DE3637325A1 - Lubricating oil filter for an internal combustion engine - Google Patents

Abstract

The invention relates to a lubricating oil filter 10 for an internal combustion engine. The filter housing 11 has a main oil filter element 12 and a reserve oil filter element 13, which can be switched into the lubricating oil flow in place of the main oil filter element, serving as back-up for the main oil filter element. A valve 30, which is moved by way of a differential pressure switch 43 by means of a solenoid 39 and controls the lubricating oil flow through the reserve oil filter element, is held in its position releasing the lubricating oil flow through the reserve oil filter element by a catch device 25, 29. The catch device can be disengaged only when the oil filter elements are removed from their operating position fitted in the filter housing. As a result, the need to change the filter element is brought promptly to the attention of the driver, whilst complete filtering of the lubricating oil is still assured for a sufficient length of time. <IMAGE>

Description

The invention relates to a lubricating oil filter for a Internal combustion engine that has a main oil filter insert and one Contains reserve oil filter insert. The smaller and a shorter service life than the main oil filter insert reserve oil filter insert only then in operation be taken when the main oil filter insert is almost exhausted is to change the main oil filter insert postpone.

An indication of the exhaustion of an oil filter insert is that Increase in pressure difference between the pressure on the Dirty oil and the pure oil side, which is therefore a reference be used on a necessary oil filter insert replacement can. However, since the dirt pick-up of an oil filter insert from Time of a significant increase in differential pressure up to total exhaustion is small, already becomes this Time usually uncleaned via a short-circuit valve Oil supplied to the lubrication points. It may not be possible to change the oil filter insert in a short time perform so that over a long period of time Dirty oil is supplied to lubrication points.

From DE-OS 34 14 608 a main oil filter and is known a reserve oil filter to provide the one hand Postpone maintenance intervals and then another perfect oil filtering until the next oil filter change guarantee. This enables the driver to access the due oil filter changes are pointed out without already hardly any cleaned oil reaches the lubrication points. With this disclosed lubricating oil filter becomes a reserve oil filter insert due to a change in pressure from a predetermined differential pressure Dependent on the increase in differential pressure opening Pressure relief valve switched on, in order to switch on  to avoid cold oil, the pressure relief valve still on Temperature-dependent electromagnetically operated valve is connected upstream, that only from a certain temperature opens and the pressure relief valve with the dirty oil pressure acted upon. Above a certain differential pressure opens the pressure relief valve gradually more and more until finally the reserve oil filter insert the complete main flow filtering take over. To indicate to the driver that a Oil filter change is required, a display device activated via a contact actuated by the pressure relief valve.

If now with this lubricating oil filter after the Main oil filter insert exhausted and the reserve oil filter insert was switched on, the engine turned off and later cold is started, the temperature-dependent valve opens first not so that up to a certain temperature the Reserve oil filter insert remains unused and the oil through the exhausted main oil filter insert or bypass valve flows.

The present invention addresses the problem that Function and mode of operation of the lubricating oil filter for one To improve the internal combustion engine so that an increased Operational safety for the lubrication of the lubrication points is achieved.

This problem is solved in that the lubricating oil filter has a filter housing with
a main oil filter insert and a reserve oil filter insert serving as a reserve for the main oil filter insert, which can be switched into the lubricating oil flow instead of the main oil filter insert,
a valve controlling the flow of lubricating oil through the reserve oil filter insert,
a differential pressure switch that switches depending on the differential pressure between the dirty oil and clean oil side of the main oil filter insert,
an electromagnet which, depending on the temperature of the lubricating oil on the basis of a signal emitted by the differential pressure switch, causes the valve body of the valve to move against the force of a closing spring, so that the lubricating oil flow is released through the reserve oil filter insert, and
a locking device that holds the valve body in its position releasing the lubricating oil flow through the reserve oil filter insert, as long as the reserve filter insert is installed in its operating position in the filter housing.

Common filter inserts can be used Main flow filter inserts are used, which are only differ in that they are based on their dimensions and design are suitable for different service lives. That the lubricating oil flow through the reserve oil filter insert controlling valve can either seen in the direction of flow or installed behind the reserve filter insert. Depending on becomes the reserve oil filter insert after opening in the first case charged with dirty oil, while in the second the Reserve oil filter insert is already contaminated with dirty oil, this however due to the closed valve on the The clean oil side of the reserve oil filter insert is negligible can get through the reserve oil filter insert.

The differential pressure switch can be used as a make or break contact trained and with a device for determining the Oil filter and oil change time according to DE-OS 35 19 026 be connected. This ensures that the Differential switch only at the desired temperature Control signal to the electromagnet, which detects the movement of the Valve body causes is delivered. The electromagnet can the movement of the valve body directly or indirectly through Adjustment of intermediate control elements. The locking device can be mechanical or electromechanical be set up and should release the  Reserve oil filter insert after switching on once in each Ensure the operating state until an exchange at least one filter insert has taken place.

The invention has the advantage that a sudden release of the reserve oil filter insert is reached when a specified differential pressure is exceeded. This flows then the dirty oil over the fresh reserve oil filter insert, so that only sufficiently purified oil to the Lubrication points reached. The locking device is a Permanent connection reached, so that even after switching off of the vehicle and a later cold start immediately Reserve oil filter insert from the dirty oil to be cleaned is flowed through. Because of the permanent connection it is also possible with simple means then the driver the oil filter insert replacement due immediately when starting the Motors to point out. The display remains until actually an exchange of at least one oil filter insert is done. Another advantage is that Locking device of the electromagnet only a low power required, since it is only used to release the reserve oil filter insert must be activated and therefore not an expensive one Power electronics for actuating the electromagnet is required.

Further advantageous embodiments are the subclaims refer to.

In a preferred embodiment, the locking device has a telescopic locking pin, which between one at Oil filter insert replacement of the part to be removed Reserve oil filter insert and the valve body is held, is supported on a filter housing part via a spring, the Force away from the valve body in the direction Reserve oil filter insert is directed, and in the Locked position engages in a recess in the valve body. At  The part can be the cover plate of the Reserve oil filter insert, which together with the Reserve oil filter insert is removed, or to others for the Telescopic locking pin act suitable stable parts. Through this Arrangement of a telescopic pen known per se becomes this against the force of a spring so between, for example End plate of a reserve oil filter insert and one Clamped filter housing part that, for example, the movable Inner pin of the telescopic pin sits on the valve body. When moving the valve body, this can then Inner pin in a specially provided recess in the Intervene valve body and this at its instantaneous Hold position. The inner pin can only be removed from the Get recess when the filter insert out of its Operating position is removed, since then on the Spring supporting the housing part the entire telescopic locking pin can move away from the valve body.

The electromagnet and the valve body can be on one axis be arranged so that the valve body directly through the Electromagnet is movable. But as little energy as possible to move the valve body is in one another advantageous embodiment of the electromagnet a control spool connected to the movement of the Valve body influencing oil flow by closing or Share holes controls. As a result, the Electromagnet can be designed even smaller so that it on the one hand little space and on the other hand also little performance needed because the spool moves in its own medium and the Valve body with support from different ones at the Open front side of the valve body pressures can.

Using an exemplary embodiment and the drawings Invention explained in more detail below. Make the drawings represents:  

Fig. 1 shows a longitudinal section through a lubricating oil filter, said valve body is shown in the position, is flowed through in only the main oil filter from the dirty oil, and, the movement of the control piston through a control slide valve;

Fig. 2 excerpts from Fig. 1, wherein

• a) the valve body in the open state when oil filter insert still installed and
• b) the closed valve body when removed Oil filter insert shows;

3a shows a section through the lubricating oil filter of Figure 1 taken along line 3-3, wherein the spool is shown in the position in which the valve body does not release the reserve oil filter element..;

FIG. 3b shows a detail from Fig 3a, in which the spool is shown in the position in which the reserve oil filter element is switched on.

. Fig. 4 is a section through the lubricating oil filter of Figure 1 along line 4-4; and

FIG. 5 shows a detail from FIG. 1, an electromagnet being connected directly to the valve body instead of the control slide.

Fig. 1 shows an oil filter 10 having a filter housing 11, in which a main oil filter cartridge 12 and a replacement oil filter 13 are arranged axially one above the other. The filter housing 11 has a filter housing cover 15 which holds the oil filter inserts 12 , 13 in position and seals the interior 16 of the filter housing from the outside. The filter housing cover 15 is firmly clamped to the filter housing with a retaining screw 14 . Both the main oil filter insert 12 and the reserve oil filter insert 13 are suitable for cleaning the dirty oil in the main stream, the only difference being that the service life of the main oil filter insert until the next change is considerably longer than that of the reserve oil filter insert. In a known manner, the interior 16 of the filter housing 11 is divided by the oil filter inserts 12 , 13 into a dirty oil chamber 17 , which surrounds the oil filter inserts, and a clean oil chamber 18 in the interior of the annular oil filter inserts. The dirty oil (marked with the arrow S ) is supplied to the dirty oil chamber 17 via the dirty oil channel 19 . The pure oil (marked with the arrow R ) leaves the filter housing 11 via the pure oil channel 20 , which is constantly connected to the pure oil chamber 18 h of the main oil filter insert 12 via the central tube 21 . The clean oil chamber 18 r of the reserve oil filter insert 13 is also connected to the pure oil channel 20 via the annular space 22 surrounding the central tube 21 . A bypass valve 55 is installed between the dirty oil channel 19 and the clean oil channel 20 in a known manner.

In Fig. 1, the passage from the annular chamber 22 to the clean oil duct 20 through a valve 30, the valve piston 31 at the abutting with the valve seat 32 the clean oil passage 20 surrounding wall 23 sealingly. The valve piston 31 is held in its closed position by a spring 33 . A control slide 37 in a bore 38 serves to open the valve 30 . For this purpose, the control slide 37 is moved by an electromagnet 39 (FIGS . 3a and 3b) with the electrical connection 56 . Depending on the operating state, the space 34 on the side facing away from the sealing surface of the piston 31 and the control space 40 are connected via the bore 38 to the duct 36 or the return duct 41 (FIGS . 3a and 3b) to the crankcase. The channel 36 is connected to the annular space 22 via the opening 35 .

As shown in FIG. 1, the valve piston 31 has a recess 29 designed as an annular groove. In a bore 24 of the filter housing 11 there is a telescopic locking pin 25 , which is supported at one end on the lower cover plate 27 of the reserve oil filter insert 13 and at the other end with the inner pin 28 on the circumference of the piston 31 . The telescopic locking pin 25 is resiliently mounted in the bore 24 so that the force of the spring 26 acts in the direction of the oil filter insert.

The dirty oil S reaches the interior of the filter housing 16 via the channel 19 in order to flow radially through the oil filter inserts 12 , 13 from the outside inwards. Normally, the valve piston 31 is in its position shown in FIG. 1, so that there is no connection between the annular space 22 , which guides the pure oil from the reserve oil filter insert 13 , and the pure oil channel 20 . As a result, only as much dirty oil passes through the reserve oil filter insert 13 as the space on the clean oil side of the reserve oil filter insert can hold. This will usually be the case when the engine is started for the first time after changing the filter insert. The reserve oil filter insert 13 is then blocked for the dirty oil, so that it is cleaned exclusively by the main oil filter insert 12 and is fed to the pure oil channel 20 via the pure oil chamber 18 h and the central tube 21 .

As a result of the closed valve 30, a static dirty oil pressure builds up on the clean oil side of the reserve oil filter insert 13 , which is used to hold the valve piston 31 in its valve seat 32 together with the spring 33 . The pure oil pressure builds up in the pure oil channel 20 and presses against the end face of the valve piston 31 . The spring 33 serves essentially to close the valve, so that for the purpose of opening the valve later, the force of the spring 33 must be less than the counterforce which presses against the effective surface of the valve piston 31 as a result of the pure oil pressure. Since the annular space 22 is connected to the space 34 on the side of the valve piston 31 facing away from the sealing surface via the opening 35 and the channel 36 shown in broken lines in FIG. 1, the control bore 38 and the control space 40 , the static dirty oil pressure also builds up there . This develops a force that is already greater than the force of the pure oil pressure in the channel 20 , so that the valve body 31 is held in its valve seat 32 .

If the main oil filter insert is so dirty that the pressure difference between the dirty oil pressure and the pure oil pressure exceeds a certain value in the normal operating state, since from this value there is only a small amount of dirt in the main oil filter insert 12 , the reserve oil filter insert 13 should be switched on automatically. This is achieved in that a differential pressure switch 43 ( FIG. 3a), which is connected via a bore 44 to the pure oil duct 20 and a bore 45 ( FIG. 3a) to the dirty oil duct 19 , switches and supplies a signal to the on-board electronics of the motor vehicle . Depending on the temperature of the lubricating oil, which should be at least 80 ° C to avoid opening the valve 30 when the lubricating oil is cold (cold start), the on-board electronics, not shown, use a known evaluation circuit (DE-OS 35 19 026) to produce the electromagnet 39 ( Fig. 3) actuated. As a result, the valve piston 31 of the valve 30 releases from the valve seat 32 and moves into the position shown in FIG. 2a. The inner pin 28 of the telescopic locking pin 25 slides along the outer circumferential surface of the valve piston up to the recess 29 provided in the valve piston, into which it then engages due to the spring arranged inside the telescopic locking pin. The reserve oil filter insert 13 is thereby permanently switched into the main flow, so that due to the contamination of the main oil filter insert, the resistance for the dirty oil flowing in via the dirty oil channel 19 through the reserve oil filter insert is lower and this therefore takes over the lubricating oil filtering. Even when the engine is switched off, the reserve oil filter insert 13 remains switched on, so that when the engine is restarted, the dirty oil filtering is immediately taken over by the reserve oil filter insert. A suitable display, for example in the dashboard, must inform the motor vehicle driver that an oil filter insert change will soon be necessary. Since the service life of the reserve oil filter insert 13 is shorter than that of the main oil filter insert 12 , but should still be a few thousand kilometers, safe and faultless lubricating oil filtering is ensured in this way until the next lubricating oil filter change.

The valve piston 31 can only return to its closed position shown in FIG. 1 when, as shown in FIG. 2b, the oil filter inserts 12 , 13 are removed from their operating position. Then the telescopic locking pin 25 moves due to the force of the spring 26 acting against the collar 42 up to a stop 46 at the end of the bore 24 , so that the inner pin 28 is pulled out of the recess 29 in the valve piston 31 . The force of the spring 33 moves the valve piston 31 back onto the valve seat 32 , since it can be assumed that no back pressure has built up in the clean oil channel 20 when the filter inserts have been removed. After installing the oil filter inserts, the state shown in Fig. 1 is restored. A suitable contact can indicate to the on-board electronics that the filter insert has been changed. Manual reset of the display for the driver is also conceivable.

The manner in which the movement of the valve piston 31 takes place using the control slide 37 is shown below. The control slide 37 located in the control bore 38 is therefore shown in FIG. 3a in the position in which the valve piston 31 (shown in dashed lines in FIG. 3a) is in its closed position. The channel 36 , which is connected to the annular space 22 via the opening 35 , and the return channel 41 to the crankcase open into the control bore 38 . The control chamber 40 is located between the mouth of the channel 36 and the return channel 41 and communicates with the chamber 34 on the rear side of the valve piston 31 . Furthermore, at both ends of the control piston 37 perpendicular to the control bore 38, leakage oil channels 47 and 48 are provided, which are connected via the channel 49 ( FIG. 4) to the return channel 41 in order to return the leakage oil which inevitably occurs via the return channel 41 to the crankcase. The control slide 37 also has two control pistons 50 , 51 which are arranged at a distance from one another so that when the control piston 50 opens the opening to the channel 36 , the control piston 51 closes the opening to the return channel 41 and vice versa. In the position shown in FIG. 3 a, the pure oil with the static dirty oil pressure, as already mentioned, passes through the channel 36 , the control bore 38 , the control chamber 40 into the chamber 34 in order to hold the valve piston 31 in its valve seat 32 . If the differential pressure now exceeds the critical value, the electromagnet 39 receives a control pulse via the on-board electronics, which is sufficient to move the control slide 37 in the axial direction in the control bore 38 such that the opening from the channel 36 to the control bore 38 through the control piston 50 closed and the opening from the control bore 38 to the return channel 41 is released by the control piston 51 . Since the control slide 37 is mounted in oil, it can be moved with little force, so that the electromagnet 39 is only in operation for a short time and only requires a small amount of power for operation.

By moving the control spool 37 ( Fig. 3b) the connection between the space 34 and the channel 36 is interrupted and at the same time a connection between the space 34 and the return channel 41 to the crankcase is established, so that in the space 34 on the sealing surface of the Valve piston 31 facing away from the original static dirty oil pressure can no longer be maintained. As a result, the force of the pure oil in the pure oil channel 20 acting on the end face of the valve piston 31 is greater than the force which is to hold the valve piston 31 in its valve seat 32 . As a result, the valve piston 31 is moved out of its valve seat 32 against the stop 52 and, as described above, the locking pin 25 can snap into the recess 29 . The pure oil located in the space 34 can get into the crankcase via the control space 40 , the control bore 38 and the return channel 41 , as indicated by the arrow K. If the valve piston 31 is engaged, the control slide 37 is moved back into its starting position by the force of a spring 53 . The control pulse must therefore be long enough to allow a reasonably safe opening of the valve 30 . If, due to a fault, the pulse is not sufficient to bring the valve 30 into the latched position, a pulse is given to the electromagnet 39 until the valve 30 has opened due to the differential pressure which is still present.

Since after the opening of the valve 30 the control slide 37 is again in its initial position and thus the channel 36 is in communication with the, even if smaller, space 34 , the pure oil pressure acts against the back of the valve piston 31 to the force of the spring 33 . This causes less friction of the inner pin 28 in the recess 29 on the valve piston 31 , so that a secure disengagement of the pin 28 from this recess 29 is ensured when the filter inserts 12 , 13 are removed.

In Fig. 5, a valve piston 31 is shown, which is connected via a valve stem 54 directly by an electric magnet 39. The valve 30 is opened directly by the electromagnet 39 , so that it has a higher output and must therefore also have a larger construction in order to carry out the movement of the valve piston 31 safely. Here too, the electromagnet 39 receives a control pulse until the pin 28 engages in the recess 29 and the differential pressure has dropped. As in the embodiment shown in FIGS. 1 to 4, the electromagnet only has to be supplied with voltage during the opening phase. When the oil filter inserts 12 , 13 are removed, the closing process is effected by the spring 33 .

• Reference symbol list: 10 lubricating oil filters
  11 filter housing
  12 main oil filter insert
  13 Reserve oil filter insert
  14 retaining screw
  15 filter housing cover
  16 interior d. Filter housing
  17 dirty oil chamber
  18 clean oil room
  19 Dirty oil duct 20 Pure oil duct
  21 center tube
  22 annulus
  23 wall
  24 hole
  25 telescopic locking pin
  26 spring
  27 cover plate
  28 Inner pin
  29 recess 30 valve
  31 pistons
  32 valve seat, sealing surface
  33 spring
  34 room
  35 opening
  36 channel
  37 spool
  38 control bore
  39 Electromagnet 40 control room
  41 Return channel to the crankcase
  42 collar
  43 differential pressure switch
  44 bore (pure oil)
  45 bore (dirty oil)
  46 stop
  47 Leak oil channel
  48 leakage oil duct
  49 connecting channel 50 control piston
  51 control piston
  52 stop
  53 spring
  54 valve lifters
  55 Bypass
  56 connections

Claims (5)

1. Lubricating oil filter for an internal combustion engine, which has a filter housing ( 11 ) with
a main oil filter insert ( 12 ) and a reserve oil filter insert ( 13 ) serving as a reserve for the main oil filter insert, which can be switched into the lubricating oil flow instead of the main oil filter insert, and
a valve ( 30 ) controlling the flow of lubricating oil through the reserve filter insert,
characterized in that in the filter housing a differential pressure switch ( 43 ) which switches depending on the differential pressure between the dirty oil and pure oil side of the main oil filter insert,
an electromagnet ( 39 ) which, depending on the temperature of the lubricating oil on the basis of a signal emitted by the differential pressure switch, causes the valve body ( 31 ) of the valve ( 30 ) to move against the force of a closing spring ( 33 ), so that the lubricating oil flow is released through the reserve oil filter insert , and
a latching device ( 25 , 29 ) which holds the valve body ( 31 ) in its position releasing the lubricating oil flow through the reserve filter insert ( 13 ), as long as the reserve oil filter insert is installed in its operating position in the filter housing ( 11 ). 2. Oil filter according to claim 1, characterized in that the latching means (25, 29) comprises a telescoping locking pin (25) which is held between a when oil filter changes to be removed part (27) of the reserve oil filter cartridge (13) and the valve body (31), is supported on a part of the filter housing ( 11 ) via a spring ( 26 ), the force of which is directed away from the valve body in the direction of the reserve oil filter insert, and which engages in a recess ( 29 ) in the valve body ( 31 ) in the detent position. 3. Lubricating oil filter according to one of the preceding claims, characterized in that the electromagnet ( 39 ) and the valve body ( 31 ) are arranged on an axis, so that the valve body can be moved directly by the electromagnet. 4. Lubricating oil filter according to one of claims 1 or 2, characterized in that the electromagnet ( 39 ) is connected to a control slide ( 37 ) which controls an oil flow influencing the movement of the valve body by closing or uncovering bores ( 36 , 41 ). 5. Lubricating oil filter according to claim 4, characterized in that the common axis of the electromagnet ( 39 ) and the control slide ( 37 ) is perpendicular to the longitudinal axis of the valve body ( 31 ) and the space ( 34 ) on which the sealing surface ( 32 ) of the valve piston ( 31 ) opposite side can be acted upon by at least one bore ( 36 ) with pure oil.