Controlling a coolant pump and/or control valve of a cooling system for an internal combustion engine of a motor vehicle

Abstract

The present disclosure relates to a method for determining an actuating value for a coolant pump or a control valve of a cooling system for an infernal combustion engine of a motor vehicle. In particular, a pre-control value for ascertaining the actuating value is determined in a first determination mode based on a prescribed first allocation as a function of an output variable of the infernal combustion engine and a temperature difference of a heat exchanger of the cooling system.

Claims

1. A method for adjusting a cooling system having a coolant pump and a control valve for an internal combustion engine based on an actuating value thereof comprising: acquiring a first temperature signal representing an inlet temperature of a heat exchanger in the cooling system; acquiring a second temperature signal representing an outlet temperature of the heat exchanger; determining a state variable based on a difference of the first and second temperature signals; acquiring an output variable including at least one of a load variable and a speed variable of the internal combustion engine; determining a pre-control value for ascertaining the actuating value in a first determination mode based on a prescribed first allocation as a function of the state variable and the output variable and then determining the actuating value using the pre-control value; adjusting at least one of the coolant pump and the control valve based on the actuating value; and determining a control value based on a control deviation between at least one of a proportional variable and a differential variable between a desired temperature and an actual temperature, wherein the actuating value is in a first control mode determined based on the control value and the pre-control value when a prescribed control criterion has been satisfied, and the actuating value is in a second control mode differing from the first control mode determined based on the control value and an integral variable of the control deviation when the criterion has not been satisfied.

2. The method according to claim 1, further comprising: adjusting the control valve based on a control deviation between a desired temperature variable and an actual temperature variable; and adjusting the coolant pump based on the pre-control value and independently of the control deviation between the desired temperature variable and the actual temperature variable.

3. The method according to claim 1, wherein the output variable comprises the load variable and the speed variable.

4. The method according to claim 1, wherein the first temperature signal represents a temperature of coolant entering the heat exchanger and the second temperature signal represents a temperature coolant exiting the heat exchanger, and the state variable is a temperature difference between the inlet coolant temperature and an outlet coolant temperature.

5. The method according to claim 1, wherein the actuating value is determined in the second determination mode is a pre-determined value.

6. The method according to claim 1, wherein the actuating value is determined in the second determination mode based on a prescribed second allocation differing from the first allocation as a function of the output variable and the state variable.

7. The method according to claim 1, wherein the pre-control value is determined in the first determination mode based on the prescribed first allocation as a function of the output variable and the state variable when the load variable satisfies a prescribed load condition, and in a second determination mode differing from the first determination mode based on a prescribed second allocation differing from the first prescribed allocation as a function of the output variable and the state variable when the load variable does not satisfy the prescribed load condition.

8. The method according to claim 1, wherein the load variable comprises a torque variable of the internal combustion engine.

9. A motor vehicle comprising an internal combustion engine and a cooling system for cooling the internal combustion engine with a coolant circuit, a coolant pump for variably conveying a coolant in the coolant circuit based on a pump actuating value, a heat exchanger, a bypass that fluidically bridges the heat exchanger, a control valve for variably dividing a coolant flow between the heat exchanger and the bypass based on a valve actuating value, and a controller configured to perform the method according to claim 1.

10. A computer program product with a program code stored on a non-transitory computer-readable medium which when executed on a controller implements the method according to claim 1.

11. A method for adjusting a cooling system having a coolant pump and a control valve for an internal combustion engine based on an actuating value thereof comprising: acquiring a first temperature signal representing an inlet temperature of a heat exchanger in the cooling system; acquiring a second temperature signal representing an outlet temperature of the heat exchanger; determining a state variable based on a difference of the first and second temperature signals; comparing the state variable to a prescribed condition; acquiring an output variable including at least one of a load variable and a speed variable of the internal combustion engine; determining a pre-control value for ascertaining the actuating value in a first determination mode when the state variable satisfies the prescribed condition based on a prescribed first allocation as a function of the state variable and the output variable and then determining the actuating value based on the pre-control value; determining the actuating value in a second determination mode differing from the first determination mode when the state variable does not satisfy the prescribed condition; adjusting at least one of the coolant pump and the control valve based on the actuating value; and determining a control value based on a control deviation between at least one of a proportional variable and a differential variable of a desired temperature and an actual temperature, wherein the actuating value is in a first control mode determined based on the control value and the pre-control value when a prescribed control criterion has been satisfied, and the actuating value is in a second control mode differing from the first control mode determined based on the control value and an integral variable of the control deviation when the criterion has not been satisfied.

12. The method according to claim 11, further comprising: adjusting the control valve based on a control deviation between a desired temperature variable and an actual temperature variable; and adjusting the coolant pump based on the pre-control value and independently of the control deviation between the desired temperature variable and the actual temperature variable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.

(2) FIG. 1 schematically represents an internal combustion engine of a motor vehicle having a cooling system and a controller; and

(3) FIG. 2 is a flow chart illustrating the sequence of a method for controlling a coolant pump and/or control valve of a cooling system.

DETAILED DESCRIPTION

(4) The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.

(5) The motor vehicle includes an internal combustion engine 3 and a cooling system for cooling the internal combustion engine 3 with a coolant circuit, which includes a heat exchanger 4 and a bypass 5 that fluidically bridges the heat exchanger 4. The cooling system includes an electrically activatable coolant pump 1 for variably conveying a coolant into the coolant circuit based on a pump actuating value (eWP) and an electrically activatable control valve 2 for variably dividing a coolant flow between the heat exchanger 4 and the bypass 5 based on a valve actuating value (RV).

(6) Temperature sensors 7.1, 7.2 acquire a coolant temperature .sub.1, .sub.2 at the inlet and outlet of the heat exchanger 4 (respectively), and transmits a signal representing the coolant temperatures (.sub.1, .sub.2) to the controller 6, which determines a temperature difference () of the heat exchanger 4 from the latter. In addition, the controller 6 acquires a signal representing a torque variable (T) and a speed variable (n) of the internal combustion engine 3.

(7) With respect to FIG. 2, the sequence of a method according to an embodiment of the present disclosure will be explained below, which is implemented by the controller 6, which is set up correspondingly for this purpose, in particular from a programming standpoint. As a consequence, the controller 6 or elements thereof in particular include a device or means according to an aspect of the present disclosure that is provided or set up to implement the method described herein.

(8) A first step S10 involves checking whether a load variable in the form of a torque (T) of the internal combustion engine satisfies a prescribed condition, in the exemplary embodiment whether it exceeds a prescribed limit (T.sub.1) or not.

(9) If the load variable (T) of the internal combustion engine 3 satisfies the prescribed condition T>T.sub.1 (S10: Y), step S20 is performed in a first determination mode to determine a pre-control value (eWP.sub.S) for ascertaining the pump actuating value (eWP) based on a prescribed first allocation (eWP.sub.1) as a function of the output variable (T, n) of the internal combustion engine 3 and the temperature difference () of the heat exchanger 4. In addition, step S20 is performed in this first determination mode to determine a pre-control value (RV.sub.S) for ascertaining the valve actuating value (RV) based on a prescribed first allocation RV.sub.1 as a function of the output variable (T, n) of the internal combustion engine 3 and the temperature difference () of the heat exchanger 4.

(10) If the load variable (T) of the internal combustion engine 3 does not satisfy the prescribed condition T>T.sub.1 (S10: N), step S30 is performed in a second determination mode to determine a pre-control value (eWP.sub.S) for ascertaining the pump actuating value (eWP) based on a prescribed second allocation eWP.sub.2eWP.sub.1 as a function of the output variable (T, n) of the internal combustion engine 3 and the temperature difference () of the heat exchanger 4. In addition, step S30 is performed in this second determination mode to determine a pre-control value (RV.sub.S) for ascertaining the valve actuating value (RV) based on a prescribed second allocation RV.sub.2RV.sub.1 as a function of the output variable (T, n) of the internal combustion engine 3 and the temperature difference () of the heat exchanger 4. In particular, the allocations eWP.sub.1 (T, n, ), eWP.sub.2 (T, n, ), RV.sub.1 (T, n, ) and RV.sub.2 (T, n, ) can be determined in the form of characteristic diagrams or lines, in particular be stored in the controller 6.

(11) After step S20 or S30, step S40 is performed to check whether a state variable of the cooling system in the form of the temperature difference () of the heat exchanger 4 satisfies a prescribed condition, in the exemplary embodiment whether it exceeds a prescribed limit (.sub.2) or not.

(12) If the state variable () of the heat exchanger 4 satisfies the prescribed condition >.sub.2 (S40: Y), the pre-control values (eWP.sub.S, RV.sub.S) determined in steps S20 or S30 in the first determination mode are retained, and a jump is made directly to step S60.

(13) If the state variable () of the heat exchanger 4 does not satisfy the prescribed condition >.sub.2 (S40: YN), a step S50 is performed in a second determination mode to set a pump actuating value (eWP) and valve actuating value (RV) to values eWP.sub.3 and RV.sub.3, which are pre-determined in the exemplary embodiment.

(14) The state variable checked in step S40 can additionally or alternatively include other variables. For example, a pre-determined pump actuating value (eWP) and valve actuating value (RV) can be computed in step S50 even if the control valve 2 was in a prescribed position for a prescribed time or the like.

(15) After a positive step S40, step S60 is performed to check whether a prescribed criterion has been satisfied or not. In the exemplary embodiment, the criterion encompasses a change rate (RV.sub.S) of the pre-control value (RV.sub.S) determined in step S20, S30 for ascertaining the valve actuating value (RV). If this change (RV.sub.S) rate exceeds a prescribed limit .sub.1 (S60: Y), step S70 is performed in a first control mode to determine the valve actuating value (RV) based on a sum of the pre-control value (RV.sub.S) and a control value (RV.sub.PD), which is determined in a known manner based on a control deviation between a desired temperature variable (.sub.S) and an actual temperature variable () of the coolant or motor and a differential variable (d.sub.S/dt or d/dt) thereof. This is denoted on FIG. 2 with the PD regulator structure as follows:
RV.sub.PD=P.Math.(.sub.S)+D.Math.(d.sub.S/dtd/dt)

(16) wherein:

(17) P represents the proportional gain; and

(18) D represents the differential gain.

(19) If the change rate (RV.sub.S) does not exceed the prescribed limit .sub.1 (S60: N), step S80 is performed in a second control mode to determine the valve actuating value (RV) based on a sum of the control value (RV.sub.PD) and an integral variable of the control deviation (.sub.sdt or dt). In other words, the integral portion is replaced by the pre-control value (RV.sub.S) in a PID regulator as long as the criterion RV.sub.S>.sub.1 is satisfied.

(20) In a step S90, the pre-control value (eWP.sub.S) for determining the pump actuating value (eWP) is determined as the pump actuating value (eWP), and the coolant pump 1 is correspondingly actuated by the controller 6. As a consequence, the coolant pump 1 is feed forward-controlled independently of a control deviation between a desired and actual temperature variable (.sub.S, ) based on the pre-control value (eWP.sub.S).

(21) By contrast, the valve actuating value (RV), as explained above with reference to steps S70, S80, is determined based on a control deviation between a desired and actual temperature variable (.sub.S, ), and the control valve 2 is correspondingly actuated by the controller 6. As a consequence, the control valve 2 is feedback-controlled based on a control deviation between a desired and actual temperature variable (.sub.S, ), in particular PID controlled, wherein the integral portion is replaced by the pre-control value (RV.sub.S), if necessary.

(22) If the state variable () of the heat exchanger 4 does not satisfy the prescribed condition >.sub.2 (S40: N), the coolant pump 1 and control valve 2 are instead actuated according to the pump actuating value (eWP=eWP.sub.S) and valve actuating value (RV=RV.sub.3) determined in step S50.

(23) Accordingly, FIG. 1 denotes the actuation of the coolant pump 1 according to or with the pump actuating value (eWP), and denotes the actuation of the control valve 2 according to or with the valve actuating value by way of the controller 6.

(24) While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.