DE102004044530A1 - Air compressor, has drive activated based on operation and/or condition of electric driving motor, such that ball bearings are supplied more grease during higher number of revolutions than during lower number of revolutions - Google Patents

Abstract

The compressor (10) has an electric driving motor (11) provided with grease-lubricated ball bearings (15, 16) and a regreasing device for the ball bearings, where the device is provided with a drive. The drive is activated as a function of operation and/or condition of the driving motor, in such a manner that the ball bearings are supplied more grease during a higher number of revolutions than during a lower number of revolutions.

Description

The Invention relates to a compressor with electric drive motor, wherein the drive motor grease lubricated bearings and one with a Drive provided relubricating the rolling bearing and preferably with over 3000 or 3600 rev / min lying speed is operated.

Stationary compressor systems can be provided with an electric drive motor. The transfer The power from the drive motor to the compressor typically occurs through a belt transmission or directly - without speed ratio - by a clutch to compensate for shaft misalignment.

to better adaptation of compressed air generation to the needs it is known to use electric drives with speed control, the Speed control typically by a frequency converter for one Three-phase motor is done. The bearing of the three-phase motors takes place regularly through grease lubricated bearings. With the high expected lifetimes of the compressors is the service life of grease in rolling bearings often critical. Usually, the service life of the grease is shorter than the life of the compressor and it must be relubricated. This relubrication is usually done by a maintenance technician by hand with a grease gun. As the compressor maintenance sometimes is forgotten, this results in a threat to operational safety. Due to lubricant failure after the end of the service life (of the grease) become the rolling bearings defective, with them the three - phase motor, and it can cause the failure of the Compressed air supply come.

From Factory are the three-phase motors usually with a service life of the grease in the rolling bearings projected, the operation with a usual on the three-phase network Speed requires, for example, 3,000 and 3,600 rpm. however be the over a frequency converter controlled three-phase motors in conjunction with compressors sometimes with higher ones Operated speeds, such as to save a transmission gear and the then incurred translation losses. At higher Speeds is the grease life is especially short.

With the device according to the invention should be a reliable Lubrication of rolling bearings of the electric drive motor the life of the compressor can be guaranteed.

Of the inventive compressor is characterized in that the drive of the relubricating dependent on from the operation and / or state of the drive motor and / or the compressor can be activated, such that the rolling bearings in at least one higher Speed more fat fed is as opposed to one lower speed. Advantageously, the function of the relubrication device dependent on adjustable by the speed of the electric drive motor.

A appropriately configured control device controls the control the relubrication device and thus the fat supply depending from the above parameters, preferably also the control of the drive motor.

Basically it is a compressor of any kind. Preferably is a screw compressor, especially with oil injection cooling, provided. advantageously, it is a compressor for air or for the production of Compressed air. However, the invention can also in connection with the Compression of other gases are used. Finally is a direct drive of the compressor, that is without a belt drive or Speed transfer, intended.

The Invention is preferred in connection with variable speed electric drive motors applied with a higher maximum Turn speed as usual in mains operation. But it is also possible an application with drive motors of other kind. As a maximum speed can be any Speed can be defined. Appropriately, the use of the specified by the manufacturer of the electric drive motor rated speed or constructively and depending on the grid frequency self-adjusting speed, as in three-phase motors. Also overlying Speeds can but in dependence from the needed Compressor speed can be defined as maximum speed, about one to achieve the compressor rated power or a maximum Compressor speed required speed of the drive motor.

Preferably the relubricating device has an electric or pneumatic Drive up. The electric drive is easy to control. Preferably becomes the electric drive for the relubricating only switched on, if the electric drive motor for the compressor is switched on. When using a pneumatic Drive (for the relubricating) this can its pressure directly from refer to the compressor.

In an advantageous embodiment of the invention, a proportionality between the speed and the fat supply is given. As a fat intake is a understood by the relubrication per unit of time delivered amount of fat. Depending on the speed, a progressive or gradually increasing supply of fat may be provided.

• a) eine Drehzahl ist als Maximaldrehzahl definiert,
• b) eine Fettzufuhr ist als maximale Fettzufuhr definiert,
• c) wenn die aktuelle Drehzahl weniger als 50% der maximalen Drehzahl beträgt, erfolgt eine Fettzufuhr von weniger als 40% der maximalen Fettzufuhr,
• d) wenn die aktuelle Drehzahl mehr als 70% der maximalen Drehzahl beträgt, erfolgt eine Fettzufuhr von mehr als 60% der maximalen Fettzufuhr.

According to a further aspect of the invention, the amount of grease discharged by the relubricating device may be controllable as a function of the rotational speed of the electric drive motor, namely as follows:

• a) a speed is defined as maximum speed,
• b) a fat intake is defined as maximum fat intake,
• c) if the current speed is less than 50% of the maximum speed, the amount of fat delivered is less than 40% of the maximum fat intake,
• d) If the current speed is more than 70% of the maximum speed, a grease supply of more than 60% of the maximum grease supply takes place.

To Another idea of the invention is that of the relubricating device delivered amount of fat depending on from the temperature of the rolling bearings adjustable. It can Several temperature sensors are used, such as one sensor each Roller bearing. A combination with the speed-dependent control is also possible, for example via temperature or speed-dependent characteristics.

advantageously, is the delivered amount of fat or fat supply in dependence of temperatures on or in the compressor or drive motor controllable. Corresponding temperature sensors can, for example, the compression end temperature, the supply air temperature, the winding temperature or the storage temperatures of the drive motor. The temperature-dependent control is basically independent of the speed-dependent Control, but is advantageously used in combination with the same.

To Another idea of the invention is the supply of fat to the roller bearings dependent on from an estimated Temperature of the rolling bearings controllable, taking into the estimate in particular one or more temperatures on and in the compressor and the time course of speed and engine power flow.

• – T_Lager,n und T_Lager,n–1, die als Schätzwerte berechneten Lagertemperaturen zum aktuellen Zeitpunkt n und zum vorherigen Zeitpunkt n – 1 sind,
• – ΔT_{Verlustwärme} die Temperaturerhöhung aus der im Lager und der im Motor jeweils auftretenden Verlustwärme ist (zu berechnen aus Motorleistung und -wirkungsgrad, wobei die Motorleistung von der Steuerung aus Druck und Drehzahl bestimmt werden kann und der Wirkungsgrad einem drehzahl- und leistungsabhängigen Kennfeld entnommen wird – Verdichterdruck und -drehzahl werden in größeren Kompressoranlagen ohnehin überwacht und zur Regelung verarbeitet) geteilt durch Wärmekapazität und multipliziert mit dem Zeitintervall (z. B. als ΔT_{Verlustwärme} = Verlustleistung·Zeitintervall/Wärmekapazität),
• – ΔT_Kühlung die Temperatursenkung aus der Kühlwirkung ist (zu berechnen aus Motoroberfläche, von der Drehzahl des Motorlüfters abhängiger Wärmeübergangszahl α, Temperaturdifferenz zwischen Lagertemperatur T_Lager,n–1 und Kühllufttemperatur T_Kühl – letztere beträgt üblicherweise maximal 40° C und ist gleich der Verdichtereintrittstemperatur, die in manchen Kompressoranlagen ohnehin erfasst und zur Regelung verarbeitet wird) geteilt durch Wärmekapazität der Wälzlager und multipliziert mit dem Zeitintervall, das in diesem Beispiel ¼ Minute beträgt, (z. B. als ΔT_Kühlung = Oberfläche·α (T_Lager,n–1 – T_Kühl)·Zeitintervall/Wärmekapazität).

Some of the data needed for an estimate of the temperature is present or calculable by design, while another part is determined from the signals of existing sensors. In the control device, for example, estimated values for the storage temperature in time intervals of ¼ minute are calculated as: T To store = T Stock, n-1 + ΔT heat loss - ΔT cooling in which

• T _{bearings, n} and T _{bearings, n-1} , which are estimated _bearing temperatures at the current time n and at the previous time n-1,
• - ΔT _{heat loss is} the temperature increase from the heat loss occurring in the bearing and in the engine (to be calculated from engine power and efficiency, whereby the engine power can be determined by the controller from pressure and speed and the efficiency is taken from a speed and power dependent map - Compressor pressure and speed are in any case monitored in larger compressor systems and processed for control) divided by heat capacity and multiplied by the time interval (eg as ΔT _{heat loss} = power dissipation · time interval / heat capacity),
• - ΔT _cooling is the reduction in temperature from the cooling effect (to be calculated from the motor surface, the heat transfer coefficient α dependent on the speed of the motor fan, temperature difference between storage temperature T _{bearing, n-1} and cooling air temperature T _cooling - the latter is usually maximum 40 ° C and is equal to the compressor inlet temperature , which in some compressor systems is already detected and processed for control) divided by the heat capacity of the rolling bearings and multiplied by the time interval, which in this example is ¼ minute (eg as ΔT _cooling = surface · α (T _{bearing, n 1} - T _cooling ) · time interval / heat capacity).

outgoing from an estimated Start temperature when switching on the controller can be so at each Time interval of the estimated value for the Storage temperature according to the respective engine load and cooling effect Getting corrected. In this way, without additional transducers the Lubricant aging in the bearings calculated and accordingly the fat feed to be controlled.

To Another idea of the invention, the fat is added or alternatively in dependence from the power consumption of the drive motor, about characteristic curves or current measurements.

The Power of the drive motor is tuned to the needs of the compressor. For example, a drive motor has a speed of over 4,500 Rpm a power consumption of more than 22 kW. Another, too in the context of the invention preferred drive motor has at over 5,000 rpm, a power consumption of more than 37 kW.

Finally, each roller bearing can be assigned its own fat reservoir and its own drive for the supply of fat. Advantageously, leads from each grease reservoir a direct channel to the rolling bearing, without branch, valve or throttle.

Advantageous embodiments of the invention are explained below with reference to a drawing:
A compressor 10 for the production of compressed air is powered by an electric drive motor 11 driven. A wave 12 of the compressor 10 is right with a wave 13 of the drive motor 11 via a clutch 14 connected. The drive motor is a variable-speed three-phase motor with frequency converter.

The wave 13 is in rolling bearings 15 . 16 stored, each having a certain fat filling at the time of manufacture. The rolling bearings 15 . 16 is ever a separate lubrication device 17 respectively. 18 assigned. These each have a reserve of fat 19 respectively. 20 and a drive 21 respectively. 22 on, with which the grease from the grease supply 19 . 20 in the respective rolling bearing 15 . 16 is convertible. The fat reserve 19 respectively. 20 is with the associated rolling bearing 15 respectively. 16 through a pipe 23 respectively. 24 connected.

The relubrication devices 17 . 18 and the drive motor 11 are to a common control device 25 connected and are supplied from this with electrical energy. Corresponding electrical lines are indicated by the reference numerals 26 . 27 and 28 Mistake. The control device is via a line 29 connected to a not shown power grid.

In one embodiment of the invention, the controller operates 25 so that the drive motor 11 and the relubricating devices 17 . 18 always work at the same time. That is, as soon as the drive motor 11 runs, get the rolling bearings 15 . 16 additional grease from the relubricating devices 17 . 18 , Once the drive motor 11 stands still, for example during short breaks or during longer interruptions in operation, no further fat gets from the fat stores 19 . 20 in the rolling bearings 15 . 16 ,

It is usual to drive the drive motor 11 depending on the pressure of a compressed air supply, not shown here. In this case, a suspension operation or a partial load control, be carried out about the regulation of the frequency. The latter is particularly suitable for screw compressors. Also in the present embodiment, a frequency control of the drive motor 11 to be possible. The control device 25 is designed accordingly.

Depending on the objective and complexity of the control device, the relubrication devices 17 . 18 be controlled depending on other parameters. So the control device 25 an operating hours counter of the drive motor 11 and depending on the actual operating hours the relubricating devices 17 . 18 drive.

Individual aggregates, sections or parts of the described device as a whole can be provided with sensors or signal generators, their information in the control device 25 are processed. Corresponding signal lines are shown in dashed lines in the figure. As sensors may be provided, inter alia:
temperature sensor 30 for the detection of the compression end temperature,
temperature sensor 31 for recording the supply air temperature of the compressor 10 .
Speed sensor 32 on the shaft 13 of the drive motor 11 .
temperature sensor 33 at the rolling bearing 15 .
temperature sensor 34 in not shown windings of the drive motor 11 .
temperature sensor 35 at the rolling bearing 16 ,

The control of relubricating devices 17 . 18 may depend on the output signals of said sensors 30 to 35 be performed.

A disproportionate, speed-dependent control is advantageous, so that at higher speeds of the drive motor 11 a disproportionately increased supply of grease to the rolling bearings 15 . 16 he follows.

Similarly, a disproportionate or other supply of rolling bearings 15 . 16 with lubricants depending on the rolling bearing temperatures or of the winding temperature of the drive motor 11 respectively. In larger compressor systems temperatures are also measured for other purposes at different locations and processed for the control of the plant as a whole or other aggregates. This applies, for example, the compression end temperature (temperature sensor 30 ) or the supply air temperature (temperature sensor 31 ). The values of these sensors can also be included in the control, in addition to or as an alternative to other values.

The relubrication devices 17 . 18 include pump assemblies known from design or mode of operation, not shown, that are powered by the electric drives 21 . 22 and the defined amounts of lubricant from the grease supplies 19 . 20 over the wires 23 . 24 in the rolling bearings 15 . 16 submit. The control device 25 can be integrated into an already provided as part of a compressor system control unit, for example as a software module or as Hardware module.

10

compressor

11

drive motor

12

wave

13

wave

14

clutch

15

roller bearing

16

roller bearing

17

regreasing

18

regreasing

19

fat stock

20

fat stock

21

drive

22

drive

23

management

24

management

25

control device

26

electrical management

27

electrical management

28

electrical management

29

electrical management

30

temperature sensor

31

temperature sensor

32

Speed sensor

33

temperature sensor

34

temperature sensor

35

temperature sensor

Claims (9)

Compressor ( 10 ) with electric drive motor ( 11 ), wherein the drive motor ( 11 ) grease-lubricated roller bearings ( 15 . 16 ) and one with a drive ( 21 . 22 ) provided relubricating ( 17 . 18 ) for the rolling bearings ( 15 . 16 ) and is preferably operated at a rotational speed above 3000 or 3600 rpm, characterized in that the drive ( 21 . 22 ) of the relubricating device ( 17 . 18 ) depending on the operation and / or condition of the drive motor ( 11 ) and / or the compressor ( 10 ) Is activated, such that the rolling bearings at least one higher speed more fat can be fed than at a lower contrast speed. Compressor according to claim 1, characterized in that the relubricating device ( 17 . 18 ) a pneumatic or electric drive ( 21 . 22 ) having. Compressor according to claim 1 or 2, characterized in that the of the relubricating ( 17 . 18 ) delivered amount of grease in dependence on the rotational speed of the electric drive motor ( 11 ), namely proportional or progressive or stepwise. Compressor according to claim 3, characterized in that the of the relubricating ( 17 . 18 ) delivered amount of grease in dependence on the rotational speed of the electric drive motor ( 11 a) a speed is defined as maximum speed, b) a grease supply is defined as maximum grease supply (amount of grease per unit of time), c) if the current speed is less than 50% of the maximum speed, a Grease supply of less than 40% of the maximum grease supply, d) if the current speed is more than 70% of the maximum speed, a grease supply of more than 60% of the maximum grease supply takes place. Compressor according to claim 1 or one of the further claims, characterized in that the grease supply to the rolling bearings ( 15 . 16 ) is controllable in dependence on the temperature of the rolling bearings. Compressor according to claim 1 or one of the further claims, characterized in that the grease supply to the rolling bearings ( 15 . 16 ) as a function of temperatures on or in the compressor or as a function of temperatures on or in the drive motor ( 11 ) is controllable. Compressor according to claim 1 or one of the further claims, characterized in that the grease supply to the rolling bearings ( 15 . 16 ) is controllable in dependence on an estimated temperature of the rolling bearings, wherein in the estimation in particular one or more temperatures at and in the compressor and the time course of speed and engine power are included. Compressor according to claim 1 or one of the further claims, characterized in that the grease supply to the rolling bearings ( 15 . 16 ) as a function of the power consumption of the drive motor ( 11 ) is controllable. Compressor according to claim 1 or one of the further claims, characterized in that each rolling bearing ( 15 . 16 ) a separate fat reserve ( 19 . 20 ) and a separate drive ( 21 . 22 ) is assigned for the fat intake.