COMPRESSOR UNIT AND METHOD FOR OPERATING THE SAME

Abstract

The present invention relates firstly to a method for operating a compressor powered by an internal combustion engine for compressing air. Furthermore, the invention relates to a compressor, which is suitable for executing the method according to the invention. A first turbocharger for supplying pre-compressed air to the internal combustion engine is disposed in an exhaust flow of the internal combustion engine. Furthermore, a second turbocharger for pre-compression of the air to be compressed by the compressor is disposed in the exhaust flow of the internal combustion engine. The method according to the invention first comprises a step in which a monitoring of a pressure of the pre-compressed air generated by the first turbocharger occurs during an operating state of the compressor. In a further step of the method, a termination of the operating state occurs as soon as the monitored pressure falls below a previously determined value.

Claims

1. A method for controlling the operation of a gas or air compressor unit, comprising an internal combustion engine, a first turbocharger for generating compressed air for the internal combustion engine and a second turbocharger for generating compressed air, wherein the first turbocharger and the second turbocharger are disposed in an exhaust flow path of the internal combustion engine, wherein the method comprises the following steps: monitoring a pressure of the compressed air generated by the first turbocharger during an operating state of the compressor unit; and changing the operating state of the compressor unit when the monitored pressure falls below a previously determined value.

2. The method according to claim 1, characterized in that, in the monitored operating state, the air compressed by the second turbocharger is conducted to a main compressor powered by the internal combustion engine, which compresses the compressed air.

3. The method according to claim 2, characterized in that the step for changing the operating state furthermore comprises a closing of a feed of intake air to the main compressor.

4. The method according to claim 3, characterized in that the step for changing the operating state furthermore comprises an activation of an intake regulator.

5. The method according to claim 1, characterized in that a volume subjected to compressed air by the second turbocharger can be opened by opening a blow-off device, wherein the method comprises the following steps: control of the blow-off device via a pressure regulator; monitoring of a control pressure caused by a pressure regulator; and changing of the operating state when the control pressure exceeds a previously determined maximum value when in the operating state.

6. The method according to claim 1, characterized in that the previously determined value is a function of a rotational rate of the internal combustion engine.

7. The method according to claim 1, characterized in that the changing of the operating state comprises a lowering of the rotational rate of the internal combustion engine from an operating rotational rate to an idling rotational rate of the internal combustion engine.

8. The method according to claim 7, characterized in that the changing of the operating state furthermore comprises a shutting off of the internal combustion engine.

9. The method according to claim 1, characterized in that the exhaust flow of the internal combustion engine flows first through the first turbocharger and subsequently through the second turbocharger.

10. The method according to claim 1, characterized in that a pressure generated by the second turbocharger is not measured.

11. The method according to claim 1, characterized in that the measurement values of the pressure generated by the first turbocharger represent monitoring data, which are transmitted to a superordinate compressor control system.

12. The method according to claim 11, characterized in that the monitoring data form an actual-characteristic, which is compared in the superordinate compressor control system with a predefined target-characteristic.

13. The method according to claim 12, characterized in that the changing of the operating state of the compressor unit first occurs when the actual-characteristic deviates from the target-characteristic by more than a predefined value.

14. A compressor unit for compressing air or gas, comprising the following components: an internal combustion engine; a first turbocharger disposed in an exhaust flow path of the internal combustion engine, having an air outlet in the flow connection with the internal combustion engine; a second turbocharger disposed in the exhaust flow path of the internal combustion engine having an air outlet for generating compressed air; a pressure sensor coupled to a flow path of the compressed air generated by the first turbocharger; and a control unit connected to the pressure sensor, which is configured to change an operating state of the compressor unit when the pressure monitored by the pressure sensor falls below a previously determined value.

Description

[0037] Further advantages, details and developments of the invention can be derived from the following description of a preferred embodiment of the invention, with reference to the drawings. Therein:

[0038] FIG. 1: shows a pneumatic circuit diagram of a preferred embodiment of a compressor according to the invention; and

[0039] FIG. 2: shows a diagram illustrating the relationship of a minimum pressure to a rotational rate.

[0040] FIG. 1 shows a pneumatic circuit diagram of a preferred embodiment of a compressor according to the invention. The compressor comprises a diesel engine 01, which functions as a drive for the compressor. The diesel engine is powered by diesel from a diesel tank 02. The diesel engine is cooled by a water cooler 03. The water cooler 03 is connected to fluid reservoir 04.

[0041] An exhaust flow 06 of the diesel engine 01 is first conducted through a first turbocharger 07 and subsequently through a second turbocharger 08. The turbochargers 07, 08 obtain air via two air filters 09, between which a difference pressure switch 11 is disposed. The pre-compressed air from the first turbocharger 07 is cooled with a first air cooler 12, upon which the diesel engine 01 is loaded with the pre-compressed, cooled air.

[0042] The pre-compressed air from the second turbocharger 08 is cooled with a second air cooler 13, and subsequently flows to an intake regulator 14 and to a blow-off device 16, wherein normally only one of the two components is open. If the intake regulator 14 is open, the pre-compressed, cooled air flows to a screw compressor 17, which is powered by the diesel engine 01, and serves to compress the pre-compressed air, i.e. for generating the pressurized air that is to be provided. If the intake regulator 14 is closed, the pre-compressed, cooled air flows out via the open blow-off device 16, such that it escapes. As a result, the second turbocharger 08 is prevented from acting on a closed volume, by means of which it could become damaged.

[0043] The pressurized air generated by the screw compressor 17 flows into a pressure reservoir 18, wherein the temperature thereof is monitored with a temperature sensor 19. Oil located in the pressure reservoir 18 flows to the screw compressor 17 via an oil filter 24 and via an oil temperature regulator 26 having an oil cooler 27 as well as a non-return valve 28, in order to supply it with oil.

[0044] A fine separator 23 is located in the pressure reservoir 18. Oil separated out by the fine separator 23 is then supplied back to the screw compressor 17 via an intake line 21 and via a non-return valve 22.

[0045] The pressure in the pressure reservoir 18 is monitored with a pressure sensor 29, and can be reduced with a safety valve 31 when an acceptable pressure has been exceeded.

[0046] The pressurized air in the pressure reservoir 18 can be removed at removal taps 32 for the desired application. When the removal taps 32 are fully open, it is then ensured with a pressure-sustaining valve 33 that a residual pressure in the pressure reservoir 18 is maintained, in order to ensure that the screw compressor 17 is always supplied with sufficient oil.

[0047] The pressurized air in the pressure reservoir 18 is also conducted to an electronic proportional regulator 36 via a pressure limiter 34. The pressure of the pressurized air regulated by the electronic proportional regulator 36 can be measured with a pressure sensor 37. The pressurized air regulated by the electronic proportional regulator 36 serves to activate the intake regulator 14 and the blow-off device 16.

[0048] There is also a quick-action stop valve 38 disposed behind the pressure limiter 34. When idling, i.e. when no pressurized air is removed at the removal taps 32, the intake regulator 14 is closed and the diesel engine 01 rotates at an idling rotational rate, some air is fed to the screw compressor 17 via a bypass valve 39 and via a non-return valve 41, in order to protect the screw compressor 17 when idling. The pressure applied to the pressure limiter 34 can also be relieved at a relief valve 42.

[0049] For the start-up of the compressor, the diesel engine 01 is accelerated to a gentle rotational rate starting from a standstill, corresponding to the idling rotational rate. The intake regulator 14 initially remains open until an operating pressure of approx. 1.5 excess pressure has been built up. The intake regulator 14 is subsequently closed by an activation of the proportional regulator 36 and a warm-up phase begins, in which the diesel engine 01 continues to run at the gentle rotational rate. The proportional regulator 36 and the quick-action stop valve 38 are open in this phase. There is therefore a control pressure at the blow-off device 16, such that it opens. As a result, the air conveyed by the second turbocharger 09 can escape into the environment. It then transitions into the operating state after the warm-up phase. Pressurized air is removed at the removal taps 32 when in the operating state. The intake regulator 14 is opened through activation with the proportional regulator 36, while the blow-off valve 16 is closed. As soon as no more air is removed at the removal taps 32, the intake regulator 14 is closed through activation with the proportional regulator 36, while the blow-off device is opened and the diesel engine 01 is run at its idling rotational rate.

[0050] In the event of a malfunction, a control line 43 leading from the proportional regulator 36 to the blow-off device 16 is blocked, e.g. when it is frozen. In this case, the blow-off device 16 does not open, while the intake regulator 14 remains closed. Consequently, the second turbocharger 08 subjects a closed volume to pre-compressed air. When in the operating state, the diesel engine 01 runs at the operating rotational rate. The second turbocharger 08 reaches its pump limit, at which point it is overloaded, which leads to damage to the second turbocharger 08.

[0051] In accordance with the invention, the actual-pressure generated by the first turbocharger 07 is monitored. A pressure sensor (not shown) directly attached to the diesel engine 01 is used for this. If this pressure drops below a value previously determined as function of the rotational rate of the diesel engine 01 (cf. FIG. 2), then the malfunction described above can be detected according to the invention. In this case, the diesel engine 01 is first brought to its idling rotational rate. As a result, the load to the second turbocharger 08 is substantially lowered, such that damage to the second turbocharger 08 is prevented. At the same time, the intake regulator 15 is activated in order to close it, in order to ensure that it is actually closed. As a result, it is ensured that the screw compressor 17 no longer takes in any air, i.e. it is not loaded, such that the diesel engine 01 can run at its idling rotational rate. After the diesel engine 01 is running at its idling rotational rate, it is shut off, such that it comes to a standstill. The detected malfunction is stored in an error memory.

[0052] In addition, the pressure measured with the pressure sensor 37 is monitored. If this pressure exceeds a previously determined maximum value, then this likewise leads to the sequence described above for terminating the operation of the compressor.

[0053] FIG. 2 shows a diagram illustrating the dependency of the previously determined minimal value for the pressure generated by the first turbocharger 07 (shown in FIG. 1) on the rotational rate of the diesel engine 01 (shown in FIG. 1). The Y-axis indicates the pressure in bars of excess pressure. The X-axis indicates the rotational rate of the diesel engine 01 in rotations per minute.

[0054] A first characteristic curve 51 indicates the pressure generated by the first turbocharger 07 as a function of the rotational rate of the diesel engine 01, when the compressor functions correctly and there is no malfunction.

[0055] A second characteristic curve 52 indicates the previously determined minimal value for the pressure generated by the first turbocharger 07 as a function of the rotational rate of the diesel engine 01, which serves in accordance with the invention as a criterion for determining the malfunction. The previously determined minimum value of the pressure generated by the first turbocharger 07 can also be determined qualitatively and/or quantitatively by means of a mathematical function, or some other means.

LIST OF REFERENCE SYMBOLS

[0056] 01 diesel engine [0057] 02 diesel tank [0058] 03 water cooler [0059] 04 fluid reservoir [0060] 05 [0061] 06 exhaust flow [0062] 07 first turbocharger [0063] 08 second turbocharger [0064] 09 air filter [0065] 10 [0066] 11 difference pressure switch [0067] 12 first air cooler [0068] 13 second air cooler [0069] 14 intake regulator [0070] 15 [0071] 16 blow-off device [0072] 17 screw compressor [0073] 18 pressure reservoir [0074] 19 temperature sensor [0075] 20 [0076] 21 intake line [0077] 22 non-return valve [0078] 23 fine separator [0079] 24 oil filter [0080] 25 [0081] 26 oil temperature regulator [0082] 27 oil cooler [0083] 28 non-return valve [0084] 29 pressure sensor [0085] 30 [0086] 31 safety valve [0087] 32 removal tap [0088] 33 pressure-sustaining valve [0089] 34 pressure limiter [0090] 35 [0091] 36 proportional regulator [0092] 37 pressure sensor [0093] 38 quick-action stop valve [0094] 39 bypass valve [0095] 40 [0096] 41 non-return valve [0097] 42 relief valve [0098] 43 control valve [0099] 44 [0100] 45 [0101] 46 [0102] 47 [0103] 48 [0104] 49 [0105] 50 [0106] 51 first characteristic curve [0107] 52 second characteristic curve