JP2023007494A - Reciprocating compressor and method for operating reciprocating compressor - Google Patents

Abstract

To provide a reciprocating compressor capable of reducing the amount of lubricant to a level required for operation, and also to provide a method for operating the reciprocating compressor.SOLUTION: In a lubricating system, at least one lubricant sensor 15 is provided for detecting a lubricating film measurement variable S representative of a lubricating film thickness of a lubricating film 11 on the cylinder surface of the cylinder 2, a lubricating system control unit 14 being designed to operate the lubricating system at least once in a predetermined calibration operating mode during operation of the reciprocating compressor 1 and to determine a lubricating film state value on the basis of the lubricating film measurement variable detected during execution of the calibrating operating mode, and the lubricating system control unit being designed, after the end of the calibration operating mode during operation of the reciprocating compressor, to control the amount of lubricant to be introduced depending on the determined lubricating film state value.SELECTED DRAWING: Figure 1

Description

The present invention is a lubricant supply system for a reciprocating compressor, the lubricant supplying system introducing a lubricant to a cylinder sliding surface of a cylinder in which a piston reciprocates in the reciprocating compressor, LUBRICANT SUPPLY SYSTEM FOR CONTROLLING THE QUANTITY OF LUBRICANT TO BE INTRODUCED—Relating to a lubricant supply system provided with a control unit. The invention further provides a reciprocating compressor comprising a lubricant supply system and a method of operating a reciprocating compressor comprising at least one cylinder in which a piston reciprocates, wherein the lubricant supply system causes the cylinders of the at least one cylinder to The method relates to a method in which the sliding surfaces are supplied with lubricant and the amount of lubricant supplied is controlled by a lubricant supply system-control unit.

In reciprocating machines, especially lubricated reciprocating compressors, reliable lubrication to the cylinders is extremely important for reliable operation. In principle, each cylinder has one or more lubricant feed points, via which lubricant can be introduced into the cylinder. The lubrication points are often lubricated by a central lubrication system. Dosing the lubricant to the cylinder as accurately as possible is essential for reliable operation. If the amount of lubricant is too low, the wear on the moving parts of the compressor will increase, especially on the piston rings that seal the piston rod or on the packing rings of the seal packings. Increased wear results in a shorter service life for these components, which in turn reduces the availability of the compressor. Conversely, too much lubricant usually shortens the service life of components such as compressor valves, due to oil-adhering effects, as well as components connected after the compressor, such as catalytic converters. shorten the useful life of the equipment in use. In addition, high lubricant volumes not only result in increased operating costs, of course, based on lubricant consumption, but also the need for special separators, etc., to remove excess lubricant from the compressed process stream. Higher capital input costs due to the need for additional equipment.

Known lubricant delivery systems are often based on a predetermined amount of lubricant for each reciprocating machine. These predetermined lubricant amounts are typically provided by the compressor manufacturer as a function of compressor type, size and process parameters and are based on empirical data or simplified computational models. These calculation models are subject to uncertainties and usually have a safety factor chosen correspondingly conservatively to cover all compressor construction styles and operating conditions, therefore usually , more lubricant than necessary is supplied. Such "over-lubrication" of the cylinders during operation is of course disadvantageous to those operating reciprocating compressors for the reasons stated above, and is therefore undesirable.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a reciprocating compressor and a method of operating a reciprocating compressor in which an excessive supply of lubricant to the cylinder is avoided and the amount of lubricant can be reduced to the extent necessary for operation. .

The above-mentioned problem is solved by the lubricant supply system mentioned at the outset as follows. That is, at least one lubricant sensor is provided for detecting a lubricant film-measurement quantity representing the lubricant film thickness of the lubricant film on the cylinder sliding surface of the cylinder, and the lubricant supply system--the control unit comprises a reciprocating operating the lubricant delivery system in a predetermined calibration mode of operation at least once during operation of the compressor to determine a lubricant film condition value based on the lubricant film-measurement detected during execution of the calibration mode of operation; and further configured to control the amount of lubricant to be introduced during operation of the reciprocating compressor after termination of the calibration mode of operation, according to the determined lubricant film condition value. That is. As a result, based on the measurement of the lubricant film thickness and the evaluation of the measurement results, the state of the lubricant film on the cylinder sleeve is automatically detected, and based on this, an appropriate amount of lubricant is automatically provided. A delivery system is obtained. This makes it possible to significantly reduce the amount of lubricant required compared to conventional lubrication systems, so that there is no over-lubrication of the cylinders.

The lubricant sensor is preferably an ultrasonic sensor, where the time resolution of the lubricant sensor is preferably between 0.01° and 5° crank angle. This allows easy detection of the lubricant film-measured quantity without the need for direct access to the cylinder sliding surface. For example, an ultrasonic sensor can easily be placed on the outside of an existing cylinder.

The lubricant supply system-control unit preferably detects the sensor value of the lubricant film-measured quantity, preferably during the piston stroke of the piston, when the piston ring of the piston is in the sensor area of the lubricant sensor. , the minimum value of the lubricant film-measured quantity detected during the piston stroke is used to determine the lubricant film condition value. This makes it possible to estimate the current lubricant film thickness in the area of the piston rings and on this basis to determine the required lubricant quantity.

Preferably, the lubricant supply system is configured for intermittent introduction of lubricant into the cylinder, preferably configured as a pump-to-point system, as a divider block system, or as a common rail system. , the lubricant supply system-control unit is configured to control the amount of lubricant by varying the frequency of intermittent introduction of lubricant and/or the injection volume of each injection. This allows established lubricant supply systems to be used and calibrated accordingly.

Lubricant supply system--The control unit advantageously performs a calibration operation at defined cycles to update the lubricant film condition value and adjust the lubricant quantity to match the updated lubricant film condition value. configured to repeat modes. This makes it possible to take into account changes that occur during operation, possibly requiring a higher or lower lubricant quantity. This is, for example, piston ring wear.

The duration of the calibration mode of operation is preferably at least 10, preferably at least 100, particularly preferably at least 1000 crankshaft revolutions of the reciprocating compressor or equivalent. This allows sufficient time to set up and evaluate various conditions of the lubricant film.

Preferably, in the calibrated mode of operation, at least two successive time ranges with different lubricant amounts are defined, and the lubricant supply system-control unit detects lubricant film detected during the at least two time ranges. - in the course of time of the measured quantity, maxima and minima are determined, from which lubricant film condition values are determined for controlling the lubricant quantity. Particularly preferably, a first time range with a defined duration and a second time range with a defined duration following the first time range are defined here, the first time range The amount of lubricant introduced during the range is determined to result in a completely wet lubricant film on the cylinder sliding surfaces, and the amount of lubricant introduced during the second time range is It is designed so that dry sliding occurs on the surface. The duration of the first time range is preferably at least 5 crankshaft revolutions and the amount of lubricant introduced during the first time range is preferably set by the compressor manufacturer. 90-200% of the volume. The duration of the second time range is preferably at least 5 crankshaft revolutions and the amount of lubricant introduced during the second time range is preferably set by the compressor manufacturer. 0% of the volume. This simulates a variety of lubricant film conditions and is used to determine representative lubricant film condition values that are generally applicable.

Advantageously, the lubricant supply system-control unit determines a difference value between the determined maximum value and the determined minimum value and determines the lubricant film boundary value from the maximum value and the determined difference value. , is configured to use this lubricant film boundary value as the lubricant film state value. The lubricant supply system-control unit preferably further comprises, during operation of the reciprocating compressor, after termination of the calibration mode of operation, the lubricant whose lubricant film-measured quantity is between the minimum value and the lubricant film boundary value. Delivery system—configured to actuate the lubricant delivery system to introduce lubricant when in the activation range. This provides, on the one hand, a differential evaluation method that is practically independent of the detected absolute value of the detected lubricant film-measured quantity, and, on the other hand, a simple index for activating the introduction of lubricant. is obtained.

The lubricant supply system is preferably also provided with a lubricant amount-detection unit for detecting the amount of lubricant supplied to the lubricant supply point, the lubricant supply system-control unit detecting the lubricant film It is arranged to compare the lubricant film-measured quantity obtained from the sensor and the lubricant quantity-lubricant quantity obtained from the detection unit, thereby checking these two values for consistency. and/or leaks in the lubricant supply system can be detected. This makes it possible to check the functionality of the lubricant sensor and detect leaks in the lubricant line. Based on this, certain actions can be taken, such as switching off the compressor or switching the lubricant supply to a conventional excess lubricant supply, which can make operation more reliable.

The present invention further uses at least one lubricant sensor to detect a lubricant film-measurement representative of the lubricant film thickness of the lubricant film on the cylinder sliding surface of the cylinder, and the lubricant supply system of the reciprocating compressor. operating in a predetermined calibration mode of operation at least once by the lubricant supply system-control unit during operation and determining a lubricant film condition value based on lubricant film-measurements detected during execution of the calibration mode of operation; , the lubricant supply system--the control unit controls the amount of lubricant to be introduced during operation of the reciprocating compressor after the end of the calibration mode of operation, depending on the determined lubricant film state value, solved by the method be done.

The invention will be explained in more detail hereinafter with reference to FIGS. 1 to 4, which show, by way of example, an advantageous configuration of the invention, schematically but not exclusively.

Fig. 3 is a cross-sectional view of a cylinder of the reciprocating compressor; FIG. 6 shows a graph in which the detected lubricant film-measurement quantity is plotted against the crank angle; FIG. 3 shows a graph in which the time course of the detected lubricant film-measurement quantity is plotted against the compressor revolutions of a reciprocating compressor; FIG. 5 shows a graph stating the percentage of lubricant quantity with respect to compressor revolutions for a reciprocating compressor; FIG. 5 shows a graph with detected lubricant film-measurement plotted against crank angle of a reciprocating compressor;

FIG. 1 shows a simplified cross-sectional view of cylinder 2 of reciprocating compressor 1 . A piston 3 is arranged in a known manner within the cylinder 2 and is reciprocable within the cylinder between top dead center OT and bottom dead center UT. The piston 3 can be driven by a crankshaft (not shown) via a connecting rod (not shown), a crosshead (not shown) and a piston rod 4 in known manner. Of course, other constructions of the reciprocating compressor 1 would also be possible. This is for example a direct drive of the piston 3 by means of a connecting rod without crosshead and piston rod 4 . In the illustrated example, a cylinder sleeve 5 , a so-called liner, is arranged in the cylinder 2 and has a cylinder sliding surface for the piston 3 formed on its inner peripheral surface.

Basically, however, a configuration without the cylinder sleeve 5 is also possible, in which case the cylinder sliding surface is provided directly on the inner peripheral surface of the cylinder 2 . Naturally, the reciprocating compressor 1 can have several cylinders 2, in each cylinder 2 a respective piston 3 can reciprocate, in which case several pistons 3 are driven by a common crankshaft. may be One or more piston rings 6 may be provided on the piston 3 and are arranged in suitable circumferential grooves in the circumference of the piston 3 . Within the scope of the present invention, piston ring 6 should generally be understood to mean piston rings with different functions. For example, the piston ring 6 can be configured as a sealing ring, support ring or scraper ring. The seal ring, for example, is configured to seal against pressure differentials, whereas the support ring typically has no sealing action and is configured to support the load of the piston 3 on the cylinder sleeve. there is Also, the scraper ring is configured to scrape off the lubricant film from the cylinder sliding surface.

Naturally, not all structural modalities need be provided on the piston 3, for example only piston rings 6, for example in the form of sealing rings. In the example shown, three piston rings 6a, 6b, 6c are provided, where the first and third piston rings 6a, 6c are configured as sealing rings and the second The piston ring 6b is constructed as a support ring. However, more or fewer piston rings 6 may be provided, for example oil scraper rings may also be provided. It can be seen here that the support ring 6b has a wider width (in the axial direction) than the sealing rings 6a, 6c. This is the normal case. Furthermore, the groove of the piston 3 in which the support ring 6b is arranged is constructed so that the support ring 6b rests directly on the bottom of the groove. Thus, the support ring 6b is substantially radially immovable, in contrast to the sealing rings 6a, 6c, in order to be able to support the load of the piston 3 better. In contrast, the sealing rings 6a, 6c can move radially within each groove in order to be able to produce a better seal. In general, the piston ring 6 can of course also have some radial projection beyond the piston 3, but for the sake of clarity this is not shown in FIG.

Formed in the cylinder 2 in a known manner is a compression chamber 7 defined by the piston 3, in which a suction valve 8 and a pressure valve 9 are arranged. During the expansion stroke, the piston 3 moves from top dead center OT to bottom dead center UT, and during the compression stroke, the piston 3 moves from bottom dead center UT to top dead center OT. During the expansion stroke, a gaseous medium to be compressed, eg air or process gas, can be sucked into the compression chamber 7 via the intake valve 8 . During the compression stroke, the medium in compression chamber 7 is compressed and discharged from compression chamber 7 via pressure valve 9 . The intake valve 8 and the pressure valve 9 are shown in FIG. 1 only as schematic circuit symbols and may have different constructions.

A plurality of intake valves 8 and pressure valves 9 may be provided on the cylinder. The intake valve 8 and the pressure valve 9 do not necessarily have to be arranged on the end surface of the cylinder 2 , and may be provided on the peripheral surface of the cylinder 2 within the compression chamber 7 , for example. For example, the suction valve 8 and the pressure valve 9 may be configured as known automatic ring valves, possibly with an unloader to keep the valves open. The unloader may be driven and controlled by a suitable compressor control unit 10 to regulate the compressor 1 capacity.

The reciprocating compressor 1 also has a lubricant supply system for supplying lubricant to the at least one cylinder 2 . The lubricant supply system has for this purpose at least one lubricant supply point 12 for introducing lubricant into the cylinder 2 for each cylinder 2 . The lubricant forms a lubricant film 11 in the cylinder 2 to minimize friction between relatively moving components, in particular between the piston 3 or piston rings 6 and the cylinder sliding surfaces. Naturally, in order to be able to distribute the lubricant in the cylinder 2 as uniformly as possible, it is also possible to provide a plurality of lubricant feed points 12, which are spaced from one another, for example axially and/or circumferentially. can be distributed in the cylinder 2, which is indicated in FIG. 1, for example, by the lubricant supply points 12a, 12b. Depending on the structural design of the piston rings 6, for example, before each piston ring 6 reaches the lubricant feed point 12, while the piston ring 6 is in the region of the lubricant feed point 12, or as the case may be, each piston ring It may be advantageous for the introduction of lubricant to take place via the lubricant feed point 12 in the compression stroke and/or the expansion stroke even after the lubricant feed point 6 has passed through the lubricant feed point 12 . The point of introduction is substantially related to the lubricant supply system used.

Various lubricant supply systems are known in the prior art, including so-called "divider block" systems, "pump-to-point" systems and "common rail" systems. In the "divider block" system, a central conveying unit for conveying the lubricant and a so-called "divider block" for distributing the lubricant to the lubricant supply points 12 of the cylinders 2 are provided. The lubricant quantities conveyed by the central conveying unit are supplied to so-called “divider blocks” where they are divided and conveyed to the individual lubricant supply points 12 . Here the lubricant is usually intermittently introduced into the cylinder 2 by means of individual injections. The amount of lubricant to be introduced is controlled here by a suitable control of the central conveying unit. For example, if the central conveying unit is designed as a piston pump, the conveying quantity can be controlled via the rpm and/or possibly the piston stroke. Here, changing the amount of lubricant during operation of the compressor 1 can be done by changing the frequency of intermittent individual injections of lubricant, for example by changing the pump speed. However, the central conveying unit allows the lubricant quantity to be changed only proportionally for all available lubricant supply points 12 . Different lubricant quantities for different lubricant supply points 12 or different cylinders 2 are generally not possible here.

In a "pump-to-point" system, each lubricant supply point 12 or each cylinder 2 is assigned its own conveying unit, for example a piston pump. Depending on the constructional design of the conveying unit, for example the stroke or cylinder volume of the piston pump, the corresponding lubricant quantity is normally likewise intermittently conveyed to the assigned lubricant supply point 12 via individual injections. be done. The conveying units, in particular the piston pumps, are usually driven via a common camshaft. Changing the amount of lubricant during operation of the compressor 1 can be done by changing the frequency of individual injections of lubricant, for example by adjusting the camshaft speed. Here too, the change in lubricant quantity is normally only carried out at a constant rate for all lubricant supply points 12 . However, in many "pump-to-point" systems it is also possible to vary the delivery volume individually, for example by means of an adjustable stroke of the piston pump. As a result, the lubricant quantity can be adjusted individually at each lubricant supply point 12 or for each cylinder 2 . For changing the amount of lubricant, for example, a suitable positioning device can be provided on the transport unit. The positioning device may, for example, be configured for manual positioning of the stroke of the piston pump or may be provided with a suitable actuator for positioning the stroke, whereby the lubrication introduced Dosage can vary from injection to injection.

There are also so-called "common rail" systems, in which the lubricant is conveyed by a high-pressure pump to a pressure accumulator, from which, by means of an electrically actuatable injector, each lubricant supply point 12 is supplied. Alternatively, each cylinder 2 can be supplied individually via a pressure line. Compared to the systems described above, such a system offers a great deal of flexibility in controlling the introduction of lubricant. In particular, the amount of lubricant can be varied not only by varying the frequency of intermittent injections, but also by very precisely and variably controlling the amount of lubricant introduced per injection. Furthermore, the point of introduction at each lubricant supply point 12 or each cylinder 2 can be adjusted individually and virtually independently of the operation of the high-pressure pump (as long as there is sufficient pressure in the pressure accumulator). This makes it possible, for example, in a reciprocating compressor 1 in which the piston 3 has a plurality of piston rings 6, to carry out multiple injections within one piston stroke, so that each piston ring 6 has It is possible to deliver a specific amount of lubricant on purpose.

In all lubricant delivery systems the lubricant introduction, e.g. the time of injection and/or the amount of lubricant per injection and/or the frequency of injections, is usually controlled via a suitable lubricant supply system-control unit 14. be done. The lubricant supply system-control unit 14 may be configured as separate hardware and/or software, or may be integrated into a higher-level control unit, such as the compressor control unit 10, for example. In FIG. 1 a "common rail" system is shown by way of example only, in which each lubricant supply point 12 is provided with one electrically controllable injector 13 . This injector 13 can be configured, for example, as an electromagnetic injector or a piezo injector. The injectors are connected to the central lubricant supply system-control unit 14 via any suitable communication connection such as electrical lines. As mentioned above, a pressure accumulator and high pressure pump are also provided, but these are not shown in FIG. 1 for the sake of clarity. The high pressure pump is preferably controlled by the lubricant supply system-control unit 14 as well. Lubricant supply system-control unit 14 can communicate with compressor control unit 10, for example, to obtain operating parameters BP of reciprocating compressor 1, which are relevant for controlling the lubricant supply system. Such operating parameters BP may, for example, contain current data about the operating state of the compressor 1, such as the load signal L, the speed signal N, the crank angle signal °KW, the lubricant temperature T, etc. . The lubricant supply system-control unit 14 can take into account these operating parameters BP when controlling the lubricant supply system.

As mentioned at the outset, the lubricant quantity was hitherto usually controlled based on the manufacturer's instructions, which often resulted in excessive lubrication, i.e. excessively high lubricant quantity than required. There was an introduction. In order to avoid this, according to the invention an automatic calibration of the lubricant supply system is set up, whereby the lubricant quantity can be adjusted to match the actual demand. For this purpose, in the lubricant supply system, at least one lubricant sensor 15 for detecting a lubricant film-measurement S representing the lubricant film thickness of the lubricant film 11 on the cylinder sliding surface of the cylinder 2. is provided in The lubricant film measurement quantity S is essentially a measure for the lubricant film thickness of the lubricant film 11 on the cylinder sliding surface in the sensor area of the lubricant sensor 15 . The lubricant sensor 15 is connected via a suitable communication connection with the lubricant supply system-control unit 14 so that the lubricant film-measured quantity S can be transferred, for example, via a suitable electrical measuring line. to the lubricant supply system-control unit 14. An acoustic sensor, in particular an ultrasonic sensor, is preferably provided as lubricant sensor 15 . Lubricant sensor 15 may, for example, be arranged at a suitable location outside cylinder 2 .

The lubricant sensor 15 is preferably axially arranged such that each piston ring 6 of the piston 3 lies in the sensor area of the lubricant sensor 15 once per piston stroke, so that lubrication The agent film thickness can be detected in the area of each piston ring 6 . As with multiple lubricant supply points 12 , multiple lubricant sensors 15 may also be arranged circumferentially and/or axially spaced from each other on the cylinder 2 . This can be advantageous especially in the case of large compressors, whereby a sufficiently large area of the cylinder sliding surface of the cylinder 2 can be covered. The time resolution of the lubricant sensor 15, in particular an ultrasonic sensor, which detects the lubricant film-measurement quantity S can be, for example, a crank angle of 0.01° to 5°.

According to the invention, the lubricant supply system-control unit 14 operates the lubricant supply system at least once in a predetermined calibrated mode of operation during operation of the reciprocating compressor 1 and detected during execution of the calibrated mode of operation Based on the lubricant film-measured quantity S, the lubricant film state value SZ is determined. After the end of the calibration mode of operation, ie during normal operation of the lubricant supply system during operation of the reciprocating compressor 1, the lubricant supply system-control unit 14, depending on the determined lubricant film state value SZ, is introduced Controls the amount of lubricant that should be applied.

As noted above, the lubricant supply system is preferably configured to introduce lubricant intermittently, preferably as a pump-to-point system, as a divider block system, or as a common rail system. The lubricant supply system-control unit 14 can adjust the amount of lubricant according to the determined lubricant film state value SZ, for example by changing the frequency of the intermittent introduction of lubricant, which can reduce the amount of lubricant compared to the manufacturer's setting. However, if the lubricant supply system is configured accordingly, for example in a common rail system, the (total) lubricant quantity introduced into the cylinder 2 can optionally be additionally or alternatively changed to , can also be changed by changing the amount of lubricant per injection of the injector 13 . In the case of a pump-to-point system or a divider block system, the frequency can be varied as described above, for example by increasing the speed of the delivery pump of each lubricant supply system.

Preferably, during the piston stroke of the piston 3, the sensor value Pi of the lubricant film-measured quantity S, which is detected when the piston ring 6 of the piston 3 is in the sensor area of the lubricant sensor 15, indicates the lubricant film state. It is used to find the value SZ. Preferably, as shown in FIG. 2, the respective local minimum of the lubricant film-measured quantity S is used here. In FIG. 2, during normal operation of the reciprocating compressor 1 (and lubricant supply system), the detected An exemplary course of the lubricant film-measured quantity S is shown. The piston 3 here corresponds to the configuration shown in FIG. 1 and accordingly has three piston rings 6a, 6b, 6c. Of course, however, more or fewer piston rings 6 may also be provided. The curve shown corresponds to the measured signal of the lubricant sensor 15 as a function of the crank angle. As can be seen from FIG. 2, depending on the number i of the piston rings 6i, a characteristic time course of the lubricant film-measured quantity S occurs, which indicates the lubrication of the lubricant film 11 on the cylinder sliding surface of the cylinder 2. It can be used as a measure for agent film thickness.

The curve now has a local minimum for each piston ring 6i, which, if each piston ring 6i is in the sensor area of the lubricant sensor 15, is the lubricant on the cylinder sliding surface. It is proportional to the lubricant film thickness of film 11 . In the example shown, this is the local minima Pa, Pb, Pc, which are hereinafter generally referred to as PEAK values Pi within the scope of the invention. The assignment of the PEAK values Pa, Pb, Pc to the respective piston rings 6a, 6b, 6c occurs correspondingly to their arrangement on the piston 3. These PEAK values Pa, Pb, Pc (generally Pi) are now defined according to the invention as lubricant film It can be used to determine the state value SZ.

In principle, however, of course, multiple lubricant sensors 15 can also be provided in the lubricant supply system in order to allow redundant detection of the lubricant film-measurement S. These lubricant sensors 15 may, for example, be circumferentially spaced from each other at a certain angle on the cylinder 2 and/or may be axially spaced from each other on the cylinder 2 . . Preferably, of course, here too each lubricant sensor 15 is arranged in such a way that all available piston rings 6i of the piston 3 are located in the sensor area of each lubricant sensor 15 once during the piston stroke. there is Two lubricant sensors 15 with different circumferential positions and the same axial position in the cylinder 2 will, for example, lead to qualitatively equal lubricant film-measurement S curves. However, these profiles can differ quantitatively from one another due to the locally different lubricant film thickness of the lubricant film 11 . However, the PEAK value Pi will be located at the same crank angle position. In contrast, two lubricant sensors 15 with different axial positions and the same circumferential position lead, for example, to qualitatively and quantitatively different profiles of the lubricant film measurement quantity S. right. In this case, the PEAK values Pi will be located at different crank angle positions. However, an advantageous differential evaluation method of the PEAK value course, which will be explained in more detail below, will again compensate for different absolute values of the PEAK values Pi.

For example, the PEAK value Pi may be detected once per crankshaft revolution or once per piston stroke and stored in the lubricant supply system-control unit 14 . In principle, however, the following may also suffice. That is, rather than the PEAK value Pi being uninterrupted, i.e. detected for each revolution of the crankshaft or each piston stroke, and stored for evaluation over time, the PEAK value Pi may be e.g. of the crankshaft rotation or a defined interruption duration of, for example, 1 to 60 seconds.

An exemplary calibration mode of operation of the lubricant supply system is described below on the basis of Figures 3a and 3b. FIG. 3b now shows the time course of the amount of lubricant introduced into the cylinder 2 during the calibration mode of operation versus the crankshaft rotation of the compressor 1 . In FIG. 3a, for the example of the first piston ring 6a, the stored PEAK value Pa, resulting from the amount of lubricant introduced, shown in FIG. Time lapse is shown. The duration of the calibration mode of operation can here, for example, be at least 10 crankshaft revolutions of the reciprocating compressor 1, preferably at least 100 crankshaft revolutions, particularly preferably at least 1000 crankshaft revolutions. Since the rotation of the crankshaft is proportional to time, basically time may be plotted on the horizontal axis.

According to the invention, the calibration mode of operation is carried out at least once during operation of the reciprocating compressor 1, for example after a break-in phase during first use or after service activities on the compressor 1. The break-in phase typically corresponds to an operating time of 12-36 hours. However, of course, in order to determine the updated lubricant film condition value SZ and adjust the lubricant quantity to match the updated lubricant film boundary value SZ, the calibration mode of operation is repeated for a number of defined cycles. It can be repeated several times. This makes it possible to take into account various wear conditions that occur during operation. These wear conditions are usually related to changes in lubricant demand.

In the calibration mode of operation, preferably at least two consecutive time ranges Zi with different lubricant quantities Mi are defined, the lubricant supply system-control unit 14 detecting during at least two time ranges In the course of the lubricant film-measured quantity S, in particular in the course of the PEAK value Pi, a maximum value Pi_max and a minimum value Pi_min are determined, from which the lubricant film state values used for controlling the lubricant quantity are determined. Find SZ (Fig. 4). Preferably, maximum Pi_max and minimum Pi_min and the corresponding detection instants are determined and (at least temporarily) stored. Storage may generally take place in a suitable memory unit, which may eg be integrated in the lubricant supply system-control unit 14 or in the superior compressor control unit 10, for example. The time range Zi and the amount of lubricant Mi introduced in the time range Zi provide different frictional forces on the cylinder sliding surface, from a fully wet lubricant film through a partially wet lubricant film to dry sliding. conditions, and thus wear conditions associated therewith, are determined to occur. The lubricant quantity M is now indicated on the vertical axis in the graph of FIG. 3b in percentage of the lubricant quantity set by the compressor manufacturer.

In the calibration mode of operation shown, a first time range Z1 having a predetermined duration and a second time range Z2 following the first time range Z1 having a predetermined duration are provided merely by way of example. It is defined. The lubricant quantity M1 introduced during the first time period Z1 is here preferably determined such that a completely moist lubricant film is produced on the cylinder sliding surfaces. In contrast, the quantity M2 of lubricant introduced during the second time period Z2 is preferably dimensioned such that dry sliding occurs on the cylinder sliding surfaces. For example, the duration of the first time range Z1 may be at least 5 crankshaft revolutions, and the lubricant amount M1 introduced during the first time range Z1 is set by the compressor manufacturer. It may be 90 to 200% of the dosage. As a result, the maximum Pa_max is typically in the first time range Z1 and the minimum Pa_min is typically in the second time range Z2. As can be seen from FIG. 3a, a characteristic drop in the curve of the PEAK value Pa occurs in the transition between the first time range Z1 and the second time range Z2.

The duration of the second time range Z2 is also preferably at least 5 crankshaft revolutions, but can of course be much longer, for example 10 crankshaft revolutions, 100 crankshaft revolutions or It may be 1000 crankshaft revolutions. The lubricant quantity M2 introduced during the second time period Z2 is preferably 0% of the lubricant quantity set by the compressor manufacturer, so no lubricant is introduced. At the end of the second time period Z2, the lubricant amount M is increased again, for example, initially to the lubricant amount M3 set by the compressor manufacturer, as indicated by the third time period Z3. you can Basically, the calibration mode of operation ends after a second time range Z2 and from this point on the lubricant supply system-control unit 14 determines the lubricant film state value SZ (Fig. 4) can be used to control the amount of lubricant during operation of the reciprocating compressor 1 .

Advantageously, as shown in FIG. 3a, first the difference value ΔPa between the determined maximum value Pa_max and the determined minimum value Pa_min is determined. Based on the maximum value Pa_max and the determined difference value ΔPa, the lubricant film boundary value Pa_grenz is now determined. Lubricant film boundary value Pa_grenz can advantageously be used as lubricant film state value SZ for controlling the lubricant quantity, as will be explained below with reference to FIG. The boundary value Pa_grenz may, for example, be determined according to the relationship Pa_grenz=Pa_max−k*ΔPa, with a percentage factor K that may range from 10% to 100%. If more than one lubricant sensor 15 is provided on the cylinder 2, the evaluation and determination of the lubricant film state value SZ, in particular the boundary value Pi_grenz, is of course preferably performed on the lubricant film − It is performed on the measured quantity S. However, it is also possible, for example, to use the average value of the maximum values Pi_max and the minimum values Pi_min of a plurality of lubricant sensors 15 and to calculate the average boundary value Pi_grenz therefrom. Similarly, a mean value can also be formed from a plurality of boundary values Pi_grenz, on the basis of which the lubricant quantity can be controlled.

FIG. 4, like FIG. 2, shows top dead center OT and bottom dead center during normal operation of the reciprocating compressor 1, especially during normal operation of the lubricant supply system (after the calibration operation mode or outside the calibration operation mode). The curve of the detected lubricant film measurement quantity S is shown over the piston stroke to UT. Additionally, FIG. 4 shows the maximum value Pa_max and the minimum value Pa_min as well as the lubricant film boundary value Pa_grenz determined previously in the calibration mode of operation. The hatched area between the minimum value Pa_min and the lubricant film boundary value Pa_grenz represents the lubricant supply system activation range 17 . The lubricant supply system-control unit 14 determines that the PEAK value Pa of the detected lubricant film-measurement S lies in the lubricant supply system-activation range 17, i.e. the PEAK value Pa to the lubricant film boundary value Pa_grenz. Upon identifying that it has been reached or fallen below, the lubricant supply system-control unit 14 drives the lubricant supply system to introduce lubricant.

This is via the lubricant supply point 12 if the PEAK value Pa of the detected lubricant film-measured quantity S is outside the lubricant supply system-activation range 17 (i.e. above the boundary value Pa_grenz). means that no lubricant is introduced into the cylinder 2. The PEAK value Pa of the detected lubricant film-measured quantity S is sufficiently low and within the lubricant supply system-activation range 17 (this is an indication for insufficient lubricant film thickness of the lubricant film 11 ), the lubricant is supplied to the cylinder 2 again. After the lubricant dosing process has been carried out, the characteristic curve of the lubricant film-measurement S (FIG. 4) becomes flatter again and the PEAK value Pa exceeds the boundary value. Depending on the lubricant used, the amount of lubricant introduced in the dosing process and the operating and wear states of the reciprocating compressor 1, etc., the characteristic course of the lubricant film-measured quantity S changes again over the crankshaft revolution, The PEAK value Pa thus slowly approaches the lubrication system activation range 17 again.

As soon as the PEAK value Pa returns to the lubricant supply system activation range 17, a new dosing process is triggered by the lubricant supply system control unit 14, followed by further processes. The (total) lubricant quantity is thus substantially controlled by adjusting the frequency of the individual injections. However, in the case of common rail systems, in addition to changing the frequency, for example, the amount of lubricant introduced per injection can also be changed. In contrast, for pump-to-point systems and divider-block systems, the quantity of lubricant introduced per injection is substantially related to the structural design of the conveying unit, e.g. cannot be changed. Adjustment of the (total) lubricant amount can therefore usually only be controlled by adjusting the frequency of the individual injections, which is done for example by changing the speed of the piston pump.

The description based on the first piston ring 6a should of course only be understood as an example and the calibration mode of operation can of course also be carried out separately for a plurality of piston rings 6i. For example, in the calibrated operating mode, the course of the lubricant film-measured quantity S of the lubricant sensor 15 can be evaluated correspondingly for each piston ring 6i, whereby in order to control the lubricant quantity, the piston ring Each lubricant film state value SZi can be obtained every 6i. For example, each boundary value Pi_grenz can now be determined for each piston ring 6i, so that for each piston ring 6i a corresponding lubricant supply system activation range 17i is determined. Here, the lubricant supply system-control unit 14 activates the lubricant during normal operation of the reciprocating compressor 1 as soon as the respective PEAK value Pi lies in the assigned respective lubricant supply system-activation range 17. The lubricant supply system can be actuated to introduce. Of course, the boundary values Pi_grenz may also be different here.

For example, if one piston ring 6i has a higher lubricant demand than another piston ring 6i, in principle the following may also suffice. That is, it may be sufficient if the calibration according to the invention is performed only for piston rings 6i with a higher lubricant demand. The boundary value Pi_grenz is therefore only determined for one piston ring 6i and the lubricant supply system-control unit 14 is located in the lubricant supply system-activation range 17i for which the assigned PEAK value Pi was determined. As soon as it does, it will trigger the lubricant supply system accordingly. As long as the lubricant supply system is suitable for this (e.g. a common rail system), the introduction of the lubricant is preferably timed so that the piston rings 6i with the highest lubricant demand are lubricated precisely. controlled by Depending on the structural design of the piston rings 6i, the introduction of the lubricant takes place during the piston stroke, preferably in front of the piston rings 6i or directly towards the piston rings 6i. As a result, the piston ring or rings 6i with a relatively low lubricant demand automatically receive a sufficient amount of lubricant. If the reciprocating compressor 1 has a plurality of cylinders 2 , the detection and evaluation of the lubricant quantity according to the invention is preferably performed separately for each cylinder 2 with at least one lubricant for each cylinder 2 . This is done by positioning the sensor 15 .

Furthermore, it may be advantageous if a lubricant quantity-detection unit is provided in the lubricant supply system to detect the lubricant quantity supplied to the lubricant supply point 12 . The lubricant quantity-detection unit may be, for example, a suitable flow sensor 16 integrated in the supply line to the lubricant supply point 12, as shown in FIG. A flow sensor 16 is preferably connected to the lubricant supply system-control unit 14 in order to transmit a measuring signal proportional to the amount of lubricant. However, a calculation model may also be provided, for example, as a lubricant quantity-detection unit, which may be implemented, for example, in the lubricant supply system-control unit 14 and the lubricant supplied to the lubricant supply point 12 The amount is calculated based on the available parameters of the lubricant supply system, such as the cylinder volume of the piston pump and the speed of the pump.

Therefore, the lubricant supply system-control unit 14 compares the lubricant film-measured quantity S obtained from the lubricant sensor 15 with the lubricant quantity obtained from the lubricant quantity-sensing unit to determine these two Values can be checked for consistency. This makes it possible, for example, to infer a malfunction of the lubricant sensor 15 if a certain deviation between these two values is ascertained. Similarly, this comparison can be used to detect leaks in the lubricant supply system. For example, if the flow sensor 16 outputs a certain expected value and the lubricant film-measured quantity S detected by the lubricant sensor 15 takes no or very low value, then a leak is indicated. may exist. This can mean, for example, that there is a leak between the flow sensor 16 and the lubricant feed point 12 . For example, if an impermissibly high deviation is observed between the quantity measurement and the lubricant film thickness measurement (or a comparable quantity derived therefrom), this may indicate, for example, a critical operating state of a reciprocating compressor. may be used as an indicator for and possibly a specific action may be initiated, for example an alarm signal or switching off one of the compressors.

Claims (20)

A lubricant supply system for a reciprocating compressor (1), comprising:
The lubricant supply system introduces a lubricant to a cylinder sliding surface of a cylinder (2) of the reciprocating compressor (1) in which a piston (3) can reciprocate,
In a lubricant supply system provided with a lubricant supply system-control unit (14) for controlling the amount of lubricant to be introduced,
At least one lubricant sensor (15) is provided for detecting a lubricant film-measurement quantity (S) representative of the lubricant film thickness of the lubricant film (11) on the cylinder sliding surface of the cylinder (2). cage,
Said lubricant supply system-control unit (14) operates said lubricant supply system in a predetermined calibration mode of operation at least once during operation of said reciprocating compressor (1), and during execution of said calibration mode of operation is configured to determine a lubricant film state value (SZ) based on the detected lubricant film-measurement quantity (S), and the lubricant supply system-control unit (14) performs the calibration operation configured to control the amount of lubricant to be introduced according to the lubricant film state value (SZ) determined during operation of the reciprocating compressor (1) after the end of the mode,
A lubricant supply system characterized by: the lubricant sensor (15) is an ultrasonic sensor,
Lubricant supply system according to claim 1, characterized in that the time resolution of the lubricant sensor (15) is preferably between 0.01° and 5° crank angle. Said Lubricant Supply System-Control Unit (14) determines that during the piston stroke of said piston (3), when the piston rings (6i) of said piston (3) are in the sensor area of said lubricant sensor (15) The detected sensor value (Pi) of the lubricant film-measured quantity (S), preferably the minimum value of the lubricant film-measured quantity (S) detected during the piston stroke, is referred to as the lubrication 3. A lubricant delivery system according to claim 1 or 2, adapted for use in determining a film state value (SZ). Said lubricant supply system is arranged for intermittent introduction of said lubricant into said cylinder (2), preferably configured as a pump-to-point system, as a divider block system or as a common rail system. has been
The lubricant supply system-control unit (14) is configured to control the amount of lubricant by varying the frequency of intermittent introduction of the lubricant and/or the injection volume of each injection. Lubricant supply system according to any one of claims 1 to 3. The lubricant supply system-control unit (14) updates the lubricant film condition value (SZ) and adjusts the lubricant quantity to match the updated lubricant film condition value (SZ). 5. Lubricant supply system according to any one of claims 1 to 4, characterized in that it is also arranged to repeat said calibration mode of operation on a defined cycle. 6. Claims 1 to 5, wherein the duration of the calibration mode of operation is at least 10, preferably at least 100, particularly preferably at least 1000 crankshaft revolutions of the reciprocating compressor (1) or equivalent. Lubricant supply system according to any one of the preceding claims. In said calibrated mode of operation, at least two successive time ranges (Zi) with different lubricant amounts (Mi) are defined,
Said lubricant supply system-control unit (14) measures a maximum (Pa_max) and a minimum value in the time course of said lubricant film-measured quantity (S) detected during at least two said time ranges (Zi) (Pa_min), from which the lubricant film state value (SZ) is determined for controlling the lubricant quantity. Lubricant supply system. defining a first time range (Z1) having a predetermined duration and a second time range (Z2) having a predetermined duration following said first time range (Z1);
The quantity (M1) of lubricant introduced during the first time period (Z1) is such that a completely wet lubricant film is produced on the cylinder sliding surface, and during the second time period the lubricant amount (M2) introduced into the range (Z2) is determined so that dry sliding occurs on the cylinder sliding surface,
Said duration of said first time period (Z1) is preferably at least 5 crankshaft revolutions and said quantity of lubricant (M1) introduced during said first time period is determined by compressor manufacture 90-200% of the lubricant amount set by the manufacturer, said duration of said second time range (Z2) is preferably at least 5 crankshaft revolutions, said second time range 8. Lubricant supply system according to claim 7, characterized in that the lubricant quantity (M2) introduced into (Z2) is 0% of the lubricant quantity set by the compressor manufacturer. Said lubricant supply system-control unit (14) determines a difference value (ΔPa) between said determined maximum value (Pa_max) and said determined minimum value (Pa_min), and determines said maximum value (Pa_max) A lubricant film boundary value (Pa_grenz) is obtained from the obtained difference value (ΔPa), and the lubricant film boundary value (Pa_grenz) is used as a lubricant film state value (SZ). ,
The lubricant supply system-control unit determines that during the operation of the reciprocating compressor (1), after the calibration operation mode, the lubricant film-measured quantity (S) is the minimum value (Pa_min) and the lubricant a lubricant delivery system between the film boundary value (Pa_grenz) - configured to drive and control said lubricant delivery system to introduce said lubricant when in an activation range (17) 9. Lubricant supply system according to claim 7 or 8. The lubricant supply system is provided with a lubricant amount-detection unit (16) for detecting the amount of lubricant supplied to the lubricant supply point (12),
The lubricant supply system-control unit (14) stores the lubricant film-measured quantity (S) obtained from the lubricant film sensor (15) and the lubrication quantity obtained from the lubricant quantity-detection unit. according to claims 1 to 9, wherein said two values can be checked for consistency and/or leaks in said lubricant supply system can be detected. Lubricant supply system according to any one of the preceding claims. A reciprocating compressor (1) having a plurality of cylinders (2),
In each cylinder (2) one piston (3) is reciprocable and has a lubricant supply system for supplying lubricant to said plurality of cylinders (2),
In a reciprocating compressor (1), wherein each of the plurality of cylinders (2) is provided with at least one lubricant supply point (12) for introducing the lubricant to the cylinder sliding surface of the cylinder (2) The lubricant supply system is constructed according to any one of claims 1 to 10,
A reciprocating compressor (1) characterized by: At least one cylinder (2) is provided with a plurality of lubricant feed points (12) and/or a plurality of lubricant sensors (15),
Preferably, a plurality of lubricant feed points (12) and/or a plurality of lubricant sensors (15) are provided in the circumferential direction of said at least one cylinder (2) and/or a plurality of lubricant feeds. 12. Reciprocating compressor (1) according to claim 11, characterized in that the points (12) and/or a plurality of lubricant sensors (15) are provided in the axial direction of the at least one cylinder (2). A method of operating a reciprocating compressor (1) comprising at least one cylinder (2) in which a piston (3) reciprocates, comprising:
supplying lubricant to the cylinder sliding surfaces of said at least one cylinder (2) by means of a lubricant supply system;
A method, wherein the lubricant quantity of said lubricant supplied is controlled by a lubricant supply system-control unit (14),
At least one lubricant sensor (15) is used to detect a lubricant film-measurement quantity (S) representing the lubricant film thickness of a lubricant film (11) on said cylinder sliding surface of said cylinder (2). ,
operating the lubricant supply system in a predetermined calibrated mode of operation by the lubricant supply system-control unit (14) at least once during operation of the reciprocating compressor (1);
determining a lubricant film state value (SZ) based on the lubricant film-measurement quantity (S) detected during the calibration mode of operation;
The lubricant supply system-control unit (14) is introduced according to the determined lubricant film state value (SZ) during operation of the reciprocating compressor (1) after the end of the calibration mode of operation. controlling the amount of lubricant to be
A method characterized by: using an ultrasonic sensor as the lubricant sensor (15),
The method of claim 13, wherein the lubricant sensor has a temporal resolution preferably between 0.01° and 5° crank angle. Said lubricant film-measured quantity (S) detected during the piston stroke of said piston (3) when the piston ring (6) of said piston (3) is in the area of said lubricant sensor (15) using the sensor value (Pi) of, preferably the minimum value of the lubricant film-measured quantity (S) detected during the piston stroke, to determine the lubricant film condition value (SZ), 15. A method according to claim 13 or 14. intermittently introducing said lubricant into said cylinder (2);
Claims 13 to 15, wherein the lubricant supply system-control unit (14) controls the lubricant quantity by varying the frequency of intermittent introduction of the lubricant and/or the injection volume of each injection. A method according to any one of repeating the calibration mode of operation at a defined cycle to update the lubricant film condition value (SZ) and adjust the lubricant quantity to match the updated lubricant film condition value (SZ); and/or the calibrating mode of operation is carried out over at least 10, preferably at least 100, particularly preferably at least 1000 crankshaft revolutions of the reciprocating compressor (1) or equivalent times, from claim 13 17. A method according to any one of 16. introducing different lubricant amounts (Mi) into the cylinder (2) in at least two successive time ranges (Zi) in said calibration mode of operation;
Said lubricant supply system-control unit (14) measures the maxima (Pa_max) and minima in the course of time of said lubricant film-measurements (Mi) detected during at least two said time ranges (Zi) (Pa_min), from which the lubricant film condition value (SZ) is determined for controlling the lubricant quantity. defining a first time range (Z1) having a predetermined duration and a second time range (Z2) having a predetermined duration following said first time range (Z1);
The amount of lubricant (M1) introduced during the first time period (Z1) is determined to produce a completely wet lubricant film on the cylinder sliding surface, and the second time period (Z2 ) the lubricant amount (M2) introduced into the cylinder is determined so that dry sliding occurs on the cylinder sliding surface,
Said duration of said first time period (Z1) is preferably at least 5 crankshaft revolutions and said quantity of lubricant (M1) introduced during said first time period is determined by compressor manufacture 90-200% of the lubricant amount set by the manufacturer, said duration of said second time range (Z2) is preferably at least 5 crankshaft revolutions, said second time range 19. Method according to claim 18, wherein the amount of lubricant (M2) introduced therein is 0% of the amount of lubricant set by the compressor manufacturer. A difference value (ΔPa) between the obtained maximum value (Pa_max) and the obtained minimum value (Pa_min) is obtained, and lubrication is performed from the obtained maximum value (Pa_max) and the obtained difference value (ΔPa). obtaining a lubricant film boundary value (Pa_grenz), using said lubricant film boundary value (Pa_grenz) as a lubricant film state value (SZ);
The lubricant supply system-control unit determines that after the calibration mode of operation, the lubricant film-measured quantity (S) is between the minimum value (Pa_min) and the lubricant film boundary value (Pa_grenz). 20. Method according to claim 18 or 19, characterized in that, when in the lubricant supply system-activation range (17), the lubricant supply system is actuated to introduce lubricant.

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