Method for operating a lubricant distribution system

Abstract

Method for operating a lubricant distribution system comprising at least one lubricant pump and at least one metering device for metered distribution of lubricant to points of consumption, comprising the following process steps: - Monitoring the progress of a definable cycle time, - After the cycle time has elapsed: - Starting the lubricant pump, - Starting the monitoring of the expiration of a monitoring period, - Starting the monitoring of when a threshold value of an operating parameter of the dosing unit is reached and - Restart monitoring the cycle time progress, - If the threshold is reached before the end of the monitoring period: - Switching off the lubricant pump, or - If the monitoring period expires before the threshold is reached: - Switching off the lubricant pump and - Output of an error message.

Description

[0001] The invention relates to a method for operating a lubricant distribution system.

[0002] Lubricant distribution systems are well known as such, as disclosed, for example, in DE 201 13 362 U1, DE 103 18 671 A1, DE 11 2011 103 953 T5, WO 2015 / 020 644 A1 and DE 11 2015 001 847 T5. They serve to meter a lubricant delivered by a lubricant pump to one or more lubrication points. Lubricant distributors connected to the pump are often designed as a block unit and are configured to deliver different metering volumes, with each lubricant distributor having, for example, one or two threaded holes on each of its two end faces for the optional connection of one or two main lines of a central lubrication system. The lubricant distributor has, for example, eight threaded holes for connecting the lines to the lubrication points. The lubricant metering itself is carried out by a metering piston, which is movably arranged in a cylinder bore in the lubricant distributor housing.With each stroke of the metering piston, a defined quantity of lubricant is dispensed. A control piston is usually provided to regulate the metering piston. The control piston opens and closes the main lines. Depending on the pressure applied, the control piston moves in one direction or the other, which in turn moves the metering piston and dispenses the corresponding amount of lubricant.

[0003] In addition to these single-line or two-line distributors, the same applies of course to other designs, for example in the case of a progressive distributor, in which several pistons deliver lubricant to several lubrication points in a corresponding manner.

[0004] For proper operation, it may be necessary to monitor the movement of the metering piston and / or the control piston, i.e., to determine whether the metering piston is performing its intended metering stroke or a specified number of metering strokes within a defined time. It is known to detect the movement of the metering piston and / or the control piston using a sensor and to transmit the sensor signal to a control unit integrated into the pump. The control unit evaluates the signals and switches the pump on or off as needed. The sensor and pump contain electronic components designed to work together.

[0005] It is an object of the invention to provide a simplified method for operating a lubricant distribution system.

[0006] This problem is solved by a preferred embodiment of the invention. Accordingly, a method for operating a lubricant distribution system comprising at least one lubricant pump and at least one metering device for metered distribution of lubricant to points of consumption is presented, comprising the following process steps: - Monitoring the progress of a definable cycle time, - After the cycle time has elapsed: - Starting the lubricant pump, - Starting the monitoring of the expiration of a monitoring period, - Starting the monitoring of when a threshold value of an operating parameter of the dosing unit is reached and - Restart monitoring the cycle time progress, - If the threshold is reached before the end of the monitoring period: - Switching off the lubricant pump, or - If the monitoring period expires before the threshold is reached: - Switching off the lubricant pump and Output of an error message.

[0007] Furthermore, a lubricant distribution system operated in this manner is specified, comprising at least one lubricant pump, at least one metering device for metered distribution of lubricant to points of consumption, and further comprising a sensor unit which has the following features: - At least one sensor element by means of which at least one operating parameter of the dosing device can be detected, - At least one programmable control unit by means of which the lubricant pump can be controlled depending on the detected operating parameter.

[0008] Integrating the control system into the sensor unit significantly simplifies the design of the lubrication pump. In the simplest case, the pump contains a switching element, such as a relay, that can interrupt the power supply. This switching element can be controlled by the control unit, allowing the lubrication pump to be easily switched on and off. However, the complete control and "intelligence" of the system reside in the sensor unit's control unit, which is typically a microchip. Many sensors used in lubrication distribution systems already incorporate an electronic microchip for the sensor's operation, which, in addition to acquiring operating parameters, is also suitable for executing the control logic. Furthermore, the pump's simplified design makes it more versatile and applicable to various types of lubrication systems.

[0009] Furthermore, the metering device can have at least one metering piston in a metering channel, the movement of which dispenses lubricant in a metered manner to one of the points of use, wherein the sensor element is designed such that the movement of the metering piston can be detected as an operating parameter. The detection of the piston's movement ensures that the operation of the lubricant distribution system can be reliably monitored.

[0010] Furthermore, the control unit can include a counter element that allows the number of metering piston movements to be stored and retrieved. The number of metering piston movements is relevant to the duration of a lubrication cycle. Generally, a specific number of metering strokes is defined, which must be executed within a fixed cycle time. Accordingly, this number must be monitored. The cycle time comprises, on the one hand, the time required to execute the defined number of metering strokes and, on the other hand, a waiting period during which no lubrication should or needs to take place. The waiting period is typically longer, or significantly longer, than the time during which metering strokes are executed. After the cycle time has elapsed, lubrication begins anew.

[0011] Furthermore, the control unit can include a timer element that allows at least two time durations to be stored as cycle time and monitoring time, and their execution to be monitored independently of each other. For monitoring the cycle time, it is also advantageous to monitor the execution of the metering strokes separately. For this purpose, a monitoring time is defined within which the specified number of metering strokes should occur. If the monitoring time expires before the defined number of metering strokes is reached, a system error occurs. Furthermore, the timer element can generate an error signal after the expiration of at least one of the time durations. The control unit and the lubrication pump can also be designed such that the lubrication pump can be switched off when the error signal is generated.

[0012] As mentioned above, the problem according to the invention is solved by a method for operating a lubricant distribution system, comprising the following process steps: - Monitoring the progress of a definable cycle time, - After the cycle time has elapsed: - Starting the lubricant pump, - Starting the monitoring of the expiration of a monitoring period, - Starting the monitoring of when a threshold value of an operating parameter of the dosing unit is reached and - Restart monitoring the cycle time progress, - If the threshold is reached before the end of the monitoring period: - Switching off the lubricant pump, or - If the monitoring period expires before the threshold is reached: - Switching off the lubricant pump and - Output of an error message.

[0013] This results in a simple, easy-to-implement procedure that allows for reliable monitoring of the system's safe operation. Error situations can be addressed quickly.

[0014] In a preferred embodiment of the method, a definable number of movements of the metering piston is used as the threshold value of the operating parameter.

[0015] In an advantageous embodiment of the invention, a valve unit is arranged between the pump and the metering device, having at least two switching states. In a first switching state, lubricant pumped by the lubricant pump is directed via a line into a reservoir. In a second switching state, lubricant pumped by the lubricant pump is directed via a line to the metering unit. The valve unit is preferably connected to the control unit and configured to be switchable between the switching states by the control unit. As soon as the pump is switched on by the control unit, the valve unit is also switched to the second switching state, so that the lubricant reaches the metering unit. A preferred lubrication system can comprise several independent metering units, each of which is assigned a sensor unit and a valve unit.In this way, a multi-circuit lubrication system can be easily set up in which independent lubrication circuits can be supplied by a lubricant pump and benefit from the advantages of the invention.

[0016] Further advantages, features, and details of the invention will become apparent from the exemplary embodiments of the invention described below with reference to the figures. These figures show: Fig. 1 a lubricant distribution system, Fig. 2 a lubricant pump connected to a sensor, Fig. 3 a sensor, Fig. 4 a schematic flowchart according to one embodiment of the invention and Fig. 5 a multi-circuit lubricant distribution system.

[0017] Fig. Figure 1 shows a progressive distribution system 1, which is operated according to a preferred embodiment of the invention. It comprises a pump unit 3, which has a lubricant reservoir 5 and a pump 7. A line 9 for lubricant connects the pump 7 to a distributor block 11, which in turn is connected via several lines 13 to lubrication points (not shown here) or further distributor blocks 15. The latter are in turn connected to lubrication points via lines 17. This setup is known per se and requires no detailed explanation. A sensor 19 is mounted on the distributor block 11, which can detect the movement of metering pistons movably arranged in the distributor block 11. The sensor 19 is connected to the pump 7 via a control line 21 and is able to switch it on and off, which is explained in detail with reference to the following figures.

[0018] In the Fig. Figure 2 schematically illustrates the interaction of sensor 19 with pump unit 3. Sensor 19 and distributor block 11 are shown here only as functional elements and therefore not as connected units. Pump unit 3 is powered via cable 23. This power supply can be, for example, 24 volts. The voltage is fed into a motor 25, which drives pump 7. Lubricant is then drawn from reservoir 5 and conveyed via line 9 to distributor block 11, and from there to the lubrication points or other distributor blocks. Sensor 19 is connected via line 21 to a relay 27 of pump unit 3, which can be used to switch a switch 29. When switch 29 is opened, motor 25 is switched off, so that no more lubricant is delivered by pump 9. The electronics in pump unit 3 are therefore particularly simple, resulting in a cost-effective and less prone-to-failure design.Furthermore, due to its simple design, the pump unit 3 can be used for various types of lubrication systems, as it does not contain any specific active elements.

[0019] In the Fig. Figure 3 shows the sensor 19 in more detail. It includes a connector 31, through which the cable 21 is connected to an electronic microchip 33. The sensor 19 also includes a housing 35, which is connected to the distribution block via an adapter 37. A detector 39 detects the movement of a metering piston (not shown here). The microchip 33 contains both the programming for the operation of the detector 39 and the control program for the pump unit 3. It typically includes various components intended for executing computer programs, such as a processor and memory elements.

[0020] In the Fig. Figure 4 shows a schematic flowchart for a control method according to a preferred embodiment of the invention.

[0021] The user can configure the relevant control parameters—cycle time, monitoring time, and number of piston strokes—using PC software or an app in conjunction with a suitably designed user interface. These parameters are stored in non-volatile memory, such as an EEPROM in the microchip 33 of sensor 19. The cycle time is selected and tailored to the specific application so that a lubrication process takes place within this timeframe. The lubrication process comprises a number of piston strokes, during which a defined quantity of lubricant is metered and distributed. Once the piston strokes are complete, the lubrication process itself is finished, and the cycle time is awaited. The remaining cycle time is typically significantly longer than the duration of the piston strokes, i.e., the actual lubrication process. Consequently, the waiting time, which is part of the cycle time, is correspondingly long.The monitoring time serves to monitor the actual lubrication process, i.e., the execution of the piston strokes. Therefore, it is set to be longer than the maximum duration of the piston strokes to prevent false error messages. However, it is typically still significantly shorter than the cycle time. The cycle time is regularly stored in the working memory (RAM) of microchip 33. When the power supply is switched off, e.g., for maintenance purposes, the remaining cycle time is stored in the EEPROM of microchip 33 so that the cycle time does not restart after the power supply is switched back on but can continue running. This prevents the lubrication points from being without lubrication for too long.

[0022] When sensor 19 is supplied with power, which is switched on in a first process step S1, the cycle time previously selected for the individual system begins to run in a process step S2. Depending on the operating state before the power was switched off, a cycle time that has already partially elapsed can also be continued. In a process step S3, the cycle time is monitored to ensure it has elapsed. After the cycle time has elapsed, the lubricant pump is switched on in a process step S4 and the lubrication process is started. The lubricant pump now delivers lubricant to the distributor block 11. At the same time, the monitoring time is started and the cycle time begins anew.

[0023] Sensor 19 now registers and counts the piston's delivery strokes. In process step S5, the counted stroke count is compared with the set value. Simultaneously, in process step S6, the elapsed monitoring time is monitored. Once the defined stroke count is reached, in process step S7 the pump is switched off and the monitoring time is reset, thus ending the monitoring. The lubrication process is complete, and the remaining cycle time continues to run in process step S2.

[0024] If the monitoring time in process step S6 expires before the defined number of piston strokes is reached, a system malfunction has occurred. Consequently, the lubricant pump is switched off in process step S8 and an error signal is output.

[0025] The sensor 19 can preferably also include IO-Link functionality for connecting sensors to automation systems. In this case, the sensor 19 is designed so that, upon detecting an IO-Link master on the control side, the device's parameterization and communication can also be performed directly via IO-Link. Accordingly, the sensor 19 has suitable connections and control elements. This means that the user can then evaluate and reparameterize the sensor during operation via an existing IO-Link structure and fieldbus systems, which simplifies integration into existing infrastructures.

[0026] Based on the invention, it is also possible to construct multi-circuit lubrication systems with a pump in conjunction with 3 / 2-way valves, which is schematically shown in the Fig.Figure 5 shows the system. It comprises three lubrication circuits 60, 61, and 62, each with a sensor 19' containing the parameters required for the respective lubrication circuit (cycle time, monitoring time, and number of piston strokes). As previously described, these parameters are stored in an EEPROM within the respective sensor 19'. Each lubrication circuit 60, 61, and 62 is also assigned a 3 / 2-way valve 65, 66, and 67, respectively. When de-energized, this valve returns lubricant delivered by the pump 7' via lines 9' to the reservoir 5' via a return line 69. Once the cycle time of one of the lubrication circuits has elapsed, the corresponding 3 / 2-way valve 65, 66, and 67 is switched, and the pump 7' is activated, via the appropriately provided switching units K1, K2, and K3. The pump 7' is connected to each of the switching units K1, K2 and K3 via a cable 73. In addition, the 3 / 2-way valve 65 is connected to the switching unit K1 via a cable 75.Accordingly, the 3 / 2-way valve 66 is connected to the switching unit K2 and the 3 / 2-way valve 67 is connected to the switching unit K3 via cables 76 and 77.

[0027] After being switched on, pump 7' delivers lubricant from reservoir 5' to the 3 / 2-way valves 65, 66, and 67. Only the 3 / 2-way valves 65, 66, and 67 that are switched on (i.e., not de-energized) allow lubricant to flow to the corresponding lubrication circuits 60, 61, and 62, respectively. The 3 / 2-way valves 65, 66, and 67 that remain de-energized return the lubricant, as no lubrication process is to take place in the corresponding lubrication circuits 60, 61, and 62. Pump 7' can have a number of pump elements corresponding to the number of lubrication circuits 60, 61, and 62. These pump elements deliver lubricant to the corresponding lines 75, 76, and 77 leading to the 3 / 2-way valves 65, 66, and 67, respectively, as soon as pump 7' is switched on. Pump 7' starts pumping as soon as at least one of the sensors 19' outputs a corresponding signal. It is also possible for several sensors 19' to output the signal simultaneously or with a slight time delay and switch on pump 7'.Therefore, a multi-circuit system can be easily built that takes advantage of the invention.

[0028] Alternatively, the lubricant distribution system can be designed as a single-line or dual-line system. The control unit can incorporate various sensors, including multiple sensors. These can be, for example, pressure switches or pressure sensors, as well as a low-level indicator sensor. Reference symbol list 1 Progressive distribution system 3 Pump unit 5.5' Lubricant reservoir 7, 7' pump 9, 13, 17 Management 11, 15 Distribution block 19, 19' Sensor 21 Control line 23, 73, 75, 76, 77 Cable 25 engine 27 relays 29 switches 31 plugs 33 microchip 35 cases 37 adapters 39 Detector 60, 61, 62 Lubrication circuit 65, 66, 67 3 / 2-way valve 69 Return line S1-S8 Process step

Claims

[1] Method for operating a lubricant distribution system comprising at least one lubricant pump and at least one metering device for metered distribution of lubricant to points of consumption, comprising the following process steps: - Monitoring the progress of a definable cycle time, - After the cycle time has elapsed: - Starting the lubricant pump, - Starting the monitoring of the expiration of a monitoring period, - Starting the monitoring of when a threshold value of an operating parameter of the dosing unit is reached and - Restart monitoring the cycle time progress, - If the threshold is reached before the end of the monitoring period: - Switching off the lubricant pump, or - If the monitoring period expires before the threshold is reached: - Switching off the lubricant pump and - Output of an error message. [2] Method according to claim 1, wherein a definable number of movements of the metering piston is used as the threshold of the operating parameter. [3] Method according to claim 1 or 2, wherein the monitoring time is set longer than a maximum expected duration for the definable number of movements of the metering piston. [4] Method according to claim 1, 2 or 3, wherein a remaining residual value of the cycle time is regularly stored during the monitoring of the cycle time.

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