Abstract:
The invention relates to a system for use in a motor vehicle, the system comprising a coolant container of a liquid circulation cooling circuit and a hydraulic oil container of a hydraulic power steering assembly, in particular for use in an internal combustion engine. The system is characterized in that the coolant container is designed in one piece with the hydraulic oil container so that the system forms a uniform component. Furthermore, the invention relates to a method for influencing the temperature of a hydraulic oil of a hydraulic power steering assembly with the coolant container of the liquid circulatioin cooling circuit.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The invention relates to a system comprising a coolant container of a liquid circulation cooling circuit and a hydraulic oil container of a hydraulic power steering assembly, in particular for use with an internal combustion engine. Furthermore, the invention relates to a method for influencing the temperature of a hydraulic oil of a hydraulic power steering assembly.  
         [0003]     2. Prior Art  
         [0004]     A system of the kind mentioned above is used in a motor vehicle, for example. In this environment, liquid-cooled internal combustion engines as a rule have a liquid circulation cooling circuit, in which a coolant/water mixture (designated as coolant for short below) is conveyed in a forced flow in a closed circuit by means of a pump. The liquid circulation cooling circuit comprises cooling ducts in the cylinder head and in the cylinder block of the internal combustion machine and as a rule a heat exchanger, in which heat transfer from the coolant to the air flowing through the heat exchanger is brought about. In this environment, the heat exchanger is often arranged in a bypass line of the liquid circulation cooling circuit, which is opened and closed by thermostatic control.  
         [0005]     A hydraulic power steering assembly as the second component of the system is used in motor vehicles to assist or facilitate the steering operation. For this purpose, a hydraulic oil, which is pressurized by means of a pump and serves to generate or increase the steering power, is provided(likewise in a closed circuit).  
         [0006]     Apart from these two fluid circuits, an internal combustion engine or a motor vehicle as a rule has a large number of devices in which a fluid is used and/or conveyed or pressurized by means of a pump. Examples of such devices are for example, the brake booster and the air-conditioning system, but also the fuel supply apparatus.  
         [0007]     Attempts have already been made many times in the past to combine the various fluid circuits in order to achieve advantageous synergy effects. In this regard, efforts are often focussed on reducing manufacturing costs, in particular by reducing the number of components, a reduction in the number of components being possible by assigning a dual function to a component which is already present.  
         [0008]     For example, DE 44 44 201 A1 describes a system in which a liquid circulation cooling circuit is combined with a hydraulic power steering assembly in an internal combustion engine in such a way that only one fluid and only one pump for conveying this fluid are necessary. In this connection, the liquid circulation cooling circuit and the hydraulic power steering assembly are combined in such a way that the cooling and power steering are pressure-fed with a coolant/water mixture from a common reservoir by means of a common pump.  
         [0009]     In the proposed concept, a pump is dispensed with, and with this pump the usually necessary drive unit for this pump as well, by virtue of which the manufacturing costs can be reduced. Moreover, the decrease in the number of components also leads to a reduction of the assembly costs. However, a smaller number of components leads not only to lower assembly costs but also to lower supply and administration costs.  
         [0010]     With the reduction in the number of components, the overall weight of the construction also decreases, in which connection efforts are always made, with regard to lower fuel consumption, to design a component variant of as low a weight as possible. A further fuel savings is achieved in the system described in DE 44 44 201 A1 in particular owing to the fact that the energy usually necessary for driving a second pump is saved.  
         [0011]     Furthermore, it is in principle an aim of designers to achieve an efficient and close packing of the entire drive unit in the engine space of the motor vehicle, which is likewise assisted by a reduction in the number of components. In this regard, it must be taken into consideration in particular that close packing is achieved not only through the omission of individual components and the construction space thus saved but also by the omission of necessary fastening means and articulation points.  
         [0012]     Against this background, the object of the present invention is to provide a system with a coolant container of a liquid circulation cooling circuit and with a hydraulic oil container of a hydraulic power steering assembly, with which the aims mentioned above are assisted and which in particular permits as close as possible a packing of the entire drive unit. A further object of the present invention is to indicate a method for influencing the temperature of a hydraulic oil of a hydraulic power steering assembly.  
       SUMMARY OF THE INVENTION  
       [0013]     The present invention is a system comprising a coolant container of a liquid circulation cooling circuit and a hydraulic oil container of a hydraulic power steering assembly, in particular for use in an internal combustion engine, which is characterized in that the coolant container is designed in one piece with the hydraulic oil container, so that the system forms a monolithic or uniform component.  
         [0014]     The invention is characterized in that a permanent connection is provided between the coolant container and the hydraulic oil container. This permanent connection is achieved by virtue of the fact that both containers are made from one piece as a monolithic component  
         [0015]     This common solution principle distinguishes the system according to the invention with coolant container and hydraulic oil container from the conventional systems, in which a separate coolant container and a separate hydraulic oil container are present, which are also arranged at a great spacing from one another.  
         [0016]     Another embodiment of the invention comprises a coolant container of a liquid circulation cooling circuit and a hydraulic oil container of a hydraulic power steering assembly, in particular for use in an internal combustion engine, which is characterized in that coolant container and hydraulic oil container is constructed from at least two components, the components being interconnected by a material connection and/or a positive connection.  
         [0017]     This alternative embodiment of the invention is characterized in that a permanent connection is provided between the coolant container and the hydraulic oil container. This permanent connection is achieved by virtue of the fact that a permanent connection is specifically introduced into the at least two components forming the system by material connection or positive connection.  
         [0018]     With the system according to the invention, the number of components can be reduced, two individual components, namely the coolant container and the hydraulic oil container, being combined to form one component. Owing to the fact that the number of components is reduced in the system according to the invention, the manufacturing costs and assembly costs can be reduced.  
         [0019]     Furthermore, the proposed system has by virtue of the principle a lower weight and a smaller space requirement as the system according to the invention is more compact than conventional systems. Fewer bearings or articulation points and fewer fastening means are required. By virtue of this, the system according to the invention permits as close as possible a packing of the entire drive unit.  
         [0020]     If the system is constructed from a number of components, it is as it were a preassembled subassembly, which helps to reduce the number of assembly steps on the production line of the motor vehicle.  
         [0021]     Embodiments of the system in which the at least two components are adhesively bonded to one another to form a material connection are advantageous. The introduction of an adhesive connection is as a rule effected without the aid of tools by direct application of an adhesive and consequently affords advantages from production-related points of view as the production process is cost-extensive. Moreover, the adhesive serves at the same time as a sealing material at the connection location of the at least two components, by virtue of which in particular the tightness of the two containers is ensured in the system concerned here.  
         [0022]     Embodiments of the system in which the at least two components are welded to one another to form a material connection are also advantageous. In the context of the present invention, welding means both the welding of metals and the welding of plastics. A welded connection is characterized by high loadability.  
         [0023]     Embodiments of the system in which the at least two components are additionally non-positively interconnected are advantageous. An additional non-positive connection of the components can be introduced by screws or clamping elements, for example.  
         [0024]     Embodiments of the system in which the coolant container and the hydraulic oil container have at least one common delimiting wall are advantageous. The common delimiting wall is characterized in that it delimits the coolant container and the hydraulic oil container at the same time. Coolant is located on one side of the delimiting wall, whereas hydraulic oil is present on the other side of the delimiting wall.  
         [0025]     This development of the system according to the invention ensures an increased heat transfer between the coolant and the hydraulic oil, it being possible for the heat transfer to take place in both directions. After a cold start, the coolant, which heats up slowly, can be used for heating up the hydraulic oil. On the other hand, during continuous operation after the warm-up period, the coolant can be used for cooling the hydraulic oil.  
         [0026]     Embodiments of the system in which the coolant container and/or the hydraulic oil container is equipped with a guide device in its interior, which directs a fluid flow guided through the container, are advantageous. Coolant is led into the coolant container and removed again. Likewise, hydraulic oil is led into the hydraulic oil container and removed again. With regard to optimized heat transfer, it is advantageous to guide the flow specifically through the container, which can be effected by means of the proposed guide device.  
         [0027]     In this connection, embodiments of the system in which a baffle plate is provided in the coolant container and/or in the hydraulic oil container in order to calm the incoming fluid flow are likewise advantageous.  
         [0028]     Embodiments of the system in which a filter is provided in the coolant container and/or in the hydraulic oil container in order to clean the fluid flow guided through the container are also advantageous. If the filter is arranged in such a way that the incoming fluid flow has to pass through the filter, this filter serves at the same time for calming the flow and thus additionally takes on the function of a baffle plate.  
         [0029]     In the case of systems of monolithic design, embodiments of the system in which the system is either designed in one piece as a cast component or in one piece as a thermoformed component are advantageous. Systems of monolithic design have the advantage that no components have to be connected and therefore no connection locations are present by virtue of the principle. The tightness of the system is therefore guaranteed in every case.  
         [0030]     The second part object forming the base of the invention is achieved by a method for influencing the temperature of a hydraulic oil of a hydraulic power steering assembly, which is characterized in that a hydraulic oil container storing the hydraulic oil is designed in such a way that the hydraulic oil container has at least one common delimiting wall with a coolant container of a liquid circulation cooling circuit of an internal combustion engine.  
         [0031]     What has been stated in connection with the system according to the invention applies likewise for the method according to the invention. Owing to the fact that the coolant container and the hydraulic oil container are combined or integrated in a system, the possibility arises of influencing the temperature of the hydraulic oil by means of the circulation cooling circuit.  
         [0032]     Restrictions which arise according to the prior art in the selection of the container material on account of the hydraulic oil temperatures being too high no longer apply. The coolant, or the liquid circulation cooling circuit, is used for conditioning the hydraulic oil.  
         [0033]     In this connection, embodiments of the method in which the hydraulic oil is, during operation of the internal combustion engine, cooled by means of the cooling liquid present in the coolant container are advantageous. In this method variant, heat transfer takes place from the hydraulic oil to the coolant. This heat is then in turn extracted from the coolant in another location, for example in a heat exchanger provided in the liquid circulation cooling circuit.  
         [0034]     Embodiments of the method in which the hydraulic oil is, in the warm-up period of the internal combustion engine, heated up by means of the cooling liquid present in the coolant container are also advantageous. After a cold start of the internal combustion engine, as a rule neither the coolant nor the hydraulic oil are at operating temperature. Rapid heating-up of the coolant is often achieved according to the prior art by virtue of the fact that a heat exchanger provided in a bypass line is not flowed through by the coolant in the warm-up period, so that no additional heat is extracted from the coolant in the heat exchanger. In the method according to the invention, the coolant, which heats up more rapidly by virtue of this, is in turn used to bring the hydraulic oil to operating temperature in as short a time as possible.  
         [0035]     Further objects, features, and advantages of the present invention will be readily appreciated, as the same becomes understood, after reading the description which follows taken in conjunction with the accompanying drawings and claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]     The invention is described in greater detail below with reference to two illustrative embodiments according to  FIGS. 1 and 2 , in which  
         [0037]      FIG. 1  shows diagrammatically a first embodiment of the system in a side view and partly in section, and  
         [0038]      FIG. 2  shows diagrammatically a second embodiment of the system in a side view and partly in section. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]      FIG. 1  shows a first embodiment of the system  1 . The system  1  comprises a coolant container  2  of a liquid circulation cooling circuit and a hydraulic oil container  3  of a hydraulic power steering assembly, the two containers  2 ,  3  each having an inlet opening  4 ,  5  and an outlet opening  6 ,  7 , via which the liquids, namely the coolant  10  on the one hand and the hydraulic oil  11  on the other hand, enter the containers  2 ,  3  and leave them again. A filter  18  for cleaning the incoming hydraulic oil  11  is arranged in the region of the inlet opening  5  of the hydraulic oil container  3 . This filter  18  serves at the same time for calming the incoming flow.  
         [0040]     Both the coolant container  2  and the hydraulic oil container  3  are equipped with a filling opening  8 ,  9 , which serves for the replenishment of coolant  10  and hydraulic oil  11  respectively and via which the liquid level  12 ,  13  in the container  2 ,  3  can be checked or monitored. The filling openings  8 ,  9  are each closed with a cap  14 ,  15 .  
         [0041]     The embodiment of the system  1  illustrated in  FIG. 1  is not of monolithic design but comprises three components  16 ,  17 ′,  17 ″ which have a material interconnection. The first component  16  of the system  1  is formed by a trough-shaped lower part  16 , in which all the inlet openings  4 ,  5  and outlet openings  6 ,  7  are fashioned. This trough-shaped lower part  16  has sufficiently high side walls to accommodate the coolant  10  and the hydraulic oil  11  completely.  
         [0042]     The hydraulic oil container  3  provided in the lower part  16  has a tubular or cylindrical basic shape and is surrounded by the coolant container  2  in such a way that the lateral surface  19  of the hydraulic oil container  3  forms a common delimiting wall  20 , that is delimits both the coolant container  2  and the hydraulic oil container  3 . Coolant  10  is located on one side of the delimiting wall  20 , whereas hydraulic oil  11  is present on the other side of the delimiting wall  20 . The direct proximity of the two liquids  10 ,  11  allows the temperature of the hydraulic oil  11  to be influenced with the aid of the liquid circulation cooling circuit, that is to say with the aid of the coolant  10 .  
         [0043]     In this connection, the heat transfer between the coolant  10  and the hydraulic oil  11  can—depending on the operating state of the internal combustion engine—be effected in both directions. After a cold start of the internal combustion engine, the coolant  10 , which heats up slowly, is used for the purpose of heating the hydraulic oil  11  as well. During continuous operation—after the warm-up period—on the other hand, the coolant  10  can be used for the purpose of cooling the hydraulic oil  11 .  
         [0044]     The trough-shaped lower part  16  is closed with a two-part lid-shaped upper part  17 , a first portion  17 ′ of the lid-shaped upper part closing the coolant container  2  and a second portion  17 ″ of the lid-shaped upper part closing the hydraulic oil container  3 . The two portions  17 ′,  17 ″ comprise the filling openings  8 ,  9 . In this connection, the hydraulic oil container  3  integrated into the trough-shaped lower part  16  passes through the first portion of the lid-shaped upper part  17 ′. This ensures good accessibility of the weld seams  21 . Furthermore, this constructional development ensures that the hydraulic oil  11  does not mix with the coolant  10  under any circumstances, in particular even when the weld seams  21  are untight and the two liquids  10 ,  11  move to a greater extent in the containers  2 ,  3 .  
         [0045]     Alternative embodiments of the system in which the system is constructed from two components, a trough-shaped lower part forming the first component and a lid-shaped upper part forming the second component, are advantageous. This division of the system into two components affords advantages from production-related points of view. Complicated shapes, in particular with undercuts, are avoided, so that the two components come within the reach of usual production methods and can be made by injection molding, for example. The upper part can also be of modular design, that is itself comprise a number of components.  
         [0046]     The material connections  21  of the three components  16 ,  17 ′,  17 ″ of the system  1  are provided in regions which are not acted on permanently by either the coolant  10  or the hydraulic oil  11 , that is in regions which are located above the two liquid levels  12 ,  13 . By virtue of this, the liquids  10 ,  11  present in the system  1  can neither escape into the surrounding environment nor mix with one another even with untight connection locations  21 . In this way, the liquids  10 ,  11  cannot attack or destroy the connection  21  either.  
         [0047]     Alternative embodiments of the system in which the connection of the at least two components is provided in regions of the system which are not acted on permanently by either the coolant or the hydraulic oil are advantageous. While it is ensured that the connection locations are made tight in order to prevent both an escape of the liquids present in the system into the surrounding environment and mixing of the two liquids with one another, it is moreover advantageous if the design of the system is effected specifically in such a way that the connection locations do not come into contact with the coolant stored in the coolant container or with the hydraulic oil present in the hydraulic oil container. On the one hand, this is because the liquids could attack and damage or destroy the connection. On the other hand, however, this procedure affords advantages for a case in which the connection is not absolutely tight. This is because no liquids escape then, only gases present in the system. A liquid loss, which would have disadvantageous effects on the liquid circulation cooling or the hydraulic power steering, is not to be feared.  
         [0048]      FIG. 2  shows diagrammatically a second embodiment of the system  1  in a side view and partly in section. Only the differences from the embodiment illustrated in  FIG. 1  are to be discussed, for which reason reference is otherwise made to  FIG. 1 . The same reference numbers have been used for the same components.  
         [0049]     In contrast to the embodiment illustrated in  FIG. 1 , the system  1  illustrated in  FIG. 2  has elements  22  in the common delimiting wall  20 , which are made from a material which has a higher specific heat capacity than the material of the delimiting wall  20 . In this way, the elements  22  assist the heat transfer between the two liquids  10 ,  11 .  
         [0050]     The elements  22  are of annular shape and extend from that outer surface of the delimiting wall  20  facing the coolant container  2  to that outer surface of the delimiting wall  20  facing the hydraulic oil container  3 . In principle, however, the elements  22  can also have other shapes, for example a rod-like shape.  
         [0051]     Embodiments of the system in which the elements extend from that outer surface of the delimiting wall facing the coolant container to that outer surface of the delimiting wall facing the hydraulic oil container are advantageous. In this alternative embodiment, the elements serve as heat bridges, which ensure direct heat transfer between the liquids.  
         [0052]     Embodiments of the system in which the hydraulic oil container has a tubular basic shape and is surrounded by the coolant container in such a way that the lateral surface of the hydraulic oil container forms the at least one common delimiting wall are advantageous. In this embodiment, the hydraulic oil container is surrounded by the coolant container. This ensures a large-surface delimiting wall, which assists or increases the heat transfer between the liquids.  
         [0053]     In an alternative embodiment of the system in which the invention is constructed essentially from plastic, the plastic preferably being polypropylene, may be advantageously used. In the alternative embodiment of the system according to the invention, in which the two containers are combined in a subassembly, however, a heat transfer takes place, which at least during normal continuous operation of the internal combustion engine, ensures that the temperature of the hydraulic oil is comparatively low, so that the hydraulic oil container can also be made of polypropylene. Both containers of the system can thus be made of the same more inexpensive plastic.  
         [0054]     In this alternative embodiment, the wording is intended to express the fact that the system can also be made completely of plastic but does not imperatively have to be made completely of plastic. Individual elements of the system can therefore perfectly well be manufactured from other materials. In this connection, essentially means that more than 70% (in mass per cent) of the system is made of plastic.