Method of operating a lubricating device, lubricating device and compressor with such a lubricating device

Abstract

A lubricant supplying device includes a feed pump that serves to pump lubricant from a lubricant reservoir to at least one lubrication point. A method for operating the lubricant supplying device includes measuring at least one operating parameter, such as temperature (T), of at least one part of a system to be lubricated and/or of the lubricant and/or of the environment. The at least one measured operating parameter (T) is supplied to a controller, where a required volumetric flow ({dot over (V)}.sub.target) of lubricant is determined based on a stored functional relationship ({dot over (V)}.sub.target= (T)) that generates the required volumetric flow ({dot over (V)}.sub.target) based upon the measured operating parameter (T). The feed pump is then actuated in order to achieve the determined, required volumetric flow ({dot over (V)}.sub.target).

Claims

1. A lubricant supply device, comprising: a feed pump configured to pump lubricant from a lubricant reservoir; at least one sensor configured to measure an operating parameter (T) of at least one part of a system to be lubricated; and a controller configured to: (i) determine, in accordance with the measured operating parameter, a target volumetric flow (V.sub.target) of lubricant based on a stored function (V.sub.target=(T)) that relates the target volumetric flow (V.sub.target) to the measured operating parameter (T) and (ii) to actuate the feed pump to achieve the target volumetric flow (V.sub.target), wherein the controller is further configured to: compare a measured current, actual volumetric flow being output from the feed pump to the target volumetric flow (V.sub.target) for the currently measured operating parameter, and in case there is a deviation between these values, reduce the deviation by changing the output of the feed pump, and wherein the feed pump includes a gear pump operably driven by a stepper motor, wherein the controller is configured to output a step number per time, which corresponds to the target volumetric flow (V.sub.target) for the currently measured operating parameter, to the stepper motor to drive the gear pump, and further comprising a reciprocating piston configured to pressurize the lubricant pumped by the gear pump.

2. The lubricant supply device according to claim 1, further comprising means for measuring the current, actual volumetric flow of lubricant being output from the gear pump and for feeding back the measured current, actual volumetric flow to the controller, wherein the means for measuring comprises a photoelectric sensor configured to measure lubricant drops.

3. A method for operating a total loss oil lubricating device configured to pump a lubricant to at least one lubrication point of a system to be lubricated, the lubricating device comprising a gear pump operably driven by a stepper motor and configured to supply the lubricant from a lubricant reservoir to the at least one lubrication point, wherein the method comprises: a) measuring at least one operating parameter (T) of at least one part of the system to be lubricated; b) determining a target volumetric flow (V.sub.target) of lubricant based on a stored functional relationship (V.sub.target=(T)) between the required volumetric flow (V.sub.target) and the operating parameter (T), and outputting a step number per time corresponding to the target volumetric flow; c) activating the gear pump to provide the volumetric flow (V.sub.target) of the lubricant determined according to step b) to the lubrication point, d) using a reciprocating piston to pressurize the lubricant pumped by the gear pump, e) measuring the current, actual volumetric flow (Actual) being output from the gear pump, and f) comparing the measured current, actual volumetric flow to the volumetric flow (V.sub.target) determined according to step b), wherein in case there is a deviation between these values, reducing the deviation by changing the output of the gear pump.

4. The method according to claim 3 further comprising measuring the current, actual volumetric flow of lubricant being output from the gear pump using a photoelectric sensor to measure lubricant drops and feeding back the measured current, actual volumetric flow to the controller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantageous designs are described in more detail below with reference to exemplary embodiments depicted in the drawings, but are not limited to said exemplary embodiments.

(2) FIG. 1 schematically shows a lubricating device for supplying a lubrication point with a defined quantity of lubricant per time.

(3) FIG. 2 shows a slightly modified solution to that according to FIG. 1.

(4) FIG. 3 shows a section through a lubricating device that operates according to the principle that is depicted in FIGS. 1 and 2.

DETAILED DESCRIPTION

(5) In FIG. 1 the structure of a lubricating device 1 is schematically depicted, as results according to a first design of the invention. Lubricating oil is pumped out from a lubricant reservoir 4 to a lubrication point 2. Here the lubricating oil is metered in a metering stage D, i.e., the volumetric flow (volume per time) is defined, while the metered oil is then pumped, in a pressure stage P, to the lubrication point 2.

(6) A feed pump 3 is provided for metering the oil, which pump is comprised of a stepper motor 6 that is connected to a gear pump 9 via a coupling 14. By application of appropriate step impulses by a controlling device or regulating device 5, smallest quantities of oil can thus be supplied in a metered manner in the pressure stage P.

(7) In the pressure stage P, a pumping element 10 in the form of a pressurizing piston takes care of the supplying of the oil to the lubrication point 2. The pressurizing piston 10 is driven by an actuator 13 (which is depicted in more detail in FIG. 3).

(8) It is important that a change in the operating conditions is detected by the lubricating device 1 and is taken into consideration in the pumping of lubricating oil. For this purpose a temperature sensor 7 is present, whichgenerally speakingmeasures an operating parameter, here in the form of the temperature T, of a part of the system to be lubricated, or of the lubricant, or of the environment. The measured value of the temperature sensor 7 is supplied to the controlling- or regulating-device 5. A function is stored therein, which expresses a target volumetric flow {dot over (V)}.sub.target in accordance with the measured temperature T, i.e., a functional relationship {dot over (V)}.sub.target=(T) between the required volumetric flow {dot over (V)}.sub.target and the operating parameter T is stored. The activation of the feed pump 3 is then effected in accordance with the thus-determined volumetric flow {dot over (V)}.sub.target.

(9) The current volumetric flow {dot over (V)}.sub.actual, i.e., the actual volumetric flow, is determined by a volumetric-flow measuring element 8. By feeding back this actual value, the regulating device 5 can hold the volumetric flow to the pre-specified, desired value. Corresponding signal lines 15 feedback the measured values from the sensors 7 and 8 to the regulating device 5.

(10) In FIG. 1 the regulating device 5 is shown separated as such from the lubricating device 1; in the solution according to FIG. 2 it is integrated into the device.

(11) In FIG. 3 a possible mechanical-engineering realization of the lubricating device can be seen. Here details are also visible, such as the lubricant outlet 11, the suction tube 12, the current terminal 16, and the data signals 17, as well as a sight glass 18 in the region of the volumetric-flow measuring element 8.

(12) A self-regulating total loss oil lubrication system is thus realized, which can be especially advantageously used for the lubricating of a compressor.

(13) The pumping volumetric flow of the total loss oil lubrication is variably adjustable and controllable in an electrical manner and reacts immediately to changing operating conditions using an internal control circuit and with precise quantities of lubricant.

REFERENCE NUMBER LIST

(14) 1 Lubricating device 2 Lubrication point 3 Feed pump 4 Lubricant reservoir 5 Controlling device/regulating device 6 Stepper motor 7 Measuring means (temperature sensor) 8 Measuring means (volumetric flow measuring element) 9 Gear pump 10 Pumping element (pressurizing piston) 11 Lubricant outlet 12 Suction tube 13 Actuator for pumping element (pressurizing piston) 14 Coupling 15 Signal line 16 Current terminal 17 Data signals 18 Sight glass D Metering stage P Pressure stage T Operating parameter (temperature) {dot over (V)}.sub.target required volumetric flow/target volumetric flow {dot over (V)}.sub.actual actual current volumetric flow/actual volumetric flow