Patent Publication Number: US-10323550-B1

Title: Protection for hydraulic lifters

Description:
FIELD 
     The present disclosure relates to preventing engine oil debris from entering a hydraulic lifter, particularly a deactivatable lifter. 
     BACKGROUND 
     Internal combustion engines typically use hydraulic valve lash adjusting lifters to maintain a zero valve clearance. Older style solid lifters maintain a small clearance between the valve and its rocker or cam follower. These solid lifters wear and must be adjusted periodically so that the clearance is not so great as to lead to undesirable levels of tappet noise, a clacking sound. With the hydraulic lifter, pressurized engine oil is supplied to hydraulic valve lash adjusting lifter through a small hole in the lifter body. When the engine valve is closed (lifter in a neutral position), the lifter is free to fill with oil thereby increasing the length of the lifter. As the camshaft lobe enters the lift phase of its travel, it compresses the lifter piston, and a valve shuts the oil inlet. Oil is nearly incompressible, so this greater pressure renders the lifter effectively solid during the lift phase. As the camshaft lobe returns to its base circle after passing through its apex the load is reduced on the lifter piston, and the internal spring returns the piston to its neutral state so the lifter can refill with oil. This small range of travel in the lifter&#39;s piston is enough to allow the elimination of the constant lash adjustment. It is desirable to keep debris out of the internal mechanism to ensure proper operation. 
     Even more sensitive than the lash adjusting function of the lifter is a valve deactivation system. Some internal combustion engines have valve deactivators on intake and/or exhaust valves on a pre-selected portion of engine cylinders. In a latched position, the valve deactivator is locked for normal operation of the valves. In an unlatched position, the lifter body is allowed to collapse and thereby fails to actuate the intake valves in engine cylinders in which an unlatch signal has been sent. The reason for deactivating a portion of cylinders is to achieve higher fuel efficiency by operating a fewer number of cylinders at a higher torque operating condition as opposed to operating all engine cylinders at a low torque operating condition, the latter of which is inherently less efficient in a spark-ignition engine. Movement of the latch assembly within the lifter is achieved by providing (or not providing) engine oil pressure in a fluid circuit dedicated for such control. 
     In some applications, pressurized oil for causing valve deactivation is provided to a lifter and the lost-motion or collapsible hardware is contained within the rocker arm such that the rocker arm collapses and fails to actuate the intake or exhaust valve with which it is associated. In either the case of the collapsing hardware being located in the rocker arm or in the lifter, the pressurized oil is provided to the lifter to access the collapsing hardware. 
     It is well known that regardless of measures taken to clean out machining and casting debris from an engine off the line, some debris remains. It has been found, particularly in the valve deactivator portion of the valve lifter (or rocker arm) such debris can cause malfunctions. Current strategies to prevent debris from entering the deactivator oil circuit within the valve lifter has been found to help; yet fails to be a guarantee for preventing debris ingress. Some way to protect the valve deactivator or rocker arm portion of the lifter and/or the valve lash adjuster portion of the lifter from being provided debris-contaminated engine oil is desired. 
     SUMMARY 
     To overcome at least one problem in the prior art a hydraulic valve lifter is disclosed that includes a lifter body, a valve deactivator recess defined in the lifter body, a valve deactivator orifice defined in the recess, such orifice providing a passage for oil into a valve deactivator portion of the valve lifter, and a filter provided within the valve deactivator recess. The filter is located to filter oil flowing into the valve deactivator orifice. 
     The filter is substantially flat with a center section slightly deformed to form a peak; and the peak is inserted into the valve deactivator orifice. 
     The filter is welded to the recess proximate the orifice defined in the recess. In an alternative embodiment, an adhesive is used to couple the filter to the recess. 
     The filter is wire mesh of a predetermined opening size. 
     The lifter further includes: a lash adjuster recess defined in the lifter body, a lash adjuster orifice defined in the lash adjuster recess in the lifter body, a lash adjuster orifice defined in the lash adjuster orifice recess; and a lash adjuster filter installed in the lash adjuster recess and located on the upstream side of the lash adjuster. The adjuster orifice provides a passage for oil into a lash adjuster portion of the valve lifter. In some embodiments, the lash adjuster filter is substantially circular, yet can be any suitable shape. The lash adjuster filter has a diameter greater than the lash adjuster orifice; and the filter is coupled to the lash adjuster recess proximate the lash adjuster orifice by an adhesive, a weld, or any suitable coupling feature. 
     In some embodiments, the filter is a wire mesh strip that has been formed into a coil. The coil is uncoiled sufficiently to install over the lifter and the coil is allowed to recoil into the recess. 
     Some embodiments include a cage disposed in the recess over the filter. The cage includes multiple sections that are coupled together via one or more snap-fit connectors. 
     Also disclosed is a variable displacement engine that has at least one engine cylinder having at least one intake or exhaust poppet valve and a rocker arm touching the valve on a first end of the rocker arm and a deactivatable lifter on a second end of the rocker arm. A body of the deactivatable lifter has a recess defined therein with a valve deactivator orifice defined in the recess, such orifice providing a passage for oil into a valve deactivator portion of the lifter. A filter, located upstream of the valve deactivator orifice, is provided within the valve deactivator recess. 
     In some embodiments, the filter is substantially flat with a center section slightly deformed to form a peak. The peak is inserted into the valve deactivator orifice. 
     The filter is coupled to the recess proximate the orifice defined in the recess. 
     The engine has an oil circuit providing lubricating oil to the engine, an oil pump disposed in the oil circuit, a branch of the oil circuit fluidly coupled to the valve deactivator orifice, and a control valve disposed in the branch. Also included is an electronic control unit (ECU) electronically coupled to the control valve. The control valve has a latched position and an unlatched position. The ECU commands the control valve position based at least on demanded engine torque. 
     In some embodiments, a lash adjuster recess defined in the body of the lifter. a lash adjuster orifice defined in the lash adjuster recess, a lash adjuster filter disposed in the lash adjuster recess, an oil circuit providing lubricating oil to the engine, an oil pump disposed in the oil circuit, and a branch of the oil circuit fluidly coupled to the lash adjuster orifice. 
     The engine further includes a deactivatable lifter associated with a valve of the engine (intake or exhaust valve), a body of the deactivatable lifter has a recess defined therein with a valve deactivator orifice defined in the recess, such orifice providing a passage for oil into a valve deactivator portion of the lifter, and a filter provided within the valve deactivator recess. 
     The filter is placed over the valve deactivator orifice and edges of the filter are welded to the recess proximate the orifice or coupled in any suitable manner. 
     The engine also includes a cylinder head with at least one intake valve, a bore defined in the cylinder head to accept the lifter, an oil circuit with an oil pump pressurizing the oil and oil provide to the cylinder head and a branch provided to the deactivatable lifter, a solenoid valve provided in the branch, and an electronic control unit (ECU) electronically coupled to the solenoid. 
     The ECU receives a plurality of signals from engine sensors; based on the signals, the ECU commands solenoid valve position. 
     The filter is a wire mesh of a predetermined opening size. 
     The engine, in some embodiments, also includes: a lash adjuster recess defined in the body of the lifter, a lash adjuster orifice defined in the lash adjuster recess, and a lash adjuster filter disposed in the lash adjuster recess. 
     The engine has an oil circuit providing lubricating oil to the engine, an oil pump disposed in the oil circuit, and a branch of the oil circuit fluidly coupled to the lash adjuster orifice. 
     In some embodiments, the lash adjuster filter is a wire mesh strip that has been formed into a coil. The coil is uncoiled sufficiently to install over the lifter. The coil is allowed to recoil into the lash adjuster recess. 
     Some embodiments include a cage disposed in the recess over the lash adjuster filter. The has multiple sections that are coupled together via one or more snap-fit connectors. 
     In some embodiments, the lash adjuster filter is provided upstream of the lash adjuster orifice and coupled to the lash adjuster recess. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of a deactivatable hydraulic lash adjusting lifter; 
         FIGS. 2 and 3  are illustrations of a portion of a valve train of an internal combustion engine with a deactivatable lifter; 
         FIG. 4  shows a portion of an oil circuit for an internal combustion engine; 
         FIG. 5  is an illustration of a portion of an internal combustion engine; 
         FIG. 6  shows a deactivatable hydraulic lash adjusting lifter; 
         FIG. 7  shows a deactivatable hydraulic lash adjusting lifter with filters over orifices in the lifter; 
         FIG. 8  shows a portion of a lifter body with a filter disposed near an orifice for oil ingress; 
         FIG. 9  shows a drawing of a coiled wire mesh filter strip; 
         FIG. 10  shows a lifter with a coiled wire mesh filter disposed in a recess in the body of the lifter; 
         FIGS. 11 and 12  are two embodiments of a cage to hold a wire mesh filter strip in place in the recess; and 
         FIG. 13  shows a lifter with a coiled wire mesh filter and a cage over the filter. 
     
    
    
     DETAILED DESCRIPTION 
     As those of ordinary skill in the art will understand, various features of the embodiments illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. Those of ordinary skill in the art may recognize similar applications or implementations whether or not explicitly described or illustrated. 
     A deactivating hydraulic lash adjusting valve lifter  10  is shown in  FIG. 1 . Lifter  10  has a generally cylindrical body  12 . A pin housing  14  is disposed within an axial bore  16  defined in adjuster body  12 . Pin housing  14  also has an axial bore  18  for receiving a plunger  20  that has a domed end  22  for engaging with a roller finger follower in an overhead-cam engine valve train. 
     Pin housing  14  has a transverse bore  24  with two opposed locking pins separated by a pin-locking spring  28 . Axial bore  16  is provided with a circumferential groove  30  for receiving the outer ends of locking pins  26 . Locking pins  26  are thrust outwards by spring  28  when pins  26  are aligned with groove  30 . When in such position, valve lifter is in valve-activation mode. As shown in  FIG. 1 , however, valve lifter is in valve-deactivation mode. 
     Upper end  32  of pin housing  14  defines a first seat for a lost-motion return spring  34  disposed within a spring chamber  35 , i.e., the space between bore  16  and pin housing  14 . Annular stop  37  serves as a second seat for lost-motion spring  34 . 
     Groove  30  defines a reservoir for providing high pressure oil against the outer ends  36  of locking pins  26  to overcome spring  28  and retract the locking pins into bore  24  to unlock the pin housing from the lifter body to deactivate the lifter. Groove  30  is in fluidic communication with an engine oil gallery (not shown) via a port  38 . Groove  30  is supplied pressurized engine oil when it is determined that deactivation of the valve is desired. Plunger  20  includes check valve components lodged at an inner end. Check valve components include a spring-loaded check ball  44  lodged against a seat  46  formed in plunger  20  separating a low-pressure oil reservoir  48  from a high-pressure chamber  50 . Oil is supplied to annular chamber  35  from an engine oil gallery via a port  54  in lifter body  12 . Chamber  35  is also in fluidic communication with reservoir  48  via a port  56  and annular groove  58  in pin housing  14  and annular groove  60  and port  62  in plunger  20 . 
     Lifter  10  is disposed in a bore in the engine with adjuster body  12  remaining stationary. When an associated cam (not shown) exerts force on plunger end  22 , in deactivation mode, plunger  20  and pin housing  14  are forced into body  12  in a lost-motion stroke, compression lost-motion spring  34 . In normal operation, plunger  20  does not move relative to pin housing  14  and the intake valve associated with the cam is operated normally. As described above, the collapsible portion that leads to valve deactivation can alternatively be disposed within the rocker arm. In such embodiment, it is common for the oil provided to the rocker arm enters in the lifter and then travels to the rocker arm. Thus, according to embodiments of the present disclosure, having a filter upstream of the inlet orifice in the lifter protects the deactivatable hardware within the rocker arm. 
     In  FIG. 2 , an illustration of a deactivatable lifter  122  is shown in which lifter  122  is in an active state. A cam shaft  117  has multiple cam lobes, one cam lobe  118  is illustrated in a position in which it is pushing down on rocker arm  120 . With lifter  122  activated, rocker arm  120  pushes down on an intake valve  114  thereby causing an associated valve spring  126  to compress. Valve  114  moves downward and lifts off its valve seat  128  to allow flow through intake port  124 . 
     In  FIG. 3 , lifter  122  is in its deactivated state. Even though cam lobe  1118  is shown such that in its state that would push down on rocker arm  120 , lifter  122  is collapsed so that there is no opening force exerted on valve  114 . Valve  114  stays seated on valve seat (not visible in  FIG. 3 ) and there is no flow through intake port  124 . 
       FIG. 4  shows the oil control branches relevant to a deactivatable hydraulic lash adjustable lifter  90 . Engine oil in a sump  70  is picked up by an oil pump  72  and pressurized. Oil is provided to filter  74  before being sent to the engine along path  76 , to a lash adjusting port (not separately shown in  FIG. 4 ) of lifter  90  via branch  88 , and to a valve deactivating port (not separately shown in  FIG. 4 ) of lifter  90  via branch  86 . Branch  86  includes a pressure sensor  82  that provides a signal to an electronic control unit (ECU)  80 . ECU  80  is also provided many other sensor inputs  84  such as temperatures, engine speed, demanded engine torque, etc. Based on sensor inputs  84  and other inputs, ECU  80  determines when to demand deactivation of lifter  90 . A control valve  78  disposed in branch  86 , is commanded to open when deactivation of lifter  90  is demanded and commanded to close when deactivation is not desired. 
     A portion of a cylinder head  160  of an internal combustion engine is shown in cross section in  FIG. 5 . A camshaft  140  has multiple cam lobes  142  one of which acts on rocker arm  144 . Lifter  138  is installed into a bore in cylinder head  160 . If it is a lash adjusting lifter, it adjusts slightly to take up lash (clearance) in the valve, rocker arm, and cam system. In embodiments in which lifter  138  is a deactivatable lifter, upon command, lifter  138  collapses when cam lobe  142  pushes on rocker arm  144  so that the rocker arm  144  has no effect on an associated intake valve  148 . Valve  148 , remains closed via valve spring  146 . If lifter is in an activated state and when lobe  142  acts upon rocker arm  144 , valve  148  moves downward to open allowing flow through intake runner  150  into combustion chamber  154 . A fuel injector sprays fuel into intake runner  150  that is swept into combustion chamber  154  with intake air during an intake stroke. A spark plug having a tip disposed in combustion chamber  154  ignites the fuel air mixture. 
     A deactivatable hydraulic lash adjustable lifter  220  is shown in  FIG. 6 . A body  202  of lifter  200  has two recesses  204  and  208 . Recess  204  has an orifice  206  that leads to a chamber within body  202  with the valve deactivation hardware. When pressurized oil is provided to orifice  206 , lifter  220  is in deactivation mode and will collapse when a force exerted thereon. Recess  208  has an orifice  210  for maintaining lash adjustment.  FIG. 7  shows filters  216  and  218  disposed over orifices  206  and  210 , respectively. Filters  216  and  218  are wire mesh and have a predetermined mesh size to trap particles that might have passed through the oil filter (shown in  FIG. 4 ). Filters  216  and  218  are welded to the surface of the recess to stay in place and to prevent particles from going around the filter. In some embodiments, the filter is coupled to the surface of the recess via adhesive. In the embodiment shown in  FIG. 7 , the filters are essentially circular and flat, yet any suitable shape can be used. Filters  216  and  218  are contained within recesses  204  and  208 , respectively, so that lifter  200  can be inserted into the bore in the cylinder head (not shown in  FIG. 7 ) for lifter  200 . In  FIG. 7 , a weld bead  220  is shown around filter  216  and weld bead  222  around filter  218 . In alternatives with adhesives,  220  and  222  are the adhesive material that might flow a bit outside of filters  216  and  218 , respectively. 
     Referring now to  FIG. 8 , a portion of a lifter body has a recess  220  with an orifice  222  defined therein. A wire mesh filter  224  is not flat but is deformed to have a slight peak in its center. The peak is inserted into orifice  222 . In some embodiments, this is helpful to locate filter  224  into orifice  222 . Filter  224  is welded to recess  220  at its periphery as shown by weld beads  226 . Alternatively, an adhesive or other suitable coupling protocol is employed. Filter  224  is shown as circular, yet can be any suitable shape. 
     Referring to  FIG. 9 , a wire mesh strip is shown that has been coiled. In  FIG. 10 , a lifter  200  has coiled filter  230  disposed in an upper recess of lifter  200 . End  232  of coiled filter  230  overlaps. 
     Cages  300  and  310  to hold a coiled filter in place are shown in  FIGS. 11 and 12 , respectively. Cage  300  ( FIG. 11 ) has a hinged joint with a pivot pin  306  and also snap fits via a tab  302  that engages with an opening  304 . Cage  310  ( FIG. 12 ) is comprised of two interlocking sections  316 , each of which have tab(s)  312  that engage with openings  314  to form a snap-fit connection. In  FIG. 13 , a cage  242  is shown in place over filter  240  in a recess of lifter  200 . Either of cages  300  or  310  or any suitable retaining feature can be used to hold filter  240  in place in the recess. Cage  242  has windows through which oil flow passes through filter  240 . Cage  242  has rings  244  at the top and bottom of the recess and vertical bars  246  spanning between rings  244 . 
     Many of the illustrations have shown a filter provided in a recess associated with an oil inlet for valve deactivation in a lifter. Such filter is equally applicable to the hydraulic lash adjuster portion of a lifter. Furthermore, it is applicable to lifters with only a hydraulic lash adjuster orifice, i.e., do not have a recess and orifice for valve deactivation. 
     While the best mode contemplated by the inventors has been described in detail with respect to particular embodiments, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. While various embodiments may have been described as providing advantages or being preferred over other embodiments with respect to one or more desired characteristics, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, recyclability, environmental factors, manufacturability, ease of assembly, etc. The embodiments described herein that are characterized as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.