ES2363702T3 - IMPROVEMENTS IN OR RELATED TO RADIATOR DEPOSITS. - Google Patents

Abstract

A radiator tank for a U-flow radiator, where the radiator tank comprises an internal bypass provided by an opening, where the opening has a valve operable between an open and a closed position, 5 characterized by the fact that the Valve can be molded entirely in the radiator reservoir.

Description

The present invention relates to an improved radiator for a motor vehicle and, more specifically, to a radiator tank provided with a shunt.

The configurations of the radiators normally used in the automobile industry are of three main types: cross flow, down flow and U flow. The selection of the type of radiator depends on several factors, one of which is that of the Vehicle distribution limitations as a whole. The U-flow radiator has the advantage that the inlet and outlet are within the same radiator tank. This circumstance provides more freedom to design the exact location of the entrance and exit.

An engine subjected to great effort (circulation through broken terrain, towing another vehicle or transit through unpaved areas) tends to overheat, if the coolant flow received through the radiator is insufficient. To meet these high flow requirements, the coolant pump may have to exceed its optimum operating parameters. These conditions can lead to the formation of partial voids in the coolant. ‘Cavitation’ is the name that is usually given to this phenomenon. When a mass of liquid in contact with a pump is subjected to a sufficiently low pressure, it can burst to produce a cavity behind the pump rotor blade. The resulting cavitation bubble will collapse as a result of the higher pressure of the surrounding medium. When the bubble collapses, the pressure and temperature of the vapor it contains will increase. The bubble will eventually collapse until it is reduced to a tiny fraction of its original size, at which time the gas inside will dissipate in the surrounding liquid and release a significant amount of energy in the form of a shock wave. This energy can degrade the internal surfaces of the pump and, especially, the rotor vanes.

In some vehicle configurations, cavitation is becoming an increasingly normal side effect of traffic conditions under high stress. Given the negative impact of cavitation on the duration of the affected engine parts, it is convenient to manage the flow of liquid through the radiator system in a way that prevents it from reaching the initial point of cavitation.

EP-0-053-003 discloses a system designed to address this problem. Said system consists of a tank for gravity feeding with a division provided with a valve that allows to manage the flow of liquid between both sides of the division.

JP-2005-325699 discloses another system designed to address this problem. This system consists of a pair of hoses connected respectively to protuberances on the inlet and outlet sides of a U-flow radiator reservoir. The hoses are joined to avoid the radiator, by means of an externally mounted valve assembly.

Said valve assembly comprises a valve that protrudes to penetrate the hoses, following a direction substantially orthogonal to the flow of liquid through the hoses. This system is designed to provide a shunt whose variable capacity depends on the degree of penetration of the valve into the tube.

Another solution applied in the automobile industry consists of a tube that directly connects the inlet and outlet hoses of the radiator. The diameter of the tube is selected to ensure that the proportion of liquid that avoids the radiator does not impair the operation of the cooling system as a whole.

The present invention is based on said concept.

According to the present invention, a radiator tank is provided for a U-flow radiator, the radiator tank comprising an internal branch provided by a hole and said hole being provided with a valve that is operable between an open and a closed position, characterizing due to the fact that the valve is integrally molded in the radiator tank.

The radiator reservoir of the present invention also overcomes the distribution problems posed by known external bypass systems. Because a radiator reservoir according to the invention has the same packing envelope as a normal U-flow one, the radiator reservoir of the present invention is fully backward compatible and does not pose any distribution problem that any normal radiator reservoir would not be found. . Also, as the deposit can be manufactured with the same tools, the need to devote large sums to this chapter is avoided.

The present invention is totally fail-safe because, if the bypass is blocked, the volume of coolant that the radiator can avoid decreases and the radiator would function as if it lacked bypass. In contrast, a failure in the system described in JP-2005-325699 could result in the loss of fluid from the engine cooling system. This circumstance has a substantially higher potential for costly engine damage than cavitation under heavy loads, because overheating affects the entire engine, including the cooling system, while cavitation damage only occurs within the coolant pump

The radiator reservoir can also comprise a separation plate for dividing an inlet and an outlet portion. The branch can be arranged in the separation plate.

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The internal shunt disposed within the radiator reservoir of the present invention considerably reduces the complexity of the radiator system as a whole. The modification of an existing separation plate to provide the new additional function of a branch allows the additional tube and related packing space used in JP-2005-325699 to be dispensed with. The consequent decrease in the components of the radiator assembly also entails a reduction of the possible points of failure.

The arrangement of the branch as an internal hole of the separation plate has the advantage that the length of the branch is unimportant. The two technical solutions discussed include external leads with a path length much greater than the cross section of the flow, which introduces an impedance inherent to the flow, simply because of the length of the bypass tube. When the branch is arranged in the separation plate, the effective length of the branch is unimportant and the magnitude of the flow depends solely on the cross-sectional area of the hole. Consequently, the necessary diameter of the branch opening is smaller than that of the external branch tube required in the previous technical solutions to obtain the same effect on the internal pressure of the system.

The branch can be an opening, and this can be circular.

A circular hole has the advantage of being made very easily and with a high level of certainty with respect to the cross-sectional area of the resulting opening. Alternatively, if the shape of the separation plate prevents obtaining the cross-sectional area through a circular opening, an oval or polygonal opening could be created to provide the required cross-sectional area without exceeding the limitations imposed by the available separation plate.

The bypass opening can be provided with a valve that can be operated between an open and a closed position. It is possible to divert the valve to the closed position. The valve can be multicuspid or reed.

The arrangement of a valve inside the opening contributes to further refining the basic premise of the internal bypass. The valve makes it possible for the transverse area of the opening to change due to the pressure differential between the inlet and outlet portions of the radiator reservoir. The valve is normally closed to ensure that the flow through the bypass only occurs when, otherwise, cavitation could occur.

The valve can be molded entirely in the radiator reservoir.

The valve can be operated to open it when the pressure difference between the inlet and the outlet portion exceeds a predetermined level.

The radiator reservoir can also comprise a sensor that detects the engine speed, as well as control means for regulating the valve when the pressure difference between the inlet and the outlet portion exceeds a predetermined level of the detected engine speed.

The present invention will be described in detail below, although only by way of example and in relation to the accompanying drawings, in which:

Figure 1 is a perspective view of a normal U-flow radiator system;

Figure 2 is a perspective view of a radiator reservoir according to a first example of the present invention;

Figure 3 is a perspective view of a portion of the radiator reservoir of the present invention shown in Figure 2;

Figure 4 is a perspective view of a radiator reservoir according to a second example of the present invention;

Figure 5 is a front view of a valve disposed within a radiator reservoir according to the second example of the present invention;

Figure 6 is a cross-sectional view of the valve shown in Figure 5;

Figures 7a and 7b are schematic diagrams of the pressure differentials in a radiator tank according to the second example of the present invention; Y

Figure 8 is a graphic representation of the pressure and flow characteristics of a radiator system.

Figure 1 shows a normal U-flow radiator system 10. The radiator system 10 comprises a core 11 and two cores or reservoirs 12, 13. The reservoir 13 is divided into two portions: an inlet portion 16 and one of exit

17. The input and output portions 16, 17 are divided by a separation plate 18. The input and output portions 16, 17 have respective input and output protuberances 14. During use, hoses (not shown in the image) are coupled to the inlet and outlet protuberances 14, 15. The normal flow through the system is as follows: the liquid penetrates the inlet portion 16 of the reservoir 13 through of the inlet protuberance 14. Next, the liquid penetrates the core 11 and follows the U-shaped path indicated by the arrows of Figure 1. Then, to leave the system 10, the liquid passes from the core 11 into the outlet portion 17 of the tank 13 and exits through the exit boss 15.

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A reservoir 23 according to a first example of the present invention is shown in Figure 2. The reservoir 23 is divided into the inlet portion 26 and the outlet portion 27 and has inlet and outlet protuberances 24, 25 similar to those in Figure 1.

The reservoir 23 also has a separation plate 28 between the inlet portion 26 and the outlet portion 27. The separation plate 27 has an opening 21 that acts as a bypass and allows the liquid to flow directly between the portion of inlet 26 and outlet portion 27, thus preventing passage through the core of the radiator system.

Figure 3 presents a perspective view of the radiator reservoir 23, centered on the separation plate 28. The bypass opening 21 which allows the circulation of the liquid between the inlet portion 26 and the outlet portion 27 is substantially circular.

The example of the present invention illustrated in Figures 2 and 3 can be mounted without any alteration of the necessary normal tooling. The opening of Figure 3 is substantially circular and has the advantage that it can be easily machined and with a high level of certainty with respect to the cross-sectional area of the resulting opening. However, in an alternative example of the present invention (which does not appear in the Figures) the shape of the opening could be selected from a variety of ovals, ellipses or polygons, to use the available area of the separation plate with maximum efficiency

28.

The hole size is selected looking for a compromise between the radiator performance and the reduction of the internal pressure of the system, necessary to avoid the start of cavitation. In practice, a circular hole 8 mm in diameter offers a correct balance between these two criteria. An orifice of this size allows approximately 150 liters of liquid to be derived per hour, at a predetermined optimum engine rotation rate. The optimum hole size will depend on the distribution of the system as a whole and the balance between the necessary pressure reduction and the effective contribution of the radiator to the engine cooling system as a whole.

The previous figures refer to a car radiator. However, a person skilled in the art will appreciate that this invention could also be applied to any motorcycle or larger vehicle that uses a U-flow radiator, although the size of the opening would have to be adapted. In the automotive industry there are families of core sizes, all of which have a radiator tank of the same size. The examples in the previous figures refer to a small core with a thickness of 16 to 20 mm. A larger radiator core may have a thickness between 27 and 35 mm. For this range a single tank size is provided with an opening whose diameter would normally be around 30 mm.

Instead of a single opening, several could be used to make the most of the available packing space.

Figures 4 to 7 show a second example of the present invention. The tank 43 is divided into an inlet portion 46 and an outlet portion 47. The tank also has inlet and outlet protuberances 44, 45 similar to those in Figure 1.

Also, the reservoir 43 has a separation plate 48. The separation plate 48 has an opening 41 which, like the opening 21 of Figures 2 and 3, acts bypass and allows the liquid to flow directly between the portion of inlet 46 and outlet portion 47, thus preventing passage through the core of the radiator system. The opening 41 is partially closed with a control valve 42. The valve 42 is presented in more detail in Figures 5 and 6.

Figure 5 shows a front view of the valve 42 of Figure 4. The valve 42 is a multicuspid valve consisting of an outer flange 49 and an inner portion 50, divided into six segments 51.

As can be seen most clearly in Figure 6, the outer flange 49 has a U-shaped cross section so that it can be pressurized with the edge of the opening 41. The thickness of the inner portion 50 is considerably smaller than that of the outer flange 49. Since the valve 42 is symmetrical, the parts on both sides of the separation plate 48 are identical and the inner portion 50 is normally aligned with the separation plate 48.

When the pressure differential across the separation plate 48 exceeds a predetermined limit value, the six segments 51 of the inner portion 50 flex to allow the liquid to communicate between the inlet portion 46 and the outlet portion 47. The Progressive increase of the pressure differential increases the flexion of the segments 51 and widens the cross-sectional area of the bypass opening, so that the liquid circulates between the inlet portion 46 and the outlet portion 47.

The flexion of segments 51 is shown schematically in Figures 7a and 7b. Figure 7a shows the segments 51 in their undetected position. This is the configuration that would be expected during normal engine operation and also when idle. When the high load conditions cause the pressure differential between the inlet portion 46 and the outlet portion 47 to exceed the predetermined boundary value, the segments 51 are flexed as seen in Figure 7B to allow the circulation of liquid directly between the inlet portion 46 and the outlet portion 47, thereby preventing passage through the radiator core.

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The predetermined limit value in which the segments 51 move to open the valve 42 is determined, at least in part, by the choice of the material for the valve 42. Normally it is a rubber material, although the use of polymers or metals. The thickness and the material chosen for the segments 51 provide an additional tuning parameter for the system, because the stiffness of the segments 51 dictates the opening speed of the valve 42 when the limiting pressure is reached.

In the illustrated embodiment, the optimum diameter of the circular opening provided when the valve 42 is in its fully open configuration usually ranges from 10 to 20 mm. However, as already explained in relation to the example of the simple opening of the present invention, the optimum diameter will depend on several seemingly contradictory criteria.

In the example of the present invention relating to a valve, the upper limit of the size of the valve is related to the size of the separation plate itself. The separation plate 48 has a rubber seal that holds the tank 43 to the core 11. This joint usually forms a 5 mm strip around the edge of the separation plate. Consequently, the upper limit established for the area of the valve 42 is the area of the separation plate 48, minus the approximately 5 mm band covered by the closure strip.

Although the example of the present invention illustrated in Figures 4 to 7 uses a multicuspid valve, other types of valves could be used. For example, a reed valve would offer the advantage of preventing the backflow of the liquid between the outlet portion 47 and the inlet portion 46. Another advantage of a reed valve is that it could be molded entirely into the reservoir 42.

In the two exposed examples of the present invention, the shunt allows a small percentage of the liquid to flow directly between the inlet portion of the radiator reservoir and the outlet portion. The result of deriving this small percentage through the opening of the separation plate is an increase in the flow of liquid to the pump and the absence of cavitation.

The diameter of the opening 21 and the limit value for the valve 42 are selected with respect to a pump graph of the type shown schematically in Figure 8. Each arc of the diagram is a line of the pressure (ordered) against the flow ( abscissa). Each arc represents a different rotation speed of the motor. Those closest to the origin represent lower speeds. The pressure drop across the engine cooling system is plotted by the T curve. When the pressure drop across the pump increases, so does the risk of cavitation. The pressure threshold at which the valve 42 should begin to open is set at the intersection of the pressure flow arc at a preferred engine speed (3000 rpm, in this example) with the total pressure drop.

In another example of the present invention (not shown), the opening threshold of the valve varies depending on the engine speed and the pressure drop through the cooling system. This feature allows the valve opening threshold to be established at the intersection of any of the arcs corresponding to different engine speeds with the total pressure drop curve of Figure 8. In this way, the valve cannot open prematurely when the Engine runs at high speed.

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Claims (6)

1. A radiator reservoir for a U-flow radiator, where the radiator reservoir comprises an internal branch provided by an opening, where the opening has a valve that can be operated between an open and a closed position, 5 characterized by the fact that the valve can be molded entirely in the radiator reservoir.

2.

The radiator reservoir according to claim 1, which also comprises a separation plate for dividing an inlet portion and an outlet portion, the branch being arranged in the separation plate.

3.

The radiator reservoir according to claim 1 or claim 2, wherein the valve is diverted to the closed position.

The radiator reservoir according to any one of the preceding claims, wherein the valve is a multicuspid valve or a reed valve.

5.

The radiator tank according to any of the preceding claims, wherein the valve can be operated to open it when the pressure difference between the inlet and the outlet portion exceeds a predetermined level.

6.

The radiator reservoir according to claim 5, which also comprises a sensor for detecting the speed

15 of the engine, as well as control means for regulating the valve when the pressure difference between the inlet and the outlet portion exceeds a predetermined level of the detected engine speed. 7. A vehicle comprising a radiator system that includes a radiator reservoir according to any of the preceding claims.