Cooling device for an internal combustion engine and method for controlling such a cooling device

Claim 2

A cooling system for an internal combustion engine, comprising: a heat exchanger; a cooling water pump coupled to said heat exchanger; a fan disposed adjacent said heat exchanger for conveying cooling air through said heat exchanger; an electric motor having a variable rotational speed coupled to at least one of said fan and said pump; and a motor control circuit coupled to said motor for controlling said speed, said circuit including, a pulse frequency generator having an output signal with a variable pulse-to-pulse ratio and a variable voltage input means for varying said pulse-to-pulse ratio, a power semiconductor device coupled to said electric motor and responsive to said output signal, and sensor means for detecting a temperature condition of said engine, including, at least three switching contacts sequentially actuated when sequentially predetermined temperature thresholds of said temperature condition are sensed by said sensor means, one of said switching contacts corresponding to a highest one of said thresholds being coupled directly to said electric motor and by passing said power semiconductor device and electronic component means coupling remaining ones of said switching contacts to said input means for providing a variable voltage to adjust said pulse-to-pulse ratio of said output signal.

Claim 3

Cooling device as claimed in claim 1, wherein said electronic component means are ohmic resistances.

Claim 4

Cooling device as claimed in claim 1, wherein said switching contacts are jointly arranged in a step switch.

Claim 5

Cooling device as claimed in claim 3, wherein said sensor means further comprises an element of temperature responsive extensible material interacting with said step switch.

Claim 6

Cooling device as claimed in claim 4, wherein said step switch is arranged at a radiator tank of said heat exchanger and said element of extensible material projects into said radiator tank so that cooling water flows therearound.

Claim 7

Cooling device as claimed in claim 1, wherein said power semiconductor device is an N-channel metal oxide field effect transistor (MOSFET) and said frequency generator is a voltage-controlled frequency generator.

Claim 8

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; wherein the power semiconductor is an N-channel metal oxide field effect transistor (MOSFET) and the operational amplifier is a voltage-controlled frequency generator; and wherein said motor circuit further comprises a switching transistor, the base of which is connected to the output of the frequency generator via two inverting switching stages, is connected between a positive pole of the voltage source and the gate of the metal oxide field effect transistor.

Claim 9

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; wherein the power semiconductor is an N-channel metal oxide field effect transistor (MOSFET) and the operational amplifier is a voltage-controlled frequency generator; and wherein said motor circuit further comprises a switching transistor, the base of which is connected to the output of the frequency generator via two inverting switching stages, is connected between a positive pole of the voltage source and the gate of the metal oxide field effect transistor.

Claim 10

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; and a switch connected between the electric power and a rotational speed sensor, wherein the switch opens in response to a predetermined rotational speed of the electric motor.

Claim 11

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; and a switch connected between the electric power and a rotational speed sensor, wherein the switch opens in response to a predetermined rotational speed of the electric motor.

Claim 12

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; and wherein said motor circuit further comprises a relay having a normally open contact provided in a line branch connected in parallel with at least two of the switching contacts, the relay being responsive to at least one of a signal which is dependent on a particular rotational speed of the internal combustion engine and a voltage level of the dynamo of the internal combustion engine.

Claim 13

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; and wherein said motor circuit further comprises a relay having a normally open contact provided in a line branch connected in parallel with at least two of the switching contacts, the relay being responsive to at least one of a signal which is dependent on a particular rotational speed of the internal combustion engine and a voltage level of the dynamo of the internal combustion engine.

Claim 14

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; and wherein said motor circuit further comprises a thermistor which is connected via a voltage divider to the non-inverting input of a second operational amplifier and the output of the second operational amplifier is connected to the non-inverting input of the first operational amplifier.

Claim 15

Cooling device for an internal combustion engine which comprises: a heat exchanger, a cooling water pump coupled to the heat exchanger, a fan disposed adjacent to the heat exchanger for conveying cooling air through the heat exchanger, an electric motor coupled to at least one of the fan and the cooling water pump, and a motor circuit connected to the electric motor for controlling the rotational speed of the electric motor, the motor circuit including an operational amplifier, a power semiconductor coupled to the electric motor and responsive to an output signal of the operational amplifier, and a sensor that detects an engine temperature condition, the sensor including at least three switching contacts which are in each case actuated when predetermined temperature thresholds are reached, wherein the switching contact for the highest predetermined temperature threshold is coupled to the electric motor and provides a bypass of the power semiconductor and the remaining switching contacts are coupled via respective electronic components to an input of the operational amplifier, the electronic components influencing an input signal applied to the input of the operational amplifier in accordance with the actuation of the switching contacts to adjust the output signal of the operational amplifier; and wherein said motor circuit further comprises a thermistor which is connected via a voltage divider to the non-inverting input of a second operational amplifier and the output of the second operational amplifier is connected to the non-inverting input of the first operational amplifier.

Claim 16

Cooling device as claimed in claim 10, wherein the thermistor is connected in parallel with the switching contacts.

Claim 17

Cooling device as claimed in claim 10, wherein the thermistor is in series with one of the switching contacts.

Claim 18

Cooling device as claimed in claim 1, wherein temperature differences between two successive switching thresholds are different, the difference between switching thresholds of higher temperatures being less than between switching thresholds of lower temperatures.

Claim 19

Cooling device as claimed in claim 1, wherein temperature differences between two adjacent switching thresholds in each case are equal.

Claim 22

Method as claimed in claim 15, wherein said rotational speed of said electric motor is controlled proportionally in dependence on the cooling water temperature until a first temperature threshold is reached.

Claim 23

Method as claimed in claim 15, wherein said rotational speed of said electric motor is controlled proportionally in dependence on cooling water temperature after a first temperature threshold has been exceeded and until a second temperature threshold is reached.