Compressor for compressing gases

Abstract

Compressor (10) for compressing gases, comprising at least one cylinder (12, 14) in which a piston (16, 18) is guided, wherein the piston (16, 18) is coupled to a piston rod (20, 22), wherein an electric drive unit (24, 26) is provided for driving the piston rod (20, 22), and wherein a control unit (30) is provided for controlling the drive unit (24, 26), wherein the control unit (30) is configured such that the piston speed and the initial position and / or the final position of the piston (16, 18) in the cylinder (12, 14) can be varied, characterized in that two further cylinders (50, 52) are provided, in each of which a piston (54, 56) is guided, wherein the pistons (54, 56) are coupled by means of a common piston rod (58), wherein an electric drive unit (60) is provided by means of which the common piston rod (58) can be driven.

Description

The invention relates to a compressor for compressing gases with the features of the preamble of claim 1. Compressors for compressing gases are known from the prior art, for example, in the form of compressors used in workshops or by DIY enthusiasts. Such compressors have a cylinder in which a piston is guided, which is usually driven by a crank mechanism. The rotation of the crankshaft is converted into a translational motion, and the piston is accelerated or decelerated sinusoidally. The crankshaft can be driven, for example, by an electric motor. This allows a gas drawn in within the cylinder to be compressed by the piston and fed, for example, to a storage tank, e.g., to provide compressed air. A disadvantage of this design is that the piston movement within the cylinder is determined by its construction and cannot be changed. The compression ratio is also fixed. Adapting the compressor to a different application, e.g.,Changing the delivery rate or compression ratio is not possible without structural modifications to the crankshaft or to the piston and cylinder. Another compressor is known from DE 31 42 950 A1. This compressor has two cylinders connected in series to achieve the highest possible compression. The two pistons running in the cylinders are coupled by means of a common spindle driven by an electric motor. The pistons are planar and, to achieve the highest possible compression, are advanced until they contact the cylinder head of the respective cylinder, with the travel speed being reduced towards the cylinder head. Since the compressor is optimized for the highest possible compression, adapting its application without design modifications is not possible. US 2009 / 0 311 114 A1 , DE 10 2004 009 913 A1 and DE 10 2009 020 973 A1 each show a compressor with features of claim 1. The invention is based on the objective of providing a compressor, using simple design means, that can be flexibly adapted to various applications. The invention solves this problem by means of a compressor with the features of claim 1. The compressor is used for compressing gases and has a (first) cylinder in which a piston is guided, the piston being coupled to a piston rod. The compressor is characterized in that an electric drive unit is provided for driving the piston rod and that a control unit is provided for controlling the drive unit, the control unit being configured such that the (average and / or maximum) piston speed and the initial and / or final position of the piston in the cylinder are variable or adjustable.This allows for relatively free parameterization of the drive with regard to the speed profile (e.g., average and / or maximum piston speed) of the piston movement and the compression ratio, since there is no piston movement predetermined by forced coupling, as is the case with a crankshaft drive. By controlling the drive unit, the electric drive unit can, for example, be stopped and / or its direction of rotation reversed before the piston reaches its maximum possible starting or ending position (reversal points) in the cylinder. This allows the compression to be adjusted. Furthermore, the delivery rate can be varied. This can be achieved with a simple design using few components. Reduced lubrication requirements for the drive are also possible, since a crankshaft drive is eliminated and the pistons are driven electromechanically.Pumping moist gases is also easier, and water hammer can be avoided by "gentle compression" (e.g., reduced piston stroke). The compressor in question is, in particular, a volumetric compressor, for example, a piston compressor. Its compression volume is formed by one or more cylindrical walls (e.g., tubular cross-section) and one or more pistons moving within them. The piston can move translationally within its cylinder. The piston fits (positively) into its cylinder, meaning the cross-section (outer cross-section) of the piston and the cross-section of the cylinder (cylinder bore cross-section) match. The cylinder and piston can have a round, oval, polygonal cross-section, or similar shape. A cylinder and a piston running within it form a compression chamber. As already mentioned, the compressor can have multiple compression chambers. The piston rod and / or piston move translationally, particularly along their central longitudinal direction. With appropriate control of the electric drive unit by the controller, the piston can perform an oscillating motion within the cylinder. Independently of this, the piston rod can be connected to the piston, for example, by being screwed to it. The drive unit can be connected to the controller via a wireless or wired connection. By controlling the drive unit, the piston speed can be changed and the reversal point(s) of the piston movement can be specified (drive parameters). It is conceivable that the controller has a wireless or wired interface through which it can be connected to a configuration device, such as a computer, smartphone, tablet, or other remote connection, to configure the drive parameters. This allows for manual or software-assisted adjustment of the drive parameters. Alternatively or additionally, one or more sensors can be provided on or in the compressor, connected wirelessly or via a wired connection to the control unit. These sensors can detect state variables (temperature, pressure, humidity, gas type or composition) of the gases supplied to the compressor and to be compressed, as explained further below. This allows the control unit to automatically configure the drive parameters; for example, the piston speed can be reduced when handling moist gases. During compressor operation, compression occurs when the piston moves within the cylinder, reducing the cylinder volume (on one side of the piston). This reduced volume increases the gas pressure within the cylinder until one or more exhaust valves open, allowing the compressed gas to escape. When the piston moves in the opposite direction (reverse movement), the cylinder volume (on the corresponding side of the piston) increases again. The pressure in the cylinder decreases, causing one or more intake valves to open, allowing fresh gas to enter the cylinder (compression chamber). This gas can then be compressed again when the piston reverses its movement. Advantageously, the compressor can have two cylinders (a first cylinder and a second cylinder), with a further piston guided in the second cylinder and coupled to another piston rod. A further electric drive unit is provided for driving this additional piston rod, and the piston rods can be driven independently of each other by means of the drive units. This allows for independent drive of the pistons, enabling individual delivery rates or volume flows. Thus, targeted adjustment of the gas supplied by each cylinder or compression chamber to the specific requirements of the consumers can be achieved. The control system mentioned above can optionally be configured and / or designed to control both drive units. In other words, the compressor for compressing gases can be equipped with at least two cylinders, each containing a piston, with each piston being coupled to a piston rod (first piston rod and second piston rod). Each piston rod is driven by an electric drive unit, allowing the piston rods to be driven independently. A control unit is provided for controlling the drive units, configured such that the (average and / or maximum) piston speed and the initial and / or final position of the pistons within their respective cylinders can be varied. The drive unit can advantageously include an electric motor that drives a threaded spindle, which in turn drives a spindle nut coupled to the piston rod. This creates a structurally advantageous drive system, as large lifting forces can be achieved even with relatively small thread pitches and low drive torques from the electric motor. The threaded spindle has an external thread that corresponds to an internal thread in the spindle nut. The threaded spindle can be, for example, the motor shaft or a section of the electric motor's shaft, or a separate shaft. The spindle nut can optionally serve as a stop against the cylinder and / or the drive unit or the electric motor. Alternatively, the drive unit can be designed as an electric linear actuator, which has a driven output element that can be displaced translationally when driven and is coupled to the piston rod. This also allows for the drive of the piston rod or piston. In a preferred embodiment, sensors can be provided at the compressor inlet to detect physical parameters of the gas supplied to the compressor at the inlet (temperature, pressure, humidity, gas type and / or gas composition) as sensor signals. The sensors are connected to the control system wirelessly or via a wired connection for transmitting these signals. This allows the piston movement (acceleration, initial position and / or final position) to be adjusted by the control system depending on the supplied gas(es). Efficiency can thus be improved and safety optimized.Advantageously, the control system can be configured such that when the sensors detect that the supplied gas exceeds a defined humidity threshold, the initial and / or final position of the piston in the cylinder is adjusted. Thus, if a humidity threshold is exceeded ("high humidity"), the initial and / or final position of the piston in the cylinder can be adjusted (shorter stroke) and / or the piston speed or acceleration can be reduced. This contributes to high operational reliability, as it reduces the risk of water hammer. If the humidity threshold, or possibly a further humidity threshold, is undershot, the initial and / or final position of the piston in the cylinder can be adjusted again (longer stroke) and / or the piston speed or acceleration can be increased.The humidity threshold(s) can be stored in the sensor(s) or in the control system. According to the invention, two further cylinders are provided, each containing a piston, the pistons being coupled by means of a common piston rod. An electric drive device is provided by means of which the common piston rod can be driven. Gas supplied to the compressor or the cylinders can also be compressed using these further cylinders, with the pistons being driven together. When driven, both pistons move in the same direction. Compression occurs in opposite directions; that is, when one of the further pistons is compressing, the second further piston can draw in gas. Advantageously, the control system is configured to control the drive unit and / or the drive device using sensor-based, model-based, or experience-based methods. Thus, in addition to conventional control approaches (position and / or time control), the control system can incorporate control logic with sensor-, model-, and / or experience-based components. Alternatively or additionally, the control system can be configured to control the drive unit and / or the drive device in a self-learning manner. This allows for a learning, self-adapting control system for the drive unit and / or the drive device. Advantageously, the common piston rod can be designed, at least partially, as a rack, with the drive unit being an electric motor whose motor shaft carries a drive pinion that meshes with the rack. Thus, the common piston rod can be driven by the electric motor using simple design features. The gear ratio between the drive pinion and the rack can be adjusted by changing the drive pinion. In a preferred embodiment, the drive unit can be wirelessly or via a wired connection to the control unit and controlled by the control unit, or a further control unit can be provided for controlling the drive unit, wherein the control unit or the further control unit is configured such that the (average and / or maximum) piston speed and the initial and / or final position of the pistons in the other cylinders can be varied. This allows for parameterization of the drive with respect to speed profile and compression ratio, so that the piston movement in the other cylinders can also be adjusted. Advantageously, one of the cylinders and one of the other cylinders can each be combined to form a compressor block. This contributes to a compact and material-saving design, since structures or components of the compressor block can be shared by the cylinders arranged together in one compressor block. The cylinder and the next cylinder of a compressor block can be advantageously connected in series. This allows for a higher compression of a gas than if the gas were compressed in only one cylinder. The outlet of the next cylinder and the inlet of the first cylinder can be flow-connected. Thus, the gas is first compressed in the next cylinder and then in the first cylinder of the compressor block. The first cylinder can be individually configured, for example, with "gentle compression" (reduced acceleration or speed of the piston). A reversed series connection is also conceivable. In this case, the outlet of the cylinder in one compressor block can be flow-connected to the inlet of the next cylinder in that same compressor block. The invention is explained in more detail below with reference to the figures, where identical or functionally equivalent elements are provided with identical reference numerals, possibly only once. The figures show: Fig. 1 an embodiment of the compressor for compressing gases in a perspective view; Fig. 2 the compressor from Fig. 1 in a side view according to arrow II in Fig. 1; and Fig. 3 the compressor from Fig. 1 in a sectional view according to the section plane III-III shown in Fig. 2. Fig. 1 shows a compressor for compressing gases, designated overall by reference numeral 10. In this example, the compressor 10 has two compressor blocks 70, 72 (see Fig. 1), in each of which a first cylinder 12, 14 and a further cylinder 50, 52 are arranged (see Fig. 3). The compressor blocks 70, 72 each have a cylinder head 74, 76, in which an inlet valve 78 and an outlet valve 80 are arranged for each cylinder 12, 14, 50, 52 (see Fig. 1). In addition, cooling channels 82, 84 are formed in each compressor block 70, 72, through which a cooling medium can flow to cool the cylinders 12, 14, 50, 52 (see Fig. 3). The cooling channels 82, 84 each have an inlet 86 and an outlet 88 (shown in the figures with a sealing plate 90). The drive components for driving the pistons running in cylinders 12, 14, 50, 52, which are described below, are arranged between the compressor blocks 70, 72. The compressor blocks 70, 72 and the drive components arranged between them can be enclosed by a housing (compressor housing) (not shown). As already indicated, the compressor 10 in the example has two first cylinders 12, 14, each containing a piston 16, 18 (see Fig. 3). The pistons 16, 18 are each coupled to a piston rod 20, 22 (first piston rod 20 and second piston rod 22), for example, by means of a screw on the piston rod 20, 22. An electric drive unit 24, 26 is provided for each piston rod 20, 22, by means of which the piston rods 20, 22 can be driven independently of each other. A control unit 30 is provided for controlling the drive units 24, 26, wherein the control unit 30 is configured such that the piston speed and the initial and / or final position of the pistons 16, 18 in their respective cylinders 12, 14 can be varied. The drive units 24, 26 are each connected to the control unit 30 by means of a control and / or signal line 31, 33. In the example, the drive units 24, 26 each have an electric motor 32, 34, which drives a threaded spindle 36, 38, by means of which a spindle nut 40, 42 can be driven, each of which is coupled to the piston rod 20, 22. The threaded spindles 36, 38 each have an external thread which corresponds to an internal thread of the spindle nuts 40, 42. A sensor 46 is provided at the compressor inlet 44, by means of which physical state variables of the gas supplied to the compressor 10 at the compressor inlet 44 (temperature, pressure, humidity, gas type, and / or gas composition) can be detected as sensor signals (see Fig. 3). In this example, the sensor 46 is connected to the controller 30 by means of a further control and / or signal line 35 for the transmission of the sensor signals. Thus, the piston movement (acceleration, initial position and / or final position of the pistons 16, 18 in the cylinder 12, 14) can be adjusted by the controller 30 depending on the supplied gas(es). The sensor 46 can optionally be provided at several or all compressor inlets (here, for the sake of clarity, only one compressor inlet 44 is shown). The control unit 30 is configured such that when the sensor 46 detects that the supplied gas exceeds a defined humidity threshold, the initial and / or final position of the pistons 16, 18 in their respective cylinders 12, 14 is adjusted. Thus, if a humidity threshold is exceeded ("high humidity"), the initial and / or final position of the piston 16, 18 in the cylinder 12, 14 can be adjusted (reduced stroke) and / or the piston speed or acceleration can be reduced. If the humidity threshold, or possibly a further humidity threshold, is undershot, the initial and / or final position of the piston 16, 18 in the cylinder 10, 12 can be adjusted again (greater stroke) and / or the piston speed or acceleration can be increased. The humidity threshold(s) can be stored in the sensor 46 or in the control unit 30. As already indicated, the compressor 10 has two further cylinders 50, 52, each containing a piston 54, 56, the pistons 54, 56 being coupled by means of a common piston rod 58, an electric drive device 60 being provided by means of which the common piston rod 58 can be driven. The pistons 54, 56 are each arranged at the ends of the common piston rod 58 and attached to it, e.g. by means of a screw on the piston rod 58. The two pistons 54, 56 move in the same direction when the piston rod 58 is driven. Compression occurs in opposite directions; that is, when one of the pistons 54, 56 compresses gas in cylinder 50, 52, the other piston 54, 56 can draw gas into cylinder 50, 52. The common piston rod 58 is at least partially designed as a rack 62, wherein the drive unit 60 is designed as an electric motor whose motor shaft carries a drive pinion 64 which meshes with the rack 62. By rotating the electric motor 60, the piston rod 58 and the pistons 54, 56 can be moved translationally via the drive pinion 64 and the rack 62. In this example, the drive unit or electric motor 60 is connected to the controller 30 via a further control and / or signal line 37 and is controlled by the controller 30. The controller 30 is configured such that the piston speed and the initial and / or final positions of the pistons 54, 56 in the other cylinders 50, 52 can be varied. This allows the drive of the pistons 54, 56 to be parameterized with respect to speed profile and compression ratio, so that the piston movement in the other cylinders 50, 52 can also be adjusted. Due to the shared piston rod 58, the pistons 54 and 56 in cylinders 50 and 52 adjust together. For example, if the (lower) end position of piston 54 in cylinder 50 is adjusted (piston 54 is moved away from cylinder head 74), this affects the (upper) initial position of piston 56 in cylinder 52 (piston 56 is moved towards cylinder head 76). It has already been explained above that one of the cylinders 12, 14 and one of the other cylinders 50, 52 are each combined to form a compressor block 70, 72. Cylinders 12, 14 and the other cylinder 50, 52 of a compressor block 70, 72 can be connected in series (not shown). For example, the outlet of the other cylinder 50, 52 and the inlet of the first cylinder 12, 14 can be flow-connected, as explained above. A reverse series connection is also conceivable. Thus, the outlet of cylinder 12, 14 of a compressor block 70, 72 can be flow-connected to the inlet of the other cylinder 50, 52 in this compressor block 70, 72.

Claims

Compressor (10) for compressing gases, comprising at least one cylinder (12, 14) in which a piston (16, 18) is guided, wherein the piston (16, 18) is coupled to a piston rod (20, 22), wherein an electric drive unit (24, 26) is provided for driving the piston rod (20, 22), and wherein a control unit (30) is provided for controlling the drive unit (24, 26), the control unit (30) being configured such that the piston speed and the initial position and / or the final position of the piston (16, 18) in the cylinder (12, 14) are variable, characterized in that two further cylinders (50, 52) are provided, each in which a piston (54, 56) is guided, wherein the pistons (54, 56) are coupled by means of a common piston rod (58), wherein an electric drive unit (60) is provided, by means of which can drive the common piston rod (58). Compressor (10) according to claim 1, characterized in that two cylinders (12, 14) are provided, wherein in the second cylinder (14) a further piston (18) is guided, which is coupled to a further piston rod (22), wherein a further electric drive unit (26) is provided for driving the further piston rod (22), wherein the piston rods (20, 22) can each be driven independently of each other by means of the drive units (24, 26). Compressor (10) according to claim 1 or 2, characterized in that the drive unit (24, 26) each has an electric motor (32, 34) which drives a threaded spindle (36, 38) by means of which a spindle nut (40, 42) can be driven, which is coupled to the piston rod (20, 22) or that the drive unit (24, 26) is designed as an electric linear drive which has a driveable and translationally displaceable output element which is coupled to the piston rod. Compressor (10) according to one of the preceding claims, characterized in that a sensor (46) is provided at the compressor inlet (44) by means of which physical state variables of the supplied gas can be detected as sensor signals, wherein the sensor (46) is connected wirelessly or wired to the control unit (30) for the transmission of the sensor signals. Compressor (10) according to claim 4, characterized in that the control (30) is configured such that when the sensor (46) detects that the supplied gas exceeds a defined moisture threshold, the initial and / or final position of the piston (16, 18) in the cylinder (12, 14) is adjusted. Compressor (10) according to one of the preceding claims, characterized in that the control unit (30) is configured such that it controls the drive unit (24, 26, 60) or the drive device (60) in a sensor-based, model-based or experience-based manner and / or that the control unit (30) is configured such that it controls the drive unit (24, 26) or the drive device (60) in a self-learning manner. Compressor (10) according to one of the preceding claims, characterized in that the common piston rod (58) is designed at least partially as a rack (62), wherein the drive device (60) is designed as an electric motor, the motor shaft of which carries a drive pinion (64) which meshes with the rack (62). Compressor (10) according to one of the preceding claims, characterized in that the drive device (60) is wirelessly or wired connected to the control unit (30) and is controlled by means of the control unit (30) or that a further control unit is provided for controlling the drive device (60), wherein the control unit (30) or the further control unit is configured such that the piston speed and the initial position and / or final position of the pistons (54, 56) in the further cylinders (50, 52) can be varied. Compressor (10) according to one of the preceding claims, characterized in that one of the cylinders (12, 14) and one of the further cylinders (50, 52) are each combined to form a compressor block (70, 72). Compressor (10) according to claim 9, characterized in that the cylinder (12, 14) and the further cylinder (50, 52) of a compressor block (70, 72) are connected in series.

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