EP0295445B1 - Liquid cooling circuit for machines especially for internal combustion engines - Google Patents

Description

The invention relates to a liquid cooling circuit in engines and machines, in particular internal combustion engines, according to the type of claim 1. Furthermore, the invention relates to cooling circuits of similar types of claims 4 and 6.

In a known device of this type according to DE-OS 32 26 508, corresponding to EP-A-0 100 917, JP-A-5923029 and US-PS 4 510 893, the air separation container is via a return suction line as a filling line with the suction side of the Coolant pump connected. When filling, the coolant flows from the bottom area of the air separation tank via the return line to the low-lying coolant pump and from there into the cooling jacket of the machine. Since the direct connection between the coolant pump and the return water tank of the cooler is closed by the cooler valve with the thermostat arranged in the cooler return line when the machine, which is always largely cold, is filled, the coolant can initially only flow into the cooling jacket and fill it. This filling process is also in the case of thermostat arrangements at the cooling jacket outlet due to the narrow internal cross section of the Vent line from the cooler flow to the filler neck is delayed, through which the air to be displaced can only escape from the cooling jacket and from the cooler. The resulting low filling speed not only increases the amount of work required, but also the volume of residual air remaining in the cooling jacket and other line sections with little or no gradient. Finally, the coolant only enters the cooler after the cooling jacket has been completely filled, via the flow line, which usually has hardly any gradient, which further reduces the filling speed and also favors residual air volumes in the cooler. An additional lengthy venting process with the machine running and the cover removed is therefore necessary. Residual air still remaining in the cooling circuit, especially dissolved in the coolant, can only be discharged to the atmosphere via the expansion tank acting as an air lock even after its failure from the solution at high temperature and its upstream at the pressure relief valves if the pressure relief valve opening values are exceeded. The advantages of an air-free cooling circuit, such as steeper pressure build-up when the coolant temperature rises and the reduced risk of corrosion for the cooling circuit components and the coolant itself, due to its extensive degassing, are therefore hardly or mostly delayed after numerous machine hot / cold cycles . In addition, after a lengthy venting process up to a high operating temperature, there is no longer sufficient pressure build-up of the coolant from its thermal expansion for subsequent operation of the machine. Due to the thermal expansion of the coolant that occurred before the closing of the closure cap without pressure build-up, the operating temperature then increases as the temperature rises further the boiling limit or the pump cavitation limit is quickly reached and machine overheating is unavoidable when operating immediately afterwards under high load.

In the opposite sense, in the cooling circuit of internal combustion engines in which fuel gas leaks penetrate the cooling circuit under high load and generally at low starting temperatures, in particular minus degrees, an excess pressure occurs in the area of the opening values of the pressure relief valves in relation to the relatively low coolant temperature , which is not sufficiently degraded even when the machine cools down during breaks in operation. In addition, the fuel gas volume parts remaining in the cooling circuit have a permanent destructive effect on the coolant additives and a corrosive effect on the interior of the cooling circuit components.

Finally, when the machine is quickly shut down from a high load, there is often strong local overheating of the coolant at hot spots in the cooling jacket with corresponding high-pressure steam bubbles, which lead to excessively high pressure in the entire cooling circuit with coolant ejection through the pressure relief valve and even until the expansion tank overflows can as well as insulating deposits of components of the coolant, in particular water stone, causes just at the hot spots.

The object of the invention is to overcome the disadvantages described above in the area of the operating boundary conditions - filling, venting, degassing, pump cavitation, overheating, shutdown reheating, for the course of the coolant temperature unnecessarily excessive course of the coolant pressure at low start or ambient temperatures and when fuel gases penetrate into the Cooling circuit in the medium operating temperature range - to be overcome by liquid-cooled machines and at the same time to reduce construction costs, costs, weight, variety of components, and possibilities for incorrect operation. Furthermore, overdimensioning of cooling circuit components and, above all, the cooling capacity, which have so far been necessary to compensate for the described interference, are to be avoided.

The invention achieves this in a surprisingly advantageous manner by using the characterizing features of patent claim 1.

This accelerates the filling of the cooling jacket and the cooler and reduces the inclusion of residual air, because the coolant flows from the filling opening equally and quickly into the cooling jacket and into the cooler and the air can flow out in counterflow, so that the high coolant Flow velocity, the residual air bubbles are largely carried along and only a small volume of residual air remains in the various coolant-carrying lines and cavities of the cooling circuit. When the machine is subsequently operated for the first time, the remaining portions of residual air from the high point of the flow are quickly flushed into the air separation container via the vent line emanating from it. In this case, if this mouth is arranged close to the engine, the low-lying cooler arrangement for heavily falling car fronts is favored by the radiator lead falling towards the radiator and an additional reduction in the coolant volume involved in the warm-up and thus a shorter warm-up time is achieved. This applies to an increased extent compared to a connection of the vent line at the high point of the cooler flow water tank, which is at least partially in the case of cross-flow coolers even together with part of the cooler field, which includes warm-up.

The temperature-controlled vent valve improves both venting and degassing as well as the system pressure build-up via temperature and speed, and the cooling circuit pressure which is excessive due to fuel gas leakages is reduced again during cooling phases. The line connection from the air separation tank to the expansion tank, which is opened by the thermo valve at low operating temperature, also enables a very simple venting process after filling, with a constant change in engine speed when the cover is closed, which means that coolant and residual air flow to the expansion tank and coolant flow into the air separation tank becomes. This results from the increase in the pump suction pressure when the speed drops and its drop when the speed increases. In connection with a level transmitter in the air separation container - according to claim 3 - the progressive ventilation can be tracked or assessed by the start of the lighting of a switched on indicator light at ever higher speed. The closing temperature of the ventilation valve, which is dependent on the pressure build-up dependent on the cooling circuit elasticity, especially hose length and elasticity, the temperature and the pump speed, avoids unnecessarily high cooling circuit overpressure values with relatively low coolant temperature values and on the other hand, ensures a sufficient distance between the pump suction pressure curve and the pump cavitation limit. High pump delivery rate due to the high motor speed at the switching point of the thermal valve leads to the fact that the vent valve, which is greatly reduced in relation to the average cooling circuit overpressure, leads to this constant atmospheric pump suction pressure at a correspondingly higher outlet pressure for the pressure build-up from the thermal expansion of the coolant as the temperature rises further. This increases safety against pump cavitation when operating at relatively high speeds.
The arrangement of all the control elements in the sealing cover on the one hand achieves a compact, cost-effective and weight-saving construction and, on the other hand, an inexpensive maintenance and repair option.

The features of claim 2 enable a particularly compact spatial allocation of the air separation container to the cooler flow and to the filler neck, whereby a very small space requirement is achieved.

The assignment of a coolant level sensor to the air separation container according to claim 3 results in a safe level monitoring of the overpressure cooling circuit and a warning display even if the coolant content is still safe to operate, because the temperature-related change in volume of the coolant triggers a display when the cooling circuit is cold when the coolant that warms up during operation again exceeds the display level and guarantees operational safety. In addition, the fill level warning display forms a monitoring display when the cooling circuit is vented after it has been refilled or refilled. The possible pumping of the residual air through the expansion tank to the atmosphere by means of the simple measure of operating the machine with a strong change in speed with an open line connection between the air separation tank and the expansion tank results in a falling start of a normal level warning light, with the residual air volume falling, which shifts steadily to a higher speed .

The features of claim 4 contain the basic arrangement of the air separation container with filler neck and filler cap at the high point of the cooler flow in the course of the venting bypass line, whereby a large part of the advantages regardless of the arrangement and design of the overpressure, underpressure and venting valves according to claim 1 is achieved, namely advantageous filling and venting and rapid warm-up. The valves can be selected in any known or previously proposed configuration and arrangement or connection, namely on the air separation tank, on the expansion tank or on both in series connection, with the latter two arrangements requiring an expansion tank with an air expansion volume.

Claim 5 provides for the additional control of a pressure relief valve from the pressure in the cooler flow for the immediate limitation of the pressure value acting on the cooler, since the valves are effective in the cooler return in all arrangements according to claim 4.

The features of claim 6 provide a temperature-controlled vent valve, which is located in the connecting line from the air separation tank to the expansion tank regardless of its arrangement. Apart from a small additional construction effort and weight, this design enables all other functional advantages of the features according to claim 1, in particular in connection with an additional filling lid arranged in a known manner at the high point of the cooler flow.

The design of the vent valve according to claim 7 has a particularly low construction cost and provides the simplest maintenance and repair options by checking and / or replacing the sealing cover as a unit. Individual components that have been tried and tested in automotive engineering are used. The assignment of the components of the valve also favors its function, since the snap spring is only acted upon by the coolant temperature after the air has been completely pushed out, so that the venting is promoted by the coolant itself when the closing / switching temperature is reached. A float instead of a closing spring is therefore only necessary in particularly difficult ventilation conditions. The closed vent valve also increases with increasing coolant pressure increasingly favored in its sealing function, because the thermal snap spring is pressed more and more against the sealing ring.

This valve design can also be used advantageously in cooling circuits of a type which differs from that according to claims 1 and 6, but has at least one atmospheric expansion tank.

The features of claim 8 also favor the filling and the operating ventilation by discharging the residual air to the air separation tank, which remains when filling in the return water tank of cross-flow coolers or which collects there during operation. A passage of cold coolant is prevented in normal warm-up operation and thus an influence on the warm-up time is avoided. On the other hand, by opening the ventilation valve after warming up at a coolant temperature above the ambient temperature of, for example, 60 ° C in the return water tank, fuel gas leaks and residual air volume parts which are preferably collected therein are immediately discharged into the air separation container. From this, they flow to the atmosphere via the expansion tank when the pressure relief valve is open, especially since the excess pressure in the cooling circuit accelerates to the opening values of the pressure relief valve due to penetrating fuel gas leaks. Any remaining leakage volume parts are discharged via the expansion tank when the cooling circuit cools below the opening temperature of the ventilation valve according to claims 1 and 6, and at the same time the cooling circuit is constantly kept at atmospheric pressure as long as the closing temperature of this temperature-controlled ventilation valve falls below remains. Negative pressure in the cooling circuit and consequent penetration of air - e.g. B. about the Seal of the coolant pump is also excluded.

The features of claim 9 contain a functional and structurally particularly advantageous embodiment of the vent / degassing valve according to claim 8 in accordance with the vent valve according to claim 7, apart from the exclusive float arrangement and the reverse temperature control with opening instead Closing above the switching temperature of the valve. Instead of the float, a conventional closing spring and a separate ball or Schwengel vent valve can also be used, as is common in coolant thermostatic valves.

The features of claim 10 enable a constant flow pressure control of the pressure relief valve in the closure cover without the pressure increase in the flow area increasing with the pump delivery rate without having to adapt this separately to the necessary highest pressure opening value of the respective application. At the same time, the overpressure valve for the forward and return areas can be designed with the same overpressure opening value, which additionally favors the construction effort and avoids or at least reduces the variety of valve and closure covers for different engine and vehicle models.

The series connection of a further pressure relief valve provided according to claim 11 keeps the coolant pressure in normal operation even when fuel gas leakage is introduced into the coolant at a relatively low level. Only when the operating load and ambient temperature are high is the temperature-dependent additional pressure valve switched to the higher coolant pressure that is then required. Unnecessary high overpressure loads of the cooling circuit due to fuel gas leaks are thereby avoided and at the same time a largely continuous discharge of these fuel gas volume parts from the cooling circuit is achieved, which additionally reduces their harmful effect on the coolant additives.

As an alternative and / or in addition to the valve control of the line connection from the air separation tank to the expansion tank according to claims 1 and 6, the claim 12 includes a manually operable venting device which without - with the venting rotary position of the closure cover - or with very little construction effort - with a vent screw - In addition to the switching temperature of a thermal valve, cooling circuit ventilation is possible in particularly difficult conditions. Here, too, the venting process is limited to operating the machine at a rapidly changing speed, possibly with short switch-off pauses, in order to allow any air bubbles to accumulate at the pump inlet to the pump pressure side.

The features of claim 13 make it possible in a simple manner and secured against pressure overloading of the expansion tank to ensure the projected operating pressure of the cooling circuit even when the cooling circuit is closed at such a high coolant temperature during maintenance and / or repair work that the required pressure build-up is no longer possible due to thermal expansion of the coolant. This is particularly true in connection with the manually operated venting device according to claim 12 and difficult venting conditions in the case of cooling circuits which are inadequately designed in this regard. An additional one Construction costs for the proposed construction details can be completely avoided according to the training options according to claims 14 and 15 compared to known cooling circuits, since only existing known components are to be dimensioned accordingly, namely the pressure resistance of the expansion tank, the attachment of the associated filler cap and the dimensions of the connector for the associated overflow hose.

Due to the features of claim 16, incorrect operation during the maintenance of the cooling circuit is largely ruled out in that an unintentional release of the cooling circuit overpressure is prevented by inadvertent opening of the associated sealing cap instead of the filling cap for the atmospheric expansion tank. The cap is only accessible when the fill cap to be removed for refilling is open. A removal of the closure cover is then no longer to be expected for the maintenance personnel, in particular in conjunction with corresponding customary warning lettering on the closure cover, with a probability bordering on certainty. The construction effort of this measure only includes a slight enlargement of the filler cap, which can have a shape and color which is favorable for the engine compartment styling.

The features of claim 17, especially in vehicles with an existing heating circuit auxiliary pump with the little additional construction of a changeover valve and its control parts, the build-up of an overpressure reaching the overpressure opening value of the overpressure valve when reheating the coolant after switching off the machine from a high operating load avoided by hot spots of the Cooling jacket locally excessive heating of the resting coolant can occur. Vapor bubbles that form at the hot spots are continuously flushed away by the coolant flow generated by the heating circuit auxiliary pump, and the remaining coolant is quickly condensed again. In this way, an otherwise occurring increase in volume of the coolant in the cooling circuit is minimized, which brings about an overpressure corresponding to the local coolant temperature and the associated boiling pressure in the entire cooling circuit. Excessive expulsion of coolant through the pressure relief valve into the expansion tank and even after it has overflowed is thus excluded.

Characteristic individual features of claims 1 to 17 already belong to the prior art from numerous publications. However, a targeted combination of these in accordance with the generic type with the characterizing features of the claims is neither suggested nor derivable without inventive step. In particular, reference is made to the maintenance instructions for the car model Nissan ZX-300 model series Z 31 - sheets LC-8 / -13 and / 18, DE-PS 25 09 995 and 28 17 976, DE-GM 1 931 736, the GB-PS 1 415 698, the EP-PS 0 101 339, and the US-PS 2,195,266, 3,047,235, 3,284,004, 4,167,159 and 4,489,883 pointed out.

Fig. 1

einen Kühlkreis für Brennkraftmaschinen einschließlich Heizkreis für eine Fahrzeuginnenraum-Heizung als Blockschaltbild,

Fig. 2

den gemäß Fig. 1 angeordneten und ausgebildeten Füllstutzen mit Verschlußdeckel und Luftabscheidebehälter im Schnitt,

Fig. 3

den Hochpunkt des Rücklauf-Wasserkastens eines Querstromkühlers mit Entlüftungsventil gemäß Fig. 1,

Fig. 4

ein Diagramm des temperaturabhängigen Druckverlaufes im Kühlkreis nach Fig. 1,

Fig. 5 - 10

eine Übersicht mehrerer erfindungsgemäßer Kühlkreis-Alternativen in schematischer Darstellung und

Fig. 11

einen Füllstutzen gemäß Fig. 1 in baulich vereinfachter und fertigungsgünstigerer Ausbildung im Schnitt.

Preferred embodiments of the invention are shown in the drawing. Show it:

Fig. 1

a cooling circuit for internal combustion engines including a heating circuit for a vehicle interior heater as a block diagram,

Fig. 2

1 arranged and designed filler neck with sealing cap and air separation container in section,

Fig. 3

the high point of the return water tank of a cross-flow cooler with a vent valve according to FIG. 1,

Fig. 4

2 shows a diagram of the temperature-dependent pressure curve in the cooling circuit according to FIG. 1,

5 - 10

an overview of several cooling circuit alternatives according to the invention in a schematic representation and

Fig. 11

a filler neck according to FIG. 1 in a structurally simplified and less expensive design in section.

An internal combustion engine 1 contains a cooling jacket 2 (arrow), into which the coolant is conveyed under pressure by a coolant pump 3. At the outlet 4 of the cooling jacket 2, a cooler flow 5 is connected with a free passage to a cross-flow cooler 6 and opens into its flow water tank 7. A short circuit 8 branches off from the cooler flow 5 to a mixing thermostat 9. A return line 11 also leads from the return water tank 10 out of the cooler 6 into the thermostat 9. A pump suction line 12 connects the thermostat 9 to the suction side 13 of the pump 3.

At a high point as close as possible to the engine 5 'of the cooler flow 5, a bypass vent line 14 is connected, which is unthrottled in a flow pressure control chamber 15 and via a throttle point 16 opens into the bottom area of an air separation container 17. This mouth is turned away from the bottom area to secure the air separation from the mouth of the bypass vent line 14, which leads to the suction side 13 of the pump 3. An electrical level sensor 18 is arranged on the underside of the air separation container 17, which controls a warning instrument in a commercially available design in the event of an air and / or gas accumulation in the air separation container 17 which endangers the function.

The air separator tank 17 concentrically surrounds the area of the high point 5 'of the cooler flow 5 and the area of the bypass vent line 14 connected to it increasing (Fig. 2). This area of the bypass vent line 14 is at the same time designed as a filler neck 19 and partially arranged within a closure cover 20. In the direction of the ventilation bypass flow, the filler neck 19, the control chamber 15 and the throttle point 16 in the closure cover 20 and the line part in the bottom region of the air separation container 17 are flowed through in succession. The usual overpressure and underpressure valves 21 and 22 are arranged in the closure cover 20, but are substantially modified and functionally developed according to the invention.

The pressure relief valve 21 is on the one hand directly controlled via a line connection 21 'to the high point of the air separation container 17 from the overpressure in the latter and on the other hand indirectly by means of a control membrane 15' from the supply overpressure in the control chamber 15 and in both cases opens the line connection 21 'from the high point of the Air separation container 17 to the atmosphere.

The vacuum valve 22 is installed in the usual way in the valve housing of the pressure relief valve 21 and at the same time is designed as a temperature and alternatively additionally float-controlled vent valve (FIG. 2). Except when there is negative pressure in the air separation container 17, the vacuum valve 22 closes by the interaction of a bimetallic snap plate spring 23 with an O-ring seal on the one hand and alternatively with a spring 24 or a float 24 'on the other hand only if both the switching temperature of the bimetal -Feather 23 exceeded and the air separation container 17 is vented, because the bimetallic spring 23 is always switched to the closed position only when it is acted upon by coolant at a sufficiently high temperature. Bleeding is additionally promoted. A float also opens the vent valve when the air system is renewed, regardless of its switching status, as long as there is no pressure difference and leads to even more residual venting. An overpressure in the air separation container keeps the bimetallic spring 23 in the closed position even when air and / or fuel gas accumulates in the air separation container 17, thereby preventing a dangerous drop in the coolant pressure during operation of the machine 1. On the other hand, with each cooling and the next cold start with warm-up, the air separation container 17 and thus the entire cooling circuit are completely vented. Furthermore, due to its switching temperature (50 ° C. in FIG. 4), the bimetallic spring 23 closes the cooling circuit only at a temperature of the coolant displaced from the air separating container 17 by the vacuum valve 21, at which the build-up at idle speed and the machine being switched off effective static system pressure SD by further thermal expansion of the coolant in cooperation with the elasticity of the entire cooling circuit, in particular of the coolant hose lines, in relation to the pump cavitation limit KG and the coolant boiling limit SG, there is a sufficient profile of the lowest possible pump suction pressure PD at maximum speed (FIG. 4). In cooperation with the dimensioning rule for the pressure relief valve 21 known from DE-OS 32 26 508, both a dangerously low pump suction pressure PD and an unnecessarily high cooler supply pressure VD are thus excluded.

A line connection 25 to the atmosphere is led to the overpressure and underpressure valves 21 and 22 via a temperature-controlled additional overpressure valve 26 to the bottom area of an atmospheric expansion, storage and air-blocking container 27. This further pressure relief valve 26 contains - like the vacuum valve 22 - a bimetallic snap disc spring 28 which interacts with an O-ring seal and is pressed against the seal by a cone spring 29 which determines the pressure value. The housing of this pressure relief valve 26 is arranged in thermal connection with the flow line 5 and / or the housing of the air separation container 17 in such a way that the temperature of the coolant there acts on the bimetal spring 28. Their switching temperature is set approximately according to the upper limit of the control temperature range of the thermostat 9, usually approximately 90-100 ° C. The sum of the overpressure values of the overpressure valves 21 and 26 thus only comes into effect (FIG. 4) if the thermostat control range is exceeded, that is only if high ambient temperature and high engine load occur at the same time. Even due to fuel gas leaks at high engine loads, the cooling circuit is not unnecessarily loaded with excessive system pressure SD, flow pressure VD and pump suction pressure PD, but the fuel gas leaks are continuously increased by the only effective first pressure relief valve 21 excreted via the expansion tank 27 to the atmosphere.

The expansion tank 27 contains a part of its volume a coolant supply 30 and the rest of an expansion volume 31. The filler cap 32 of the expansion tank 27 is equipped with a conventional locking bead attachment, which, however, is coordinated according to the invention such that an overpressure valve function is achieved by detaching the cover 32 at a certain excess pressure in the expansion tank 27. To introduce the overpressure from z. B. 1 bar in the expansion tank 27 and the vacuum valve 22 also in the entire cooling circuit, the cover 32 is provided with a hose connector 33, which both carries an overflow hose 34 and after its removal for the connection of a tire inflation device or an air pump suitable is. In this way, the functional reliability of the cooling circuit can be guaranteed in a simple, cost-effective manner even after it has been closed while the machine is already at operating temperature, in particular after a lengthy venting process or after a pressure-releasing process that requires repair and subsequent high-load operation at a high ambient temperature.

At the high point 10 'of the return water tank 10 of the cross-flow cooler 6, which forms a particularly effective air and leakage gas collection point, a further vent line 37 is connected to the bypass vent line 14 via a vent valve 35 and a throttle point 36. The vent valve 35 in turn consists of a bimetallic snap disc spring 38 which interacts with an O-ring seal and which is brought into and out of operation by a float 39 when coolant or air or fuel gas is at the high point 10 ' is present. The bimetal disc spring 38 has a switching temperature of about 60 ° C, so that at normal operating temperature of the cooling circuit there is a constant venting and degassing bypass flow to the air separation container 17. In contrast, during machine warm-up, the vent valve 35 is always closed after the outflow of air or fuel gas, so that the warm-up of the machine is not prolonged by a cooling effect of this vent stream.

A vehicle interior heater with a left and right heater heat exchanger 42 and 43 and a left and right heater control valve 44 and 45, respectively, is connected to the cooling circuit via a heater supply and return line 40 and 41, respectively and an additional electric heater pump 46 connected in a conventional manner. The heating flow line 40 branches off from the cooler flow 5 and the heating return line 41 opens into the elevated thermostat 9. Between the additional heating pump 46 and the control valves 44 and 45, a changeover valve 47 is arranged, which by means of a not shown electrical control circuit when the machine 1 is turned off at a high operating temperature, the heating flow line 40 is reversed into a cylinder head return line 48. The coolant flow through the hot cylinder head that can be achieved when the machine 1 is switched off immediately flushes away coolant vapor bubbles that occur at hot spots and achieves their immediate subsequent condensation in the further coolant flow, as a result of which local vapor bubble accumulations with corresponding pressure build-up in the entire cooling circuit and consequent ejection of coolant, in extreme cases even up to overflow of the expansion tank 27 is avoided.

FIGS. 5 to 10 show different assignment options for the cooling circuit components according to the invention using the same basic principle.

In Fig. 5, the arrangements of the air separation tank 17 at the high point 5 'of the cooler flow 5, the atmospheric expansion tank 27 in a separate design and the vent valve 35 on the return water tank 10 are shown in accordance with FIGS. 1 to 3.

In Fig. 6, on the other hand, the cooler flow 5 at its high point 5 'is only equipped with a filler neck 19 and a valveless cap 20'. The air separator tank 17 is attached or molded to the return water tank 10 and combined with the expansion tank 27. Whose filling cover 32 has a molded cover 32 'for the closure cover 20 of the expansion tank 27, which largely precludes incorrect operation when refilling the expansion tank 27 and thus a loss of overpressure when the coolant is warm.

7 to 10, the air separation tank 17 and the atmospheric expansion tank 27 are combined in accordance with FIG. 6, but are arranged separately from the cooler 6. The bypass vent line 14 in Fig. 7 at the high point 5 'of the cooler flow 5, in Fig. 8 at the high point of the flow water tank 7 and in Figs. 9 and 10 directly at a high point of the cooling jacket 2 of the machine 1st connected.

9 and 10, an additional filling line 19 'is branched off from the cooler flow 5, which is completed by the cap 20 immediately. In Fig. 9, a filler neck 19 is arranged next to the air separation container 17, while in Fig. 10 the filling line 19 'within the air separation container 17 connects to the closure cap 20.

The hydraulic connection of the functional elements is identical in all versions with FIGS. 1 to 3.

In FIG. 11, in contrast to FIG. 2, the cooler inlet 5 on the one hand and the air separation container 17 and the filler neck 19 on the other hand are not arranged coaxially and concentrically with one another but mutually intersecting and arranged side by side. - The filler neck 19 can also be arranged centrally within an annularly branched section of the cooler inlet 5, the insert 49 closing a connection opening between the filler neck 19 and the radiator inlet 5, which is then also circular. - The filler neck 19 opens in both cases down into the coaxial air separator tank 17 and to the side in the cooler flow 5, so that each a large connection opening 17 'and 5' are available with the cap 20 removed for rapid filling. The closure cover 20 closes in addition to the filling opening of the filler neck 19 and the connection openings 17 'and 5' against each other. For this purpose, a hollow cylindrical insert 49 closes tightly on the underside of the closure cover 20 and is supported with its lower end face by an O-ring 50 at the upper edge of the air separation container 17. The interior of the insert 49 continues the air separation container 17 upwards towards the underside of the closure cover 20. The inner structure of the closure cover 20 corresponds to that of FIG. 2, but its flow pressure control chamber 15 is in reverse Direction from the outside from the high point 5 'of the cooler flow 5 radially inward and axially downward through the corresponding throttle point 16 and an adjoining part of the bypass vent line 14 flows through, which is integrally formed in the insert 49 as a coaxial tube 51. The underside of the closure cover 20 is connected via radially distributed openings 52 to its internal pressure and vacuum valves 21 and 22 (FIG. 2), so that air and gas accumulations always flow out first through the valve openings from the high point of the air separation container 17 can. A hose connection piece 53 for a hose 54 with a relatively large cross-section is formed on the underside of the air separation container 17, both of which additionally expand and improve the volume of the air separation container 17 and thus also its function.

Via side connections 55 and 56, a float chamber 57 of an electrical coolant level sensor 18 is connected at the bottom to the air separation container 17 and at the top to the valves 21 and 22 in the closure cover 20. Another vent line 37, which starts from the return water tank 10 of the cross-flow cooler 6 (FIGS. 1 and 3), can be connected to the float chamber 57 in a simple manner, since its connections are also suitable as an effective venting and degassing volume. In addition to the plug connections 55 and 56 shown, a one-piece design with the filler neck 19, the air separating container 17 and the cooler flow section (5) can also be advantageously carried out.

To protect against malfunctions of the valves 21 and 22 in the closure cover 20 are on the underside of the insert 50 and in the upper region of the float chamber 57 each a fine screen 58 is arranged, which are acted upon exclusively by the coolant flowing in and out through the valves 21 and 22 and are therefore not subject to unnecessary contamination from the circulating coolant.

1, the filler cap 32 (FIG. 1) of the expansion tank 27 can be equipped with corresponding overpressure and underpressure valves which replace the valves 21 and 22 in the closure cover 20 of the filler neck 19 or are in line with these, so that there is an overpressure reservoir with air cushion. The mode of operation of the air separation container 17 with improved filling and venting and shortened warm-up of the machine cooling circuit is also used.

Claims (17)

1. A liquid cooling circuit in engines and machines, more particularly internal combustion engines, comprising an air separator (17) which is disposed in a branch vent passage (14) from a high point (5') in the radiator inflow (5- comprising the engine cooling jacket (2) and the radiator inlet tank (7)) to the radiator return flow (11 - comprising the radiator outlet tank (10) and the suction side (13) of a coolant pump (3) at the inlet of the engine cooling jacket), the air separator being provided at its high point with a filling nozzle (19) comprising an inlet opening and a closure cover (20), the high point of which is connected by conduits via an excess-pressure valve (21) and a negative-pressure valve (22) in the closure cover (20) to the bottom region of an atmospheric compensating tank (27), at least one excess-pressure valve (21) limiting the pressure in the air separator (17) and, by means of a control line, in the radiator inflow (5), characterised in that the air separator (17) is disposed at the high point (5') of the radiator inflow (5), the filling nozzle (19) has openings connecting to the high points of the radiator inflow (5) and of the air separator (17), the closure cover (20) closes the filling opening of the nozzle (19) and also the connecting openings from one another, a throttled flow connection (throttle 16) forming part of the branch vent passage (14) leads from the high point (5') of the radiator inflow (5) to the near-bottom region of the air separator (17), the closure cover (20) has a direct connecting passage serving as a control line, between the connecting opening of the filling nozzle (19) and the radiator inflow (5) on the one hand and the excess-pressure valve (21) limiting the pressure in the radiator inflow (5) and the servomotor (control diaphragm 15') thereof on the other hand, and a temperature-controlled vent valve (thermal catch spring 23) is disposed in the flow connection from the high point of the air separator (17) to the compensating tank (27) and has a closed-switch temperature which is below the thermostatically-controlled normal operating temperature of the coolant and above which the pressure curve of the coolant, depending on thermal expansion, elasticity and pump operation, at the suction side (13) of the coolant pump (3) is such as to ensure cavitation-free operation.
2. A cooling circuit according to claim 1, characterised in that the filling nozzle (19) opens directly into a high point (5') of the radiator inflow (5), the air separator (17) concentrically surrounds the filling nozzle (19) and, via their connecting opening, its high point is connected to the valves (21, 22) in the closure cover (20), and the radiator inflow (5) extends through the air separator (17) in the region of the mouth of the filling nozzle (19).
3. A cooling circuit according to claim 1, characterised in that the air separator (17) has a coolant level pick-up (18).
4. A liquid cooling circuit in engines and machines, more particularly internal combustion engines, comprising a filling nozzle (19) and a filling cover (20) in the filling opening thereof at a high point (5') in the radiator inflow (5), a compensating tank (27) with a filling cover (32) and expansion and storage spaces (30, 31), an excess-pressure valve (21) and a negative-pressure valve (22) in one of the filling covers (20, 32) and a connecting passage (25) from the high point of the filling nozzle (19) to the bottom region of the compensating container (27), characterised in that an air separator (17) is disposed on the filling nozzle (19) of the radiator inflow (5) and is disposed in a vent branch passage (14) from a high point (5') of the radiator inflow (5) to the radiator return flow (11), the cross-section being constricted (16) between the radiator inflow (5) and the air separator (17), and the high point of the separator being connected to the connecting passage from the filling nozzle (19) to the bottom region of the compensating tank (27).
5. A cooling circuit according to claim 4, characterised in that an excess-pressure valve (21) in the closure cover (20) is controlled, via a control line, by the pressure in the radiator inflow (5).
6. A liquid cooling circuit in engines and machines, more particularly internal combustion engines, comprising an air separator (17) disposed in a branch vent passage (14) from a high point (5') in the radiator inflow (5) to the radiator return flow (11), the high point of the air separator having a filling nozzle (19) with a filling opening and a closure cover (20), the high point of which is connected by conduits via an excess-pressure valve (21) and a negative-pressure valve (22) in the closure cover (20) to the bottom region of an atmospheric compensating tank (27), the vent passage (14) having a constriction (16) before the place where it opens into the air separator (17), characterised in that a temperature-controlled vent valve (23) is disposed in the flow connection (25) from the high point of the air separator (17) to the compensating container (27) and has a closed-switch temperature which is below the thermostatically-controlled normal operating temperature of the coolant and above which the pressure curve of the coolant, determined by thermal expansion, elasticity and pump operation, at the suction side (13) of the coolant pump (3) is such as to guarantee cavitation-free operation thereof.
7. A liquid cooling circuit in engines and machines, more particularly internal combustion engines, comprising an atmospheric compensating tank (27) disposed downstream of excess-pressure, negative-pressure and vent valves (21, 22) to atmosphere, characterised in that the temperature-controlled vent valve (23) is also constructed as a negative-pressure valve (22) in the closure cover (20) and its valve body constitutes a thermal catch spring which co-operates with a sealing ring constituting a valve seat and opening and is urged towards the sealing ring by a spring (24) and/or a float (24'), the spring (24) or float (24'), the valve body (23) and the sealing ring being coaxially disposed in the aforementioned sequence, vertically above one another, in the body of the excess-pressure valve (21), with a valve opening disposed parallel to the valve opening thereof.
8. A cooling circuit according to claim 1, 4 or 6, characterised in that an additional vent passage (37) opens into the air separator (17) and extends from the high point (10') of the radiator outlet tank (10) and,at the connection there, has at least one venting or degassing valve (25) controlled by air or gas on one side and by temperature on the other side and opening when air and/or gas arrives or when the run-up temperature of the cooling circuit is above a preset value.
9. A cooling circuit according to claim 8, characterised in that the venting or degassing valve (35) has a closure means in the form of a float (39), a valve body in the form of a thermal catch spring (38) and a valve seat and opening in the form of an O-ring, which are disposed in the aforementioned sequence coaxially and vertically above one another in a valve chamber.
10. A cooling circuit according to claim 1 or 5, characterised in that the connection of the control line (14) to the radiator inflow (5) comprises an ejector-like structure such that the excess pressure in the radiator inflow (5), which increases with the speed of the engine or the delivery of the coolant pump, is purposively changed and introduced into the control line (14).
11. A cooling circuit according to claim 1 or 6, characterised in that an additional excess-pressure valve (26) which closes in dependence on temperature is connected in series with the excess-pressure valve or valves (21) in the flow connection (25) between the air separator (17) and the compensating tank (27), the switching temperature of the additional valve being above the thermostatically controlled normal operating temperature of the coolant, and the excess-pressure valves (21, 26) have opening values adjusted to one another such that,at the switching temperature of the additional excess-pressure valve (26) and simultaneously at the maximum engine speed or pump delivery rate, the excess pressure at the pump outlet (13) is sufficiently far from the pump cavitation limit, and at the maximum planned operating temperature the aforementioned condition is achieved by the additional opening value of the excess-pressure valves (21, 26) and this value is above the boiling pressure corresponding to the maximum locally-occurring planned coolant temperature after switching off the engine (1) after a heavy load.
12. A cooling circuit according to claim 1 or 6, characterised in that the flow connection (25) between the air separator (17) and the compensating tank (27) comprises a manually operated vent device which, in its vent position, opens by means of a vent screw or a rotary vent position of the closure cover (20) of one of the excess-pressure, negative-pressure, venting and/or thermal valves (21, 22 and 23) or a vent opening parallel thereto.
13. A cooling circuit according to claim 1, 6 or 12, characterised in that the compensating tank (27) has a connection (33) above its filling-level range for temporarily conveying compressed gas on to the surface of the coolant so as to convey coolant through the flow connection (25) to the air separator (17) and through the negative-pressure, venting and/or thermal valves (22, 23) and the vent opening into the cooling circuit and build up a corresponding pressure therein.
14. A cooling circuit according to claim 13, characterised in that the compensating tank (17) is made pressure-resistant up to approximately the average cooling-circuit operating pressure and has an excess-pressure safety valve.
15. A cooling circuit according to claim 14, characterised in that the filling cover (32) of the compensating tank (27) is constructed in the form of an excess-pressure safety valve and is secured to the compensating tank (27) so as to be released when the pressure is excessive, a connecting nozzle (33) with a removable overflow pipe (34) serving as a connection for supplying gas under pressure.
16. A cooling circuit according to claim 1, 4 or 6, characterised in that the air separator (17), the compensating tank (27) and their filling covers (20, 32) are respectively disposed directly adjacent one another, and the filling cover (32) of the compensating container (27), when in the closed position, overlaps the filling cover (20) of the air separator (17).
17. A liquid cooling circuit according to any of claims 1, 4 and 6, characterised in that a heating branch circuit (40, 41) which branches from a high outlet from the cooling jacket contains an additional electric pump (46) and a heating device (42, 43), the additional pump (46) is switchable on when the machine (1) is switched off when hot, provided the coolant and/or component is at a minimum temperature at that time, a simultaneously-actuated changeover valve (47) conveys the coolant from the cooling jacket (2) not into the heating device (42, 43) but into the cooling jacket (2) through an inlet opposite the outlet, and the flow of coolant through the cooling jacket (2), more particularly through the cooling jacket of the cylinder head of internal combustion engines, is dimensioned so as to ensure that the intensity at hot spots is sufficient to detach and condense steam bubbles.

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