Cooling system and method for an internal combustion engine system with a retarder

Abstract

This invention relates to a cooling system and method for an internal combustion engine system with a retarder. An internal combustion engine system is disclosed, comprising an internal combustion engine, a retarder, and a cooling system for cooling the internal combustion engine and the retarder. The cooling system includes a cooling fan whose output is controlled in response to retarder power output and coolant temperature conditions to drive the coolant temperature toward a target temperature associated with desired retarder performance characteristics.

Description

Technical Field

[0001] This application relates to internal combustion engine systems, and more particularly to cooling systems and methods for internal combustion engine systems including retarders. Background Technology

[0002] An internal combustion engine system may include an internal combustion engine and a retarder, which helps to decelerate the internal combustion engine and / or the vehicle propelled by the internal combustion engine, reducing the amount of friction braking and / or engine braking required during operation of the internal combustion engine system. The retarder typically requires cooling during startup, and retarder cooling can be integrated with the cooling system used for the internal combustion engine.

[0003] Existing cooling systems for internal combustion engines and retarders are ineffective at controlling the temperature of the cooling fluid within the system to maintain retarder effectiveness. For example, if the cooling fluid is too hot, it can trigger engine protection actions such as derating to prevent engine damage. If the cooling fluid is too cold, retarder efficiency decreases, affecting both fuel economy and retarder effectiveness. Therefore, further improvements in the thermal management of retarders used with internal combustion engine systems and the cooling systems used for them are needed.

[0004] Disclosure of illustrative embodiments

[0005] To clearly, concisely, and accurately describe the illustrative embodiments of this disclosure, the ways and processes of making and using them, and to enable the practice, making, and use of them, reference will now be made to certain exemplary embodiments, including those illustrated in the accompanying drawings, and they will be described using specific language. However, it should be understood that this does not constitute a limitation on the scope of the invention, and that the invention includes and protects such changes, modifications, and further applications of the exemplary embodiments that will conceive of those skilled in the art. Summary of the Invention

[0006] This disclosure includes a cooling system and method for a thermal management internal combustion engine system, the internal combustion engine system including an internal combustion engine and a retarder. The cooling system includes a cooling fan controlled to operate at a fan duty cycle output determined in response to retarder power output and coolant temperature parameters, to drive or drive the coolant temperature toward or to a target temperature associated with desired retarder performance characteristics.

[0007] In one embodiment, a cooling system for an internal combustion engine system is disclosed. The cooling system includes at least one cooling circuit for coolant circulation used to cool the internal combustion engine and a retarder used to cool the internal combustion engine system. The at least one cooling circuit includes at least one heat exchanger and a cooling fan associated with the at least one heat exchanger for cooling the coolant passing through the at least one heat exchanger. The cooling system also includes an electronic control system comprising at least one electronic control unit. The electronic control system is configured to determine a fan duty cycle output of the cooling fan in response to the power output of the retarder and the temperature conditions of the coolant. The fan duty cycle output sets the speed of the cooling fan to drive or drive the coolant temperature toward or to a target temperature associated with retarder performance, such as a target temperature providing desired retarder performance characteristics. The electronic control system also operates the cooling fan in response to the cooling fan duty cycle output to drive the coolant temperature toward the target temperature.

[0008] In one embodiment, a method is provided for cooling an internal combustion engine system including an internal combustion engine and a retarder. The method includes: determining that the retarder is effective; determining the power output of the retarder; determining temperature conditions for cooling the coolant in the retarder; determining a fan duty cycle output that sets the speed of a cooling fan operable to cool the coolant, the fan duty cycle output being based on the power output of the retarder and the temperature conditions of the coolant; and operating the cooling fan based on the fan duty cycle output to drive or drive the coolant temperature toward or to a target temperature associated with retarder performance.

[0009] This invention is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help limit the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits will become apparent from the following description and drawings. Attached Figure Description

[0010] Figure 1 This is a schematic illustration of one embodiment of an exemplary internal combustion engine system, which includes an internal combustion engine and a retarder, and serves as a cooling system for cooling the internal combustion engine and the retarder.

[0011] Figure 2 It is used for Figure 1 A schematic diagram of an exemplary control for a cooling system, the exemplary control being used to provide a fan duty cycle output for a cooling fan that cools the coolant during the activation of the retarder.

[0012] Figure 3 It is used for operation Figure 1The flowchart describes the process of cooling the retarder to control its cooling towards or at a target temperature associated with the retarder's performance. Detailed Implementation

[0013] Reference Figure 1 The illustration shows a schematic depiction of an exemplary internal combustion engine system 100 including an internal combustion engine 102 and a retarder 104. The internal combustion engine system 100 also includes a cooling system 120 operable to cool the internal combustion engine 102 and the retarder 104. The retarder 104 is operable to maintain speed stability and / or decelerate the internal combustion engine 102 and / or the vehicle propelled by the internal combustion engine 102 in response to a retarder activation signal from an electronic control system 110. The cooling system 120 is configured to cool the engine 102, and the retarder 104 is cooled by the cooling system 120 during certain operating conditions, such as when the retarder 104 is activated.

[0014] In one embodiment, retarder 104 is connected to the output shaft 106 of engine 102. In another embodiment, retarder 104 is a hydraulic retarder. In yet another embodiment, retarder 104 is configured to apply braking to engine 102 and / or the vehicle by electronically controlling the flow of oil or other hydraulic fluid into a bladed chamber of retarder 104 such that braking force is transmitted to the output shaft 106 of engine 102. Retarder 104 may be connected to an oil cooler or other device that exchanges heat from the hydraulic fluid with coolant in cooling system 120. Cooling of the hydraulic fluid in retarder 104 by cooling system 120 during retarder activation serves to prevent overheating and drive the coolant temperature toward a target temperature of retarder 104 associated with the desired performance of retarder 104.

[0015] In the illustrated embodiment, the cooling system 120 includes a first cooling circuit 122 connected to the engine 102 and a second cooling circuit 124 connected to the retarder 104. The first cooling circuit 122 includes a coolant line 128 connected to a heat exchanger 126, such as a radiator, and a bypass 130 for allowing all or part of the coolant flow to bypass the heat exchanger 126 during certain operating conditions. The first cooling circuit 122 may also include other components connected to the coolant line 128, such as a pump 132 and other components not shown, such as a second heat exchanger or cooler, a second coolant pump, a battery, electronics, a refrigeration system, one or more additional cooling circuits, and / or one or more waste heat recovery systems.

[0016] Cooling system 120 includes a thermal management valve 140 operable to selectively connect a second cooling circuit 124 to a first cooling circuit 122 in response to activation of retarder 104. The second cooling circuit 124 includes a coolant line 134 connected to the thermal management valve 140 and the retarder 104. One or more additional components may be connected to the coolant line 134, such as another coolant pump and / or cooler (not shown). In one embodiment, coolant is supplied to the second cooling circuit 126 via the thermal management valve 140, although other arrangements are also contemplated. In other embodiments, retarder 104 is integrated into the first cooling circuit 122.

[0017] Thermal management valve (TMV) 140 is movable between a first position and a second position, in which the TMV prevents coolant flow through the second cooling circuit 124, and in the second position, coolant flow is provided through the second cooling circuit 124. In an embodiment, TMV 140 may also have a configuration that controls the coolant flow to heat exchanger 126. In an embodiment, TMV 140 is a variable thermostat with a ball valve controlled by an actuator in response to TMV commands from electronic control system 110 ranging from a fully closed (0%) condition to a fully open (100%) condition, and to any position in between.

[0018] The first cooling circuit 122 also includes a cooling fan 134 operable to generate an airflow through the heat exchanger 126 to help cool the coolant flowing through the heat exchanger 126. In an embodiment, the cooling fan 134 is electronically controlled and engaged to engage the output shaft of the motor 136 to operate at a speed commanded by the electronic control system 110. In an embodiment, the speed of the cooling fan 134 is generated by controlling the motor 136 in response to a fan speed command from the electronic control system 110, the fan speed command being based on a fan duty cycle output using pulse width modulation (PWM) to control the output for the cooling fan 134 between 0% (fan off) and 100% (fan maximum speed).

[0019] The command speed of the cooling fan 134 is based on a fan duty cycle output determined to control the coolant temperature during the activation of the retarder 104. The fan duty cycle output sets the fan speed of the cooling fan 134 such that the coolant temperature is controlled toward and / or at a target temperature associated with the retarder performance of the retarder 104. As discussed further below, the fan duty cycle output is based on the power output of the retarder 104, the speed of the internal combustion engine 102, and coolant temperature conditions, such as the coolant temperature and its change relative to a previous coolant temperature.

[0020] The target temperature for the coolant used for retarder performance may include a temperature or temperature range that allows the retarder 104 to operate at peak efficiency for fuel economy and / or braking purposes. The target temperature may include a single temperature or temperature range. In one embodiment, the target temperature may differ from, for example, by up to 10% of the most preferred or designed target temperature. In another embodiment, the target temperature may differ from the most preferred or designed target temperature by up to 5%. In yet another embodiment, the target temperature may differ from the most preferred or designed target temperature by up to 2%. In still another embodiment, the target temperature may differ from the most preferred or designed target temperature by up to 1%. In one specific embodiment, the target temperature range is the most preferred or designed target temperature for the retarder 104. In this embodiment, the target temperature is 88 degrees Celsius, but other target temperatures are conceivable depending on the retarder design and performance characteristics.

[0021] In this embodiment, the cooling fan 134 and the thermal management valve 140 are controlled by a controller 112, which may be an electronic control unit (ECU) as part of an electronic control system (ECS) 110. When the retarder 104 is activated, the actuator (not shown) of the thermal management valve 140 responds to a control command from the controller 112 to provide a coolant flow to the retarder 104. The electric motor 136 responds to a control command from the controller 112 to selectively drive the output from the motor 136 to provide the desired speed for the cooling fan 134.

[0022] Cooling system 120 may include one or more sensors to provide signals indicating operating parameters (speed, pressure, temperature, flow rate, etc.) of one or more cooling systems, engines, and / or retarders. For example, cooling system 120 may include a first temperature sensor 114 associated with a first cooling circuit 122 and a second temperature sensor 116 associated with a second cooling circuit 124. Temperature sensors 114, 116 may be connected to controller 112 to provide coolant temperature data to controller 112. Multiple engine sensors 118 may provide engine data, such as speed data of internal combustion engine 102, to controller 112. Furthermore, retarder 104 is connected to controller 112 to provide information about the operation of retarder 104, such as retarder output torque, temperature, and other parameters.

[0023] Controller 112 is configured to implement and / or output control commands to control the operation of the electric motor 136 of the cooling fan 134 and / or the thermal management valve 140, directly or via the controller of the electric motor 136 and / or the thermal management valve 140. The control commands may be, for example, on / off commands to start / stop the electric motor 136 of the cooling fan 134, and / or positioning commands to control the orientation and / or position of the thermal management valve 140. It should be appreciated that... Figure 1 The concept describes the control relationship between the aforementioned components, which can be implemented using various communication hardware and protocols, such as one or more Controller Area Networks (CAN) or other communication components.

[0024] The electronic control system 110 and controller 112 can be implemented in any of a number of ways, combining or distributing control functions across one or more control units. The controller 112 can execute operational logic defining various control, management, and / or regulation functions. This operational logic can be in the form of dedicated hardware, such as a hardwired state machine, an analog computing machine, programming instructions, and / or other forms that will be conceived by those skilled in the art. The controller 112 can be provided as a single component or a collection of operatively coupled components; and can be constituted by a digital circuit system, an analog circuit system, or a hybrid combination of both. When in a multi-component form, the controller 112 can have one or more components remotely located relative to other components in a distributed arrangement. The controller 112 may include multiple processing units arranged to operate independently in a pipelined processing arrangement, a parallel processing arrangement, etc. It should also be understood that the controller 112 and / or any of its components may include one or more signal conditioners, modulators, demodulators, arithmetic logic units (ALUs), central processing units (CPUs), limiters, oscillators, control clocks, amplifiers, signal conditioners, filters, format converters, communication ports, clamping circuits, delay devices, memory devices, analog-to-digital (A / D) converters, digital-to-analog (D / A) converters, and / or various circuit systems or components that a person skilled in the art would conceive of for performing the desired communication.

[0025] refer to Figure 2 A schematic illustration of an exemplary control 200 for controlling the operation of a cooling system 120 for cooling a retarder 104 is provided. The control 200 provides a fan duty cycle output 202 for a cooling fan 134. The fan duty cycle output 202 sets the speed of the cooling fan 134 to drive the coolant temperature in the cooling system 120 toward a target temperature associated with retarder performance during startup of the retarder 104, such that the retarder 104 operates with desired retarder operating characteristics.

[0026] The fan duty cycle output 202 is based on the coolant temperature condition 204 and the retarder power output 210, such as retarder braking power. The retarder power output 210 is determined based on the retarder torque output 212 (such as retarder braking torque) and the speed of the internal combustion engine 102. The retarder torque output 212 can be transmitted from the retarder 104 to the controller 112 via a communication link (such as via J1939 communication on the controller area network of the electronic control system 110). The retarder power 210 and the speed of the internal combustion engine 102 are used to determine the basic fan duty cycle output for the cooling fan 134.

[0027] The basic fan duty cycle output is then adjusted for the coolant temperature condition 204 via a fan duty cycle offset. The temperature condition 204 used to determine the fan duty cycle offset includes, for example, the coolant temperature 206 and the coolant temperature change 208 relative to a previous coolant temperature. Temperature condition 204 can determine whether the coolant temperature is above or below the target temperature of retarder 104, whether the coolant temperature is moving towards or away from the target temperature, and / or the rate and / or direction of the coolant temperature change. Temperature condition 204 and the speed of internal combustion engine 102 are used to determine the fan duty cycle offset that adjusts the basic fan duty cycle output. As a result, based on the current coolant temperature relative to the target temperature of retarder 104 and whether the coolant temperature is increasing or decreasing towards or away from the target coolant temperature, the basic speed of the cooling fan 134 used to cool the coolant based on the retarder power output and engine speed is increased or decreased.

[0028] refer to Figure 3 A method or process 300 is provided for operating the cooling system 120 to drive the coolant of the cooling retarder 104 toward a target temperature. Process 300 begins at 302, such as in response to a key-on or engine-start event. Process 300 continues at condition 304 to determine whether the retarder 104 is effective. If condition 304 is "no", process 300 continues at operation 306 to control the cooling system 120 using a nominal cooling control scheme for the internal combustion engine 102, without controlling the coolant temperature for retarder performance.

[0029] If condition 304 is "yes", process 300 continues along two paths to determine a basic fan duty cycle output based on the power output from retarder 104 and a fan duty cycle offset based on coolant temperature conditions. To determine the basic fan duty cycle output, process 300 continues at operation 308. Operation 308 determines the torque output of retarder 104, which can be received as a Controller Area Network (CLAN) message output from retarder 104 to controller 112. Process 300 continues at operation 310 to determine the power output of retarder 104. The power output of retarder 104 can be calculated at operation 310 as the product of the speed of internal combustion engine 102 and the torque output of retarder 104 determined at operation 308.

[0030] Process 300 continues from operation 310 at operation 312. Operation 312 determines a basic fan duty cycle output (fan_ret) in response to the power output of retarder 104 and the speed of internal combustion engine 102 determined at operation 301. In an embodiment, a lookup table stored in the memory of controller 112 or elsewhere in electronic control system 110 provides basic fan duty cycle values ​​for various engine speeds and power outputs of retarder 104. The basic fan duty cycle output at operation 312 is selected from the lookup table based on the calculated power output of retarder 104 and the associated speed of internal combustion engine 102.

[0031] To determine the fan duty cycle offset, process 300 continues from condition 304 at operation 314. Operation 314 determines the coolant temperature condition, such as the coolant temperature in the second cooling circuit 124. Process 300 continues from operation 314 at operation 316 to determine another coolant temperature condition, such as the coolant temperature change relative to the previous coolant temperature. The coolant temperature change can be, for example, the rate, direction, or amount of change in coolant temperature, and other indicators such as whether the coolant temperature increases toward or away from the target temperature, or the coolant temperature change relative to the target temperature.

[0032] Process 300 continues from operation 316 at condition 318. Condition 318 determines whether the coolant temperature change determined at operation 316 indicates that the coolant temperature is increasing relative to the target temperature. If condition 318 is "yes", process 300 continues at operation 320. Operation 320 determines the fan duty cycle offset (fan_offset) from a first lookup table that provides fan duty cycle offset values ​​for various coolant temperatures and engine speeds, which increase the base fan duty cycle output to increase coolant cooling and drive the coolant temperature toward the target temperature.

[0033] If condition 320 is "No", process 300 continues at operation 322. Operation 322 determines the fan duty cycle offset (fan_offset) from a second lookup table that provides fan offset values ​​for various coolant temperatures and engine speeds. This fan offset value reduces the base fan duty cycle output to reduce coolant cooling and drive the coolant temperature toward the target temperature. The fan duty cycle offset values ​​in the lookup tables at operations 320 and 322 can be derived from testing, calculation, and / or other means, whereby the fan duty cycle offset values ​​provide a calibrated fan speed adjustment to drive the coolant temperature toward the target temperature.

[0034] From operations 312, 320, and 322, process 300 continues at operation 324 to determine the fan duty cycle output. In this embodiment, the fan duty cycle output is determined as the sum of the basic fan duty cycle output (fan_ret) determined at operation 312 and the fan duty cycle offset (fan_offset) determined from operation 320 or operation 322. The controller 112 can then control the speed of the cooling fan 134 based on the fan duty cycle output determined at operation 324 to drive the coolant temperature of the cooling retarder 104 toward a target temperature.

[0035] According to one aspect of this disclosure, a cooling system for an internal combustion engine is provided. The cooling system includes at least one cooling circuit for circulating coolant in an internal combustion engine and a retarder for cooling the internal combustion engine system. The at least one cooling circuit includes at least one heat exchanger and a cooling fan associated with the at least one heat exchanger for cooling coolant passing through the at least one heat exchanger. The cooling system also includes an electronic control system including at least one electronic control unit. The electronic control system is configured to determine a fan duty cycle output of the cooling fan in response to the power output of the retarder and the temperature conditions of the coolant. The fan duty cycle output sets the speed of the cooling fan to drive the coolant temperature toward a target temperature associated with retarder performance. The electronic control system is also configured to operate the cooling fan in response to the fan duty cycle output to drive the coolant temperature toward the target temperature.

[0036] In one embodiment, at least one cooling circuit includes a bypass for bypassing at least one heat exchanger.

[0037] In one embodiment, at least one cooling circuit includes a first cooling circuit for circulating coolant to the engine and at least one heat exchanger, and a second cooling circuit for circulating coolant for use in a cooling retarder. The second cooling circuit is connected to the first cooling circuit via a thermal management valve.

[0038] In another embodiment, the electronic controller is configured to control the thermal management valve to supply coolant to the second cooling circuit in response to the activation of the retarder.

[0039] In an embodiment, at least one heat exchanger is a radiator.

[0040] In an embodiment, at least one cooling circuit includes at least one pump for circulating coolant in at least one cooling circuit.

[0041] In one embodiment, the cooling fan can operate at any speed in the range of 0% to 100% of the maximum fan speed in response to the fan duty cycle output.

[0042] In another embodiment, the electronic control system is configured to: detect torque output from the retarder; calculate power output from the retarder based on the torque output and the speed of the internal combustion engine; and determine a basic fan duty cycle output in response to the power output of the retarder and the speed of the internal combustion engine.

[0043] In another embodiment, the electronic control system is configured to determine the fan duty cycle offset in response to the coolant temperature conditions and the speed of the internal combustion engine, and to determine the fan duty cycle output in response to the basic fan duty cycle output and the fan duty cycle offset.

[0044] In another embodiment, if the coolant temperature is increasing, the fan duty cycle offset is determined by selecting a fan duty cycle offset from a first lookup table based on the coolant temperature and the speed of the internal combustion engine. If the coolant temperature is not increasing, the fan duty cycle offset is determined by selecting a fan duty cycle offset from a second lookup table based on the coolant temperature and the speed of the internal combustion engine.

[0045] In another embodiment, the basic fan duty cycle output is determined by selecting the basic fan duty cycle output from a basic fan duty cycle lookup table based on the power output of the retarder and the speed of the internal combustion engine.

[0046] In an embodiment, the temperature conditions of the coolant include the coolant temperature and the change in coolant temperature relative to the previous coolant temperature.

[0047] According to another aspect of this disclosure, a method for cooling an internal combustion engine system including an internal combustion engine and a retarder is provided. The method includes: determining that the retarder is effective; determining the power output of the retarder; determining temperature conditions for cooling the coolant in the retarder; determining a fan duty cycle output that sets the speed of a cooling fan operable to cool the coolant, the fan duty cycle output being based on the power output of the retarder and the temperature conditions of the coolant; and operating the cooling fan based on the fan duty cycle output to drive the coolant temperature toward a target temperature associated with retarder performance.

[0048] In this embodiment, the target temperature is 88 degrees Celsius.

[0049] In this embodiment, the fan duty cycle output sets the speed of the cooling fan to any speed within the range of 0% to 100% of the maximum fan speed.

[0050] In one embodiment, the method includes: detecting torque output from a retarder; calculating the power output of the retarder based on the torque output and the speed of the internal combustion engine; and determining a basic fan duty cycle output based on the power output of the retarder and the speed of the internal combustion engine.

[0051] In another embodiment, the method includes: determining a fan duty cycle offset in response to coolant temperature conditions; and determining a fan duty cycle output as the sum of a basic fan duty cycle output and a fan duty cycle offset.

[0052] In this embodiment, if the coolant temperature is increasing, the fan duty cycle offset increases the base fan duty cycle output, and if the coolant temperature is decreasing, the fan duty cycle offset decreases the base fan duty cycle output.

[0053] In one embodiment, the method includes circulating coolant through a first cooling circuit connected to an internal combustion engine and a second cooling circuit connected to a retarder. A cooling fan cools the coolant as it passes through a heat exchanger connected to each of the first and second cooling circuits.

[0054] In another embodiment, the method includes opening a thermal management valve to fluidly connect a second cooling circuit to a first cooling circuit in response to determining that the retarder is effective.

[0055] While illustrative embodiments of this disclosure have been illustrated and described in detail in the accompanying drawings and foregoing description, the drawings and description are to be considered illustrative in nature and not restrictive. It should be understood that only certain exemplary embodiments are shown and described, and protection is intended for all changes and modifications falling within the spirit of the claimed invention. It should be understood that while the use of words such as “preferred,” “ideally,” “preferred,” or “more preferred” in the above description indicates that a feature so described may be more desirable, it may not be necessary, and embodiments lacking such features may be contemplated within the scope of the invention, defined by the appended claims. When reading the claims, it is intended that the use of words such as “a,” “an,” “at least one,” or “at least a portion” is not intended to limit the claims to only one item unless specifically stated otherwise in the claims. When the language “at least a portion” and / or “a portion” is used, the item may include a portion and / or the entire item unless specifically stated otherwise. Non-limiting examples of content that may be claimed in one or more non-provisional applications claiming priority to this application include the following.

Claims

1. A cooling system for an internal combustion engine system, the cooling system comprising: At least one cooling circuit for cooling the internal combustion engine and retarder of the internal combustion engine system, the at least one cooling circuit including at least one heat exchanger and a cooling fan associated with the at least one heat exchanger for cooling the coolant passing through the at least one heat exchanger; and An electronic control system, comprising at least one electronic control unit, is configured to: The fan duty cycle output of the cooling fan is determined in response to the power output of the retarder and the temperature conditions of the coolant. The fan duty cycle output sets the speed of the cooling fan to drive the coolant temperature toward a target temperature associated with the performance of the retarder. and The cooling fan is operated in response to the fan duty cycle output to drive the coolant temperature toward the target temperature.

2. The cooling system according to claim 1, wherein, The at least one cooling circuit includes a bypass for bypassing the at least one heat exchanger.

3. The cooling system according to claim 1, wherein, The at least one cooling circuit includes a first cooling circuit for circulating coolant to the engine and the at least one heat exchanger, and a second cooling circuit for circulating coolant for cooling the retarder, the second cooling circuit being connected to the first cooling circuit via a thermal management valve.

4. The cooling system according to claim 3, wherein, The electronic controller is configured to control the thermal management valve in response to the activation of the retarder to supply coolant to the second cooling circuit.

5. The cooling system according to claim 1, wherein, The at least one heat exchanger is a radiator.

6. The cooling system according to claim 1, wherein, The at least one cooling circuit includes at least one pump for circulating coolant in the at least one cooling circuit.

7. The cooling system according to claim 1, wherein, The cooling fan is capable of operating at any speed in response to the fan duty cycle output, ranging from 0% to 100% of the maximum fan speed.

8. The cooling system according to claim 1, wherein, The electronic control system is configured to: Detect the torque output from the retarder; The power output from the retarder is calculated based on the torque output and the speed of the internal combustion engine; and The basic fan duty cycle output is determined in response to the power output of the retarder and the speed of the internal combustion engine.

9. The cooling system according to claim 8, wherein, The electronic control system is configured to: The fan duty cycle offset is determined in response to the temperature conditions of the coolant and the speed of the internal combustion engine; and The fan duty cycle output is determined in response to the basic fan duty cycle output and the fan duty cycle offset.

10. The cooling system according to claim 9, wherein: If the coolant temperature is increasing, the fan duty cycle offset is determined by selecting the fan duty cycle offset from a first lookup table based on the coolant temperature and the speed of the internal combustion engine; and If the coolant temperature does not increase, the fan duty cycle offset is determined by selecting the fan duty cycle offset from a second lookup table based on the coolant temperature and the speed of the internal combustion engine.

11. The cooling system according to claim 9, wherein, The basic fan duty cycle output is determined by selecting the basic fan duty cycle output from a basic fan duty cycle lookup table based on the power output of the retarder and the speed of the internal combustion engine.

12. The cooling system according to claim 1, wherein, The temperature conditions of the coolant include the coolant temperature and the change in the coolant temperature relative to the previous coolant temperature.

13. A method for cooling an internal combustion engine system, the internal combustion engine system comprising an internal combustion engine and a retarder, the method comprising: It was determined that the retarder was effective; Determine the power output of the retarder; Determine the temperature conditions for the coolant used to cool the retarder; The fan duty cycle output is determined, the fan duty cycle output setting enables the speed of the cooling fan to operate to cool the coolant, the fan duty cycle output being based on the power output of the retarder and the temperature conditions of the coolant; as well as The cooling fan is operated based on the fan duty cycle output to drive the coolant temperature toward a target temperature associated with the retarder performance.

14. The method according to claim 13, wherein, The target temperature is 88 degrees Celsius.

15. The method according to claim 13, wherein, The fan duty cycle output sets the speed of the cooling fan to any speed within the range of 0% to 100% of the maximum fan speed.

16. The method of claim 13, further comprising: Detect the torque output from the retarder; The power output of the retarder is calculated based on the torque output and the speed of the internal combustion engine. as well as The basic fan duty cycle output is determined based on the power output of the retarder and the speed of the internal combustion engine.

17. The method of claim 16, further comprising: The fan duty cycle offset is determined in response to the temperature conditions of the coolant; as well as The fan duty cycle output is determined as the sum of the basic fan duty cycle output and the fan duty cycle offset.

18. The method according to claim 17, wherein, If the coolant temperature is increasing, the fan duty cycle offset increases the base fan duty cycle output; and if the coolant temperature is decreasing, the fan duty cycle offset decreases the base fan duty cycle output.

19. The method of claim 13, further comprising circulating the coolant through a first cooling circuit connected to the internal combustion engine and a second cooling circuit connected to the retarder, wherein, The cooling fan cools the coolant as it passes through a heat exchanger connected to each of the first and second cooling circuits.

20. The method of claim 19, further comprising: In response to determining that the retarder is effective, the thermal management valve is opened to fluidly connect the second cooling circuit to the first cooling circuit.

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