The invention relates to a fluid cooling apparatus, comprising at least one heat exchanger unit for cooling at least one working or cooling fluid, which is heated or used during the operation of mobile working machines, which have an engine covering to cover the engine, motor, or chassis parts, and, furthermore, comprising a tank that contains the working and/or cooling fluid and has a predeterminable outer wall contour.
Cooling devices for working or cooling fluids can be used for a plurality of applications and are readily available in a variety of embodiments on the market. One important area of application of such cooling devices is the use in working machines with a hydraulic system. For example, it can be a so-called open fluid circuit, for example, in the form of working hydraulics or as a closed hydrostatic drive, for example, in the form of a travel drive. For example, DE 10 2008 027 424 A1 discloses a fluid cooling apparatus for hydraulic oil that serves as the working fluid for the hydrostatic drive of a mobile working machine.
The installation of cooling devices inside the covering creates for working machines not only a spatial problem due to the available installation space, but also thermal problems. Even though the available installation space is typically extremely limited, an adequate and safe removal of the heat dissipated by the heat exchanger unit must be guaranteed. As a result, it is customary to install partitions, which form a seal relative to the respective covering, in order to prevent the cooling air, which is heated inside the covering, from being sucked in and flowing back again to the cooling primary air stream. However, it has been demonstrated that such seals fail due to vibrations and shocks during the rough operation of mobile working machines and, hence, create thermal problems.
Proceeding from this prior art, the object of the present invention is to provide a fluid cooling apparatus of the type under consideration in such a way that it is better able to satisfy the requirements to be applied to mobile working machines during operational use.
The invention achieves this object by means of a fluid cooling apparatus having the features specified in claim 1 in its entirety.
Accordingly, an essential feature of the invention lies in the fact that at least parts of the outer wall contour of the tank are a component of the engine covering.
Since the tank is a component of the engine covering and the pertinent tank surface is not located under the covering, the tank itself contributes to the improved removal of heat. Since it is possible to dispense with that part of the covering that is taken over by the tank itself, the result is additionally a reduction in the structural weight.
The arrangement can be configured in such an advantageous way that those parts of the outer wall contour of the tank that face the surrounding area merge with the outer engine covering along a connecting point as a component of the outer engine covering. As a result, the tank itself can form a connecting point of the outer chassis of the working machine, for example, in the form of a front or rear section that merges with an engine compartment hood at the connecting point.
In this context, the connecting point with a distinct advantage can produce seamlessly the continuous transition between the pertinent outer engine covering, for example, in the form of the engine compartment hood, and the outer wall contour of the tank.
If, at the same time, a gasket, which extends in the shape of a line, is arranged between the outer engine covering, for example, the hood, and the outer wall contour of the tank along the connecting point, then there is the distinct advantage that the tank itself performs the function of a partition that eliminates the risk of being able to suck in its own heated air when in operation.
In view of an especially compact design, the arrangement can be configured advantageously such that the tank has an integrated receiving channel for receiving a filter unit in the peripheral region of the tank housing and that the tank has a fan device in the region of the tank's face side facing the surrounding area; and this fan device is also integrated with its fan cover into the outer engine covering as a component of the outer engine covering.
In order to form an especially compact unit, the tank can be provided with a continuous central recess inside the tank housing; and the fan blades are driven inside this central recess.
If, in this case, the heat exchanger unit is connected to the tank housing in the manner of an air fin cooler on the side opposite the fan device or is an integral component of the tank housing, then the entire system of the fluid cooling apparatus forms a combined structural unit that requires only a small amount of installation space in the working machine.
The filter device that belongs to the fluid cooling apparatus can have, in an especially advantageous way, valve units that include, for example, a precharge valve, a replenishing valve, or a bypass valve, so that an uninterrupted supply of fluid, of which the temperature is controlled in a suitable way by means of the cooling device, to the pertinent consumer is guaranteed.
The invention is explained in detail below by means of one exemplary embodiment that is shown in the drawings. Referring to the drawings:
FIG. 1 shows in schematic form a highly simplified and detached perspective view of just the front vehicle part of a mobile working machine that is provided with an exemplary embodiment of the fluid cooling apparatus according to the invention;
FIG. 2 shows the construction of the hydraulic system of the fluid cooling apparatus as a hydraulic circuit diagram;
FIG. 3 is a perspective oblique view of the fluid cooling apparatus that is removed from the working machine, when seen in the direction of the rear side of the tank housing;
FIG. 4 is a side view of the exemplary embodiment of the fluid cooling apparatus;
FIG. 5 is a perspective detail view of just the heat exchanger unit and adjacent thereto the fan device of the exemplary embodiment, and
FIG. 6 is a perspective oblique view, when seen in the direction of the front side of the exemplary embodiment, wherein the fan device is shown in the folded down state.
FIG. 1 is a highly simplified drawing of just the front vehicle region of a mobile working machine 1, with the region which is connected to the cab 3 and where hydraulically operated working devices, such as the crane boom, the excavator, stacker, or the like, may be found, having been omitted. The section of the working machine 1 that is shown in FIG. 1 could be just as well the rear part. In order to supply the consumer (not illustrated) according to need, the working machine 1 has an exemplary embodiment of the fluid cooling apparatus 5 according to the invention. This fluid cooling apparatus is disposed on the respective end region of the working machine 1 and forms, with the outer wall contour 7 of the associated fluid tank 9, a component of the outer covering, which in the present case is an engine compartment hood 11. This hood can be swiveled up around the hinges 13 in order to provide access to the engine compartment.
The hydraulic circuit diagram of the fluid cooling apparatus 5 that is shown in FIG. 2 shows a heat exchanger unit, designated as a whole as 10, for cooling at least one fluid, especially in the form of hydraulic oil. Furthermore, the fluid cooling apparatus 5 comprises a filter device, designated as a whole as 12, for filtering the fluid that can be passed to a consumer 14. In the present case, the consumer 14 is supposed to consist of a hydrostatic drive of a vehicle, in particular, in the form of a construction machine. This hydrostatic drive can be supplied in the conventional way with fluid by means of a feed pump (not shown in detail) or a group of feed pumps. Furthermore, the fluid cooling apparatus 5 has an air flow device 16 in the manner of an air cooling fan or a fan ventilator. The flow device is driven by a drive device 18, which in the present case consists of a hydraulically operated motor. However, the hydraulic motor can also be replaced by an electric drive motor (not illustrated). Running parallel to the hydraulic motor 18, a pressure limiting valve 22, which protects the motor from overload, is connected to the hydraulic circuit 20. In the fluid flow direction, downstream of the motor, there is a manually actuatable 3/2-way switching valve 24, which in its illustrated passage position establishes the fluid circuit from the motor 18 to the heat exchanger unit 10. In the other switching position, the valve 24 shuts off the hydraulic circuit in the direction of the heat exchanger unit 10, an arrangement that offers the possibility of being able to perform maintenance work, for example, to replace the used filter elements of the filter device 12 without being hampered by the afterflow of fluid in the circuit 20.
Furthermore, it is also very clear from FIG. 2 that the input side of the hydraulic motor 18 is connected to the hydraulic circuit 20 with the said consumer 14 by way of a first connecting point 26. In this context, a constant proportion of the amount of fluid is supplied directly to the motor in order to enable a faultless operation of the motor 18. In the secondary branch, the remaining amount of fluid, optionally with a variable volumetric amount, is conducted to the heat exchanger unit 10 in the fluid direction downstream of the switching valve 24 by way of an additional second connecting point 28. This heat exchanger unit is protected against overload by means of a conventional check valve 30. In an additional parallel connection to the check valve 30 and to the heat exchanger unit 10, a temperature-controlled 2/2-way proportional valve 32 is connected to the hydraulic circuit 20 and, as the fluid temperature rises, switches into the blocked position in order to deliver in this way the heated fluid exclusively to the heat exchanger unit 10. Since the fluid to be transported is viscous, especially in the cold start phase, and, moreover, does not need to be cooled in the cold state, the load on the heat exchanger unit 10 can be reduced by suitably opening the proportional valve 32 in the direction of the passage position.
In every instance, a definable return amount flows to the filter device 12 with its first filter element 34. Then the resulting filtered and, therefore, cleaned fluid flows through the output line 36 to a second filter element 38, which is located upstream of the consumer 14 with the feed pump. In an additional secondary branch 40, the output line 36 subsequently opens into a replenishing device that is designated as a whole as 42. The replenishing device, which is oriented relative to the tank side 44 in the secondary branch 40, has a precharge valve 46, which passes over to the tank side 44 in its open position and in the opposite direction assumes its closed position, which is shown in FIG. 2. Such a precharge valve consists preferably of a spring-loaded check valve. Parallel to the precharge valve 46, with the corresponding fluid linkage upstream and downstream of the precharge valve to the secondary branch 40, a replenishing valve 48 is connected to the fluid circuit 20 and, designed as a check valve, closes toward the tank side 44 and assumes the open position in the opposite direction toward the hydraulic consumer 14. Whereas the precharge valve 46 typically has a precharge pressure of, for example, 0.5 bar, the replenishing valve 48 opens immediately, if the feed pump of the consumer 14 continues to demand storage fluid from the tank side 44; this is especially the case when not enough fluid continues to flow in by way of the filter element 34.
Furthermore, the first filter element 34 in a parallel connection has a bypass valve 50, which, designed as a spring-loaded check valve, opens toward the tank side 44 and, otherwise, is set to a bypass opening pressure of, for example, 2 bar. If the filter element 34 of the filter device 12 is fouled and is thus blocked, the amount of fluid can travel to the hydraulic consumer 14 when the bypass valve 50 is opened. In such a bypass case, the filtration of the return amount to the consumer 14 is carried out by way of the second filter element 38.
The precharge pressure of, for example, 0.5 bar on the precharge valve 46 ensures that pressurized fluid coming from the filter device 12 is available to the hydraulic consumer 14. If the precharge pressure of the fluid return amount, which travels from the first filter element 34 into the output line 36 and the secondary branch 40, rises, the precharge valve 46 opens toward the tank side and relieves the return amount until the nominal pressure provided for the consumer 14, in the present case 0.5 bar, is reached. If too little fluid flows subsequently into the hydraulic circuit 20 by way of the first and second connecting point 26, 28, the intake side of the feed pump for the consumer 14 allows a replenishment from a tank storage amount in that the replenishing valve 48 of the replenishing device 42 opens in the direction of the consumer 14 and, accordingly, ensures a continued flow of the fluid medium. Hence, when the consumer 14 is operating, there is never an undersupply of consumer fluid, a feature that for safety reasons constitutes a necessity for operating hydrostatic travel drives.
FIGS. 3 to 6 show more details of the construction of the exemplary embodiment of the fluid cooling apparatus 5, which is integrated into the working machine 1 in such a way that the fluid cooling apparatus 5 forms the front or rear end of the vehicle body. FIG. 1 shows that the outer wall contour 7 of the tank 9 merges seamlessly and continuously with the hood 11 at a connecting point 15 (FIG. 1); and this hood forms an additional part of the outer covering. It is clear from FIGS. 3 and 4 that a line-shaped gasket 17, which forms a seal between the tank 9 and the adjoining hood 11, extends along the connecting point 15. The tank 9 is made of an impact-resistant and weather-proof synthetic plastic material, for example, a polyamide, such as PA6, by means of a rotational molding process or consists of a molded sheet metal part. Moreover, the tank is constructed in such a way that the outer contour 7 of the tank forms the end of the vehicle body with a slightly curved top side 21 and also curved sides 23, with the top side 21 and the sides 23 tapering slightly toward a front wall 25. On the rear side and adjacent to the gasket 17, the tank 9 forms a rear wall 27, which has a plane surface, apart from a recess channel 31, which is formed on the rear wall 27 at the edge and is configured for the filter device 12. Between a wide opening 29 (FIG. 6) in the front wall 25 and the rear wall 27, the tank housing forms a continuous central recess 33 (FIG. 6), which forms an air flow channel between the opening 29 in the front wall 25 and a corresponding opening of the rear wall 27. FIG. 3 shows that the heat exchanger unit 10 is attached to this opening, which is not visible in the drawing, in the form of an air fin cooler.
In the region of the front wall 25, the central recess 33 of the tank housing accommodates a fan device 35 having fan blades 37 that are driven by a hydraulic motor 18 (FIG. 2). The fan device 35 is arranged in the opening 29 of the central recess 33 in such a way that its front fan cover 39, composed of circular grill rings 41 and radially extending grill crosspieces 43, forms in the manner of a cooler grill a component of the outer covering of the vehicle front or the vehicle rear (see FIG. 1).
The tank 9, which is made preferably of a synthetic plastic material, such as polyamide PA6, in a rotational molding process or is made as a molded sheet metal part, has a fill port 51, which is located in a centered manner at the top, on the rear wall 27. The interior of the tank 9 is fluidically connected directly to the receiving channel 31, which contains the filter device 12, so that a direct fluid connection with the replenishing line 52 (FIG. 2) is formed. In this case, the replenishing valve 48 is connected to this replenishing line so that an outer pipeline is not necessary. As stated above, the invention, in which the outer wall contour 7 of the tank is a component of the covering, does not require a partition inside the engine covering, because the tank 9 itself fulfills the function of the partition, which prevents the intake of its own heated air. Therefore, there is no risk that a failure of the seals between any partition and the covering parts could result in a subsequent intake of heated air. Moreover, such a risk could not exist in the device according to the invention, even if the gasket 17 were to fail at the connecting point 15 with the hood, because in this case an inlet gap, which is optionally formed, if desired, at the connecting point 15, would only lead to an air inlet from the surrounding area and, thus, would not adversely affect the cooler performance. Therefore, the gasket 17 is required only to protect against splash water, rain, or dirt. An additional advantage of the invention lies in the fact that it makes a contribution to the reduction of noise, because the fan device 35 is surrounded by the tank 9 with the fluid located in said tank, a feature that overall leads to noise suppression.
Instead of a central filling option for the fluid tank 9, tank filling on the edge or in any other position is also possible. The outer shape of the tank can be adapted to the contour of the engine covering and can also have a shape according to the drawing in FIG. 1. When seen in the direction of FIG. 2, uncooled oil from the working hydraulics can be filtered by means of a connecting line, which is not shown in detail, above the filter 12. The fan device 35 can be mounted, on the one hand, on the cooler 10 and, on the other hand, directly on the tank 9, preferably on the side 27 facing the cooler.
Patent Application
20130220574
