DE10316017A1 - Method for regulating and controlling a cooling system for a motor vehicle combustion engine has throttle controlled cooling and bypasss branches in cooling circuit - Google Patents

Abstract

A method for controlling and/or regulating a cooling system for a motor vehicle combustion engine comprises pumping (5) coolant outside the engine through a cooling branch (3a,7,8,9) and a by-pass branch (3b,4). Flow through the branches can be independently throttled by the control means. An independent claim is also included for a control and/or regulating system for the above.

Description

State of technology

The The invention relates to a method for control and / or regulation a cooling system an internal combustion engine of a motor vehicle, in which a coolant from a coolant pump is circulated and where the coolant outside the internal combustion engine at least by a cooler branch and by a bypass branch flows.

The The invention further relates to a control and / or regulation of a cooling system an internal combustion engine of a motor vehicle, with a coolant pump to circulate a coolant and with at least one cooler branch and a bypass branch through which coolants outside the internal combustion engine flow can.

To a cooling circuit for one The internal combustion engine of a motor vehicle usually includes a heat source to be cooled (the internal combustion engine), which by means of a coolant by free or forced Chilled convection becomes. The temperature difference over the heat source is from the heat input and the size of the coolant flow dependent, while the absolute temperature of the coolant through the heat input the heat source that Heat dissipation via the circuit located cooler and the heat capacities of the Materials is determined.

Currently are used in engine cooling systems mechanical water pumps used by motor vehicles, which have V-belts are driven by the crankshaft of the engine. The pumps are dimensioned such that even in the most critical operating conditions, for example when driving uphill at high speed, high load and low vehicle speed, none prohibited high engine temperature or temperature difference across the engine occurs. The mixing ratio between your bypass branch and the cooler branch is by an expansion operated Thermostatic valve depending from the coolant temperature set. The thermostatic valve is dimensioned so that none prohibited high coolant temperature established.

Around more efficient heat management in the cooling system an internal combustion engine for To reach a motor vehicle, z. B. the possibility of one Control or regulation of the engine cooling system as required with the aim of reducing fuel consumption and emissions or to comply with exhaust gas limit values and also increase comfort. there allowed to critical limits of the component load are not exceeded. A special one critical component is z. B. the cylinder head temperature. These goals can by optimizing the coolant flow and the load-dependent regulation of the engine temperature level.

A Alternative, the need-based adjustment of the coolant flow allows provides an electrically adjustable water pump, which, however, the The disadvantage is that they are significantly more expensive than a mechanical one Water pump is and on the other hand in today's electrical systems with 12V voltage some of the required Pumping capacities cannot easily be achieved.

Out the SAE Technical Paper Series 961813 by Jilian Yangg from Ford Motor Co. entitled “Coolant Pump Throttling - A Simple Method to Improve the Control Over SI Engine Cooling System "by the International Off-highway & powerplant Congress & Exposition, Indianapolis, Indiana, August 26-28, 1996 is a cooling system for an internal combustion engine of a motor vehicle in which the pump as a mechanically driven coolant pump accomplished is. With the aim of improving the heating of the combustion chambers the author suggests a cold start and an improvement in exhaust gas and consumption values, the coolant flow the coolant pump to throttle. There are two different versions proposed. For one, it strikes the author proposed a throttle plate in the bypass branch of the cooling system use. On the other hand, the strikes Author proposes to install a throttle valve directly at the pump outlet. In the first alternative, the coolant flow in the by branch to be regulated while in the second alternative, the total coolant flow of the cooling system can be regulated.

The The invention has for its object a flexible control and / or Control of coolant flows in one cooling system specify an internal combustion engine of a motor vehicle.

Advantages of invention

The Task is solved by a method for controlling and / or regulating a cooling system an internal combustion engine of a motor vehicle, in which a coolant from a coolant pump circulated is where the coolant outside the internal combustion engine flows at least through a cooler branch and through a bypass branch and at your throttling of a coolant flow with control and / or regulating means through the radiator branch and a coolant flow independent through the bypass branch performed by each other.

Through the independent control and / or regulation of the coolant flows through the cooler branches and the bypass branch can be used to specify the coolant flows particularly flexibly in the method according to the invention. In particular, compared to conventional cooling circuit systems, it is possible not only to completely interrupt the cooler branch after a cold start in order to achieve faster heating of the internal combustion engine, but in addition the coolant flow through the bypass branch can be throttled in order to achieve the heating of the internal combustion engine even faster.

A measure provides that by means of a predeterminable activation of the control and / or regulating means a desired one Coolant temperature is set. This development makes the method according to the invention used in a particularly flexible manner, a coolant target temperature adjust.

A other training provides that by means of tax and / or Control means a predeterminable total coolant flow is set.

The inventive method allows it continues that independently from the boundary condition of the predetermined total coolant flow by means of the Control and / or regulating means a predetermined mixing ratio Coolant flows through Cooler- and bypass branch can be set. In other words: it is possible, a certain total coolant flow and a mixing ratio of the Coolant flows between your cooler and adjust the bypass branch. (The mixing ratio is the manipulated variable for motor temperature control).

The Task continues to be solved by controlling and / or regulating a cooling system of an internal combustion engine of a motor vehicle, with a coolant pump for circulating a refrigerant and with at least one cooler branch and a bypass branch through which coolants outside the internal combustion engine flow can, the control and / or regulating means for independent throttling a coolant flow through the radiator branch and a coolant flow is formed by the bypass branch.

The control according to the invention and / or control has the same advantages as the method according to the invention.

advantageous Developments of the method according to the invention and the control according to the invention and / or regulation result from dependent claims as well from the description below.

drawing

1 shows a cooling system according to the prior art, 2 shows a cooling system according to the invention, 3a shows a first embodiment of a method according to the invention, 3b shows the same embodiment in a different representation, 4 shows a hydraulic network according to the invention and 5 shows a representation for determining the desired hydraulic resistance according to the invention.

The Regulation of the coolant flow (Volume flow) and the temperature level in a cooling system The internal combustion engine is also conventional with mechanical Water pump possible if the bypass and the cooler branch can be decoupled from each other. By being independent of each other possible Throttling the cooler and the bypass branch, the mixing ratio of the coolant flows through the cooler and the bypass branch can be set flexibly. The coolant flow can be determined despite the speed of the internal combustion engine The working point of the mechanical water pump can be set by the total hydraulic resistance of the system is changed. The throttle valves are set so that in System the desired one mixing ratio between the radiator and the bypass branch as well as the desired total hydraulic resistance sets a desired one Total coolant flow of the cooling system results. A prerequisite for carrying out the method according to the invention is knowledge of the hydraulic resistances of the cooling circuit components as well knowledge of the pump characteristic of the mechanical water pump.

1 shows an example of a conventional cooling system. Corresponding 1 becomes an internal combustion engine 1 flowed through by a coolant. The coolant flows through a line 2 from the internal combustion engine 1 out and flows through a three-way cooler valve 3 , via a bypass branch 4 , a coolant pump 5 and a line 6 back to the internal combustion engine 1 , Furthermore, part of the coolant flows from the three-way cooler valve 3 , over a line 7 to a cooler 8th , from there via a line 9 and also via the coolant pump 5 and management 6 back to the internal combustion engine 1 ,

Elsewhere, the coolant leaves via a line 10 the internal combustion engine 1 and flows from there via a heating valve 11 , a line 12 , a heating heat exchanger 13 , a line 14 , the coolant pump 5 and management 6 back to the internal combustion engine 1 , The administration 10 , the heating valve 11 , The administration 12 , the heating heat exchanger 13 as well as the management 14 form one Heating branch.

In 1 three temperature sensors are also shown, which record the temperatures at certain points in the cooling system. This is the temperature sensor 15 which is the temperature in line 2 detected, the temperature sensor 16 which is the temperature in line 6 detected and the temperature sensor 17 which is the temperature in line 9 detected. The temperature sensor 15 thus detects the temperature at an output of the internal combustion engine 1 , The temperature sensor 16 thus detects the temperature at an input of the internal combustion engine 1 , The temperature sensor 17 thus detects the temperature of the coolant at an outlet of the radiator fan system 8th ,

2 shows a cooling system according to the invention. Here are the parts that match those in 1 shown parts each have the same reference numerals and only the difference to 1 received. In contrast to 1 is the three-way cooler valve shown there 3 through two separate valves 3a and 3b replaced. Here is a cooler valve 3a in the line 7 used, causing the line 7 in two sub-lines 7a and 7b divides. On the line 4 became a bypass valve 3b used, causing the line 4 into the parts 4a and 4b is divided. The cooler valve 3 , the sub-lines 7a . 7b , the cooler 8th and the line 9 form a cooler branch. The bypass valve 3 and the sub-lines 4a . 4b form a bypass branch.

By using two separate valves according to the invention 3a and 3b the target mixing ratio and the total target coolant flow can be set. If necessary, it must be assumed that all of the coolant pumps 5 short-circuiting other branches can also be separated, such as the heating branch 10 - 14 , On the determination of the target mixing ratio between the cooler branch 3 . 7a . 7b . 8th . 9 and the bypass branch 3b . 4a . 4b and the determination of the total coolant flow through the entire cooling system is not further discussed in the context of this invention, since this is of no importance for the essence of the invention and this data can be determined in a separate thermal management process control.

3a shows a first embodiment of the method according to the invention. It is shown schematically how the corresponding positions of the two valves from the target mixing ratio and the total target coolant flow 3a and 3b to 2 be determined.

First, depending on the speed n of the internal combustion engine 1 the working point of the coolant pump 5 determined and depending on your total target coolant flow Vp by means of a first map 31 the desired hydraulic system resistance R is determined. This desired hydraulic system resistance R and a desired mixing ratio MV are the inputs of the second and third characteristic fields 32 . 33 , From your second map 32 the radiator valve is out 3a and from the third map 33 out the bypass valve 3b driven. From the two maps 32 . 33 Accordingly, signals are obtained that correspond to the target positions of the valves 3a . 3b correspond.

By connecting the three maps accordingly 31 . 32 . 33 is the control of the valves according to the invention 3a and 3b reached. Alternatively, instead of the three two-dimensional maps 31 . 32 . 33 two three-dimensional maps can also be used.

3b shows the same embodiment in a different representation. In a first step 34 the input variables setpoint mixing ratio MV, total setpoint coolant flow Vp and speed n of the internal combustion engine 1 detected. Based on this input data is in one step 35 the total hydraulic resistance R of the cooling system is determined by means of the total target coolant flow Vp and the speed n. This total hydraulic resistance R is applied to the crotch 36 transmitted, in which, based on the target mixing ratio MV and the total target coolant flow Vp control variables for the cooler valve 3a and the bypass valve 3b be determined. In the final step 37 will eventually become the radiator valve 3a and the bypass valve 3b controlled accordingly.

The first map 3l to determine the desired hydraulic resistance R and, if necessary, the second and third map 32 . 33 can be generated automatically when the internal combustion engine is applied. Here, the map of the coolant pump 5 be known that indicates the pressure difference over the pump dependency of the coolant flow and the pump or internal combustion engine speed. Furthermore, the hydraulic resistances of the components should be known if necessary. In the case of the pump map, a hydraulic resistance can clearly be found for each pair of data from the coolant flow and speed. To determine the maps 32 . 33 The respective valve or throttle body position must be stored in the respective map depending on the desired mixing ratio and your desired hydraulic resistance. The data of the maps 32 . 33 are strongly coupled with each other because the mixing ratio and, depending on the working point, the hydraulic resistance of the cooling system strongly depend on the valve position of each individual valve 3a . 3b or depends on the position of each throttle body. Assuming tur bulent flow, the pressure drop is approximately proportional to the square of the coolant flow. Analogous to electrical engineering, a hydraulic equivalent resistance R of the cooling system can be determined for all valve positions using a hydraulic network, provided the hydraulic resistances of the components and the resistance characteristics of the valves 3a . 3b are known.

An example of such a hydraulic network according to the invention is in 4 shown. The individual resistances of the components add up to the total resistance analogously to an electrical circuit. This results in the system characteristic. The desired total coolant flow of the cooling system through the coolant pump 5 results from the intersection of the pump characteristic with the system characteristic.

The details are in 4 shown: the hydraulic resistance 41 the internal combustion engine 1 , the hydraulic resistance 42 of the heating branch 10 - 14 , the hydraulic resistance 43 one not shown in the internal combustion engine 1 contained cylinder head, the hydraulic resistance 44 of the bypass valve 3b , the hydraulic resistance 45 of the bypass branch 4a . 4b without the bypass valve 3b , the hydraulic resistance 46 of the radiator valve 3a and the hydraulic resistance 47 of the rest of the cooler branch 7a . 7b . 8th . 9 without the radiator valve 3a , Here are the hydraulic resistances 44 . 45 of the bypass valve 3b and the rest of the bypass branch 4a . 4b connected in series. This series connection is in turn connected in parallel to the series connection made of hydraulic resistance 46 of the radiator valve 3a and hydraulic resistance 47 of the rest of the cooler branch 7a . 7 . 8th . 9 , The parallel connection of the hydraulic resistors 44 . 45 on the one hand and 46 . 47 on the other hand is connected in series to the hydraulic resistance 43 of the cylinder head of the internal combustion engine 1 , The resulting series connection of the hydraulic resistors is in turn connected in parallel to the hydraulic resistor 42 of the heating branch 10 - 14 , The current circuit of hydraulic resistors 42 - 47 is in turn connected in series with the hydraulic resistance 41 the internal combustion engine 1 , Overall, the in 4 shown series and parallel connection of the hydraulic resistors 41 - 47 the total hydraulic resistance of the cooling system. The parallel connection of the series connections of the hydraulic resistors also results 44 . 45 and 46 . 47 the ratio of the flow through the bypass and cooler branch 3b . 4a . 4b ; 3a . 7a . 7b . 8th . 9 and thus the mixing ratio.

5 shows characteristic curves for determining the desired hydraulic resistance. In 5 coolant flows Vp are shown on the horizontal axis, while pressure differences dp are shown on the vertical axis. Pump speeds are in each case for the speeds n1, n2 and n3 (n1>n2> n3) 51 . 52 . 53 shown. A system characteristic curve is also shown 54 , which results (in the case of turbulent flow) from the multiplication of the hydraulic resistance R by the square of the coolant flow Vp. From a mathematical point of view, this represents the system characteristic 54 represents a parabola, the pressure difference dp being a function of the square of the coolant flow Vp, the square of the coolant flow Vp being linked to the hydraulic resistance R as a factor.

With decreasing hydraulic resistance R, the slope of the system characteristic becomes 54 lower and ultimately results in a system-related minimum hydraulic resistance R sys min, its dependence on the coolant flow Vp with the reference number 55 is provided. However, if the hydraulic resistance R increases, the system characteristic curve increases 54 , and the system characteristic 54 would move further in the direction of the vertical axis. Knowing the current speed n of the internal combustion engine 1 and a desired total coolant flow Vp can thus be determined from the intersection of the coolant flow Vp sought with the corresponding pump characteristic 51 - 53 determine the sought system characteristic from which the sought hydraulic resistance R can be determined. For example, in the illustration 5 the intersection points for the coolant flows Vp1, Vp2, Vp3 56 . 57 and 58 with the corresponding pump characteristic 51 - 53 shown. Through these intersections 56 - 58 the system characteristic results 54 , whereby the sought hydraulic resistance R can be inferred.

The illustrated method according to the invention can be integrated, for example, in a control unit of a motor vehicle, which, for example, also has the task of controlling the internal combustion engine 1 takes over. The functional relationships shown can e.g. B. can be represented by appropriate mathematical functions, a multi-dimensional map or by several maps in the engine control unit. Overall, there is a particularly flexible and exact possibility of independently controlling coolant flows Vp and mixing ratios between the cooler branch 3a . 7a . 7b . 8th . 9 and bypass branch 3b . 4a . 4b , whereby a simple, possibly computer-aided or automated applicability is given. The data required for the application are easy to measure, but should also be known or made known as part of the cooling system dimensioning from the vehicle manufacturer or from the component supplier.

Claims (10)

Method for controlling and / or regulating a cooling system of an internal combustion engine ( 1 ) of a motor vehicle, wherein a coolant from a coolant pump ( 5 ) is circulated and the coolant outside the internal combustion engine ( 1 ) at least through a cooler branch ( 3a . 7a . 7b . 8th . 9 ) and through a bypass branch ( 3b . 4a . 4b ) flows, characterized in that with control and / or regulating means a throttling of a coolant flow through the cooler branch ( 3a . 7a . 7b . 8th . 9 ) and a coolant flow through the bypass branch ( 3b . 4a . 4b ) is carried out independently of one another. Method according to claim 1, characterized in that by means of a predeterminable control of the control and / or Control means a temperature of the coolant is set. A method according to claim 1 or 2, characterized in that that by means of the control and / or regulating means a predeterminable total coolant flow (Vp) of the coolant is set. A method according to claim 3, characterized in that by means of the control and / or regulating means a predetermined mixing ratio of the coolant flows through the cooler and bypass branch ( 3a . 7a . 7b . 8th . 9 ; 3b . 4a . 4b ) is set. Method according to 4, characterized in that at least from the predeterminable mixing ratio, the predeterminable total coolant flow (Vp) and a speed (n) of the internal combustion engine ( 1 ) and / or the coolant pump ( 5 ) and / or a position of the heating valve ( 11 ) Control variables for the control and / or regulating means are determined. Method according to claim 5 , characterized in that from the predeterminable total coolant flow (Vp) and the speed (n) of the internal combustion engine ( 1 ) and / or the coolant pump ( 5 ) a total hydraulic resistance (R) of the cooling system is determined. A method according to claim 5 or 6, characterized in that from maps ( 31 . 32 . 33 ) Control variables for a cooler valve ( 3a ) in the cooler branch ( 3a . 7a . 7b . 8th . 9 ) and a bypass valve ( 3b ) in the bypass branch ( 3b . 4a . 4b ) can be determined. Method according to claims 6 and 7, characterized in that the maps ( 31 . 32 . 33 ) are stored in a memory at least depending on the predefinable mixing ratio and your total hydraulic resistance (R) of the cooling system. A method according to claim 6, characterized in that for determining the total hydraulic resistance (R) of the cooling system, a map ( 31 . 32 . 33 ) is stored in a memory. Control and / or regulation of a cooling system of an internal combustion engine ( 1 ) of a motor vehicle, with a coolant pump ( 5 ) for circulating a coolant, with at least one cooler branch ( 3a . 7a . 7b . 8th . 9 ) and a bypass branch ( 3b . 4a . 4b ) through which the coolant outside the internal combustion engine ( 1 ) can flow, characterized in that control and / or regulating means for the independent throttling of a coolant flow through the cooler branch ( 3a . 7a . 7b . 8th . 9 ) and a coolant flow through the bypass branch ( 3b . 4a . 4b ) are provided.