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Apparatus for monitoring an oil thermostat

  • US 10,287,934 B2
  • Filed: 11/04/2015
  • Issued: 05/14/2019
  • Est. Priority Date: 11/06/2014
  • Status: Active Grant
First Claim
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1. An apparatus for monitoring an oil thermostat arranged in an oil circuit of an internal combustion engine, wherein the oil thermostat is configured to supply an oil flow to a first flow branch in which an oil cooler is arranged or to a bypass flow branch depending on an admission temperature (T2) of the oil flow supplied to the oil thermostat which is measured at an oil sump, wherein a first outlet of the oil thermostat, which outlet is assigned to the first flow branch, is closed when the admission temperature (T2) lies below a first temperature threshold value (T1), wherein the apparatus comprises:

  • (a) a sensor device which is configured to measure the admission temperature (T2) of the oil as a first parameter by means of which a current desired operation of the oil thermostat can be derived, and to determine at least one second parameter by means of which a current actual operation of the oil thermostat can be derived; and

    (b) an evaluation device which is configured, depending on the first parameter and the second parameter, to identify an occurrence of a malfunction of the oil thermostat, wherein(a) the sensor device is configured to measure a second oil temperature (T3) downstream of the oil cooler and upstream of the internal combustion engine and to determine a temperature difference (Δ

    T) from the admission temperature (T2) minus the second oil temperature (T3) as the second parameter; and

    (b) the evaluation device identifies the occurrence of a malfunction of the oil thermostat,(b1) when the admission temperature (T2) lies below the first temperature threshold value (T1), at least one predetermined reaction period (Z1) has elapsed since the admission temperature (T2) has been below the first temperature threshold value (T1), and the temperature difference (Δ

    T) is greater than a first threshold value (Δ

    T1), or(b2) when the admission temperature (T2) is above the first temperature threshold value (T1) at least one predetermined reaction period (Z1) has elapsed since the admission temperature (T2) has been above the first temperature threshold value (T1), and the temperature difference (Δ

    T) is smaller than a second threshold value (Δ

    T2);

    or(c) when, after the first temperature threshold value (T1) is exceeded by the admission temperature (T2), an increase of the temperature difference (Δ

    T) proceeds more slowly than a predetermined desired increase of the temperature difference (Δ

    T).

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