Abstract:
Apparatus for separating oil from crankcase ventilation gases of an internal combustion engine having at least two oil separators in the form of cyclones connected in parallel and traversed by the crankcase ventilation gases. The apparatus is equipped with a control valve that divides the volumetric flow of the crankcase ventilation gases into at least two subflows, depending on the magnitude of the volumetric flow, and conducts the subflows to the at least two oil separators. A control piston releases or blocks access of the gases to additional cyclones depending on the dynamic pressure of the crankcase gas.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of international patent application no. PCT/EP2004/050972, filed Jun. 1, 2004, designating the United States of America, and published in German as WO 2004/105955 on Dec. 9, 2004, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application no. DE 103 25 055.7, filed Jun. 2, 2003.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to an apparatus for switching or controlling cyclone separators. Cyclone separators are used, for example, in the crankcase ventilation of internal combustion engines. They serve to separate the crankcase gas from liquid components, such as oil mist. The crankcase gas is set into rotation inside the cyclone separator. The oil mist or oil droplets are deposited along the wall of the cyclone separator and flow back into an oil pan via a discharge pipe. The deoiled gas is conducted to the intake tract of the internal combustion engine via a pressure control valve and is returned to the intake air.  
         [0003]     The amount of crankcase gas depends on the operating state of the engine and may range, for example, from 50 to 220 liters per minute. A cyclone separator has an optimal operating point at a specific gas amount. To reliably deoil the different amounts of gas, a plurality of switchable cyclones must be provided, which are switched on or off depending on the gas amount. Approaches to solve this problem are known, e.g., the use of additional valves to switch the cyclones on or off.  
         [0004]     U.S. Pat. No. 6,684,864 (=DE 199 18 311) discloses a method for deoiling crankcase ventilation gases and an apparatus for carrying out this method. In this device, the volumetric flow of the crankcase gases is divided into at least two partial streams, and at least one partial stream is guided through at least one oil separating element. The size of the partial streams is regulated as a function of the magnitude of the volumetric flow.  
         [0005]     U.S. Pat. No. 6,942,709 (=DE 102 05 981) discloses a system with switchable cyclones for separating particles or droplets from a fluid stream. At least two cyclones, which have a tangential inlet opening for the fluid stream, are connected in parallel. Each inlet opening for the fluid stream can be opened or closed individually. Controlling the fluid stream is very important for the optimal deoiling of crankcase gases because the optimal efficiency of the cyclones is limited to a very narrow operating range. Control of the volumetric flow must therefore be designed precisely for this optimal operating range. On the other hand, the system should be simple in construction and have little or no tendency to malfunction.  
       SUMMARY OF THE INVENTION  
       [0006]     Accordingly, it is an object of the present invention to provide an improved apparatus for controlling a flow of gas to one or more cyclone separators.  
         [0007]     Another object is to provide an apparatus that makes it possible to reliably control a flow of crankcase ventilation gas to one or more cyclones to maintain optimum cyclone performance.  
         [0008]     A further object is to provide an apparatus for controlling a flow of gas to one or more cyclones which can effectively adapt to a variable volume flow of gas.  
         [0009]     It is also an object of the invention to provide an apparatus for controlling a flow of gas to one or more cyclones which has a simple and reliable construction.  
         [0010]     These and other objects are achieved in accordance with the presently claimed invention by providing an apparatus for separating oil from crankcase ventilation gases of an internal combustion engine, the apparatus comprising at least two oil separator cyclones connected in parallel through which the crankcase ventilation gases flow, and a control member which divides the volumetric flow of the crankcase ventilation gases into partial streams depending on the size of the volumetric flow and guides the partial streams into the at least two oil separator cyclones, the control member comprising a control plunger and a compression spring which urges the control plunger against the pressure of the crankcase gases, the control plunger opening or blocking access of the gases to additional cyclones depending on the dynamic pressure of the gases.  
         [0011]     An advantage of the invention is that a control plunger is provided. This control plunger is configured in such a way that it opens or closes the access of the gases to a first or an additional cyclone as a function of the dynamic pressure of the crankcase gas. A compression spring is provided to reset the control plunger or as a force component acting against the dynamic pressure of the crankcase gas. This makes it possible to efficiently control and divide the volumetric flow into several partial streams.  
         [0012]     In accordance with a further embodiment of the invention, the access to the at least two cyclones is cylindrical and contains a mounting pin to receive the compression spring and the control plunger. According to this embodiment, three cyclones are advantageously provided, and the control piston has a passage in the bottom and is in communication with the first cyclone. Thus, if the volumetric flow is very low, only the first cyclone is active and separates the liquid from the gases, but if a higher volumetric flow needs to be cleaned, the control piston moves against the force of the compression spring out of its rest position and opens an additional passage for the volumetric flow, and if the volumetric flow increases further, a third aperture to the third cyclone is opened. Consequently, if the volumetric flow is at its maximum, all three cyclones admit flow and are available for cleaning the crankcase gas. To seal the control plunger and its lateral surface, the control plunger may be provided with suitable seal rings.  
         [0013]     The cyclones are advantageously arranged in a common housing. This housing has a bottom outlet, which in a further refinement of the invention is provided with a valve and adapted to return the collected liquid to the liquid circuit, e.g., the oil circuit of the internal combustion engine.  
         [0014]     The volumetric flow may also be controlled via a diaphragm valve. This diaphragm valve is controlled by the pressure differential between the pressure of the crankcase gas in front or upstream of the cyclone, i.e., the pressure of the oil-laden crankcase gases, and the pressure of the crankcase gases behind or downstream of the cyclone. The pressure differential causes additional cyclones to open or close. At a maximum pressure differential, all cyclones are open.  
         [0015]     In accordance with a further preferred embodiment of the invention, the diaphragm valve is made of an elastic diaphragm biased by a compression spring. On this diaphragm two tappets are provided on a disk. The tappets close or open the access to two cyclones. Instead of a disk and the tappets, the diaphragm valve alternatively may comprise a plunger that moves along a cylinder wall. Openings are provided in this cylinder wall, which are in communication with the cyclones, and these openings are closed or opened by the movement of the plunger. This relatively simple construction is likewise suitable for controlling the distribution of the crankcase gases and thus achieving an optimal cleaning action.  
         [0016]     These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings, in which:  
         [0018]      FIG. 1  is a schematic representation of an apparatus according to the invention for deoiling crankcase gases;  
         [0019]      FIG. 2  is a schematic top view of the apparatus of  FIG. 1 ;  
         [0020]      FIG. 3  is a depiction of a variant apparatus with a diaphragm valve;  
         [0021]      FIG. 4  is an illustration of a further variant with a diaphragm plate, and  
         [0022]      FIG. 5  is a three-dimensional representation of a valve for controlling the switching of cyclones. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0023]     The apparatus  10  depicted in  FIG. 1  comprises three cyclones  11 ,  12 ,  13 , which are arranged in a common housing  14 . The housing has a bottom outlet  15 , which is closed by an outlet valve  16 . The outlet valve  16  opens the opening  17  when a specific liquid pressure acts on the valve. The housing  14  is closed with a cover  18 . Located above the cover  18  is an end element  19 , which receives the crankcase ventilation gases cleaned by the cyclones  11 ,  12 ,  13 . These gases are guided to the outlet pipe  22  via the pipe  20  and a pressure control valve  21 . The clean crankcase gases can be supplied to the intake tract of an internal combustion engine. The oil-laden gases flow into the apparatus through the opening  23 .  
         [0024]     Opening  23  is shown in greater detail in  FIG. 2 . In this figure, like components are identified by the same reference numerals. The cyclones  11 ,  12 ,  13  are depicted in a plan view. Feed lines  24 ,  25  and  26  open from common opening  23  and lead to the respective cyclones. The opening  23  is cylindrical and has a control plunger  27  arranged therein. The control plunger  27  is mounted on and simultaneously guided by a mounting pin  28 . A compression spring  29  is pushed over the holding pin and biases the control plunger toward the opening  23 , i.e, the spring  29  exerts a force on the control plunger in the direction of the opening  23 . The control plunger  27  has at least one opening  30  on the bottom facing the compression spring. Thus, the inlet opening  23  for the oil-laden crankcase gases is in communication with the feed line  26  for the cyclone  13 . This means that in a first position of the control plunger indicated by broken lines in which the control plunger closes the feed lines  24  and  25 , only the feed line  26  is in communication with the opening  23 , so that the oil-laden crankcase gases are fed only to the cyclone  13 . If the volumetric flow and thus the dynamic pressure on the control plunger  27  increase, the control plunger moves toward the cyclone  13  against the force of the compression spring  29  and initially opens the feed line  24  leading to cyclone  11 . Thus, two cyclones for cleaning the crankcase gases are active. If the dynamic pressure increases further, the control plunger also opens the feed line  25  leading to cyclone  12 , so that all three cyclones admit crankcase gases. The control plunger is equipped with three seal rings  31 ,  32 ,  33 , which assure that the crankcase gases are correctly and optimally supplied to the individual cyclones in every position of the control plunger.  
         [0025]      FIG. 3  shows another configuration of an apparatus according to the invention for deoiling crankcase ventilation gases comprising three cyclones  34 ,  35  and  36 . Each of the cyclones has its own feed line  37 ,  38  and  39 , respectively. The oil-laden crankcase gases reach the feed lines via the opening  40 . A diaphragm valve  41  is provided to control the distribution of the volumetric flows to the cyclones. This diaphragm valve is comprised of a flexible or elastic rubber diaphragm  42 , which is clamped between the housing  43  and a cover  44 . The center of rubber diaphragm  42  carries a disk  45  on which two tappets  46 ,  47  are disposed. The tappet  46  closes the feed line  39 , and the tappet  47  the feed line  38 . In the illustrated position of diaphragm  42  and disk  45 , the feed line  38  is open, while the feed line  39  closed. On the side of the rubber diaphragm  42  opposite the disk, a compression spring  48  and a spring guide  49  are provided. The compression spring  48  exerts a force on the rubber diaphragm  42  in the direction of the feed lines  38 ,  39  and thus biases the diaphragm valve toward the position in which feed lines  38  and  39  are closed. The space within the cover  44  communicates via the opening  50  with the feed line for the gases cleaned by the cyclone, such that the pressure of the connecting line extends into the space within the cover  44 . The opposite side of the rubber diaphragm  42  is subject to the pressure of the oil-laden crankcase gases through the opening  51 . This means that if the pressure on the side of the oil-laden gas is low, the tappets  46 ,  47  close the feed lines  38 ,  39 . If the pressure on the side of the oil-laden gas increases, the diaphragm  42  is urged against the force of the compression spring  48  and moves in the direction of the compression spring, such that first the feed line  38  and then the feed line  39  are opened.  
         [0026]      FIG. 4  schematically illustrates another solution to controlling the gas distribution among the cyclones  52 ,  53 ,  54 . The cyclones are situated next to a crankcase ventilation gas feed line  55 . Within the feed line  55  there is a slide valve  56 , which is attached to a diaphragm  57 . In this embodiment the diaphragm is likewise subject to the pressure of the clean gas on the right and the oil-laden gas on the left. The slide valve  56  has a passage  58 . While the cyclone  52  is open in every operating state, the opening  58  shifts depending on the pressurization of the diaphragm and opens the cyclone  53 ,  54  depending on the pressure differential across the diaphragm. As in the other embodiments, a compression spring (not shown) may be provided to bias the valve toward a position in which access to one or both of cyclones  53  and  54  is blocked.  
         [0027]      FIG. 5  is a three-dimensional representation of a housing for a control plunger  60  similar in construction to that shown in  FIG. 2 . Control plunger  60  is located in a cylindrical housing  61  and can move therein in the direction of the arrow  62 . The support at the end of the housing is effected via a compression spring  63 . This compression spring is affixed to the control plunger  60  by brackets  64 ,  65 ,  66 . The control plunger is subject to the flow pressure of the crankcase gas in direction A against the end plate  71 . Depending on the volumetric flow, this flow pressure causes plunger  60  to move against the pressure of the spring  63 . Because of an annular gap between the end plate  71  and the housing wall  61 , the crankcase gas can flow past the end plate and reach a first cyclone. The control plunger  60  is displaceably mounted on a support  72 . This support  72  has guide surfaces  67 ,  67   a . The support  72  is clasped by the control plunger  60  in the region of these guide surfaces and the peripheral wall arranged in this region. The control piston  60  can move along the support  72  on this dovetail guide. Two openings  68 ,  69  are provided in the support  72  itself. These openings communicate with the other cyclones (not shown). A window  70  on the control plunger  60  opens these openings  68 ,  69  or closes them if the crankcase gas pressure is low. In the position shown here, the crankcase gas pressure is at its maximum, i.e., these two cyclones and a continuously open cyclone are all open. If the crankcase gas pressure drops, the control plunger first closes the opening  69  and then the opening  68 . This configuration shows a simple and effective valve to control and distribute the crankcase gas stream among the several cyclones. It is of course also possible to control a plurality of cyclones by using corresponding configurations of the window  70  or additional openings below this window.  
         [0028]     The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations within the scope of the appended claims and equivalents thereof.