Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
  • F04B49/10—Other safety measures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
  • F04B39/06—Cooling; Heating; Prevention of freezing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
  • F04B49/02—Stopping, starting, unloading or idling control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
  • F04B49/06—Control using electricity
  • F04B49/065—Control using electricity and making use of computers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B2201/00—Pump parameters
  • F04B2201/08—Cylinder or housing parameters
  • F04B2201/0801—Temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B2203/00—Motor parameters
  • F04B2203/02—Motor parameters of rotating electric motors
  • F04B2203/0205—Temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B2205/00—Fluid parameters
  • F04B2205/11—Outlet temperature

Definitions

• the invention relates to a method referred to in the preamble of claim 1 for controlling the operation of a compressor.
• compressors are frequently used in which a gaseous or liquid medium can be brought to a pressure which is above the ambient pressure.
• the gaseous or liquid medium is often used as a control pressure medium, for example actuators, in particular piston-cylinder arrangements, can be acted upon.
• An application in motor vehicles results from the need to provide the air springs of a level control system so with compressed air that it brings the body of the vehicle in a driving situation equitable distance to the road surface. Since such a level control system does not constantly provide for a height adjustment of the body of the vehicle, an associated compressor is required only ever put into operation if the need exists.
• the corresponding compressors are usually designed as electric motor driven piston compressors. In order to minimize the cost of the compressors used relatively small compressors are increasingly used, which are thermally significantly burdened in a possibly longer-lasting operation, so that components can heat unacceptably high. Excessive thermal stress is usually first the exhaust valve or the piston seal of a reciprocating compressor damaged, which can ultimately lead to failure of the compressor and thus the level control system.
• a compressor can be operated variably in terms of its on and off times.
• the current duty cycle should be adapted to the current operating conditions of the compressor.
• the switch-on duration can be varied, for example as a function of the prevailing in the environment of the compressor air temperature and air flow rate such that the duty cycle is shortened becomes, as the ambient temperature increases, and is prolonged as it decreases.
• the ambient temperature can be determined based on a model calculation from the current vehicle exterior air temperature and / or theharamotoransaug Kunststofftemperatur.
• the disadvantage here is that the known method as all duty cycle methods is consistently inaccurate because it does not take into account the thermodynamic properties of the compressor itself.
• the controller takes, for example, no influence on the temperature band in which the compressor is ultimately operated.
• a method for temperature-controlled control of a compressor for air suspension of a motor vehicle is known, which is designed as an estimation method and manages without a separate temperature sensor on the compressor.
• the compressor is switched off by a control unit when a temperature estimate calculated by the latter exceeds an upper threshold value, or is switched on or is allowed to be switched on if a lower threshold value is undershot.
• the respective last temperature estimated value is increased by a certain temperature jump when the compressor is switched on, the extent of which depends on the height of the last estimated value.
• the estimated value is increased during a compressor operation in a predetermined manner and lowered at standstill of the compressor in a predetermined manner.
• the disadvantage here is that the underlying for the process linear relationships in practice usually not present, since at large temperature differences, the temperature changes are greater than at small temperature differences. The temperature jump also does not take place in reality immediately, so that in this area, the control technology availability of the compressor is disadvantageously reduced.
• EP 1 644 640 B1 a method of the type in question for controlling the operation of the compressor is known, in which the compressor is switched off by a controller to prevent thermal damage when a maximum value of the compressor temperature is reached or exceeded, and at least two system components compressor power requests to the Aim the controller and the Controller allocates compressor power to system components based on compressor power requests.
• the invention has for its object to provide a method referred to in the preamble of claim 1 for controlling the operation of a compressor in which the flexibility of the control is increased.
• the invention is based on the finding that the operation of the compressor can be made more flexible and adapted to the respective requirements when incoming compressor power requests of the system components are not necessarily processed in the order of their temporal input.
• the invention is based on the idea to take into account in the allocation of compressor power according to the respective compressor power requests, to which increase the compressor temperature would cause the processing of the respective compressor power request. If the compressor has been switched off by the controller when a maximum value of the compressor temperature has been reached, incoming compressor power requests are initially not answered by the controller in order to allow the compressor to cool down so that thermal damage is avoided.
• the control unit determines, based on an instantaneous compressor temperature calculated or measured as an estimated value, whether the temperature increase ⁇ T1 associated with the processing of the request becomes Reaching or exceeding the maximum compressor temperature would result. In this case the request will not be answered. However, if at the same time a further request or among several other requests before a request whose execution would lead to a lower temperature increase .DELTA.T2, which does not lead to exceeding the maximum value of the compressor temperature from the current compressor temperature, this request may according to the invention in the execution preferred become.
• the compressor After processing of the request and an associated increase in the temperature of the compressor by ⁇ T2 the compressor cools down again. If a compressor temperature is reached which is so low that, starting from the instantaneous compressor temperature, the expected temperature difference ⁇ T1 does not lead to an exceeding of the maximum value of the compressor temperature, then the initially unanswered request can be answered.
• the inventive method can also be carried out when there are a plurality of requests that can be stored according to their temporal input in the manner of a queue, but according to the invention are not necessarily processed according to the temporal order of their input. If there are several inquiries that would lead to different temperature increases of the compressor temperature, it is quite possible that these requests are processed in the inventive method according to the time sequence of their input, provided that this order of processing the criteria used in the invention, namely the current Compressor temperature and expected when processing the request increase the compressor temperature corresponds.
• a further development of the invention provides that a request is selected from a plurality of compressor power requests from the control unit, the execution of which does not lead to exceeding the maximum value of the compressor temperature on the basis of the instantaneous compressor temperature and the expected increase in the compressor temperature during execution. In this way, thermal damage to the compressor are reliably avoided.
• Another development of the invention provides that the allocation of compressor power is performed independently of the time sequence of the input of the compressor power requests. In this way, a high degree of flexibility is achieved in the processing of inquiries. However, it is not excluded that the order of execution of the requests coincidentally corresponds to the chronological order of their receipt.
• Another advantageous embodiment of the invention provides, in the allocation of compressor power, a classification of the compressor power requests, for example, in terms of safety aspects, is taken into account. If, for example, a compressor power request for a particularly system-important function, for example in a motor vehicle for the vehicle safety or pedestrian protection relevant system function, so a request can be prioritized, so that this prioritization overrides the inventively used for the allocation of compressor power criteria.
• Embodiment the cooling of the processor continues until the associated with the safety-related system function compressor performance request is processed.
• the instantaneous compressor temperature can be measured or calculated as a temperature estimate by the control unit.
• a calculation of the instantaneous compressor temperature as a temperature estimate has the advantage that sensors for sensing the compressor temperature are not required. In this way, a particularly simple and interference-insensitive construction.
• Corresponding methods for calculating the compressor temperature are, for example, by DE 103 30 121 A1 and EP 1 644 640 B1 are known and are therefore not explained here.
• a compressor for example in connection with a level control system of a motor vehicle, is controlled by a control unit.
• the compressor is turned off by the thermal damage prevention control unit when a maximum value ⁇ Tmax of the compressor temperature is reached or exceeded.
• the request S1 requires a compressor power P1 and leads to an increase in the compressor temperature by .DELTA.T1.
• the request S2 needs a compressor power P2 and leads to an increase of the compressor temperature by ⁇ T2
• the request S3 needs a compressor power P3 and leads to a temperature increase ⁇ T3.
• ⁇ T1 ⁇ T2 ⁇ T3 be assumed.
• the controller continuously calculates the current compressor temperature as a temperature estimate, and determines whether the compressor has already cooled enough to be able to respond to compressor power requests.
• the control unit determines that, based on the instantaneous compressor temperature, the temperature increase ⁇ T3 associated with the request S3 would result in exceeding the maximum value of the compressor temperature ⁇ Tmax, the lower temperature increase ⁇ T1 associated with the request S1 will not result in exceeding the maximum value ⁇ Tmax Compressor temperature leads, so the request S1 is first answered, so that the requesting system component, the required compressor power P1 is allocated, so that the associated system function is performed. After completing the appropriate system function, compressor cooling can continue. If the cooling has progressed so far that the temperature increase ⁇ T2 associated with the request S2 would not lead to the maximum value of the compressor temperature being exceeded, then this request can first be answered. Only then and after a further cooling of the process, the query S3 is answered.
• the control unit would only restart the compressor when it has cooled down to such an extent that the temperature increase ⁇ T3 associated with the request S3 would not result in exceeding the maximum compressor temperature. If the compressor is cooled down accordingly, the required compressor power P3 is allocated according to the request S3. Inquiries S1 and S2, which would lead to lower temperature increases of the compressor temperature, are therefore not preferred in the case of such a classification. Society

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Control Of Positive-Displacement Pumps (AREA)

Applications Claiming Priority (1)

Publications (2)

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ID=42674733

Family Applications (1)

Country Status (2)

Citations (10)

• 2009
  • 2009-04-06 DE DE200910003745 patent/DE102009003745A1/de not_active Withdrawn
• 2010
  • 2010-01-25 EP EP20100151519 patent/EP2395243B1/fr active Active

Patent Citations (12)

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