Methods and devices for saving fuel in motor vehicles with and without cabin heating

Abstract

Device for cooling and heating a motor vehicle with an internal combustion engine (1) which is cooled by means of a motor coolant pump (7) circulated by means of, with a) a cooling circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a radiator branch (6a) with a vehicle radiator (8) and a radiator thermostat (6), b) a bypass branch (6b) leading through the engine coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit and is open to flow when the radiator thermostat (6) is closed, c) a ventilation circuit leading through the engine coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a) with a water reservoir (9), d) a heating heat exchanger circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a heating branch (4a) with a heating heat exchanger (4), e) an additional valve (6bv) controllable by an engine control unit (16), with which the bypass branch (6b) can be closed when the radiator thermostat (6) is closed, f) a cooling circuit through which the engine coolant pump (7) carries the internal combustion engine (1) and an auxiliary branch (6d) with an engine oil cooler (30), which is open to flow when the radiator thermostat (6) is closed, g) a cooling circuit through which the engine coolant pump (7) leads the internal combustion engine (1) and an auxiliary branch (6e) with a transmission oil cooler (40), which is open to flow when the radiator thermostat (6) is closed, h) an air-side temperature control system in which the temperature of the air (20) supplied to a cabin of the motor vehicle can be adjusted by means of the mixing via an air temperature control flap (5) of an air mass flow (21) supplied through the heating heat exchanger (4) with an unheated bypass air mass flow (22), characterized in that the cooling circuit with the auxiliary branch (6d) with engine oil cooler (30) and the cooling circuit with the auxiliary branch (6e) with transmission oil cooler (40) lead together through a valve (6cv) which is controlled by the engine control unit (16) and in the closed state interrupts both auxiliary branches (6d, 6e) together.

Description

[0001] The invention relates to methods and devices according to the preamble of the independent patent claims.

[0002] The invention relates in particular to a method and a device for operating an engine cooling and heating system with improved use of the engine waste heat for cabin heating purposes and for fuel saving.

[0003] In particular, it also relates to an air-side controlled heating and air conditioning unit in motor vehicles, with a heating heat exchanger which extracts heat from the coolant of the drive engine and transfers it to the cabin air conveyed through the heating heat exchanger by means of a heating fan, as well as to various approaches to saving fuel in air-side and water-side controlled air conditioning units. Partial aspects of the invention have already been described in DE 10 2004 058 869 A1 of the applicant of the same name dated December 6, 2004, and are further developed here in particularly effective embodiments.

[0004] It is well known that thermal management measures can be used to reduce fuel consumption in modern cars. Rapid heating of the coolant and engine oil, and thus also of the engine components, as well as raising the thermostat opening temperature during partial load, are particularly effective means of achieving fuel consumption improvements. In this context, DE 10 2004 058 869 A1 describes particularly effective methods for improving fuel consumption and / or cabin heating at low cost and, in some cases, even with cost savings compared to current production vehicles.

[0005] From DE 10 2004 058 869 A1 is Fig. 1 discloses a cooling system in which a cooling circuit passes through an engine coolant pump, an internal combustion engine, a thermostat, and a vehicle radiator, and which comprises several cooling circuits passing through the internal combustion engine and the engine coolant pump, through which flow occurs when the thermostat is closed and bypasses the vehicle radiator. During warm-up, a single additional valve controlled by an engine control unit can interrupt a bypass circuit passing through a bypass branch, an engine oil cooler circuit passing through an engine, and a venting circuit passing through an expansion tank. Opening the additional valve inevitably results in flow through these three circuits passing through the internal combustion engine.In this cooling system, a heater core circuit, which runs through a heating branch with a heater core heat exchanger, the engine coolant pump, and the internal combustion engine, bypasses the auxiliary valve and thermostat. The radiator circuit, the bypass circuit, the engine oil cooler circuit, and the vent circuit all pass through the thermostat and exit the thermostat via a common outlet toward the engine coolant pump. Flow through the engine oil cooler is only possible if the auxiliary valve opens the vent circuit and the bypass circuit in addition to the oil cooler circuit. In addition, Fig. 6 of DE 10 2004 058 869 A1 taught the return (starting from Fig. 1) as in Fig. 6 of DE 10 2004 058 869 A1. In this respect, DE 10 2004 058 869 A1 also teaches a variant of the Fig. 1 of DE 10 2004 058 869 A1, in which the venting circuit can be interrupted by the thermostat when the auxiliary valve is open or closed. A major advantage of the approach of DE 10 2004 058 869 A1 is that significant fuel savings can be achieved using very inexpensive means. This is particularly significant in statutory emissions tests and other operating modes.

[0006] US 2003 / 0 177 986 A1 discloses a cooling system with six valves controllable by the engine control unit, avoiding the use of an expansion thermostat, for the separate cooling of six cooling circuits passing through the internal combustion engine. These cooling circuits are routed through an engine coolant pump and the internal combustion engine to a common outlet water tank, where they are divided into six separate cooling circuits. Thus, US 2003 / 0 177 986 A1 discusses a cooling system in which six separate cooling circuits outside the internal combustion engine are each assigned their own valve controllable by an engine control unit.Specifically, a valve that can be controlled by the engine control unit is described in a cooling circuit with a vehicle radiator, in a bypass circuit without a heat exchanger, in a ventilation circuit with an expansion tank, a heating heat exchanger circuit with a heating heat exchanger, a cooling circuit with an oil cooler and a cooling circuit for intake air preheating.

[0007] For these circuits, US 2003 / 0 177 986 A1 provides instructions on how the associated individual valves are to be operated individually. How the six valves are to be switched / changed relative to each other during warm-up remains largely unclear given the multitude of switching options.

[0008] For the ventilation circuit, US 2003 / 0 177 986 A1 proposes regulating its flow depending on the coolant temperature or increasing its coolant flow as the coolant temperature increases. The information regarding the valve in the heating circuit indicates that a water-side temperature control is used for the cabin heater, rather than an air-side one (see, for example,

[0083] of US 2003 / 0 177 986 A1).

[0009] Regarding the oil cooler, it is particularly unclear whether a transmission oil cooler or an engine oil cooler is meant, although the specified target oil temperatures of up to 140°C indicate an engine oil cooler. If the valve in the oil cooler circuit is used to preheat the oil, an oil temperature is used together with a coolant temperature, or a difference between these two temperatures.

[0010] Overall, a vote of the Fig. 1 and Fig. 2 of US 2003 / 0 177 986 A1, a real challenge in terms of the associated costs and the necessary coordination of the multitude of possible interventions of the engine control.

[0011] DE 195 08 102 C1 discloses a thermal management strategy using a radiator fan and a temperature-independent valve for different coolant flows.

[0012] DE 34 40 504 A1 discloses a cooling system with five valves controlled by the engine control unit for separate cooling of the cylinder head and cylinder block by two separate coolant pumps. Another valve, in the form of a heater control valve, is arranged in a heater core circuit. This heater control valve is assigned a dedicated control unit, which is designed for manual control by the driver.

[0013] DE 22 06 266 C2 discloses a device for operating an engine cooling and heating system with an expansion thermostat arranged on the engine outlet side and an auxiliary valve arranged in the main coolant flow upstream of the thermostat 6 arranged on the engine outlet side. Closing the auxiliary valve reduces or prevents the coolant flow in a cylinder head during warm-up, while the coolant flows through a cylinder block without being obstructed by the auxiliary valve.

[0014] DE 103 32 947 A1 discloses a device for operating an engine cooling and heating system with an engine coolant pump that can be deactivated with a clutch, an electrically operated auxiliary pump in the heating circuit, and a thermostat (second control unit) arranged on the engine output side for controlling the flow through the internal combustion engine and the heat dissipation at a vehicle radiator in a cooling circuit. In addition to the thermostat, a switching valve (first control unit) is arranged between the engine coolant pump and a coolant inlet in each cylinder head and cylinder block (cylinder crankcase). This switching valve can be controlled by an engine control unit and can supply the coolant coming from the engine coolant pump to the cylinder head and / or the cylinder block, depending on the setting.A first setting is described in which the changeover valve supplies the coolant coming from the engine coolant pump only to a connection assigned to the cylinder head, and a second setting in which the changeover valve supplies the coolant coming from the engine coolant pump only to a connection assigned to the cylinder block (crankcase). In the second setting, the coolant first flows through the cylinder block and then via the cylinder head gasket to the cylinder head. In both settings, the coolant supplied to the cylinder head or the cylinder block flows via a common coolant outlet located on the cylinder head. This means that when the engine coolant pump and / or electric auxiliary pump are switched on, at least the cylinder head is always flowed through, whereas in the first setting there is only a relatively small flow through the cylinder block.The cylinder head is fluidically connected to the cylinder block via openings in the cylinder head gasket, so that even in the first setting, one can only speak of a separate flow through the cylinder head and cylinder block to a limited extent, i.e., only "partial split cooling" is present. In one variant (. Fig. 2) The document DE 103 32 947 A1 teaches the integration of an exhaust gas recirculation cooler (EGR cooler) and an engine oil cooler in such a way that the coolant conveyed through these two components is taken directly after the engine coolant pump and only merges with the coolant conveyed through the cylinder head or cylinder block downstream of the cylinder block and downstream of the cylinder head. Flow through only the EGR cooler and / or only the engine oil cooler without simultaneous flow through the internal combustion engine (the cylinder head and / or the cylinder block) is not possible in DE 103 32 947 A1 with any adjustment of the second control unit or the engine coolant pump. This also applies if the engine coolant pump is deactivated by the clutch and only the electric auxiliary pump is activated.When the engine coolant pump and / or the electric auxiliary pump are operating, at least parts of the internal combustion engine, the heater core, and other heat exchangers are flowing. Flow through the engine oil cooler without any flow through the heater core is not provided. The complexity of the device taught in DE 103 32 947 A1 is quite considerable, given the use of the changeover valve for the cylinder block and cylinder head, the electric auxiliary pump, and a switchable coolant pump as an addition to the existing radiator thermostat.

[0015] DE 103 32 949 A1 describes a substantially comparable device for operating an engine cooling and heating system to the above-discussed and equally prioritized DE 103 32 947 A1 by the same applicant, wherein a further control unit controls the flow through a transmission oil cooler. Flow through only the EGR cooler or only the engine oil cooler or only the transmission oil cooler without simultaneous flow through the internal combustion engine (the cylinder head and / or the cylinder block) is not possible with any adjustment of the second control unit or the engine coolant pump. This also applies if the engine coolant pump is deactivated by the clutch and only the electric auxiliary pump is activated. The complexity of the device taught in DE 103 32 949 A1 is also quite considerable.

[0016] Furthermore, in air-side controlled heaters, i.e. heaters in which the temperature of the air fed into the cabin is adjusted by mixing an air flow fed through the heater core with a non-heated bypass air mass flow, it is known to use shut-off valves to prevent the coolant flow in the heater branch when driving without heating. This results in faster engine warm-up and improves fuel consumption. This measure also minimizes the heat transfer to the cabin air that is undesirable when the cooling effect is set to maximum. This helps improve comfort and, in vehicles with air conditioning, may also improve fuel consumption by reducing the drive power of the air conditioning compressor. To shut off the cooling water side of the heating branch, conventional applications use solenoid valves or valves with vacuum units as actuators, which are controlled by a vacuum solenoid valve. The control is generally ultimately via a digital I / O port of the engine control unit or the heating / air conditioning unit and allows for "open" and "closed" settings. Flow control, e.g., via cyclic opening and closing, as is common with water-side controlled heaters, is not used, as the air-side temperature control takes over the regulation of the cabin temperature.

[0017] In terms of fuel consumption, the systems described above, with air-side air temperature control and a cooling water-side shutdown option for the heating branch, have the disadvantage that even at low heating demand, the water valve in the heating branch must be opened. In previously known designs of these systems, this directly results in a loss of fuel consumption benefits due to the "switched off" heat-active mass in the heating branch.

[0018] In practice, the number of journeys where it's possible to completely forgo a certain amount of heating power consumption is relatively small. In fact, even in spring and fall, a certain amount of heating is almost always required to keep the windows clear of fogging. Even in summer, a certain amount of heating power consumption is often unavoidable, especially in vehicles with air conditioning, where a certain amount of heat is constantly drawn from the heater core for temperature control and dehumidification. The effectiveness of the additional water valve with air-side temperature control in terms of fuel savings is therefore almost exclusively limited to the statutory emissions test, which is conducted without heating or air conditioning at temperatures of approximately 22-25°C, and to driving situations with maximum cooling demand ("pull-down") in vehicles with air conditioning. Given current fuel prices, the cost of an additional shut-off valve in the heating system relative to the achievable fuel savings is often just below the threshold for economic implementation, so that to date, very many vehicles have not utilized this fuel-saving option.

[0019] The object of the invention is to further develop the heating system according to DE 10 2004 058 869 A1 and to provide a fuel-saving cooling and heating system that is superior to the cited prior art.

[0020] This problem is solved by the methods and devices according to the independent claims. The dependent claims also solve this problem.

[0021] In particular, the problem is solved of redesigning a heating and air conditioning unit, in particular a heating unit with air-side control of the cabin heating, in such a way that fuel savings are achieved with and without useful heat extraction at the cabin heat exchanger and in particular with useful heat extraction at the cabin heat exchanger with limited heating requirements and thus an excess of potential heating power.

[0022] In particular, costs can be reduced by using components that can be used both to improve heating when heating requirements are high and to improve fuel consumption.

[0023] The optional extension of the application range of the valve in the heating branch to operating points with heat extraction improves the cost / benefit ratio in particular to such an extent that an economical introduction is already possible at today's fuel prices.

[0024] In particularly preferred embodiments of the invention, by throttling the cooling water flow in the heating branch as needed, the maximum amount of heat that can be transferred to the heating heat exchanger is limited to a value that is below the value achievable at full coolant flow but is at least large enough for the air-side temperature control to set the desired air outlet temperature by suitably mixing cold bypass air and warmer air from the heating heat exchanger. By fulfilling a minimum heating criterion, it is ensured in such particularly preferred embodiments of the invention that sufficient control latitude, i.e. suitable enthalpy flow pairings with cold and warm air flow, is available for rapid control and thus for meeting climate comfort requirements.

[0025] Compared to a conventional air-side-controlled air conditioning system, this results in more air flow through the heater core and correspondingly less air flow through the unheated bypass branch under most operating conditions, with the operating point unchanged (i.e., the total air mass flow and cabin intake temperature unchanged). On the other hand, the cooling water in the heater core is cooled significantly more due to the lower coolant flow rate.

[0026] Depending on the heating power requirement, this approach – with the correct dosage of the coolant mass flow relative to the required heat output – can achieve a reduction of the effective heat-active mass in the heating system branch by 50-75%. This is due, on the one hand, to the fact that the coolant leaves the heating system heat exchanger at almost ambient temperature over a wide range of the heat extraction map, and especially at low heat extraction rates. This means that large areas of the heating system heat exchanger are heated significantly less than with high coolant mass flow. The return lines remain almost at ambient temperature even at relatively low heat extraction rates.

[0027] When the air conditioning is in operation, the return line temperature sometimes even falls below the ambient temperature, ie it is almost at the air temperature at the evaporator outlet. Especially in conventional engine cooling systems with engine coolant bypass (see e.g. 6b in the prior art Fig. 1), to which a bypass valve (6bv) is added according to the independent patent claims, this extremely low temperature is indeed desirable, as it even creates a certain heat pump effect, which ultimately benefits engine warming. Without an engine coolant bypass flow - corresponding applications will be described later - the full cooling potential will generally not be utilized during fuel-optimized operation, at least during journeys without maximum heating requirements, among other things to avoid local overheating of the engine and, depending on the engine, also to achieve heat transfer from the cylinder head to the cylinder block.

[0028] In some of the application examples, especially with low heat extraction from the heater core, even the heater supply line remains at a reduced temperature level due to surface heat losses averaged over the length of the line, thus requiring less engine waste heat for heating. In other words, the reduction in coolant flow reduces the effective heat-active mass in the entire heating branch in such particularly preferred applications of the invention. This results in lower heat output for heating and, due to the lower surface temperatures, also savings in surface heat losses.

[0029] To implement the processes according to the invention, it is particularly advantageous to use high-performance heat exchangers, especially counterflow heat exchangers, which ensure good heat transfer and uniform temperature distribution even at low cooling water flow rates. However, by foregoing the full range of fuel savings potential, significant advantages can still be achieved with many standard series heater core heat exchangers and even with simple crossflow heat exchangers.

[0030] It is particularly advantageous if a map is stored in the control unit of the climate control unit or the engine control unit as a minimum heating criterion. This map ensures that the coolant flow rate in the heating branch decreases as heat extraction from the heater core decreases, and in particular, that the coolant outlet temperature of the heater core is reduced as much as possible toward ambient temperature despite low heat extraction. This ensures that the coolant is always cooled as much as possible, thus ensuring that the engine waste heat is primarily used to heat the engine and thus save fuel.

[0031] In connection with the control characteristics, it should be noted that with relatively high heat extraction and based on high coolant flow rates, especially with very efficient heating heat exchangers, a reduction in the coolant mass flow does not always result in a reduction in the heating effect in the cabin, but sometimes in an increase in the cabin heating effect. To utilize the full potential, it is particularly advantageous here to have an additional characteristic map characterizing the range in which a reduction in the coolant flow rate results in an improvement in the cabin heating performance, and that, in the event of an excess of heating potential, an additional reduction in the coolant flow rate below the flow rate value of the maximum heating output occurs.

[0032] In multi-zone air conditioning systems, it is important to ensure that sufficient heating potential is available for the zone with the greatest heat extraction. Uneven heat extraction inevitably results in a loss of cooling and thus fuel savings potential unless each zone has its own cooling water flow restrictor. Therefore, when limiting the system to a single cooling water flow restrictor, it is particularly advantageous if the minimum heating criterion in multi-zone air conditioning systems has an initial map range for approximately uniform heat extraction for the individual zones and additional map ranges for uneven heat extraction for the individual zones. It is particularly advantageous if the coolant flow in the heating branch is higher with uneven heat extraction than with even heat extraction.

[0033] If optimum cooling is to be achieved even in multi-zone air conditioning systems, it is particularly advantageous if zone-dependent minimum heating criteria are met by means of separate throttling devices for the cooling water flow rates through the individual zones of the heating heat exchanger, so that in addition to meeting the local heating output requirements, the temperature at the heating return is reduced as much as possible.

[0034] While this requires some effort, it is certainly feasible at a reasonable cost, especially for highly efficient heat exchangers designed primarily for low coolant flow rates with simple thermostats, such as bimetallic thermostats. In this configuration, it is often sufficient to ensure that the coolant return temperature is always below a defined limit of, for example, 20°C, and that at higher temperatures, only a small leakage flow occurs to convey the temperature information. At high heat output draw, the return temperature drops below 25°C, and the valve opens.

[0035] Since air outlet temperatures above 50°C and, at the same time, comparatively high air mass flows are often required in winter, it is obvious that such a simple implementation in winter driving requires a high-performance heat exchanger that is capable of operating at low coolant flow rates and, at the same time, a relatively high air flow rate.

[0036] This optional method and the corresponding device for operating a heating and air conditioning unit in motor vehicles with air-side temperature control, which are described in more detail in exemplary embodiments several times within the scope of the description of the invention, with a heating heat exchanger which extracts heat from the coolant of the drive engine and releases it to the cabin air conveyed through the heating heat exchanger by means of a heating fan and is characterized in that the cooling water throughput in the heating branch is temporarily throttled in the direction of reduced heating potential by means of a throttling device, are only one of a whole series of particularly preferred embodiments of the invention, to which the invention is not restricted according to the independent claims.

[0037] Fig. Figure 1 initially shows a cooling and heating circuit known from the prior art. It has a heating branch 4a with a heating heat exchanger 4, which draws heat from the cooling system of the internal combustion engine 1. An electric valve 2 sets a defined coolant mass flow, as independently as possible of the engine speed. This coolant mass flow is converted, for example, using the coolant temperature of sensor 15 in the engine control unit 16 and with the aid of the heat exchanger characteristic map, as a function of the fan position, the ambient temperature, and the current position of the air temperature control flap 5, into a theoretical air temperature of the air mass flow 20 at the outlet from the heater. If this temperature deviates from the target temperature, the air temperature control flap 5 adjusts.

[0038] If the position of the air temperature control flap 5 is very close to one of the two end stops, the coolant mass flow is changed by opening or closing the valve 2 so that a position with sufficient safety margin for robust temperature control with the air temperature control flap 5 is again achieved.

[0039] To increase control quality, it is particularly advantageous if, in addition to calculating the temperature of the air mass flow 20, a sensor measures its temperature. Many vehicles already have such a sensor; with sufficient response speed, the computational operations for determining the outlet temperature of the air mass flow 20 with minimal dead time may even be dispensed with.

[0040] From the heater core 4, the coolant flows back to the internal combustion engine 1 via the radiator thermostat 6 and the engine coolant pump 7. In addition to the heater branch 4a, the coolant also flows through the bypass branch 6b when the radiator thermostat 6 is closed. The coolant flow rate in the bypass branch 6b is considerably greater than in the heater branch, so that this ultimately homogenizes the engine coolant temperature largely independently of the heater return temperature and also defines the thermostat opening temperature of the radiator thermostat 6.

[0041] As is generally the case with air-side controlled air conditioning systems, if the heater core 4 provides excess heat, the air temperature control flap 5 takes over the temperature control of the cabin intake temperature by mixing an unheated bypass air mass flow 22 with the heated air mass flow 21. However, in contrast to known systems, the superimposed coolant flow adjustment results in a significant reduction in coolant and component temperatures throughout the entire heating branch. This not only requires less engine waste heat to heat the heating branch, but also reduces heat losses to the environment due to the lower surface temperatures.

[0042] The resulting fuel saving is particularly characterized by the fact that it is present under almost all operating conditions of the heating and, where applicable, the air conditioning system.

[0043] However, it is essential to exercise appropriate care in the design of the components and in the coordination of the control parameters. Against this background, Fig. Figure 2 shows an exemplary characteristic map with curves for the flow dependence of the average temperature of the effective heat-active mass in the heating branch, on the one hand, and curves for the corresponding useful heat extraction at the heating heat exchanger, on the other. The effective heat-active mass consists primarily of the flow line with valve 2, the heating heat exchanger 4, and the return line, and is mass-averaged according to its local temperature distribution and component mass. In this data set, the heating heat exchanger 4 is characterized by its high efficiency even at low coolant flow rates; with somewhat simpler heat exchangers, some characteristic map points are not entirely achievable.

[0044] For an exemplary operating point with +80°C flow temperature and +7°C ambient temperature or +7°C outlet temperature from the evaporator of the air conditioning system, the heat extraction at the heating heat exchanger naturally depends to a large extent on the current fan setting or the air mass flow 21. It is known from practice that, depending on the driver and the ambient conditions, almost the entire range of the air mass flows shown can occur.

[0045] From each set of curves, pairs of curves with the same air mass flow rate must be compared. If, for example, the matching curves for an air mass flow rate of 5 kg / min are compared, the curve for the mass-average temperature shows that with an unthrottled, i.e. high, coolant volume flow rate, the mass-average temperature is only slightly below the flow temperature of 80°C. If, in contrast, the coolant mass flow rate is throttled from 12 l / min to approx. 1.4 l / min for a heating power requirement of, for example, 5 kW, the average temperature can be reduced to below 50°C. If the heating power requirement is less than 1 kW, the average temperature can even be reduced to below 40°C by reducing the coolant throughput to very low values ​​of 0.3 l / min or less. Fig. Figure 2 clearly shows that the reduction in the effective heat-active mass can still be achieved even with very low air mass flows and thus inevitably very low heat extraction from the heating heat exchanger. Especially with these low heat extractions, a less efficient heating heat exchanger is sufficient to realize the benefits. Fig. 2 also makes it clear how important it is to carefully coordinate the control strategy described above for valve 2 and air temperature control flap 5 in order to fully utilize the savings potential and yet still provide safety reserves for uniform temperature control.

[0046] The design of the system according to Fig. 1 has the particular advantage that in the statutory exhaust gas test, ie when the heating and air conditioning are completely switched off, a complete shutdown of the heating branch is possible and no potential is wasted.

[0047] Considering the costs for valve 2 and the fact that in customer hands it is very rare for an operation without any heat output to occur, Fig. 3 a particularly advantageous embodiment of a cooling and heating circuit. The throttling element 2 used here is not an electrically operated valve, but a purely thermostatically operated valve, which is now arranged in the return flow of the heating branch or even in a largely cooled zone of the heating heat exchanger 4. This valve is in the closed end position above +25°C, for example, and has a small leakage flow in order to transport the coolant temperature information to the thermostatic valve 2. Below 25°C, the thermostatic valve 2 opens and attempts to regulate the return flow temperature to +25°C. This ensures, on the one hand, that when heat is drawn at a high level, there is a sufficient flow at the heating heat exchanger to satisfy the heating requirements, and, on the other hand, when heat is drawn at a low level, the flow is throttled so much that the desired reduction in the coolant and component temperatures in the entire heating branch is ensured.Looking at the map in . Fig. 2 clearly shows that this approach requires a high-performance heat exchanger capable of delivering the same heat output at flow rates of around 2 l / min as conventional heat exchangers at 10-15 l / min. However, the additional costs for such a high-performance heat exchanger are offset by the fact that it is required anyway to fully utilize its potential, and this also significantly simplifies the application. At the same time, the cost savings for the thermostatic valve compared to an electric valve can be offset. Given the low cost of a simple thermostatic valve with an approved leakage limit, this approach appears quite attractive.

[0048] Working with a fundamentally reduced flow rate in the heating branch significantly expands the scope for using heating heat exchangers with a higher tube / fin density and, if necessary, switching to the more efficient counterflow design. However, part of the pressure loss saved at lower flow rates is particularly advantageously used to equip the supply line with a slightly smaller cross-section. This not only results in advantages in terms of the heat-active mass and surface heat losses, but also in the dead time of heating temperature control, especially at very low flow rates.

[0049] To maximize fuel savings potential and simplify the application, the combination of the electric valve with the thermostatic valve is particularly advantageous. This not only allows for complete shutdown of the heating branch but also extends the control range.

[0050] The leakage current and the control temperature of the thermostatic valve 2 in Fig. 3 naturally define the upper limit of the air heating temperature at relatively warm ambient temperatures. With a very good heat exchanger, a control temperature of around 25°C is sufficient to operate with or without air conditioning, even with very low leakage. For simpler heat exchangers, it is advantageous to increase the control temperature to approximately 30-35°C and / or slightly increase the leakage to ensure sufficient heating capacity is always available.

[0051] Especially for engines with heating power deficit, but also to maximize cabin heating in winter, it is particularly advantageous if the cooling circuit according to Fig. 4 When heating demand is high, bypass branch 6b is closed, as are cooler branch 6a and vent branch 9a. This is generally advantageous for maximizing heating efficiency. However, in conjunction with the system in the version with a high-performance heat exchanger, the heating performance benefits are even greater, since the average heat-active mass of the engine is now also significantly reduced with a correspondingly low coolant flow rate.

[0052] In the particularly advantageous cooling system according to Fig. 4, the bypass valve 6bv is used for this purpose and the return flow from the water tank 9 is rerouted to the cold side of the radiator thermostat 6. When heating requirements are high and engine power is low, the bypass valve 6bv is closed so that not only the heat-active effective mass of the heating branch is minimized, but also the heat-active mass of the engine. As soon as there is an excess of heat for the cabin heating, it is particularly advantageous with this arrangement to additionally throttle the coolant mass flow in the heating branch. Depending on the engine design, it is then best to keep the bypass valve 6bv closed for operation with optimal fuel consumption in order to continue to achieve the smallest possible heat-active mass in the heating branch. This is advantageous for engine designs in which the extremely low return temperature is largely compensated for by flow processes within the engine and in particular by natural convection inside the engine.The drop in the water-side heat transfer coefficient in the water jacket of the cylinder bores then makes an additional contribution to fuel consumption savings, particularly through the reduction of friction losses in the piston group and through increased heat transfer to the engine oil.

[0053] However, in engine designs where internal compensating flows are less pronounced, it is particularly advantageous to open the bypass valve 6bv in order to ensure heat transport from hot spots in the engine cooling circuit, in particular from the cylinder head or, if applicable, from the exhaust gas recirculation cooler, to the engine inlet and thus also to the cylinder bore.

[0054] It is particularly advantageous to open the bypass valve 6bv only partially or intermittently, thus ensuring that only as much coolant flows through the engine as is necessary for sufficient heat transfer from the cylinder head to the engine inlet. Especially with low to medium heat extraction at the heater core 4, a fraction of the flow rate at the engine with the bypass valve fully open is generally sufficient at low engine load. A look at the coolant flows to be expected when minimizing the heat-active mass in the heating branch according to Fig. 2 shows that just a few l / min of bypass volume flow are sufficient to raise the coolant inlet temperatures at the engine inlet to approximately the engine outlet temperature level. A calculation example should illustrate this: If coolant flows at 80°C at the engine outlet in heater branch 4a and is cooled to +7°C at a coolant volume flow of 0.5 l / min, then with the radiator thermostat 6 closed a bypass volume flow of 5 l / min is sufficient to raise the engine inlet temperature at the engine coolant pump 7 to 73°C, i.e. there is then a largely homogeneous coolant temperature in the engine of 73-80°C. Compared to a conventional cooling system, the engine coolant throughput has fallen from, for example, 50 l / min, i.e. 15 l / min from heater branch 4a and 35 l / min from bypass branch 6b, to 5.5 l / min.Common correlations for the rough estimation of the heat transfer in the water jacket of the cylinder bore show a relationship between the heat transfer coefficient α and the Reynolds number and thus the coolant flow rate or the flow velocity u of α ~ u. 0,8, so that with this rule of thumb for the transition from 50 l / min to 5.5 l / min there is a theoretical difference in the water-side heat transfer of approximately a factor of 6. Even if the above correlation predicts a somewhat excessive drop in heat transfer, especially towards very low flow rates, practice shows the fundamental correctness of this analysis. The considerable drop in the heat transfer coefficient is accompanied not only by a significant increase in the temperature at the cylinder bores, but ultimately also by faster heating of the engine oil. Both effects have a positive effect on fuel consumption not only in the early phase of engine warm-up but also during longer driving periods with low engine load and heating power consumption.

[0055] When engine outlet temperatures above the thermostat opening temperature of, for example, 85°C are reached, especially when heat extraction at the heater heat exchanger 4 is low, the point is quickly reached at which the clocked opening of the bypass valve 6bv opens the radiator thermostat 6. From this point on, controlled mixing of the bypass volume flow with the heater volume flow is made significantly more difficult by the fact that three volume flows as well as the temperature-dependent opening of the radiator thermostat 6 must now be taken into account when determining the clock frequency or opening duration of the bypass valve 6bv. Against this background, it is particularly advantageous, especially in applications in which an electrically switchable valve is used as the throttling element 2 in the heater branch 4a, if the coolant volume flow in the heater branch is partially or fully opened after a minimum temperature has been reached in operating situations with excess heat.

[0056] In order to avoid temporary overcooling of the engine, it is particularly advantageous if the flow rate increase in the heating branch is carried out in such a way that the bypass valve 6bv is at least temporarily open during the transition to high flow rate.

[0057] In order to reliably prevent the temporary inflow of cold coolant from the radiator branch, it is particularly advantageous to carry out this switchover when the coolant outlet temperature from the engine is below the thermostat opening temperature of, for example, 85°C.

[0058] If there is a slight excess of engine waste heat, the bypass valve 6bv is closed again even if the coolant temperature at the engine outlet continues to rise to values ​​significantly above the thermostat opening temperature, so that the flow and temperature in the heater branch 4a alone define the extent to which the radiator thermostat 6 opens and thus the heat dissipation to the environment. For high control quality of the engine coolant temperature at elevated temperature levels, it is particularly advantageous if the coolant flow in the heater branch 4a is throttled by the electric valve 2 to values ​​that just barely provide sufficient cooling for the engine.Especially in conjunction with a heater core already designed for reduced total flow rates, a wide range of engine partial load operating points, with and without heating, can be encountered here, in which the radiator thermostat 6 automatically performs a very sensitive throttling of the coolant flow through the engine. The low heat transfer coefficient in the water jacket of the cylinder bore with the low total flow through the engine, which occurs due to the closed bypass valve 6bv and the only minimally open radiator thermostat 6, ultimately leads to the desired increase in component and oil temperatures. With conventional radiator thermostats and the high cooling potential of the vehicle radiator, the coolant temperature difference between the engine inlet and engine outlet is in the range of around 20K.

[0059] This approach also sometimes achieves operating situations in which a slightly higher coolant flow rate would actually be desirable in order to avoid potential engine overheating or, especially when the engine's heat surplus is relatively low and the coolant flow is already largely reduced - and thus the heat transfer coefficient is largely reduced - to achieve a higher temperature at the engine inlet without opening the vehicle radiator 8. In a particularly advantageous embodiment of a cooling and heating circuit, it is therefore proposed to arrange the coolant return line of the heating branch downstream of the radiator thermostat 6 and upstream of the engine coolant pump 7.This results in a significant decoupling of the opening of the radiator thermostat 6 from the flow through the heater branch, so that with low heat output drawn from the heater core 4, coolant temperatures at the engine inlet can be set well above the opening temperature of the radiator thermostat. The gain in bandwidth for the engine component temperatures adjustable by means of the bypass valve 6bv and the throttle body 2 is quite significant. To compensate for the disadvantages that arise from the fact that the interaction of the radiator thermostat 6 with the heater return no longer automatically provides very sensitive temperature control at important engine partial load points, which temperature control can be very sensitively stepped by electrical actuation of the valve 2, a correspondingly more precise control of the bypass valve 6bv with special consideration of the local flow rates and temperatures is advantageous.

[0060] These explanations using the example according to Fig. 4 show that the approach shown here, especially in conjunction with an additional valve 6bv, has a significant potential for fuel consumption savings. The costs for the design according to Fig. 4 are limited in the simplest case to the bypass valve 6bv and the thermostat valve 2 in the heating branch or alternatively a second electrical valve 2 in the heating branch and are far below the costs of alternative technologies for saving fuel consumption.

[0061] The practical implementation of the measures according to Fig. 4, while fully utilizing the demonstrated fuel saving potential, requires - despite the simplicity of the components - a considerable amount of application effort. Especially when dosing the bypass valve 6bv in the range above the thermostat's nominal temperature of, for example, 85°C, there is a certain potential for error in the application, including unintentional or excessive opening of the cooler branch, associated with losses in fuel savings. Furthermore, there is also the risk that excessive demands on the component and the control system will consume a significant portion of the cost advantages. This statement applies to the Fig. 4, and more specifically for the integration of the heating return downstream of the thermostat. Only an engine-specific analysis can ultimately determine whether it might not be more cost-effective to use a somewhat less precisely controlled bypass valve 6bv, while still achieving most of the benefits of the system shown here.

[0062] Another particularly advantageous design of a cooling and heating circuit can be found in Fig. 5. In addition to Fig. 4, the additional bypass branch 6c is located here, parallel to the bypass branch 6b with bypass valve 6bv, which, however, does not end at the radiator thermostat 6, but rather downstream, preferably directly near the pump inlet of the engine coolant pump 7. In its simplest form, this is a line with a small cross-section and a corresponding throttling effect, or a line with a thermostat valve 6cv, which opens, for example, at a coolant temperature of 60°C. Instead of the external line, internal engine channels can also be used.

[0063] In both cases, i.e., with and without thermostat valve 6cv, the flow in bypass branch 6b is many times greater than in the additional bypass branch 6c when the radiator thermostat 6 is closed and the bypass valve 6bv is open. This flow specification is important, on the one hand, for good heating performance and for limiting the flow-dependent cooling effect on the cylinder bores, with and without heating. On the other hand, it also ensures that a sufficient amount of coolant flows through the vehicle radiator 8 when cooling is required at high temperatures, i.e., when the bypass branch 6b is closed.

[0064] This design of the cooling system, which at first glance appears somewhat complicated, is particularly advantageous because, with the bypass valve 6bv closed in a first setting, it allows an improved heating effect with reduced fuel consumption and, in further settings with the coolant mass flow in the heating branch partially reduced well below the maximum heating output and the bypass valve 6bv only opened when there is a risk of overheating, it allows a minimization of fuel consumption taking into account the respective heating output requirement up to the statutory exhaust gas test without heating.

[0065] The 6cv thermostatic valve is particularly helpful in maximizing heating output because it ensures that the main coolant flow passes through the heater core 4 down to a minimum engine-side coolant temperature. This ensures that, by limiting the overall engine flow rate, there is also a very strong temperature stratification on the engine itself at relatively low engine coolant inlet temperatures. This means that the heat-active mass of the engine is minimized, as is the heat-active mass in the heater branch. The bypass branch 6b and the vent branch 9a, as well as the cooler branch 6a, are closed here anyway. In many applications, however, sufficient heating output is available under all winter driving conditions even without the 6cv thermostatic valve. This means that in operating situations with high heat output draw, it may be more fuel-efficient to forgo the 6cv thermostatic valve on some engines.Therefore, it is even better to replace the 6cv thermostat valve with a valve electrically controlled by the engine control unit as needed. However, in most applications, no valve or thermostat will be used at all for cost reasons.

[0066] A certain proportion of fuel savings with the cooling and heating system according to Fig. 5, as already described, has the fact that the cold return line of the coolant in the heating branch is located upstream of the inlet point 7e of the additional bypass branch 6c and that the bypass branch 6b is arranged in the vicinity of the radiator thermostat 6 such that its coolant flow flows past the expansion element of the radiator thermostat 6 when the bypass valve 6bv is electrically opened. In conjunction with the design of the heating circuit, which provides a temperature of the returning coolant significantly below the thermostat opening temperature even with low heat extraction at the heating heat exchanger 4, the radiator thermostat 6 remains closed when required, ie without opening the bypass valve 6bv, up to very high engine temperatures. Thus, with the arrangement according to Fig. 5 solely leave it to the engine control unit 16 to determine the effective thermostat opening time by opening the bypass branch 6b: Since the bypass coolant flow is, by design, much greater than the heater coolant flow, when the bypass valve 6bv opens, the engine coolant temperature defines the opening of the radiator thermostat 6. In this way, the bypass valve 6bv can be used to switch back and forth between an elevated engine coolant temperature of, for example, 110°C and a lower coolant temperature of, for example, 85°C, depending on the engine load. The introduction of the heater return flow, which is deliberately kept cold, upstream of the introduction point 7e of the additional bypass branch 6c acts in this context as a thermal barrier layer, so that the thermostat is not heated up by heat conduction or natural convection to such a temperature level that it temporarily opens unintentionally and releases cold water from the radiator.Since a certain amount of heat is almost always removed from the heating heat exchanger during practical driving, this provides particularly robust protection against unintentional opening of the radiator thermostat.

[0067] In Fig. 4 is like in Fig. 3, a thermostatic valve is particularly inexpensive as the throttling device 2. However, an electric valve with appropriate control can also be used. In this case, it is particularly advantageous to provide a fail-safe protection that, in the event of excessive engine temperature, e.g., due to a failure of the bypass valve 6bv, completely opens the valve 2, thus leading to at least a partial opening of the vehicle radiator 8.

[0068] When using an electric valve 2, it is preferably completely closed during the statutory emissions test, i.e., without heating, at least until critical component or coolant temperatures are reached. The advantage of the thermal barrier layer then no longer exists, but at least there is no active heat transfer to the radiator thermostat 6, which could inadvertently open it.

[0069] The additional bypass branch 6c, with the extraction of coolant from warm or overheating-prone zones of the cooling system or engine and its specific opening at position 7e downstream of the radiator thermostat 6 and upstream of the engine cooling water pump 7, naturally costs some potential for maximum heating output in winter without the valve 6cv or from its opening, since it reduces the temperature stratification on the engine.

[0070] In some circumstances, there may also be a minimal loss of maximum cooling capacity, since when the bypass branch 6b is closed, a larger partial mass flow does not flow through the vehicle radiator 8. Against this background, the targeted dimensioning for a significantly lower flow in the additional bypass branch 6c compared to the bypass branch 6b in the open state is engine-dependent and must be carried out with appropriate care.

[0071] In return, the result is an overall system that, compared to today's series-production cooling and heating systems, not only offers better winter heating, but also significantly reduces fuel consumption due to faster engine warm-up with reduced heat extraction from the heater. Furthermore, this not only reduces the risk of local overheating when the bypass valve 6bv is closed, but also significantly improves the control quality of the engine temperature. The equalizing effect of the flow in the additional bypass branch 6c enables the use of a relatively coarsely metered and slow bypass valve 6bv, significantly simplifying the calibration effort.As tests show, many standard series radiator thermostats 6 with typical opening temperatures between 80 and 90°C tend to open briefly when exposed to excessively strong coolant flow, which has previously been heated to, for example, 110-120°C with the bypass valve 6bv closed. This allows an excessive amount of cold coolant to flow into the internal engine cooling circuit. This can result in significant fluctuations in engine component temperature and, in particular, thermal stratification with subcooled coolant in the lower engine zones and on the cylinder bore, coupled with reduced fuel economy.

[0072] Pulsed or only partial opening of the bypass valve 6bv provides partial relief, but as already described increases control effort and component costs.

[0073] The specific advantages of the Fig. The integration of the heater return line into the effective range of the radiator thermostat 6, as shown in Figure 5, has already been described. In conjunction with the additional bypass branch 6c with and without valve 6cv, advantages arise that fully justify the additional cost of this unusual design in many applications. The advantages, especially when the engine coolant temperature exceeds the nominal thermostat temperature of the radiator thermostat 6, for example, 85°C, are quite significant and are illustrated here once again with some exemplary numerical values: In a conventional cooling system in a passenger car without bypass valve 6bv and without additional bypass branch 6c, a distribution of approximately 15 l / min through the heater branch and 35 l / min through the bypass branch is a frequently encountered distribution with the radiator thermostat 6 closed or only slightly open at partial engine load and engine speeds of 1500 to 2000 rpm.

[0074] If we consider, as an example, a thermally stable operating point with 5 kW excess heat at the engine and no heat extraction at the heater core 4, i.e. the excess heat must be dissipated at the vehicle radiator 8, this results in a throughput in the vehicle radiator of 1-3 l / min for example in a conventional cooling system and constant driving with an 85°C radiator thermostat. The total coolant throughput through the engine is approximately 50-55 l / min with the thermostat slightly open. Closing the bypass valve 6bv reduces the total volume flow through the engine to approximately 20 l / min assuming a typical pump characteristic curve. The control characteristics of the radiator thermostat 6 and the oversizing of the vehicle radiator at moderate driving speeds ensure that the coolant temperature at the engine inlet is close to the thermostat's nominal temperature of 85°C.At 5 kW heat absorption of the coolant in the engine, the coolant temperature rises to around 88-89°C by the time it leaves the engine under thermally stable conditions. This temperature level is well below the value that should be aimed for at this part-load point for optimum fuel consumption. 110-120°C are more desirable temperatures here. The use of an electrically heated map-controlled thermostat in the previously known design is certainly capable of delivering this level of temperature for the cooling water within the engine, but has the disadvantage that it does so with a total coolant mass flow of 50-55 l / min, meaning that the component temperature does not rise as much as would be helpful for optimising consumption due to the increased heat transfer coefficient. A further increase in the coolant temperature above 120°C is not advisable, particularly for safety and cost reasons. In addition, the electrically heated map-controlled thermostat has a...Thermostats are known to have the disadvantage that an undesirably long delay time can occur when switching to low component temperatures during sudden full engine load.

[0075] The combination of throttling the coolant flow rate in the bypass branch 6b and in the heater branch helps to overcome the problems described above and is therefore superior to the electrically heated thermostat in this respect as well as in the switching speed to low component temperatures.

[0076] First, the calculation without the additional bypass branch 6c: If the coolant flow rate in the heating branch is reduced to, for example, 1.5 l / min when the bypass valve 6bv is closed, this delivers a cooling flow of around 1.5 l / min, so that a total of 3 l / min flow through the engine. Due to the system, the radiator thermostat delivers coolant of just over 85°C, so that, given the 5 kW of heat absorption in the engine, this results in an engine outlet temperature of around 114°C. The average engine coolant temperature is therefore somewhat lower than with the electrically heated thermostat. However, the increase in engine component temperature and the engine oil temperature is just as good or even better than with the electrically heated thermostat due to the coolant flow rate being around a factor of 16-18 and the resulting drastically reduced water-side heat transfer coefficient. The reserves for ultra-fast switching to high cooling output by opening the bypass valve 6bv or, if necessary, also the electrically heated thermostat.The advantages of actuated valve 2 are obvious. The heat transfer coefficient, and thus the cooling effect, increases without any time delay and is partially supported by the subcooled zones in bypass branch 6b. Furthermore, compared to operation with high coolant flow, it is primarily the zones of the engine structure near the combustion chamber, and thus also the cylinder bore, that are at an elevated temperature level, rather than the entire engine structure, including the coolant. This means that less engine mass needs to be cooled when switching to low component temperatures. Tests have shown that the vehicle cooling branch opens so quickly that no problems with engine overheating are to be expected under sudden full load.

[0077] These specific advantages with low total coolant flow through the engine are particularly evident when the engine is at steady-state operating temperature and excess heat needs to be dissipated.

[0078] Particularly when the engine is not yet fully warmed up, there is very little excess heat, and high heat extraction from the heater core, minimizing the total coolant flow through the engine leads to very low flow values, combined with very high temperatures in the cylinder head and very low coolant temperatures at the engine inlet, as well as a highly engine-dependent temperature level on the cylinder bore. As the coolant velocity changes towards zero, the gain in heat transfer is initially significantly reduced by the transition to laminar flow, until ultimately, due to the dominance of superimposed natural convection and a further reduction in flow, no further reduction in heat transfer can be observed. Thus, the gain in the heat transfer coefficient at extremely low inlet temperatures in some engines can no longer overcompensate for the disadvantages of the low coolant inlet temperature.In this case, it is often more advantageous to increase the flow rate slightly, for example, by temporarily opening the bypass valve 6bv or increasing the coolant flow rate in the heating branch, thereby slightly increasing the overall flow rate through the engine. However, if the return temperature of the heating branch 4a or the coolant temperature in the bypass branch 6b is above the thermostat opening temperature of, for example, 85°C, this will result in the following in the arrangement shown. Fig. 4 especially with very low excess engine heat and particularly already in the heating phase of the engine coolant from, for example, 85°C to 115°C to unintentional losses due to premature opening of the radiator thermostat 6. As already described, relocating the return line of the heating branch to a position downstream of the radiator thermostat 6 helps here. However, this is associated with certain disadvantages in terms of control quality and fail-safe behavior, among other things.

[0079] If the additional bypass branch 6c is now included in the calculation, an exemplary additional mass flow of 5 l / min in the additional bypass branch leads to a significant reduction in the temperature uneven distribution within the engine. The additional bypass line ensures targeted heat transport from the cylinder head to the cylinder block without leading to an unintentional opening of the thermostat. In this calculation example, the mixture of 3 l / min of coolant from the heater and cooler branch at approximately 85°C with the 5 l / min in the additional bypass branch 6c ultimately leads to a stable operating point of approximately 102°C at the engine inlet and 113°C at the engine outlet. Slight fluctuations in the flow rates and the heat quantities transferred in the cooler and heater branch have a much smaller effect on the control quality of the engine component temperature.With a total flow rate of 8 l / min through the engine, the heat transfer coefficient is still significantly below the base value of 50-55 l / min, whereby the increased coolant inlet temperature from 85°C to 102 °C compared to the configuration with a total flow rate of 3 l / min largely eliminates the disadvantages caused by the slightly increased heat transfer coefficient.

[0080] In analogous calculations with even smaller total coolant flow rates through the engine, as with regard to Fig. 2 are to be expected quite frequently in practice, the cylinder bore temperature with bypass branch 6b is ultimately even higher in many engines than without bypass branch 6b, since the effects already described above come to the fore under the dominance of natural convection on the water-side internal engine heat transfer.

[0081] The previous statements on Fig. 5 have concentrated largely on operating conditions with heat dissipation at the heater core and, where applicable, at the vehicle radiator. However, even during the warm-up phase and without any heat dissipation at the vehicle radiator 8, the arrangement according to Fig. 5 is particularly advantageous. This particularly applies to the fact that an excessively cold engine inlet temperature and an excessively large temperature spread, with disadvantages related to mechanical stress and an excessively cold cylinder bore, are absolutely avoided even when extreme cooling occurs in the heating branch to deactivate the heat-active mass of the heating branch. This minimizes the risks of incorrect application beyond the permissible mechanical limits of the engine.

[0082] Especially in the statutory emissions test without heating and with heating branch 4a preferably deactivated by an electric valve 2, the additional bypass branch 6c ensures that the bypass valve 6bv or valve 2 only needs to be opened at very high coolant temperatures well above the thermostat opening limit. The risk of unintentional heat dissipation via the vehicle radiator thus completely eliminates the risk in many areas of the emissions test, and even with a fairly crude control strategy and inexpensive bypass valves 6bv, the EUDC of the MVEURO, for example, can be operated with a well-dosed cooling effect.

[0083] It is particularly advantageous if, in the early phase of the emissions test, valve 6cv completely shuts off the flow through the engine and only opens once a minimum coolant temperature has been reached in the engine, ensuring heat transfer from the cylinder head to the cylinder block or cylinder bore with minimal heat loss to the environment. The smaller line cross-sections compared to bypass branch 6b, the smaller dimensions of a corresponding valve 6cv, and the partial elimination of heat losses for the partial heating of the radiator thermostat 6 and the line section up to the inlet point 7e, particularly contribute to largely loss-free and low-delay heat transfer, even with a relatively low flow rate selected in the additional bypass branch 6c.

[0084] The initial flow velocity of zero is particularly advantageous because, during this phase, the coolant in the cylinder head is not yet warmer than that in the block. Rather, the relatively high friction losses on the cold cylinder bore dominate the bore temperature and the heat balance, so any convective cooling is detrimental. This approach, with the option of completely shutting off the heating branch with an electric valve 2, is particularly advantageous in statutory emissions tests.

[0085] In contrast, if real-world operation is the primary focus, i.e., heat is almost always extracted from the heater core 4, then, as already mentioned, the variant with a thermostatic valve as the throttle element 2 is more cost-effective. For engines with a heat deficit or when a particularly good heating effect of the vehicle is paramount, the 6cv valve is used to close the additional bypass branch up to a minimum coolant temperature of, for example, 60°C at the engine outlet, thus achieving maximum heating output.

[0086] If, on the other hand, the heating effect is sufficient anyway and a cost-effective thermostatic valve is used as the throttle device 2, then with a design focus on fuel consumption, especially when the additional bypass branch 6c is designed for a relatively low throughput, it is most effective to dispense with the valve 6cv altogether. Even with the system-related very cold return temperatures in the heating branch even at low heat output draw, after the two coolant flows from branches 6c and 4a have been mixed, only moderate subcooling occurs at the engine inlet relative to the engine outlet. The basic design of the coolant flow in branch 6c at relatively low values ​​aims in particular to ensure that the total coolant flow through the engine with the bypass valve 6bv closed is in the range where a reduction in the flow only results in a limited reduction in heat transfer.When the heat extraction from the heating heat exchanger is low, the flow in the heating branch 4a is so low that a basic flow in branch 6c of 2-5 l / min is sufficient to achieve significant fuel consumption advantages.

[0087] The overall system can be tuned particularly sensitively toward optimal fuel consumption if the additional bypass branch 6c also includes a coolant flow control. In the simplest case, this is again achieved electrically, i.e., via a valve 6cv that can be controlled by the engine control unit. This valve sets an increased additional bypass flow in branch 6c for fuel-optimized operation, particularly when there is high heat extraction in the heater branch and / or high excess waste heat from the engine. When there is low excess heat and simultaneously low heat extraction in the heater branch, it sets a reduced additional bypass flow in branch 6c.

[0088] When cooling demand is high and bypass valve 6bv is open, the electric valve 6cv initially does not close to support the control with the cyclical timing of the bypass valve 6bv and to dampen temperature fluctuations. Only when a very high cooling effect is required does valve 6cv close to maximize the coolant flow through the vehicle radiator 8.

[0089] With systems according to Fig. 5, the application effort and costs for the bypass valve 6bv, including its control, are reduced. Furthermore, the system is particularly suitable for setting very high coolant temperatures at the engine outlet without inadvertently opening the radiator thermostat 6. It is particularly characterized by the fact that, if necessary, very high coolant temperatures can also be present at the engine inlet. These high coolant temperatures at the engine inlet can be set at partial engine load, particularly with and without heat dissipation at the vehicle radiator 8.

[0090] The operating mode with high coolant temperature and variable coolant flow through the engine is one of the particular strengths of this design. Previously known cooling systems with thermostatic control of the vehicle radiator 8 are not capable of delivering a comparably high average component temperature level in the lower engine partial load range. For example, with a conventional electrically heated map-controlled thermostat, the coolant flow and thus the cooling effect are significantly higher at a comparable coolant temperature than with the system according to Fig. 5 can be set. In particular, in contrast to the design shown here, the total coolant flow through the engine cannot be influenced by the engine control unit, so that different component temperatures can be achieved at the same maximum coolant temperature. In order to set the engine load and engine speed dependent map of the local component, coolant and oil temperatures that can be covered here depending on the design variant, it has previously been assumed that an expensive electrically adjustable coolant pump is required as a replacement for the engine coolant pump in conjunction with an electrically heated map-controlled thermostat or even with an electrically continuously adjustable rotary vane thermostat instead of the much cheaper standard radiator thermostat with an expansion actuator.

[0091] In a further embodiment of a cooling and heating system, Fig. 6 two further additional branches 6d for an optional engine oil cooler 30 and 6e for an optional transmission oil cooler 40. Again, optional thermostats 6dv and 6ev or electric valves ensure that when the coolant is cold, on the one hand the heating output is improved and, on the other hand, during warm-up the available heat initially benefits the engine and its cylinder bores. Here, too, it is particularly advantageous to ensure, by appropriately dimensioning the components and line cross-sections, that the total coolant throughput in branches 6c, 6d, 6e when the engine is warm is significantly lower than in the open bypass branch 6b, so that there are just as few problems with the cooling effect of the cooler as with the control quality of the cooler thermostat 6. This is particularly important when there are several additional branches, since the thermostat regulates to a mixed temperature of the cooler branch, heater branch and bypass branch 6b.This control temperature is all the less accurate the larger the internal currents in branches 6c, 6d and 6e are, and in extreme cases can be several °K lower than the effective engine coolant temperature without the internal "short circuits" or branches 6c, 6d, 6e. EI. Switchable valves 6cv, 6dv and 6ev may help to alleviate this problem, but to minimize the heat-active masses and for a response with little dead time, significantly smaller line cross-sections will be selected than for the bypass branch 6b, especially since the total coolant flow through the engine should be significantly lower than when the bypass valve 6bv is open.

[0092] In terms of cost-benefit ratio, limiting the system to thermostatic valves for branches 6e and 6d is generally the most advantageous option. The previously described tasks of the additional bypass branch 6c can also be partially performed by one of the branches 6d or 6e.

[0093] For the best fuel consumption when the heater branch 4a is switched off with an electric valve 2, it is particularly advantageous if, starting from the cold engine operating state, no coolant initially flows through the engine, then the additional bypass branch 6c opens at a first switching temperature of the coolant, the oil cooler bypass branch 6d opens at a second switching temperature and, after further engine warm-up, the transmission oil cooler branch 6e opens at a third switching temperature. The dimensioning of branch 6c for a low flow rate and a similar procedure in branches 6d and 6e ensure that sufficient engine cooling can always be set by opening the bypass valve 6bv and that the control temperature of the radiator thermostat does not lead to an impermissible increase in the engine inlet temperatures.

[0094] In particular, the preferred design of the system, with high-performance heat exchangers and a reduction in the coolant flow at all heating heat exchanger operating points, ensures that even in the most diverse situations with heating operation, there is a reduced overall flow through the engine, which provides a fuel consumption advantage by reducing the heat transfer coefficient in the water jacket.

[0095] In particular, the integration of branches 6c, 6d, 6e and, if necessary, also the heating branch 4a in the inlet point 7e upstream of the engine coolant pump 7 and downstream of the radiator thermostat 6, in interaction with the bypass valve 6bv, which, in contrast to the branches mentioned, acts directly on the radiator thermostat 6 when opened, results in the necessary degrees of freedom to raise the coolant temperature within the engine by means of the engine control unit 16, if necessary, to temperatures well above the actual opening temperature of the radiator thermostat 6 of, for example, 85°C. At the same time, the total coolant flow rates through the engine remain at reduced values, preferably over a wide partial load range of the engine, in contrast to conventional systems with an electrically heated thermostat, so that fuel consumption advantages result in the lower partial load range and during the entire warm-up period.

[0096] The system is designed according to Fig. 6 is particularly characterized in that the high coolant temperatures at the engine outlet, which are reached particularly quickly due to the minimization of heat losses, promote the heating of the engine oil or transmission oil during warm-up and, in particular, prevent premature heat dissipation at the vehicle radiator. In this context, a conventional integration of the cooling water flowing back from the oil cooler into the heater return line or the bypass branch 6b would very quickly lead to an unintentional opening of the radiator thermostat 6.

[0097] It is obvious that the coordination of the coolant flow rates through the engine oil cooler 30 and the transmission oil cooler 40 requires a certain degree of care in order to avoid insufficient heat transfer in the respective heat exchangers due to insufficient cooling water flow rates despite high flow temperatures, so that ultimately the bypass branch 6b has to be opened prematurely in order to avoid potential engine overheating.

[0098] Conversely, the interactions described above exist, which suggest or even necessitate a significant limitation of the coolant flow through the two oil coolers 30 and 40. Against this background, working with high-performance heating heat exchangers 4 and a fundamentally limited flow is very helpful in defusing this conflict of objectives. However, conventional heating heat exchangers with the throttling shown here via electric valves 2 also help in a wide range of engine maps to limit the coolant flow through the internal combustion engine and still maintain it at a level that is reasonable for the oil coolers 30 and 40. It is particularly helpful that the procedure is specifically designed according to Fig. 6 leads to very high oil inlet temperatures, so that oversized oil coolers are not required.

[0099] In particular, there is Fig. 6 the already mentioned cost saving potential of omitting the additional bypass branch 6c and opening one of the oil cooler branches directly with a thermostat valve 6dv or 6ev after the initial coolant standstill.

[0100] To further alleviate this conflict of objectives regarding the flow rates in the engine and through the oil coolers, the particularly advantageous design according to Fig. 7, the possibility of integrating one or both oil coolers 30 and 40 in such a way that they extract the coolant directly at the pump outlet of the engine coolant pump 7 or directly in the vicinity of the engine inlet. The total coolant flow through the engine is thus limited at the points relevant for the water-side heat transfer to the flow in the additional bypass branch 6c, so that the desired reduction in the heat transfer coefficient occurs again within the engine, with simultaneous heat transport from the cylinder head to the cylinder block or to the oil coolers 30 and 40 via branch 6c. The system according to Fig. 7 is particularly attractive because it not only allows for significantly higher coolant flow rates through the oil coolers 30 and / or 40, but also provides a higher pressure drop to work with slightly smaller oil coolers. The slightly lower oil temperature compared to the integration according to Fig. 6 is accepted here in favor of the higher oil cooler throughput and to minimize the coolant throughput through the engine, among other advantages. The overall system offers the important advantage that, when branches 6d and 6e are open, brief cold water phases due to excessive opening of the bypass valve 6bv and thus of the radiator thermostat 6 are damped even more than is already achieved with the additional bypass branch 6c. A very uniform engine component temperature profile over time, at a consistently elevated level, is thus ensured even with certain control weaknesses of the bypass valve 6bv. The same applies to strong fluctuations in the throughput and temperature level of the heater branch.

[0101] The advantages of this specific integration of the oil coolers 30 and / or 40 with regard to the control quality are so significant that it is also possible to work with a connection of the heating return at position 7e, as in Fig. 8. The measures described above regarding the design and control quality of the bypass valve 6bv, which could significantly increase costs, are generally not necessary here. This statement applies in particular to the preferred variant with high-performance heating heat exchangers and reduced base flow, as well as to the variant with conventional heating heat exchangers with a high base coolant flow and electrically controlled valve 2 in the heating branch.

[0102] Even if the throttle element 2 in the heater branch is omitted, the system with bypass valve 6bv, bypass branch 6b and integration of the heater return at position 7e is still more fuel-efficient than conventional systems with a non-electrically controlled bypass branch 6b. This is due in particular to the fact that premature opening of the radiator thermostat 6 is avoided and, moreover, the total coolant mass flow through the engine is smaller compared to the base system without bypass valve 6bv or with the bypass valve open. In this context, a conventional integration of the heater return at the inlet to the radiator thermostat 6 would lead to premature opening of the radiator thermostat 6 at high coolant temperatures and high throughput through the heater or without throttling and heat extraction at the heater heat exchanger 4 due to the high return temperature at many operating points.

[0103] As already described in detail, the auxiliary bypass branch 6c also helps save fuel in cases where the engine could be overcooled due to high heat extraction at the heater core 4 and a relatively low heater core flow. Furthermore, it also serves to even out control fluctuations when the bypass valve 6bv is temporarily opened.

[0104] A particularly versatile and less sensitive configuration shows Fig. 9 with additional integration of an engine oil cooler 30 and a transmission oil cooler 40. This system can be used very efficiently to improve fuel consumption with a high-performance heat exchanger and a design for a low base flow, but with certain losses also with completely conventional heater core heat exchangers with a high base flow. It is clear that with regard to the range of fuel savings achievable in daily driving under the most diverse driving conditions and the most diverse heat output draws from the heater core, systems with a throttle body 2 in the heater branch are better for both variants. Conversely, however, systems with the integration of the heat exchanger return downstream of the radiator thermostat and bypass valve 6bv with additional bypass branch 6c, as well as in particular additional branches 6d and / or 6e with integration according to Fig. 9 is still very attractive for cost-limited fuel consumption reduction measures. This is due not least to the somewhat lower demands on the heater core 4, the elimination of an active throttle element 2, and the relatively low application effort, which enables quick and problem-free application on a wide variety of engine-vehicle combinations.

[0105] A very special advantage of the constellations according to Fig. 7-9 is that it is very easy to adjust them either toward improved cabin heating or improved fuel consumption. For this purpose, measures are available that promote, prevent, or even reverse heat transfer in the engine oil cooler 30. The simplest implementation here is with a valve 6dv electrically operated by the engine control unit 16.

[0106] The possibilities are manifold and will only be illustrated here with an example based on Fig. 7. Valves 6cv and 6ev are now thermostatic valves that open branch 6c at 60°C and the additional branch 6e at 70°C. Valve 2 is an electrically controlled valve by the engine control unit 16, as is valve 6dv of the additional branch 6d.

[0107] To maximize the heating effect, a high-performance heat exchanger 4 is used with a coolant flow rate throttled to, for example, 2 l / min. Thus, at high heat output levels, the coolant return temperature of the heating branch is significantly reduced.

[0108] To maximize the heating effect, the valve 6dv is initially closed for a few minutes until the oil temperature has increased above the return temperature of the cooling water in the heating branch.

[0109] Simply opening valve 6dv then improves the heating effect, as the cooling water now draws heat from the engine oil. This keeps the oil and the engine components that come into contact with the oil somewhat cooler, reducing heat loss to the environment. Engine friction at the bearings may be slightly reduced. However, the overall balance in terms of fuel consumption is largely neutral, given the low coolant throughput of just 2 l / min and the now slightly preheated coolant at the engine inlet. The final effect is that the lower heat losses for heating the engine and the engine oil, as well as the lower surface heat losses on the engine surface including the oil pan, result in faster heating of the coolant at the engine outlet and thus better heating performance.By maintaining the cabin heating output and additionally in conjunction with a reduction in the air mass flow 20, which is possible due to higher cooling water supply temperatures, further fuel savings can ultimately be achieved.

[0110] In contrast, permanent closure of valve 6dv from the start until the heating is switched off due to excess heat in the cabin provides a middle ground between good heating and good fuel consumption, whereby from engine coolant temperatures above the 60°C opening temperature of the thermostat valve 6cv in the additional bypass branch 6c and after the heating is switched off, the fuel consumption-reducing heat exchange between engine oil and coolant is activated by opening the valve 6dv, which is electrically controlled in this example.

[0111] It has already been discussed several times that valve 6cv in the additional bypass branch can be omitted if necessary or that its function can be at least partially integrated into valve 6dv or 6ev in the two branches 6d or 6e. In the simplest case, the flow path is simply a corresponding flow channel from the cylinder block to the pump housing or a small line used to cool additional components, in particular the turbocharger. The great importance of small cross-sections in branch 6c for minimizing the heat-active masses and dead times for heat transport was also discussed in detail, as was the need to ensure, where appropriate, that when the radiator is fully open, the main coolant mass flow should go through the radiator and not through the inner bypass branches, which do not even intervene in the control process at the radiator thermostat 6.

[0112] Depending on the specifications for the vehicle, it is still cheaper than alternative solutions - if these exist at all - to make the valve 6cv a little more complex and to provide an electrical control of the valve 6cv, for example as shown in Fig. 10 and Fig. 11 is explicitly indicated by the dashed connecting line from valve 6cv to engine control 16. Such arrangements allow the maximum control range for the coolant flows through the engine and the individual heat exchangers in the cooling system, in particular the heater core 4, the engine oil cooler 30, the transmission oil cooler 40, the vehicle cooler 8, and, if applicable, the exhaust gas recirculation cooler and other components to be realized.

[0113] In this context, the design according to Fig. 12, in which the valve 6cv is a differential temperature control valve and in particular contains a sensor actuator which detects the temperature difference between the engine inlet and engine outlet and ensures that the temperature difference is not greater than a defined predefined value. In the exemplary embodiment shown, a first minimum sensor volume flow in branch 6t1 is fed to a first expansion cell and tempers it, and a second minimum sensor volume flow is fed to a second expansion cell. The two partial flows are then diverted, for example, via line 6t3. The appropriate superposition of the two sensor cell deflections ultimately provides the desired differential temperature control. In the simplest case, the superposition takes place via a common membrane which separates the two cells and which then opens or closes the valve via a tappet. This is of course only one of the many conceivable methods of differential temperature control.

[0114] Typical differential temperature settings for good fuel consumption are usually between 2°K and 10°K, depending on the engine. If it is ensured that the differential temperature control only becomes active at 60°C and valve 6cv remains closed until then, the heat-enhancing aspects of the cooling and heating system shown here can also be largely utilized when bypass valve 6bv is closed.

[0115] If you count the number of additional thermostatic and electrically operated valves in Fig. 5-12, the question almost inevitably arises as to whether this high number of additional valves is truly expedient or feasible in practice, given the current cost pressure in the automotive industry. Against this background, a comparative cost / benefit analysis using a recently launched mass-produced passenger car with an electric engine coolant pump is very useful as a guide. This is presented here as an example, without claiming to be complete or specifying exact component prices, in comparison with the application according to Fig. 11. Here are some particularly striking differences: 1. The series application in question has, in particular, an electric coolant pump instead of a belt-driven engine coolant pump 7. 2. An electrically heated map-controlled thermostat is used instead of the conventional thermostat. 3. The map thermostat is located like the radiator thermostat 6 in Fig. 11 between the radiator outlet and the engine inlet and has a bypass branch 6b, but in contrast to Fig. 11 without additional bypass valve 6bv. 4. In contrast to the radiator thermostat 6, the map thermostat has Fig. 11 has two valve plates in the cooler branch and thus a somewhat lower pressure loss. It is therefore more expensive, plus the costs for the heatable expansion element including control. When the cooler branch 6a is open, the map-controlled thermostat closes the bypass branch 6b, just as the cooler thermostat 6 does in Fig. 11. 5. The heating is in contrast to Fig. 11 is designed with standard components for high coolant flow and has an air-side control without an additional water-side valve 2. 6. The entire engine cooling circuit is designed for low pressure loss in order to make an electric water pump feasible in terms of performance and, in particular, has larger coolant cross-sections than the circuit according to Fig. 11.

[0116] If - in comparison to an inexpensive standard cooling system - the additional costs of the embodiment with the inventive procedure according to Fig. 11 through the • electric bypass valve 6bv, • the valve 2 and the high-performance heat exchanger 4 in the heating branch 4a, • the additional bypass branch 6c with electric valve 6cv and • the two thermostat valves 6dv and 6ev, preferably designed as inexpensive bi-metal components, are added together, resulting in only a fraction of the additional costs that the electric coolant pump and the electric map-controlled thermostat already generate in the series vehicle in question.

[0117] The fuel saving potential in the statutory exhaust gas test, ie without heating in the design according to Fig. 11 rather better than worse. This is partly due to the fact that, although the electric water pump can be switched off for almost the entire ECE portion of the MVEURO cycle, leakage losses still occur when switched off due to natural convection in the cooling circuit or thermosyphon action. In this exemplary embodiment with a system according to the invention, a certain advantage is already present due to the closing of valves 6bv, 6cv, 6dv, and 6ev in the first few minutes of the cycle.

[0118] Far more important, however, is the fact that in order to make optimal use of the available heat in the MVEURO, it is very important, at least after some time, to also use the heat transfer in the engine oil cooler 30 and transmission oil cooler 40 to transfer heat from the coolant to the respective oil. As soon as the electric water pump in the MVEURO is activated, this means that flow occurs through the heater branch and the bypass branch 6b, even though this is not actually necessary. It follows that the associated heat losses in the subsequent part of the cycle have a negative impact on fuel consumption at least until a significant amount of excess heat has to be dissipated at the vehicle radiator. The oil heating, which is generally not yet complete by this time, ensures that the disadvantages often still exist even when heat has long since needed to be dissipated at the vehicle radiator.

[0119] In addition, due to the relatively poor efficiency chain, the electric coolant pump must save as much pump drive power as possible in order to avoid a significantly less favorable pump drive power in the overall cycle than with the conventional belt-driven pump in Fig. 11. Both effects mean that tribologically optimal utilization of the oil coolers 30 and 40 in the electric coolant pump is only partially feasible.

[0120] Furthermore, it should be noted in this context that in the known application with electric coolant pump, no use is made of the particularly advantageous possibility of using it analogously to Fig. 11, so that even with small total flows through the engine, a relatively high coolant flow through the engine oil cooler 30 or the transmission oil cooler 40 results. This results in the system according to Fig. 11, even with very small coolant flow rates through the engine, a very good heat transfer in the oil coolers 30 and 40. Small coolant flow rates are, in turn, precisely the means of choice to ultimately save fuel during the warm-up phase and with only a small excess of engine waste heat by reducing the water-side heat transfer coefficient.

[0121] With this embodiment, with an inventive decoupling between the actual engine cooling requirement and the heat transfer in the oil circuits, as well as the maximization of the oil temperatures, the time until heat has to be dissipated via the cooler branch 6a is maximized, ie the bypass branch 6b remains completely closed, for example, over large areas of the MVEURO. On the one hand, for this reason, and on the other hand, because in the design according to Fig. 11, a relatively simple cycling of the bypass valve 6bv allows for well-dosed heat dissipation at the vehicle radiator 8 without major fluctuations in the engine coolant temperature, and in particular, no electrically heated thermostat is required to adjust the desired temperature levels within the engine depending on the engine load. Even with an electrically heated thermostat as a redundant safeguard, the cost analysis would still favor the design according to Fig. 11 fail. However, this supposed improvement would not even be safer: This is because when an expansion element is used in conjunction with, for example, an opening temperature of 85°C without electrical heating, a high cooling effect and reduction in the engine component temperature is possible much more quickly than by taking the detour of heating an expansion element with, for example, an opening temperature of 110°C. The relevant advantages here, including the spontaneous increase in the heat transfer coefficient with increased throughput through the engine and the high heating rate of the 85°C expansion element when exposed to cooling water at 110°C, have already been described. In particular, there is no risk of the expansion element overheating internally if the electrical pairing is unsuitable.Current supply and coolant-side heat transfer, associated with certain risks for the thermostat service life and sometimes observed overshoots when the engine cools down.

[0122] With regard to real-world operation, the system with an electric coolant pump claims to deliver particularly good heating performance due to the ability to maximize the coolant flow through the heating heat exchanger with high electric pump power. However, given the detailed interactions of the process shown here, particularly the advantages regarding heat losses and the heat-active masses to be heated, it should be obvious that the design according to Fig. 11, with a high-performance heat exchanger and significantly lower coolant flow, is by far the superior system in terms of rapid cabin heating. Experimental studies also confirm this. Furthermore, it should be clear that the increased drive power of the electric coolant pump has a direct negative impact on fuel consumption, not to mention that the high coolant flow through the engine also results in an increase in engine friction, thus resulting in an additional disadvantage in fuel consumption.

[0123] However, it appears even more important that the system must always heat up a larger heat-active mass even in driving situations with limited cabin heating requirements, both without air conditioning and in air conditioning mode to temper the subcooled air. The disadvantages here lie not only in the heat-active mass of the heating circuit, but also, among other things, in the bypass branch, which is forced to flow with a volume flow many times that of the volume flow in the heating branch, even when cabin heating power is drawn low, so that even relatively small volume flows in the heating branch make a high overall volume flow through the engine unavoidable. This not only has a negative impact on fuel consumption through the loss of engine component and oil temperature, but also through the drive power of the electric pump with its relatively poor efficiency chain.

[0124] Furthermore, the system with electric engine coolant pump mentioned above does not have the necessary degrees of freedom to optimally utilize the two oil coolers 30 and 40, and especially at low engine loads in both partially warmed and warmed-up operating states, to achieve a small coolant flow through the engine and the heating circuit with good efficiency of the two oil coolers. In real driving conditions, these characteristics result in significant fuel consumption disadvantages compared to the much cheaper system according to Fig. 11.

[0125] The considerable cost advantages are largely retained even if the specifications for a specific vehicle call for residual heat utilization, i.e. heating even when the engine is not running, or after-run cooling, i.e. circulation of the coolant after the engine has been switched off. Even a very small additional pump with less than 10W electrical power can provide this function, so that the costs for such a pump are kept within reasonable limits. Furthermore, in conjunction with throttling to a reduced heating volume flow, it is very efficiently possible to implement the functionality of valve 2 using a speed-controlled displacement pump, in particular a gear pump, so that valve 2 can be omitted. Alternatively, a low-cost impeller pump, which has already proven itself millions of times, can be used. Here, too, it is particularly advantageous to implement the switchability of valve 2 via the electric pump.In the simplest case, this is achieved by controlling the speed of the impeller pump in conjunction with a thermostatic valve 2 combined with a reduced leakage, which is located in the heating return line. Alternatively, a spring-loaded valve 2 can be used anywhere in the heating branch, but this is preferably integrated directly into the impeller pump.

[0126] In particular, depending on the application, it is quite possible to start from Fig. 11 cost-reducing simplifications, while sacrificing some advantages that the electric pump system cannot provide, while still achieving a fuel consumption advantage for both the customer and the MVEURO. Potential approaches to this have already been described in detail, so only one example will suffice below.

[0127] For example, the omission of the use of a high-performance heating heat exchanger 4 in Fig. 11, although there are some losses in real-world fuel consumption and maximum cabin heating efficiency, the system is still better than the comparison system with an electric coolant pump. In the MVEURO, the advantages are fully retained and even expanded by one degree of control freedom, so that in Fig. 11, it is sufficient to configure valve 6cv as a simple thermostatic valve. Valve 2 in the MVEURO is then only opened once thermostatic valve 6cv has opened. The subsequent timing of valve 2 can then provide the desired metering of the total coolant flow through the engine in the partially heated state and ensure that sufficient metering accuracy of the heat supply is available even during heat dissipation with simultaneous opening of bypass valve 6bv and valve 2.

[0128] If the design focus is exclusively on the MVEURO, the thermostat valve 6dv in the auxiliary branch 6d can even be omitted in this configuration. The engine oil cooler 30 is then supplied with coolant at the same time as the auxiliary bypass branch 6c is activated. Depending on the engine, this can be quite fuel-efficient, especially since the total coolant flow through the engine remains low due to the initially closed heater valve. When cabin heating is required, omitting the valve 6dv represents a disadvantage, since the standard heater core requires a high coolant flow, and the oil cooler 30 without the valve 6dv increases the effective heat-active mass.For small to medium cabin heating requirements, the coolant return temperature can be reduced by reducing the coolant volume flow in heating branch 4a, even with a standard heater core, to such an extent that no heat is transferred at the oil cooler 30, i.e., the omission of valve 6dv can be compensated for. The additional use of a high-performance heater core not only extends the scope for this measure up to the maximum heating requirement, but heat can even be actively transferred from the engine oil to the coolant. It has already been described in detail that, taken together, these measures can dramatically improve cabin heating performance. As measurements show, this can even lead to the elimination of auxiliary heaters in diesel cars.

[0129] The original application and the present application are largely aimed at implementing the implementation of high temperatures in the engine while minimizing temperatures outside the engine and switching between the individual ranges with a respective focus on minimizing fuel consumption, maximizing heating power and maximizing engine power or overheating protection using a conventional and very cost-effective radiator thermostat 6.

[0130] However, the described physical principles for minimizing heat losses and for minimizing fluctuations in engine component temperature with limited dosing accuracy and reaction speed of the radiator thermostat 6 and the bypass valve 6bv can also be implemented in systems with a replacement valve freely controllable by the engine control unit 16 instead of the conventional radiator thermostat 6. The interactions regarding control quality in particular make it possible to work with significantly coarser-meshed components than was previously necessary. One application example here is the well-known rotary slide valve, the series introduction of which has so far failed, not least due to the costs of the high positioning accuracy and the difficulty of tuning.

[0131] Some weaknesses of the well-known electrically heated map-controlled thermostat, considered on their own, have already been discussed. The fact that additional electrical heating may actually impair control characteristics and possibly also operational reliability has also been described. In addition to the slower switching to reduced engine component temperatures, this has particular fail-safe disadvantages. Since, in the event of a failure of the electrical power supply, only the upper control temperature is available, the failure is more critical than, for example, with a bypass valve 6bv with a solenoid valve, which, when set to "normally open," is unproblematic in terms of engine performance and operational reliability in the event of a failure of, for example, the electrical line.

[0132] However, there are also applications where at least a very quickly opening electrically heated thermostat, i.e. a design with high electrical heating output, can be largely reconciled with the idea presented here. The individual measures for damping potential overshoots when the cooler branch opens at very high electrical current offer advantages that should not be underestimated. In this context, it is important that the switchover to a high coolant throughput in the bypass branch 6b with the electrical bypass valve 6bv can take place very quickly and in particular as soon as an increased engine load is detected by the engine control unit. The fact that the almost deadtime-free increase in the coolant throughput through the bypass branch 6b and thus also through the engine simultaneously causes a jump in the cooling of the engine components, long before the electrical current is applied.The fact that the radiator thermostat can be energized also offers an expanded range of potential uses. In contrast to the generally more cost-effective variant with an unheated standard radiator thermostat with an opening temperature of, for example, 85°C, the temperature difference between the thermostat's nominal temperature and the coolant temperature at the engine outlet does not make a significant contribution to the expansion element's rapid response. Rather, this must be achieved through a correspondingly high electrical output of the heater and / or thermal insulation of the expansion element. Coordinating these parameters, and in particular the required electricalPower is relatively complex given the relatively wide range of flow and temperature conditions in the bypass, cooler, and heater branches, so that overshoots can certainly occur during opening. These are fundamentally undesirable, but should be avoided, especially with low excess heat and low coolant flow through the engine. The dampening effect according to the exemplary embodiments with additional branches according to the invention is very helpful here.

[0133] If, on the other hand, this problem can be addressed using suitable components, and the ability to switch to reduced component temperatures at ultra-fast speeds is not the primary design criterion, the use of an electrically heated thermostat is certainly attractive in some applications. In particular, the increased control temperature without electrical power supply offers the advantage that heat dissipation at the radiator occurs at a higher coolant temperature, thus providing even more scope for reducing the coolant flow through the engine. Partial electrical power supply can further increase the scope for slightly higher excess engine heat. This often allows for a smoother transition between phases with and without opening of the bypass valve 6bv.Another important advantage here is that the individual branches can now, in principle, also open in the vicinity of the radiator thermostat 6. This means that, especially for branches 6c, 6d, 6e and the heating return, the connection on the radiator thermostat, which is usually already provided as the heating return, can be used instead of an additional connection piece downstream of the radiator thermostat. This is possible because there is no longer any risk of the warm coolant opening the radiator thermostat.

[0134] The requirements for the heating branch with regard to a return temperature below the thermostat opening temperature also become less critical, so that the heating branch can also intervene more strongly in the metering of the engine coolant flow rate by means of an electric valve, particularly when the radiator thermostat 6 is still closed.

[0135] In order to minimize the heat-active mass but also to improve the damping effect, it is generally better to arrange the branches 6c, 6d and 6e at positions 7e downstream of the radiator thermostat 6 and to position the heating return, which is largely cooled in many operating points, further upstream, in particular at the current standard position on the radiator thermostat 6.

[0136] In conclusion, it should be noted that the concept shown here can be used very efficiently both in the variant without an electrically heated radiator thermostat 6, which is particularly preferable for cost optimization, and with an electrically controlled radiator thermostat 6, and that this concept still provides fuel consumption advantages even in applications where an electric coolant pump replaces the belt-driven engine coolant pump 7.

[0137] It is a distinct advantage that the local reduction in coolant temperatures in the heating branch 4a, but also in the rest of the coolant system, and especially the very spontaneous response of the cooling when the additional valves open, help to eliminate reservations regarding the conventional electric thermostat. Particularly in vehicles designed for high driving dynamics, the use of the electrically heated thermostat is sometimes dispensed with due to its slow response time, even though it represents a simple and proven method for saving fuel consumption. Both the approach without an electrically heated thermostat and the approach with electrical heating result in considerably better cooling response times. The cooling reserve is generally higher when using the approach without an electrically heated thermostat than with an electrically heated thermostat, so that in generallittle cooling potential needs to be maintained, but if necessary the measures described below can also be used accordingly.

[0138] When used with an electrically heated thermostat, it is advantageous, particularly when very high demands are placed on cooling dynamics, if at partial engine load, at least from a minimum temperature of the coolant or the engine components, at least one additional valve controllable by the engine control unit 16 in a coolant branch leading through the engine, in particular a bypass valve 6bv in the bypass branch 6b and / or a valve 6cv in a branch 6c without a heat exchanger and / or a valve 6dv in a branch 6d with an engine oil cooler 30 and / or an additional valve in a branch 6e with a transmission oil cooler 40, and / or a valve 2 in the heating branch 4a, is partially or completely closed to provide a cooling reserve and is opened by the engine control unit 16 in the event of a sudden transition to a very high engine load. This always provides a potential for increasing the cooling effect by increasing the coolant flow, regardless of the local coolant temperatures.

[0139] It depends on the basic function of the valves whether they remain open after the transition to high cooling capacity, such as the bypass valve 6bv, or are closed, such as valves 6cv without heating heat exchangers or cooling-critical components.

[0140] Conversely, valves 6dv and 6ev ia are often already largely open at partial load, so the scope for using full opening as a cooling reserve during the transition to high load is naturally limited. Nevertheless, it is advantageous for them to be fully opened, if necessary, starting from a partially open state when the engine is warm or partially warmed up at partial load, and to remain open to protect the oil from overheating. List of reference symbols 1 internal combustion engine 2 Throttle valve, valve / thermostat valve in the heating branch or in the heating heat exchanger circuit 4 heating heat exchangers, high-performance heat exchangers 4a Heating branch, branch 5 air-side control damper of an air-side temperature control (air temperature control damper) 6a Radiator branch 6 Radiator thermostat, thermostat valve, radiator thermostat replacement 6b Bypass branch 6bv bypass valve, additional valve 6c additional bypass road, branch 6cv valve / thermostat valve in the additional bypass branch 6c 6d Additional branch / branch with engine oil cooler 30 6dv valve / thermostat valve in the additional branch 6d with engine oil cooler 30 6e Additional branch / branch with transmission oil cooler 40 6ev valve / thermostat valve in the additional branch 6e with transmission oil cooler 40 7 Engine coolant pump 7e Introduction point, position downstream of the radiator thermostat 6 and upstream of the engine coolant pump 7 8 vehicle radiators 9 water tanks 9a Ventilation branch 16 Engine control 20 Air mass flow at the outlet of the heating and air conditioning unit 21 Air mass flow of an air-side temperature control system conveyed through the heating heat exchanger (4) 22 unheated bypass air mass flow of an air-side temperature control 30 engine oil cooler, oil cooler 40 transmission oil cooler, oil cooler

Claims

[1] Device for cooling and heating a motor vehicle with an internal combustion engine (1) which is cooled by means of an engine coolant pump (7) circulated coolant, with a) a cooling circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a cooling branch (6a) with a vehicle radiator (8) and a radiator thermostat (6), b) a bypass branch (6b) leading through the engine coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit and can be flowed through when the radiator thermostat (6) is closed, c) a ventilation circuit with a water tank (9) passing through the engine coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a), d) a heating heat exchanger circuit with a heating heat exchanger (4) passing through the engine coolant pump (7), the internal combustion engine (1) and a heating branch (4a), e) an additional valve (6bv) which can be controlled by an engine control unit (16) and with which the bypass branch (6b) can be closed when the radiator thermostat (6) is closed, f) a cooling circuit leading through the engine coolant pump (7) to the internal combustion engine (1) and an additional branch (6d) with an engine oil cooler (30), through which the cooling circuit can flow when the radiator thermostat (6) is closed, g) a cooling circuit leading through the engine coolant pump (7) to the internal combustion engine (1) and an additional branch (6e) with a transmission oil cooler (40), through which the cooling circuit can flow when the radiator thermostat (6) is closed, h) an air-side temperature control, in which the temperature of the air (20) conveyed into a cabin of the motor vehicle can be adjusted by means of the mixture via an air temperature control flap (5) of an air mass flow (21) conveyed through the heating heat exchanger (4) with a non-heated bypass air mass flow (22), characterized by that the cooling circuit with the additional branch (6d) with engine oil cooler (30) and the cooling circuit with the additional branch (6e) with transmission oil cooler (40) together lead through a valve (6cv) which is controlled by the engine control (16) and, when closed, interrupts both additional branches (6d, 6e) together. [2] Device according to claim 1, characterized by that, starting from the cold engine operating state, initially no coolant flows through the internal combustion engine (1) and the valve (6cv) is closed. [3] Device according to one of claims 1-2, characterized bythat the valve (6vc) has only one coolant inflow. [4] Device according to one of claims 1-2, characterized by that the valve (6vc) has only one coolant outlet. [5] Device according to one of claims 1-3, characterized by that the valve (6vc) has only one coolant inlet and only one coolant outlet. [6] Device according to one of claims 1-5, characterized by that the cooler circuit with cooler branch (6a), the bypass circuit with bypass branch (6b), the venting circuit with venting branch (9a) and the heating heat exchanger circuit with heating branch (4a) do not pass through the valve (6cv). [7] Device according to one of claims 1-6, characterized bythat the cooler circuit with cooler branch (6a), the bypass circuit with bypass branch (6b), the venting circuit with venting branch (9a) and the heating heat exchanger circuit with heating branch (4a) do not lead through the valve (6cv) and at least one operating state is stored in the engine control (16) in which these four circuits are closed simultaneously by means of the cooler thermostat (6), the additional valve (6bv) and a valve (2) arranged in the heating branch (4a). [8] Device for cooling and heating a motor vehicle with an internal combustion engine (1) which is cooled by means of an engine coolant pump (7) circulated coolant, with a) a cooling circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a cooling branch (6a) with a vehicle radiator (8) and a radiator thermostat (6), b) a bypass branch (6b) leading through the engine coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit and can be flowed through when the radiator thermostat (6) is closed, c) a ventilation circuit with a water tank (9) passing through the engine coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a), d) a heating heat exchanger circuit with a heating heat exchanger (4) passing through the engine coolant pump (7), the internal combustion engine (1) and a heating branch (4a), e) an additional valve (6bv) which can be controlled by an engine control unit (16) and with which the bypass branch (6b) can be closed when the radiator thermostat (6) is closed, f) wherein the cooling circuit, the bypass circuit, the ventilation circuit and the heating heat exchanger circuit flow through both a cylinder block and a cylinder head of the internal combustion engine (1), g) a cooling circuit leading at least through the engine coolant pump (7) and an additional branch (6d) with an engine oil cooler (30) and / or an additional branch (6e) with a transmission oil cooler (40), which can be flowed through when the radiator thermostat (6) is closed and which removes the cooling water in the vicinity of the engine inlet or at a position downstream of the coolant pump (7) which is still slightly heated, h) an air-side temperature control, in which the temperature of the air (20) conveyed into a cabin of the motor vehicle can be adjusted by means of the mixture via an air temperature control flap (5) of an air mass flow (21) conveyed through the heating heat exchanger (4) with a non-heated bypass air mass flow (22), where i) the additional valve (6bv) is used to temporarily reduce the coolant flow through the internal combustion engine (1) very significantly or to completely prevent it, in particular during engine warm-up and at partial load, while the cooling circuit leading through the additional branch (6d) with engine oil cooler (30) and / or the additional branch (6e) with transmission oil cooler (40) flows through or can at least flow through. [9] Device for cooling and heating a motor vehicle with an internal combustion engine (1) which is cooled by means of an engine coolant pump (7) circulated coolant, with a) a cooling circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a cooling branch (6a) with a vehicle radiator (8) and a radiator thermostat (6), b) a bypass branch (6b) leading through the engine coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit and can be flowed through when the radiator thermostat (6) is closed, c) a ventilation circuit with a water tank (9) passing through the engine coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a), d) a heating heat exchanger circuit with a heating heat exchanger (4) passing through the engine coolant pump (7), the internal combustion engine (1) and a heating branch (4a), e) an additional valve (6bv) which can be controlled by an engine control unit (16) and with which the bypass branch (6b) can be closed when the radiator thermostat (6) is closed, f) wherein the cooling circuit, the bypass circuit, the ventilation circuit and the heating heat exchanger circuit flow through both a cylinder block and a cylinder head of the internal combustion engine (1), g) a cooling circuit leading at least through the engine coolant pump (7) and an additional branch (6d) with an engine oil cooler (30) and / or an additional branch (6e) with a transmission oil cooler (40), which can be flowed through when the radiator thermostat (6) is closed and which removes the cooling water in the vicinity of the engine inlet or at a position downstream of the engine coolant pump (7) which is still only slightly heated, h) an air-side temperature control, in which the temperature of the air (20) conveyed into a cabin of the motor vehicle can be adjusted by means of the mixture via an air temperature control flap (5) of an air mass flow (21) conveyed through the heating heat exchanger (4) with a non-heated bypass air mass flow (22), i) the radiator circuit and the ventilation circuit are interrupted by the closed radiator thermostat (6). [10] Device for cooling and heating a motor vehicle with an internal combustion engine (1) which is cooled by means of an engine coolant pump (7) circulated coolant, with a) a cooling circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a cooling branch (6a) with a vehicle radiator (8) and a radiator thermostat (6), b) a bypass branch (6b) leading through the engine coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit and can be flowed through when the radiator thermostat (6) is closed, c) a ventilation circuit with a water tank (9) passing through the engine coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a), d) a heating heat exchanger circuit with a heating heat exchanger (4) passing through the engine coolant pump (7), the internal combustion engine (1) and a heating branch (4a), e) an additional valve (6bv) which can be controlled by an engine control unit (16) and with which the bypass branch (6b) can be closed when the radiator thermostat (6) is closed, f) wherein the cooling circuit, the bypass circuit, the ventilation circuit and the heating heat exchanger circuit flow through both a cylinder block and a cylinder head of the internal combustion engine (1), g) a cooling circuit leading at least through the engine coolant pump (7) and an additional branch (6d) with an engine oil cooler (30) and / or an additional branch (6e) with a transmission oil cooler (40), which can be flowed through when the radiator thermostat (6) is closed and which removes the cooling water in the vicinity of the engine inlet or at a position downstream of the engine coolant pump (7) which is still only slightly heated, h) an air-side temperature control, in which the temperature of the air (20) conveyed into a cabin of the motor vehicle can be adjusted by means of the mixture via an air temperature control flap (5) of an air mass flow (21) conveyed through the heating heat exchanger (4) with a non-heated bypass air mass flow (22), where i) the heating branch (4a) is assigned a valve (2) which can be controlled by the engine control (16) and which can interrupt the heating heat exchanger circuit. [11] Device for cooling and heating a motor vehicle with an internal combustion engine (1) which is cooled by means of an engine coolant pump (7) circulated coolant, with a) a cooling circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a cooling branch (6a) with a vehicle radiator (8) and a radiator thermostat (6), b) a bypass branch (6b) leading through the engine coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit and can be flowed through when the radiator thermostat (6) is closed, c) a ventilation circuit with a water tank (9) passing through the engine coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a), d) a heating heat exchanger circuit with a heating heat exchanger (4) passing through the engine coolant pump (7), the internal combustion engine (1) and a heating branch (4a), e) an additional valve (6bv) which can be controlled by an engine control unit (16) and with which the bypass branch (6b) can be closed when the radiator thermostat (6) is closed, f) wherein the cooling circuit, the bypass circuit, the ventilation circuit and the heating heat exchanger circuit flow through both a cylinder block and a cylinder head of the internal combustion engine (1), g) a cooling circuit leading at least through the engine coolant pump (7) and an additional branch (6d) with an engine oil cooler (30) and / or an additional branch (6e) with a transmission oil cooler (40), which can be flowed through when the radiator thermostat (6) is closed and which removes the cooling water in the vicinity of the engine inlet or at a position downstream of the engine coolant pump (7) which is still only slightly heated, h) an air-side temperature control, in which the temperature of the air (20) conveyed into a cabin of the motor vehicle can be adjusted by means of the mixture via an air temperature control flap (5) of an air mass flow (21) conveyed through the heating heat exchanger (4) with a non-heated bypass air mass flow (22), i) the engine oil cooler (30) and / or the transmission oil cooler (40) has / have or has / have associated with it a flow control in the form of a valve (6dv, 6ev) controlled by the thermostat or by the engine control unit (16), j) the valve (6dv) in the additional branch (6d) with engine oil cooler (30) and / or the valve (6ev) in the additional branch (6e) with transmission oil cooler (40) has / have only one coolant inflow and only one coolant outflow. k) a valve (2) which can be controlled by the engine control (16) and which can interrupt the heating heat exchanger circuit is assigned to the heating branch (4a), l) the cooling circuit leading through the additional branch (6d) with engine oil cooler (30) and / or the cooling circuit leading through the additional branch (6e) with transmission oil cooler (40) bypasses the heating branch (4a), m) the radiator circuit and the ventilation circuit are interrupted by the closed radiator thermostat (6). [12] Device according to one of claims 8-9, characterized by that the heating branch (4a) is assigned a valve (2) which can be controlled by the engine control (16) and which can interrupt the heating heat exchanger circuit. [13] Device according to one of claims 8-12, characterized by that the additional branch (6d) with engine oil cooler (30) and / or the additional branch (6e) with transmission oil cooler (40) takes the coolant at the pump outlet or at the engine inlet of the internal combustion engine (1). [14] Device according to one of claims 8-13, characterized bythat a setting of the engine control (16) is possible in which the heating heat exchanger circuit is not flowed through by the coolant. [15] Device according to one of claims 8-10, characterized by that the cooling circuit leading through the additional branch (6d) with engine oil cooler (30) does not have a valve. [16] Device according to one of claims 8, 10 or 12-15, characterized by that the radiator circuit and the ventilation circuit are interrupted by the closed radiator thermostat (6). [17] Device according to one of claims 8-16, characterized by that the radiator circuit and the ventilation circuit are interrupted by the closed radiator thermostat (6) and the ventilation circuit bypasses the vehicle radiator (8). [18] Device according to one of claims 8-10 or 12-17, characterized bythat the cooling circuit leading through the additional branch (6d) with engine oil cooler (30) and / or the cooling circuit leading through the additional branch (6e) with transmission oil cooler (40) bypasses the heating branch (4a). [19] Device according to one of claims 8-18, characterized by that the cooling circuit leading through the additional branch (6d) with engine oil cooler (30) and / or the cooling circuit leading through the additional branch (6e) with transmission oil cooler (40) bypasses the radiator thermostat (6). [20] Device according to one of claims 7, 10-12, characterized by that the coolant flow rate in the heating heat exchanger circuit is temporarily throttled towards reduced heating potential by the valve (2) in the heating heat exchanger circuit intervening. [21] Device according to one of claims 1-9, 13-21, characterized bythat the coolant flow rate in the heating heat exchanger circuit is temporarily throttled towards reduced heating potential by the engine control (16) controlling an electrically driven pump accordingly. [22] Method for cooling and heating a motor vehicle with an internal combustion engine (1) which is cooled by means of an engine coolant pump (7) circulated coolant, with a) a cooling circuit passing through the engine coolant pump (7), the internal combustion engine (1) and a cooling branch (6a) with a vehicle radiator (8) and a radiator thermostat (6), b) a bypass branch (6b) leading through the engine coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit and can be flowed through when the radiator thermostat (6) is closed, c) a ventilation circuit with a water tank (9) passing through the engine coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a), d) a heating heat exchanger circuit with a heating heat exchanger (4) passing through the engine coolant pump (7), the internal combustion engine (1) and a heating branch (4a), e) an additional valve (6bv) which can be controlled by an engine control unit (16) and with which the bypass branch (6b) can be closed when the radiator thermostat (6) is closed, f) wherein the cooling circuit, the bypass circuit, the ventilation circuit and the heating heat exchanger circuit flow through both a cylinder block and a cylinder head of the internal combustion engine (1), g) a cooling circuit leading at least through the engine coolant pump (7) and an additional branch (6d) with an engine oil cooler (30) and / or an additional branch (6e) with a transmission oil cooler (40), through which cooling circuit can flow when the radiator thermostat (6) is closed, h) an air-side temperature control, in which the temperature of the air (20) conveyed into a cabin of the motor vehicle can be adjusted by means of the mixture via an air temperature control flap (5) of an air mass flow (21) conveyed through the heating heat exchanger (4) with a non-heated bypass air mass flow (22), i) wherein a valve (2), which can be controlled in particular by the engine control (16), is assigned to the heating branch (4a) and can interrupt the heating branch (4a), characterized by , that j) in a statutory exhaust gas test or in another operating situation with the cabin heating switched off, the heating branch (4a) is temporarily flowed through and temporarily not flowed through, and k) the cooling circuit carrying the additional branch (6d) with engine oil cooler (30) and / or the additional branch (6e) with transmission oil cooler (40) takes the cooling water in the vicinity of the engine inlet or at a position downstream of the engine coolant pump (7) which is still only slightly heated and through which it flows or at least can be flowed. [23] Method according to claim 22, characterized by , the additional branch (6d) with engine oil cooler (30) and / or the additional branch (6e) with transmission oil cooler (40) takes the coolant at the pump outlet or at the engine inlet of the internal combustion engine (1). [24] Method according to one of claims 22-23, characterized by that the cooling circuit leading through the additional branch (6d) with engine oil cooler (30) does not have a valve. [25] Method according to one of claims 22-24, characterized by that the cooling circuit leading through the additional branch (6d) with engine oil cooler (30) and / or the cooling circuit leading through the additional branch (6e) with transmission oil cooler (40) bypasses the heating branch (4a), the radiator branch (6a) and the radiator thermostat (6). [26] Method according to one of claims 22-23 or 25, characterized by that the additional branch (6d) with engine oil cooler (30) and / or the additional branch (6e) with transmission oil cooler (40) has a flow control which is thermostatic or controlled by the engine control unit (16) and which prevents / prevents its flow down to a minimum temperature of the coolant. [27] Method according to one of claims 22-26, characterized by that the radiator circuit and the ventilation circuit are interrupted by the closed radiator thermostat (6). [28] Method according to one of claims 22-26, characterized bythat the radiator circuit and the ventilation circuit are interrupted by the closed radiator thermostat (6) and the ventilation circuit bypasses the vehicle radiator (8). [29] Method according to any one of claims 22-28, characterized by that an additional valve (6bv) is used to temporarily reduce or completely prevent the coolant flow through the internal combustion engine (1), in particular during engine warm-up and at partial load. [30] Method according to one of claims 22-27, characterized in that the additional valve (6bv) is replaced by using a radiator thermostat (6) which can be controlled by the engine control (16) or a radiator thermostat (6) in the form of a radiator thermostat replacement (6) which can be set by the engine control (16), in particular in the form of a rotary slide valve. [31] Method according to one of claims 22-30, characterized bythat in the statutory exhaust gas test or in the other operating situation with the cabin heating switched off, at least after some time, a heat transfer in the engine oil cooler (30) and / or in the transmission oil cooler (40) can be used to transfer heat from the coolant to the respective oil. [32] Method according to one of claims 22-28, 30-31, characterized by that the radiator thermostat (6) is an electrically heatable radiator thermostat (6) controlled by the engine control (16) and an operating mode is stored in the engine control (16) in which the valve (2) in the heating branch (4a) is partially and / or completely closed and is opened by the engine control (16) in the event of a sudden transition to a very high engine load. [33] Device according to one of claims 1-7, 9-21, characterized bythat the additional valve (6bv) is replaced by using a radiator thermostat (6) which can be controlled by the engine control (16) or a radiator thermostat (6) in the form of a radiator thermostat replacement (6) which can be set by the engine control (16), in particular in the form of a rotary slide valve. [34] Device according to one of claims 1-21, characterized by that a valve (2), which can be controlled in particular by the engine control (16), is assigned to the heating branch (4a), which valve can interrupt the heating branch (4a) and in a statutory exhaust gas test or in another operating situation with the cabin heating switched off, the heating branch (4a) is temporarily flowed through and temporarily not flowed through. [35] Device according to one of claims 1-21, characterized bythat at least one cooling circuit, via which coolant leads from a cylinder head of the internal combustion engine (1) via the engine coolant pump (7) to a cylinder block of the internal combustion engine (1), is always flowed through when the engine coolant pump (7) is in operation. [36] Device according to one of claims 7, 10-12, 20, characterized by that the radiator thermostat (6) is an electrically heatable radiator thermostat (6) controlled by the engine control unit and an operating mode is stored in the engine control unit (16) in which the valve (2) in the heating branch (4a) is partially and / or completely closed and is opened by the engine control unit (16) in the event of a sudden transition to a very high engine load. [37] Device according to claim 36, characterized by that the operating mode is assigned to an operation without heat output drawdown. [38] Method for operating a device according to any one of claims 1-21, characterized bythat at least one cooling circuit, via which coolant leads from a cylinder head of the internal combustion engine (1) via the engine coolant pump (7) to a cylinder block of the internal combustion engine (1), is always flowed through when the engine coolant pump (7) is in operation. [39] Method for operating a device according to any one of claims 7, 10-12, 20, characterized by that the valve (2) in the heating branch (4a) is partially and / or completely closed and is opened by the engine control (16) in the event of a sudden transition to very high engine load. [40] Method according to claim 39, characterized by that it is assigned to an operation without heat output consumption. [41] Device for operating a heating and air conditioning unit in motor vehicles, a) with air-side temperature control, b) with a heating heat exchanger (4) which can extract heat from a coolant of an internal combustion engine (1) and transfer it to the cabin air conveyed through the heating heat exchanger (4) by means of a heating fan, wherein c) the coolant flow rate in a heating branch (4a) can be temporarily throttled by means of a throttle device, d) wherein the throttling of the coolant flow rate in the heating branch (4a) can be effected by one or more coolant valves controlled by an engine control unit (16) or an air conditioning control unit, e) with an electrically heatable expansion material radiator thermostat (6) controlled by the engine control unit (16), with a radiator branch (6a) with vehicle radiator (8), a bypass branch (6b) bypassing the vehicle radiator (8) and further coolant branches, wherein an additional valve (6bv) also controlled by the engine control unit (16) temporarily closes the bypass branch (6b), f) a valve (2) which can be controlled by the engine control (16) switches off the coolant flow in the heating branch (4a) as required, g) the additional valve (6bv) is used to significantly reduce or completely prevent the coolant flow through the internal combustion engine (1) temporarily, particularly during engine warm-up and at partial load, h) a radiator circuit passing through the internal combustion engine (1), the vehicle radiator (8) and the radiator thermostat (6) and a venting circuit passing through the internal combustion engine (1), a venting branch (9a) with a water tank (9) and the radiator thermostat (6) are interrupted by the closed radiator thermostat (6) and the venting circuit bypasses the vehicle radiator (8), i) an additional branch (6d) with an engine oil cooler (30) and / or an additional branch (6e) with a transmission oil cooler (40) in a cooling circuit bypassing the heating heat exchanger (4) can be flowed through when an engine coolant pump (7) is operating with the radiator thermostat (6) closed, and j) an operating mode is stored in the engine control unit (16) in which, in a statutory exhaust gas test or in another operating situation with the cabin heating switched off, the heating branch (4a) is temporarily flowed through and temporarily not flowed through, and / or k) an operating mode is stored in the engine control (16) in which the valve (2) in the heating branch (4a) is partially or completely closed and is opened by the engine control (16) in the event of a sudden transition to a very high engine load. [42] Device for operating a heating and air conditioning unit in motor vehicles, a) with air-side temperature control, b) with a heating heat exchanger (4) which can extract heat from a coolant of an internal combustion engine (1) and transfer it to the cabin air conveyed through the heating heat exchanger (4) by means of a heating fan, wherein c) the coolant flow rate in a heating branch (4a) can be temporarily throttled by means of a throttle device, d) wherein the throttling of the coolant flow rate in the heating branch (4a) can be effected by one or more coolant valves controlled by an engine control unit (16) or an air conditioning control unit, e) with a radiator thermostat (6) controlled by the engine control unit (16), in particular an electrically heatable expansion radiator thermostat (6) or a valve freely controllable by the engine control unit (16) instead of a conventional radiator thermostat, with a radiator branch (6a) with vehicle radiator (8), a bypass branch (6b) bypassing the vehicle radiator (8) and further coolant branches, wherein an additional valve (6bv) also controlled by the engine control unit (16) temporarily closes the bypass branch (6b), f) a valve (2) which can be controlled by the engine control (16) switches off the coolant flow in the heating branch (4a) as required, g) the additional valve (6bv) is used to significantly reduce or completely prevent the coolant flow through the internal combustion engine (1) temporarily, particularly during engine warm-up and at partial load, h) a radiator circuit passing through the internal combustion engine (1), a ventilation branch (9a) with a water tank (9) and the radiator thermostat (6) and a ventilation circuit passing through the internal combustion engine (1), the vehicle radiator (8) and the radiator thermostat (6) are interrupted by the closed radiator thermostat (6) and the ventilation circuit bypasses the vehicle radiator (8), i) an additional branch (6d) with an engine oil cooler (30) and / or an additional branch (6e) with a transmission oil cooler (40) in a cooling circuit bypassing the heating heat exchanger (4) can be flowed through when an engine coolant pump (7) is operating with the radiator thermostat (6) closed, and j) an operating mode is stored in the engine control unit (16) in which, in a statutory exhaust gas test or in another operating situation with the cabin heating switched off, the heating branch (4a) is temporarily flowed through and temporarily not flowed through. [43] Device according to one of claims 41-42, characterized by that the coolant flow in the heating branch (4a) is temporarily also one of the determining coolant flows through the internal combustion engine (1). [44] Device according to one of claims 41-43, characterized by that high-performance heating heat exchangers are used and that a reduction in the coolant flow rate in a first operating mode is only used to improve fuel consumption. [45] Method for operating a heating and air conditioning device in motor vehicles with air-side temperature control with a device according to one of claims 1-21 or 41-44, characterized bythat in an operation with heating power extraction, the cooling water flow rate in the heating branch (4a) is temporarily throttled by means of a throttling device in the direction of reduced heating potential in such a way that a minimum heating criterion, which characterises a required minimum heating power potential, can still be met by means of the associated setting of the air-side temperature control. [46] A method for operating a device according to any one of claims 1-21 or 41-44, characterized by that in a setting of the engine control (16) the coolant flow rate in the heating branch (4a) is throttled and the control flap (5) of the air-side control is at least temporarily not at one of the two end stops in an operation with heat extraction at the heating heat exchanger (4).

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