DK148544B - FRESH WATER COOLING SYSTEM FOR COMPRESSOR-LED COMBUSTION ENGINES WITH AIR INTERNAL COOLER - Google Patents

Description

U8564

The invention relates to a fresh water cooling system for compressor-fed internal combustion engines, preferably of medium speed diesel engines, which system, in addition to the cooling caps of the engine cylinders and a fresh water cooler, also comprises an air intercooler for cooling the combustion air, after leaving the compressor in said cylinder said cooling system having a high temperature circuit comprising said engine cooling caps, and further comprising a circulation pump disposed in said cooling water direction, a low temperature circuit comprising said air intermediate cooler, and a heat exchanger circuit comprising said fresh water cooler wherein said connection between said various circuits in such a way that the hot cooling water in the high-temperature circuit, after leaving the engine, is branched into three parts, the first part being passed through the heat exchanger circuit through the fresh 1C * water cooler, the second part passing through the low-temperature circuit through the air intermediate cooler, and the third part is returned to the engine cooling shells after being mixed with the first and the breath parts.

A fresh water cooling system of this kind is known from the specification

PO

to German Patent Specification No. 2,610,378. According to this prior art, after leaving the fresh water cooler, the first cooling water part is divided into two partial streams, one of which is directed directly back to the engine cooling sheath, while the other partial flow is directed to the air intermediate cooler. Before passing this second partial flow to the air intermediate cooler, it is mixed with the second cooling water part which is branched directly from the cooling water flow flowing from the engine cooling shells. This mixture takes place in a charge air cooling water control valve controlled by a sensor which senses the temperature of the charge air after the air intermediate cooler. After the location of the second cooling water part is branched from the cooling water stream flowing from the cooling shells of the engine, the remainder of this flow is divided into said first and said third cooling water part by means of a cooling water control valve controlled by a sensor which senses the temperature of the cooling water. leaving the engine cooling hoods. The third cooling water part is passed back to the engine cooling sheath through a 35 bypass line, while the said cooling water part as mentioned is directed to the fresh water cooler for therefrom to be divided into the two mentioned partial streams.

The fresh water cooling system of the present invention is peculiar in that it is arranged so that the other party

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2 is mixed with the first batch after the fresh water cooler in proportions determined by a first temperature regulator located at the intersection of these two circuits, and then, at constant temperature via the low temperature circuit, to be passed through the air intermediary and 5 then by a second temperature regulator to be mixed with the cooling water of the one third of the branched parts of the high temperature circuit in proportions determined by this second temperature controller to then be re-supplied at constant temperature to the high temperature circuit, and via this engine's cooling caps.

Hereby it is obtained that the inlet temperature of the cooling water supplied to the air intermediate bunker and that the inlet temperature of the cooling water supplied to the engine cooling hoods is constantly regulated in such a way that they remain stable within each set of very limited intervals. The value of this in terms of engine wear cannot be overstated.

In addition, the system offers significant advantages when starting the system, since the cooling water will then be circulated past the fresh water boiler until the operating temperature is reached. A further advantage of the system according to the invention is that it is based on the use of conventional thermostatic valves, while the charge air cooling water control valve, which according to the said German specification controls the temperature of the cooling water supplied to the air intermediary and whose temperature is controlled depending on the temperature. of the air supplied to the engine must be of a much more complicated construction with a temperature sensor located at a distance from the valve itself, which in turn controls the valve in question.

The invention will now be explained in more detail with reference to the drawing, in which fig. 1 shows a simplified diagram of an embodiment of the cooling water system according to the invention; FIG. 2 in section and side view a combined ventilation, expansion and pressure holding tank belonging to the system, ° 9 fig. 3 characteristics of the entire system measured by a special engine.

35 In FIG. 1, a dash-dot line indicates which details are suitable for mounting directly on the motor itself or which may be conveniently included therein. These are therefore conveniently supplied as a unit from the factory. From a cooling water jacket 1, from which in this case four cooling streams flow out, the cooling water 3 follows a main flow 2 to a venting chamber 4 which is placed at the top of a combined venting, expansion and pressure holding tank 3. Below this chamber 4 and separated from this by means of a partition 5 lies the expansion and pressure holding chamber of the tank 6. The more detailed design of the tank will be described in more detail in connection with fig. 2. After the venting in the chamber 3, the cooling water leaves this in the form of a main flow 7 passing through a flow adjustment device in the form of a flow adjustment valve 8. At a first branch point 9 located after the flow adjustment valve 8 and a second further position located in the flow direction. branch point 10, the cooling water flow is divided into three parts; namely, a first party 13, a second party 11, and a third party 15.

The first part 13 is branched at the branch point 10 to which the cooling water arrives after the second part 11 has been branched at the first branch point 9 and the third part 15 together with the first part 13 constitutes the cooling water flowing to the second branch point 10. The second part 11 is supplied via a first temperature controller Tj an air intercooler heat exchanger 12. In the temperature controller, the second part 11 is mixed with the first 20 part 13, which comes directly from a fresh water cooler 21, which is preferably located outside the engine. This second part 13 is branched as mentioned at the previously mentioned second branch point 10, and is therefore now returned after passage through the fresh water cooler 21. The temperature controller T1 is adapted to continuously supply the air-cooler 12 with a constant temperature cooling water stream 14. Thus, the temperature controller only determines the mixing ratio between the breath and the first cooling water part 11 and 13. At a second temperature controller Tg located immediately after the air cooler cooler 12, the cooling water flow from the air flour cooler is coupled to the third mentioned branch at cooling branch 10. Combined, the cooling water flow 14 and the third cooling water part 15 again give a main flow 16 with the same flow rate as the main flow coming from the engine cooling hoods 2. Also the temperature controller Tg is adapted to adjust the mixing ratio 35 between the different tempered streams 14 and 15. The cooling jacket 1 of the motor will thus continuous water could be fed with constant temperature. On its way to the engine cooling hoods, the cooling water stream 16 passes a cooling water pump 17. It is this pump which together with the aforementioned power adjustment valve 8 determines the

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4 total cooling water flow through the system. From the structure outlined above, it will be seen that each change of cooling water temperature at some point in the system involves a change of the different cooling water parts 11, 13 and 15 with respect to their proportional size, which gives a constant holding of the temperature in the currents 14 and 16.

This means that a near-constant air temperature of the air driven into the engine is obtained, depending on an appropriately selected pump characteristic, combination and selection of the thermostat-10 valves' control ranges, as well as the choice of cooling area and K-value characteristics of the moisture intermediate cooler (see the attached characteristics in Fig. 3).

In FIG. 1, there is also a pressure holding connection 18 and two venting connections 19 and 20 respectively for the air intermediate cooler 12 15 and the fresh water cooler 21. A raw water line for the fresh water cooler 21 is designated 22. The raw water circuit includes both a circulation pump and suitable components for controlling the raw water flow. is not included in the drawing, since it is primarily intended to illustrate the fresh water cooling system.

20 Pi the same way, lubricating oil coolers and various safety and control systems, which are usually included in an engine installation of this type, are omitted to make the figure as clear as possible.

In the drawing, however, there is indicated a cooling water preheater 25, which is connected in its own circulation circuit 23 with separate 25 cooling water pump 24.

This circuit is used during heat retention and, alternatively, for a short time before starting the engine in extremely cold conditions.

The FIG. 2, as previously mentioned, consists of an upper venting chamber 4 and a lower expansion and pressure holding chamber 6 which is separated by a partition 5. The chamber 6 is accessible from the outside through a pressure-tight lid 26 , which is disposed on top of the tank, and which is provided with a pressure regulator, and which is further arranged over a nozzle 27 which passes through the upper chamber 4 and down to the lower chamber. The normal water surface in the lower chamber is drawn in the drawing. The vent chamber located above is, as shown in the drawing, completely filled with cooling water in the normal case.

The upper chamber 4 has an inlet 28 and an outlet 29. The inlet 148544 5 and the outlet open into different parts of the chamber, and between them is arranged a guide surface 30 extending transversely of the chamber.

The cooling water is thereby forced to follow the path indicated in the drawing with a dashed pill line. By lowering the impulse 5 of the water flow by the change of direction caused by the control plate, and by the change to a larger cross-sectional area in the tank, a transition to laminar flow is achieved, thereby providing an efficient venting of the cooling water flow.

Exhausted air will collect in the upper part of the chamber and, through TO, a vent pipe 31 has access to the tank's lower chamber. The conduit 31 has an opening 32 in the upper part of the chamber 4 and an opening 33 below the liquid surface in the chamber 6. In the drawing, a cleaning plug 34 is also drawn. In the inlet 28 there is a vent hole 35 for preventing an air accumulation in the pipe bend during the pipes 15 system. Thus, in the lower chamber 6 of the tank, whose gas part (air) is compressed and accommodates the expansion as the water in the system is heated, the pressure holding line 18 and the vent seals 19 and 20, respectively, from the air-meal cooler 12 and fresh water cooler 21 (cf. Fig. 1).

20 In the FIG. 1, the safety surface of the expansion and pressure holding chamber 6 is not shown in further detail, which must be kept within limited variations. In the tank, for this purpose, a float 36 can be connected which at a low level closes a level switch for supplying additional cooling water to the system from a conventional branch tank (not shown) and another swimmer 37 which, at normal level, breaks the level switch and finally an alarm swimmer 38 which at an extremely low level triggers an alarm.

In FIG. 2, a level scale 39 is shown next to the tank 3.

This level scale corresponds to a 30 level reading tube located on the outside of the tank 3 which is connected to the expansion and pressure holding chamber. The vent chamber 4 is further provided with an air outlet valve 40. The level scale 39 has three markings "low", "high" and "fill". In normal operation, the level of the chamber 6 must be within the normal operating range between the markings for high 35 and low water level respectively. The level mark "fill." is used in filling an empty system where the air outlet valve 40 must also be open. When cooling water is filled up to this level and valve 40 is closed and the system is started, the water in the system is redistributed so that the upper chamber 4 is filled and an air-filled expansion space is formed in the lower chamber 6.

Moreover, as regards the general operation of the fresh water cooling system of the invention, it can be noted that the capacity of the water pump 17 is adjusted by the flow adjustment valve 8 such that 5. a desired temperature rise over the engine is achieved at full power.

This also increases the pressure level in the jacket cooling, so that the temperature limit for vapor formation is increased, thereby avoiding such vapor formation on the highly heat-generating surfaces of the engine. The flow adjustment valve 8 may consist of a lockable throttle valve or a fixed 10 throttle disk.

The temperature controller mixes high-temperature water with cold water from the fresh water cooler 21 to constant inlet temperature for the air intermediate cooler 12.

The temperature controller Tg mixes high and low temperature water to 15 constant inlet temperature in the high temperature circuit (jacket cooling).

When the engine is started, the temperature controller Tg briefly controls water circulation through the high-temperature circuit alone until the operating temperature is reached.

However, some preheating effect in the air intercooler 12 is achieved partly by a small connection hole in the elements of the temperature controllers and partly by the air intercooler 12's vent line 19. As soon as the engine has reached normal operating temperature, the temperature controllers Tg and T1 also control the water through the low-temperature aircooler, ie cool down 25 if the load requires it, or preheat if required.

When the operating temperature is also obtained in the low temperature circuit, the temperature regulator T ^ begins to dilute, at increased load, - water from the fresh water cooler 21 into the low temperature circuit and to give an increased cooling effect to the air intermediate cooler 21. As can be seen, the arrangement is such that increased cooling power is obtained in the air intercooler 12 for increasing load in the motor, causing the motor thermal load to be held down.

The pressure relief in the system is constituted by the static level of the water in the lower chamber together with the pressure rise by virtue of the expansion of the water and acts through the pressure holding conduit 18, which connects the lower chamber 6 with the suction side of the pump 17, which guarantees that no disturbances (cavitation) occur in the pump. Alternatively, an external pressure may be connected to the riser 27. This riser, which originates from the lower chamber 6, is further provided with a pressure-tight lid 26, which includes a pressure regulator which partly opens at a certain overpressure (safety function), and partly opens immediately below the atmospheric line (vacuum function).

In addition, it should be noted that the flushing in the vent pipe 31 from the upper chamber to the bottom (the expansion part), opens below the water level, so that no expansion of the expansion part occurs, which ensures minimal oxygen addition to the system water. In addition, the vent pipe 31 guide means that no air pockets are drawn up to the upper chamber when the engine is stopped, thereby making the assessment of the liquid level also safer.

The advantages of the system according to the invention should be summarized as follows: 15 - Only a cooling system for both jacket and air intermediate cooling, where all functions are built into the engine with the exception of the fresh water cooler.

Air meal limiting cooling efficiency increases with increasing engine load, keeping engine thermal load 20 down.

Preheating (tempering) of the suction air takes place at the start and during operation under Arctic conditions (condensation is avoided).

Continuous venting (degassing) is ensured.

25 - Corrosion-proof system as oxygen addition of water does not occur.

More uniform and cheaper materials for pipes, luminaires and air meal limb chillers can be used (compared to raw water cooling).

30 - Simplified operation.

- Essentially simplified engine installation.

Furthermore, the fresh water cooling system according to the invention is shown in FIG. 3 exemplified with relevant data for such a cooling system by a compressor-fed air-cooled "medium speed" diesel engine with 35 developed power and rpm according to the propeller law. The current motor, as shown in the diagram, was equipped with a directly powered water pump. The engine speed is marked on the X-axis and, moreover, the different curves dare speak for themselves.