperature and / or component temperature of the compressor system and controlling the cooling device based on a detected air temperature, oil temperature and / or component temperature.

[0045] The air temperature, oil temperature, and / or component temperature can be measured directly using a temperature detection unit or derived, and in particular calculated, from other measured and / or operating parameters. Unlike a calculation, a derivation does not necessarily yield a specific quantitative temperature reading, but can, for example, qualitatively classify the respective temperature based on predetermined limits of other measured parameters. Such a derivation may also include calculation steps, with the qualitative assessment being the decisive factor in the result. In contrast, a calculation from other parameters provides a quantitative result for controlling the cooling system. The specific quantitative calculation from other measured parameters can also be understood as an indirect measurement.

[0046] The cooling unit is controlled based on the qualitative result of a derivation and / or the quantitative result of a direct or indirect measurement. The mechanical and signal-related decoupling of the cooling unit's operation from the compressor's operation, achieved through control based on detected temperatures, results in the advantages already described for the compressor system.

[0047] In one embodiment of the method, at least one cooling fluid volume flow parameter, in particular a cooling fluid volume flow rate, a cooling fluid volume flow temperature and / or a switching-on and / or switching-off time of the cooling device, is controlled on the basis of the detected air temperature, and / or oil temperature and / or component temperature.

[0048] The cooling fluid flow rate and / or the on / off switching point of the cooling system have a comparatively low-latency effect on the temperature balance of the compressor system, whereas when changing the cooling fluid flow temperature, the corresponding fluid inertia with respect to a temperature change must be taken into account. However, the alternative or supplementary selection of the cooling fluid flow temperature can, for example, through connection to heat exchangers, the activation of heat exchangers, and / or other configurations, result in energy-efficient cooling. Referring again to the control of the cooling fluid flow rate and / or the on / off switching point, changing the cooling fluid flow rate offers the advantage of protecting the components of the cooling system from high-frequency switching.On the other hand, independent control of the cooling device via on and / or off times can also be implemented for cooling devices where the cooling fluid volume rate is not adjustable.

[0049] Due to its high availability and low cost, air is primarily used as the cooling fluid, thus providing air cooling. However, other fluid heat transfer media, such as water or oil, can also be used. In this context, it is also possible, either alternatively or additionally, to implement variable cooling by using different heat transfer media with correspondingly different heat capacities and / or thermal conductivities. For this purpose, the cooling system can include coolers operating with different heat transfer media, which can be controlled separately and / or switched between different inlets for different heat transfer media. The use of different heat transfer media, as well as adjusting the cooling fluid flow temperature, can also be used at low ambient temperatures, especially during intermittent compressor operation, to prevent or at least reduce condensation.In such a case, the cooling device functions as a heating device.

[0050] In one embodiment, in particular by controlling a cooling device of a compressor system with a piston compressor, an oil temperature and / or intercooler outlet temperature and / or an aftercooler outlet temperature is controlled based on the detected component temperature.

[0051] When the oil temperature is used as a control variable, the component temperature refers specifically to component temperature detection at the compressor, while the component temperature in relation to the intercooler outlet temperature and / or the aftercooler outlet temperature refers specifically to component temperature detection at the intercooler and / or aftercooler. However, all of the aforementioned component temperatures can also be measured and taken into account accordingly in the control device.

[0052] Alternatively, in particular for controlling a cooling device of a compressor system with an oil-lubricated rotary compressor, an air temperature, in particular an aftercooler outlet temperature, is controlled on the basis of the detected air temperature, in particular a detected aftercooler outlet temperature, and / or the detected oil temperature, in particular a detected oil sump temperature.

[0053] Both the detected air temperature and the detected oil temperature allow conclusions to be drawn about the risk of overheating or condensation. In particular, the detected oil temperature can also be used to assess the probability of water entering the oil. By using both detected temperatures to control the air temperature, not only can redundant control be implemented, but it is also possible to adjust the air temperature more precisely according to demand. For example, the control device can change at least one cooling fluid flow rate parameter of the cooling system to increase cooling capacity if one of the detected temperatures exceeds a predetermined limit.Furthermore, it may be provided that the change in at least one cooling fluid volume flow parameter varies depending on whether the respective limit value is exceeded by the detected air temperature or whether the respective limit value is exceeded by the detected oil temperature, for example, the cooling capacity is increased significantly more when the air temperature limit value is exceeded than when the oil temperature limit value is exceeded, or vice versa.

[0054] In a further training course, a differential comparison of the detected air temperature and the detected oil temperature is performed as a control variable for a control system between an internal and an external oil circuit when the temperature difference exceeds a predetermined limit value.

[0055] This results in the advantages already described for the compressor system.

[0056] In another aspect, temperature losses, especially temperature losses through a housing, and / or temperature inertias, especially an inertia of oil temperature, are taken into account as disturbance variables in the control system, especially via a proportional element.

[0057] The advantages here are analogous to those mentioned for the compressor system. Furthermore, various temperature losses and / or inertias can be weighted differently by the control device in order to adapt the control of the cooling unit more precisely to the requirements.

[0058] Furthermore, the invention relates to a computer program product comprising program code stored on a machine-readable medium, which, when executed on a data processing device, is configured to cause the data processing device to execute the method described above.

[0059] The computer program product makes it possible, among other things, to easily retrofit signal-controlled cooling devices of conventional compressor systems.

[0060] The invention will now be explained in more detail with reference to one embodiment and the accompanying figures. The figures show, in detail: F igur 1 shows a schematic representation of a compressor system according to a first embodiment of the invention. Figure 2 shows a schematic representation of a compressor system according to a second embodiment of the invention. Figure 3 shows a schematic representation of a compressor system according to a third embodiment of the invention. Figure 4 shows an exemplary control system for a cooling device based on a compressor system according to the Figures 1 to 3 can be used. Figure 5shows an exemplary control system for a cooling device based on a compressor system according to the Figures 1 to 3 can be used.

[0061] Figure 1Figure 1 shows a schematic representation of a compressor system 1 with a compressor 10 and an aftercooler 20 according to a first embodiment of the invention. The air to be compressed is first guided through the compressor 10, compressed there, and then passes through the aftercooler 20, as indicated by the arrows. The compressor system 1 also includes a control device 30, which controls the cooling unit, which in the present embodiment comprises two fans 40. During operation, each fan can generate a cooling air volume flow 41, which is directed primarily to the compressor 10 and / or the compressor outlet via one fan 40 and primarily to the aftercooler outlet and / or the aftercooler 20 via the other fan 40. The control device 30 is configured to adjust both the on / off times of the fans 40 and the cooling air volume flow rate of the fans 40 by controlling the fan speed.

[0062] In the present embodiment, the control of the fans 40 is based on an evaluation of the temperatures detected by the temperature detection units 50a, 50b, and 50c. Temperature detection unit 50a detects an aftercooler outlet temperature, temperature detection unit 50b detects an oil sump temperature of the oil sump 11 of the compressor 10, and temperature detection unit 50c detects a component temperature of the compressor 10. The temperature detection units 50a, 50b, and 50c can be connected to the control device 30 via cables, as shown for temperature detection unit 50a, or configured for wireless communication with the control device 30, as shown by omitting the connection line for temperature detection units 50b and 50c. Figure 1As shown, if any of the detected temperatures exceeds a predetermined limit, the fans 40 are switched on, regardless of whether the compressor is operating. Conversely, if at least one of the detected temperatures falls below the respective limit values ​​for the detected aftercooler outlet temperature, the detected oil sump temperature, and / or the detected component temperature, the fans 40 are switched off. The fans 40 are controlled individually as needed, although synchronous control can also be provided to simplify the control process. In the latter case, various limit value configurations can be stored in the control device 30 for more precise cooling management. Furthermore, the control device 30 can adjust the cooling capacity of the fans 40 based on the temperature by controlling the fan speed.

[0063] Even though the fans 40 in the present embodiment are controlled via the detected aftercooler outlet temperature, the detected oil sump temperature, and the detected component temperature, the control device 30 can alternatively or additionally be configured to continue operating the fans for at least a predetermined period after the compressor has switched to intermittent operation, i.e., to provide a run-on time. Such a run-on time can also be linked to the level of the temperature detected at the time of shutdown, so that the run-on time is only provided above the predetermined temperature limit and / or the duration of the run-on time depends on such a temperature.

[0064] Figure 2 Figure 1 shows an oil-lubricated compressor as an exemplary second embodiment of compressor system 1. Here, as also in Figure 3The same reference numerals are used for identical components. The second embodiment differs from the first embodiment by providing an inner oil circuit 23 and an outer oil circuit 22, which is routed through an oil cooler 21. The oil cooler 21, like the compressor 10 and the aftercooler 20, is cooled as needed by a fan 40. The fan 40 associated with the oil cooler 21 is also controlled by the control device 30, although the signal connection has not been shown here for clarity. To switch the oil flow from the inner oil circuit 23 to the outer oil circuit 22, in which the oil passes through the oil cooler 21, the aftercooler outlet temperature detected by the temperature detection unit 50a and the oil sump temperature detected by the temperature detection unit 50b are taken into account.As long as the oil sump temperature does not exceed a predetermined maximum limit and the aftercooler outlet temperature also remains below a predetermined limit, the oil is routed to the oil sump 11 via the internal oil circuit 23. If either of these criteria is not met, the system switches to the external oil circuit. Accordingly, the fan 40 associated with the oil cooler 21 is activated when the system switches to the external oil circuit. Activation can also be linked to other events, such as a detected oil sump temperature, an oil cooler temperature, or planned pre- or post-run operation.

[0065] As a third embodiment, it shows Figure 3As an example, consider a compressor system 1 with a two-stage compressor, compressor 10. The process air 60 first passes through the first compression stage of compressor 10 before being directed into an intercooler 24. The intercooler outlet temperature is detected by the temperature detection unit 50d. After passing through the intercooler 24, the process air 60 is fed to the second compression stage of compressor 10 and then discharged via the aftercooler 20.

[0066] Figure 3Figure 50e also shows an exemplary temperature detection unit for detecting an intake temperature or ambient temperature, which can also be applied to the previous embodiments. The detected intake temperature can be used to provide for a run-on operation of the cooling device based on operating and / or ambient data, so that the cooling device continues to operate for a predetermined period and / or until the occurrence of a predefined event. A correspondingly predefined event could, for example, be the temperature falling below a maximum differential with the intake temperature.

[0067] Figure 4 shows an exemplary control system for a cooling device based on a compressor system according to the Figures 1 to 3can be applied. Such a control system generally comprises an actuator 100 and a control loop 200, wherein the control system controls the controlled quantity y S according to a reference variable w, a manipulated variable u S and taking into account possible disturbances d. In application to the in Figure 1 In the first embodiment shown, for example, the air temperature is controlled as the variable yS via the cooling air volume flow rate provided by the fans 40 as the manipulated variable uS and taking into account the temperature losses and thermal inertia as disturbance variables d. In contrast to the one shown in Figure 5In the exemplary control system shown, the control is event-based, for example, according to whether a predetermined limit value of the detected temperatures is exceeded or fallen below. The fans are then controlled based on predetermined control parameters, while in the regulation process, the control parameters are adjusted by the control device 30 according to determined control deviations.

[0068] The corresponding in Figure 5 The control system shown comprises an actuator 110, a controlled system 210, a measuring element 310, and a controller 410. Applied to the control device 30 of the compressor system 1 according to the [reference to be added] Figure 1In the illustrated embodiment, the air outlet temperature of the cooling system and the oil sump temperature are measured as controlled variables y, and the difference between the respective reference variable w and the determined actual value yM is calculated. The control variable u is then transferred from the control deviation e to the actuator 110 via the controller 410. The manipulated variable uR, here for example the fan speed, is then fed back into the control loop, which in turn takes into account the temperature losses and thermal inertia as disturbance variables d.

[0069] If the fans 40, or rather their respective fan speeds, are controlled independently of one another, a separate control loop can be provided for each fan. However, as described above, the control system can also initially control the fans together, particularly at the same fan speed, and make their respective independent adjustments dependent on a difference in the controlled variables. In this case, the control error of the difference between the controlled variables and the reference variable of this difference in the controlled variables is also incorporated into the control system; that is, the difference in the controlled variables, depending on its control error, determines the independent control of the fans 40. The difference in the controlled variables, i.e., here the difference between the aftercooler outlet temperature and the oil sump temperature, can also be used to control the internal and external oil circuits of the compressor 10 as a second manipulated variable.

[0070] The invention is not limited to the described embodiments. Although the cooling device has been described using fans, other cooling units, such as heat exchangers through which the air in the compressor system passes and / or is passed, can also be used. The cooling capacity of the heat exchangers can be adjusted by their positioning, orientation, and / or, in the case of the heat transfer fluids flowing through the heat exchangers, by the cooling fluid flow rate, the cooling fluid flow temperature, and / or by changing the heat transfer fluid. REFERENCE MARK LIST

[0071] 1 Compressor system 10 Compressor 11 Oil sump 20 Aftercooler 21 Oil cooler 22 Outer oil circuit 23 Inner oil circuit 24 Intercooler 30 Control device 40 Fan 41 Cooling air volume flow 50a Temperature detection unit (aftercooler outlet temperature) 50b Temperature detection unit (oil sump temperature) 50c Temperature detection unit (component temperature) 50d Temperature detection unit (intercooler outlet temperature) 50e Temperature detection unit (intake temperature / ambient temperature) 60 Process air flow 100, 110 Actuator 200 Control loop 210 Controlled loop 310 Measuring element 410 Controller d Disturbance variable(s) e Control deviation u Controlled variable u R , u S Manipulated variable y Controlled variable y M Actual value y S Controlled variable wreference variable

Claims

1. Compressor system (1) for a rail vehicle, having: a compressor (10), a cooling apparatus (40), a post-cooler (20) located downstream of the compressor (10) in the direction of flow of air flowing through the compressor (10), and a control device (30), wherein the control device (30) is configured to control the cooling apparatus (40) independently of the operation of the compressor (10), and to be able to provide a variable cooling fluid volumetric flow rate, which can be specified by the control device (30) as a manipulated variable (uR, uS), wherein the compressor system has a temperature detection unit (50a, 50b, 50c, 50d) for detecting a post-cooler outlet temperature of the air and an oil sump temperature, wherein the control device (30) is configured to control the cooling apparatus (40) on the basis of temperatures detected by the temperature detection unit (50a, 50b, 50c, 50d), characterized in that the control device (30) is configured to take into account a difference comparison of the post-cooler outlet air temperature with a respective predetermined limit value of the post-cooler outlet air temperature and the oil sump temperature with a respective predetermined limit value of the oil sump temperature as an input variable for controlling the cooling apparatus (40).

2. Compressor system (1) according to claim 1, wherein the cooling fluid volumetric flow rate is a cooling air volumetric flow rate.

3. Compressor system (1) according to claim 1 or 2, wherein the compressor system has a temperature detection unit (50a, 50b, 50c, 50d) for detecting a component temperature, wherein the control device (30) is configured to additionally control the cooling apparatus (40) based on the component temperature.

4. Compressor system (1) according to any one of the preceding claims, wherein the compressor system (1) comprises an intermediate cooler (24) which is located downstream of the compressor (10) in the direction of flow of the air flowing through the compressor (10), and the control device (30) is configured to control the cooling apparatus (40) based on an intermediate cooler outlet air temperature detected by the temperature detection unit (50a, 50b, 50c, 50d).

5. Compressor system (1) according to any one of the preceding claims, wherein the control device (30) is a central control device of the compressor system (1).

6. Compressor system (1) according to claim 5, wherein the central control device is an inverter.

7. Compressor system (1) according to any one of the preceding claims, wherein the temperature detection unit (50a, 50d) or a further temperature detection unit is provided in the region of the post-cooler (20) and / or the intermediate cooler (24) of the compressor system.

8. Compressor system (1) according to any one of the preceding claims, wherein the control device (30) is configured to use the difference comparison as a manipulated variable (uR, uS) for controlling an internal and external oil circuit at a respective temperature difference above a predetermined limit value.

9. Compressor system (1) according to any one of the preceding claims, wherein the control device (30) is configured to take temperature losses and / or temperature inertia into account as disturbance variables (d) for controlling the cooling apparatus (40).

10. Compressor system (1) according to any one of the preceding claims, wherein the cooling apparatus (40) comprises at least one fan (40).

11. Compressor system (1) according to any one of the preceding claims, wherein the control device (30) is configured to carry out a run-on operation of the cooling apparatus (40) after the compressor (10) has been switched to a stop operation, and / or to activate the cooling apparatus (40) only partially or not at all when the compressor (10) starts up.

12. Method for controlling a cooling apparatus (40) of a compressor system (1) according to any one of claims 1 to 11, having the steps: - detecting an air temperature, oil sump temperature and / or component temperature of the compressor system (1), and - controlling the cooling apparatus (40) on the basis of a detected air temperature, oil sump temperature and / or component temperature, wherein at least one difference comparison of the post-cooler outlet temperature of the air with a respective predetermined limit value of the post-cooler outlet air temperature and of the oil sump temperature with a respective predetermined limit value of the oil sump temperature is taken into account as an input variable for controlling the cooling apparatus (40).

13. Method according to claim 12, wherein at least one cooling fluid volume flow parameter of the cooling apparatus (40) is controlled on the basis of the detected air temperature, oil temperature and / or component temperature.

14. Method according to claim 13, wherein through the control of a cooling apparatus (40) of a compressor system (1) with a piston compressor, an oil temperature and / or an intermediate cooler outlet temperature and / or a post-cooler outlet temperature is controlled on the basis of the detected component temperature, or wherein through the control of a cooling apparatus (40) of a compressor system (1) with an oil-lubricated rotary compressor, an air temperature is controlled on the basis of the detected air temperature and / or the detected oil temperature.

15. Method according to claim 14, wherein the difference comparison between the detected air temperature and a respective predetermined limit value of the post-cooler outlet air temperature and the detected oil sump temperature and a respective predetermined limit value of the oil sump temperature is used as a manipulated variable (uR, uS) for control between an internal and an external oil circuit at a temperature difference above a predetermined limit value.

16. Method according to any one of claims 12 to 15, wherein in the control temperature losses and / or thermal inertia are taken into account as disturbance variables (d).

17. Computer program product having a program code which is stored on a machine-readable medium and which is configured such that, when executed on a data-processing apparatus, the data-processing device causes the method according to any one of claims 12 to 16 to be carried out.