US20090173303A1 - Hydraulic lash adjuster equipped with auxiliary check valve - Google Patents
Hydraulic lash adjuster equipped with auxiliary check valve Download PDFInfo
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- US20090173303A1 US20090173303A1 US11/968,713 US96871308A US2009173303A1 US 20090173303 A1 US20090173303 A1 US 20090173303A1 US 96871308 A US96871308 A US 96871308A US 2009173303 A1 US2009173303 A1 US 2009173303A1
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- Prior art keywords
- check valve
- lash adjuster
- plunger assembly
- plunger
- valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/20—Adjusting or compensating clearance
- F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
- F01L1/24—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically
- F01L1/2405—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically by means of a hydraulic adjusting device located between the cylinder head and rocker arm
Definitions
- the present invention relates to valve trains for internal combustion engines. More particularly, the present invention relates to an improved hydraulic lash adjustment device for use in a valve train for internal combustion engines.
- This invention relates to hydraulic lash adjusters for internal combustion engines and to a system comprising a hydraulic lash adjuster in combination with an auxiliary check valve therefore.
- hydraulic lash adjusters are variable length devices capable of automatically varying their length to eliminate any gaps or “lash” within a valve train system.
- hydraulic lash adjusters Upon installation into an engine valve train, hydraulic lash adjusters shorten from their free, extended length to an installed length consistent with positive closure of their associated engine valves. The installed length varies by engine valve location due to valve train system manufacturing variations, temperature, and wear.
- hydraulic lash adjusters incorporate a combination seal-check valve which closes the high pressure chamber within the hydraulic lash adjuster as necessary to transmit cam motion to an engine valve.
- the disclosure of U.S. Pat. No. 6,598,572 differs from that of U.S. Pat. No. 2,956,557 in that the former adds a spring which biases the combination seal-check valve normally open.
- the invention comprises an improvement in hydraulic lash adjusters of the type described in U.S. Pat. No. 2,956,557 which incorporate a combination seal-check valve.
- the improvement comprises an auxiliary check valve system, the purpose of which is to facilitate installation of this particular type of hydraulic lash adjuster into an engine valve train.
- An overview of an engine valve train is described in U.S. Pat. No. 2,956,557 and that description is incorporated herein by reference.
- the novel auxiliary check valve provided by the invention is devised to be maintained in the open state until installed in an engine valve train and the camshaft is rotated through one full revolution.
- valve event is defined as the period during which cam lift is non-zero.
- the hydraulic lash adjuster must automatically extend to an operating length consistent
- the invention differs from known prior art hydraulic lash adjusters which comprise an external, cylindrical body within which is slideably fitted a cylindrical plunger equipped with a check valve that limits the flow of fluid, usually engine oil, out of a “high pressure” chamber enclosed by the body and the plunger.
- the plunger is select fitted to the body with a typical plunger-to-body diametrical clearance of approximately 5.1-5.8 ⁇ m (0.000200-0.000230 in.) to provide an annular passageway through which a small amount of fluid may be displaced from the high pressure chamber during the valve event, thereby allowing the hydraulic lash adjuster to shorten from its operating length in anticipation of dimensional changes in the associated valve train components due to thermal effects and wear.
- a plunger return spring concurrently extends the plunger to eliminate lash and the check valve opens to permit the passage of fluid from the internal reservoir to the high pressure chamber.
- the hydraulic lash adjuster of this invention pertains to the kind described in U.S. Pat. No. 2,956,557 which differs from those commonly in production today in that it incorporates a combination seal-check valve in lieu of the select fit plunger-to-body clearance and separate check valve.
- the plunger-to-body clearance is essentially sealed, instead of shortening from its operating length over the entire duration of the valve event, it shortens from its operating length only at the beginning of the valve event. It does so when the plunger is moved through the distance necessary to abut the seal against the seal gland, e.g., 0.13 mm (0.005 in.).
- a hydraulic lash adjuster of that kind is difficult, if not impossible, to install in an engine valve train because the plunger must typically be depressed up to 2 mm (0.080 in.) to attain the appropriate installed length.
- This invention accordingly has the objective of providing an improvement over prior art hydraulic lash adjusters of the type described in U.S. Pat. No. 2,956,557 and U.S. Pat. No. 6,598,572 by the addition of an auxiliary check valve which permits the plunger to be freely depressed to the limit of its travel and by this action, to be semi-permanently closed until resetting is necessary to facilitate reinstallation such as during engine service.
- an auxiliary check valve which permits the plunger to be freely depressed to the limit of its travel and by this action, to be semi-permanently closed until resetting is necessary to facilitate reinstallation such as during engine service.
- the invention in essence provides a hydraulic lash adjuster assembly for an internal combustion engine having a lash adjuster body with a bore formed therein, a plunger assembly, a fluid chamber containing said plunger assembly; the chamber being equipped to contain therein a supply of hydraulic fluid.
- the pressure chamber is formed between the bottom of said first bore and said plunger assembly.
- the plunger assembly has a valve opening to permit the fluid communication between the fluid chamber and said pressure chamber.
- a check valve is provided for selectively opening and closing said plunger assembly valve opening.
- the check valve is arranged such that the check valve opening remains open until closed by concurrent engagement of the check valve element and the plunger assembly with the bottom of the bore body in response to movement of the plunger assembly in an inward direction with respect to the bore body, and such that the check valve opening then remains closed until opened by outside intervention.
- a biasing means urges the plunger assembly in an outward direction with respect to the bore, thus enlarging the pressure chamber to take up slack in the valve drive train.
- a sealing means engaged with the bore body is activated to move in sealing engagement with the plunger assembly in response to movement of the plunger assembly in an inward direction with respect to the bore for restricting fluid flow from the pressure chamber and to inhibit further movement of the plunger assembly in an inward direction.
- the lash adjuster being arranged such that the plunger assembly is disengaged from said sealing means and pressure in said pressure chamber is relieved upon movement of the plunger assembly in an outward direction, so that a limit of inward movement can take place each time a load is applied to the plunger assembly before the pressure chamber is again closed.
- FIG. 1 is a cross-sectional view of a prior art hydraulic lash adjuster.
- FIG. 2 is an elevational view of the hydraulic lash adjuster of the present invention.
- FIG. 3A is a cross-sectional view taken along line 3 - 3 of FIG. 2 showing the auxiliary check valve in the closed position ready for engine operation.
- FIG. 3B is a cross-sectional view taken along line 3 - 3 of FIG. 2 showing the auxiliary check valve in the open position, ready for installation into an engine valve train.
- FIG. 3C is a cross-sectional view taken along line 3 - 3 of FIG. 2 showing an alternative construction of the auxiliary check valve in the closed position ready for engine operation.
- FIG. 3D is a cross-sectional view taken along line 3 - 3 of FIG. 2 showing the alternative construction of the auxiliary check valve illustrated in FIG. 3C , in the open position ready for installation into an engine valve train.
- FIG. 4 is a detail, fragmented, enlarged sectional view of the lower encircled portion of FIG. 3A to better illustrate the combination seal-check valve and auxilary check valve.
- FIG. 5 is a detail, fragmented, enlarged sectional view of the lower encircled portion of FIG. 3B to better illustrate the combination seal-check valve and auxiliary check valve.
- FIG. 6 is a perspective view of the auxiliary check valve pin.
- FIG. 7 is a perspective view of an alternative construction auxiliary check valve pin.
- This present invention provides the means to facilitate hydraulic lash adjuster installation by providing an auxiliary check valve which remains open until the lash adjuster plunger has been moved to the limit of its travel.
- the hydraulic lash adjuster relatively easily assumes its proper installed length.
- a final step in hydraulic lash adjuster installation is the rotation of the camshaft through one full revolution. During the rotation the valve closing force of each engine valve spring is in turn transmitted to each hydraulic lash adjuster. This force is sufficient to overcome the opposing force of the plunger return spring and allow the hydraulic lash adjuster to shorten to the limit of its available travel.
- the plunger assembly displaces fluid through the auxiliary check valve from the high pressure chamber to the reservoir chamber. Viscous drag forces acting on the check valve pin element of the auxiliary check valve are insufficient to move it since it is held in place within the check valve body, for example, by means of an interference fit or a spring.
- the end of the check valve pin extending from the check valve body contacts the lash adjuster body and stops such that the check valve body element of the plunger assembly continues to move until the tapered surfaces of the check valve pin and check valve body are mated, halting the flow of fluid through the auxiliary check valve and halting as well the movement of the plunger assembly.
- the plunger return spring extends the plunger assembly, and as it does so, the combination seal-check valve opens and fluid is drawn from the reservoir chamber to the high pressure chamber until the hydraulic lash adjuster installed length is achieved.
- the auxiliary check valve remains closed due to the action of a self-locking taper between the check valve pin and the check valve body and/or the hydraulic pressure sustained in the high pressure chamber.
- the auxiliary check valve is able to be reset to the open position, for example during engine valve train service, by depressing the check valve pin through the rocker arm lubrication port of the ball plunger while holding the ball plunger fixed.
- a prior art hydraulic lash adjuster 1 comprising a body 3 , a plunger assembly 5 defined by a ball plunger element 7 and a leakdown plunger element 9 which are received within the body 3 in close fitting relationship and which define a reservoir chamber 11 between them.
- the bottom of the leakdown plunger element 9 forms, in cooperation with the end of a reduced diameter portion 13 of the body bore, a high pressure chamber 15 .
- a separate check valve 17 is provided in the end of a passage 19 which connects the reservoir chamber 11 and the high pressure chamber 15 .
- the check valve 17 which is shown as a ball, but which can be a flat disk or the like, is retained by a check valve retainer 19 which is in interference fit with a counter bore 21 formed in the leakdown plunger element and which provides a seat for the plunger return spring 23 .
- An oil feed hole 27 opens into the body bore and intersects an oil feed groove 29 which in turn intersects an oil feed hole 31 in the ball plunger element 7 to supply hydraulic fluid to the reservoir chamber 11 .
- An axial port 33 at the top supplies lubricant to a rocker arm (not shown) which engages the semi-spherical end 35 formed at the upper end of the ball plunger element 7 .
- the plunger assembly 5 is retained within the body 3 by means of a cap retainer 37 .
- the amount of plunger deflection or “leak down” which occurs during an engine valve event is controlled by the fit between the body bore and the outside diameter of the leakdown plunger element 9 , requiring the clearance between these members to be held very precisely, e.g., to the range of about 5.1-5.8 ⁇ m (0.000200-0.000230 in.), which can only be achieved by machining the individual parts to extremely close tolerances and selectively pairing the leakdown plunger elements and the bodies to obtain the desired clearance.
- This is an extremely demanding requirement; a requirement alleviated by the present invention.
- FIG. 3A a cross-sectional view of the hydraulic lash adjuster 41 configured in accordance with a preferred embodiment of the invention is shown, comprising a body 43 and a plunger assembly 45 slideably fitted within the bore of body 43 .
- the plunger assembly 45 is provided with a cap element 47 and a valve seat element 49 which is received within the base of the body 43 with the cap 47 and top of the valve seal 49 defining a reservoir chamber 51 between the interior of cap 47 and the top of the valve seat 49 .
- the bottom of the valve seat element 49 forms, in cooperation with the bottom portion 53 of the interior of body 43 , a high pressure chamber 55 .
- a combination seal-check valve 57 is provided between passageways and component clearances which connect the reservoir chamber 51 and the high pressure chamber 55 .
- the combination seal-check valve 57 shown comprises a ring with a locational transition or locational interference fit with the interior bore of the body 43 .
- the combination seal-check valve 57 is free to move within the axial space created between the valve seat 49 and a ring seal retainer 59 which is in interference fit on the end portion of valve seat 49 .
- the bottom face of the valve seat 49 provides a seat for the plunger return spring 61 .
- An oil feed hole 63 opens into the body 43 and intersects an oil feed groove 65 in the cap element 47 which intersects an oil feed hole 67 in the cap element 47 to supply hydraulic fluid to the reservoir chamber 51 .
- An axial port 69 in the top of the semi-spherical top end 71 supplies lubricant to a rocker arm (not shown) which engages the semi-spherical end 71 formed at the top of the cap 47 .
- the plunger assembly 45 is retained within the body 43 by means of a retainer 73 .
- auxiliary check valve is comprised of a valve pin element 75 which is slideably fitted through the bore 77 in valve seat 49 .
- the amount of plunger deflection which occurs during an engine valve event is controlled not by “leak down” as in prior art hydraulic lash adjusters of the kind illustrated, for example, by FIG. 1 , but by the axial clearance 79 ( FIG. 4 ) between the combination seal-check valve 57 and the valve seat 49 as shown in FIGS. 3A and 4 . Because the combination seal-check valve 57 of the invention is interference fitted to the bore of the body 43 , when the plunger assembly 45 shown in FIG. 3A is depressed relative to the body 43 during the initial portion of the engine valve event, the combination seal-check valve 57 remains stationary until the plunger assembly has moved through a distance equal to the axial clearance 79 .
- the hydraulic pressure forces act on the combination seal-check valve 57 to enforce respectively axial and radial seals where its surfaces abut the valve seat 49 and the bore of the body 43 as shown in FIG. 5 .
- the plunger return spring 61 extends the plunger assembly 45 relative to the body 43 to compensate for any lash in the engine valve train (not shown) and as it does so, the axial clearance 79 is restored as shown in FIG. 4 and fluid is transferred from the reservoir chamber 51 to the high pressure chamber 55 in the manner previously described.
- the hydraulic lash adjuster of the invention comprises a valve pin 75 that is positioned relative to the valve seat 49 by utilizing an interference fit between the mating cylindrical surfaces of valve pin 75 and the bore 77 ( FIG. 5 ) of valve seat 49 .
- an alternative embodiment may utilize alternatives, such as a conventional spring or a frangible element to position the valve pin 75 relative to the valve seat 49 .
- the plunger return spring 61 extends the plunger assembly 45 relative to the body 43 to compensate for any lash in the engine valve train (not shown) and as it does so, the axial clearance 79 is restored and fluid is transferred from the reservoir chamber 51 to the high pressure chamber 55 in the manner previously described and is position ready as shown in FIG. 3B for engine operation.
- the mating lower portion 95 of valve pin 75 ( FIG. 6 ) and valve seat 49 surfaces comprise a self-locking taper which semi-permanently maintains the valve in the closed position as shown in FIG. 4 .
- the bottom end portion 99 of the valve pin 75 which extends below the plunger assembly 45 limits plunger travel in the bore at the bottom 101 ( FIG. 5 ) of the body 43 of the hydraulic lash adjuster assembly.
- the valve pin 75 may be reset as shown in FIG. 5 , for example during engine valve train service, by depressing the pin 75 relative to the plunger assembly 45 through the port 69 .
- FIGS. 3C and 3D illustrate an alternate auxiliary check valve wherein the auxiliary check valve mechanism comprises a spherical configuration 105 positioned on the bottom of the body 43 and a suitably configured opening 77 in the bottom of the auxiliary check valve mechanism
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Abstract
An auxiliary check valve is provided in a hydraulic lash adjuster of the type wherein the plunger-to-body clearance is sealed. The auxiliary check valve is derived so that it remains open until the plunger has been moved to the limit of its travel by rotation of the engine camshaft during engine assembly. The auxiliary check valve permits fluid within the hydraulic lash adjuster high pressure chamber to be displaced to the reservoir chamber allowing the hydraulic lash adjuster to shorten from its free length to the proper installed length.
Description
- The present invention relates to valve trains for internal combustion engines. More particularly, the present invention relates to an improved hydraulic lash adjustment device for use in a valve train for internal combustion engines.
- This invention relates to hydraulic lash adjusters for internal combustion engines and to a system comprising a hydraulic lash adjuster in combination with an auxiliary check valve therefore. Those skilled in the art of engine valve train design recognize that hydraulic lash adjusters are variable length devices capable of automatically varying their length to eliminate any gaps or “lash” within a valve train system.
- Upon installation into an engine valve train, hydraulic lash adjusters shorten from their free, extended length to an installed length consistent with positive closure of their associated engine valves. The installed length varies by engine valve location due to valve train system manufacturing variations, temperature, and wear. As disclosed in U.S. Pat. Nos. 2,956,557 and 6,598,572, hydraulic lash adjusters incorporate a combination seal-check valve which closes the high pressure chamber within the hydraulic lash adjuster as necessary to transmit cam motion to an engine valve. The disclosure of U.S. Pat. No. 6,598,572 differs from that of U.S. Pat. No. 2,956,557 in that the former adds a spring which biases the combination seal-check valve normally open.
- As a practical matter, these prior art hydraulic lash adjusters are difficult, if not impossible, to install in an engine valve train during automated assembly and also during manual assembly under ordinary environmental conditions. During installation of these prior art hydraulic lash adjusters, an internal plunger displaces fluid from the high pressure chamber to the reservoir past a combination seal-check valve. However, viscous drag forces coincident to fluid flow cause the combination seal-check valve to close, halting both fluid flow and plunger motion, and thereby preventing the hydraulic lash adjuster from assuming the proper installed length. With respect to the hydraulic lash adjuster disclosed in U.S. Pat. No. 6,598,572, the viscosity and velocity of the fluid displaced around the combination seal-check valve tends to produce viscous drag forces which exceed the leaf spring load, prematurely, thereby closing the check valve and preventing the hydraulic lash adjuster from assuming the proper and desired installed length. The occurrence of installation difficulties of this kind is a principal reason why prior art hydraulic lash adjusters that incorporate a combination seal-check valve are not commonly in commercial use.
- The invention comprises an improvement in hydraulic lash adjusters of the type described in U.S. Pat. No. 2,956,557 which incorporate a combination seal-check valve. The improvement comprises an auxiliary check valve system, the purpose of which is to facilitate installation of this particular type of hydraulic lash adjuster into an engine valve train. An overview of an engine valve train is described in U.S. Pat. No. 2,956,557 and that description is incorporated herein by reference. In accordance with the invention, the novel auxiliary check valve provided by the invention is devised to be maintained in the open state until installed in an engine valve train and the camshaft is rotated through one full revolution. In the installation the first actuation of the valve train bottoms the plunger, thereby semi-permanently closing the auxiliary check valve of the invention which is devised to be maintained closed by means such that the bottoming action of the plunger assembly, fits into or over a feature on the bottom of the plunger assembly so as to permanently or semi-permanently close off the high pressure chamber until such time as the valve train requires service and the check valve is manually reset to the open state.
- To ensure proper valve train operation, hydraulic lash adjusters must, during each valve event, shorten from their operating length by an amount slightly greater than that required to ensure positive closure of the associated engine valves. This is especially true when starting an engine at extreme cold environmental conditions, e.g., at temperatures of the order at about 40° C. A “valve event” herein is defined as the period during which cam lift is non-zero. At the end of the valve event, the hydraulic lash adjuster must automatically extend to an operating length consistent
- The invention differs from known prior art hydraulic lash adjusters which comprise an external, cylindrical body within which is slideably fitted a cylindrical plunger equipped with a check valve that limits the flow of fluid, usually engine oil, out of a “high pressure” chamber enclosed by the body and the plunger. The plunger is select fitted to the body with a typical plunger-to-body diametrical clearance of approximately 5.1-5.8 μm (0.000200-0.000230 in.) to provide an annular passageway through which a small amount of fluid may be displaced from the high pressure chamber during the valve event, thereby allowing the hydraulic lash adjuster to shorten from its operating length in anticipation of dimensional changes in the associated valve train components due to thermal effects and wear. At the end of the valve event, a plunger return spring concurrently extends the plunger to eliminate lash and the check valve opens to permit the passage of fluid from the internal reservoir to the high pressure chamber.
- As noted hereinabove, the hydraulic lash adjuster of this invention pertains to the kind described in U.S. Pat. No. 2,956,557 which differs from those commonly in production today in that it incorporates a combination seal-check valve in lieu of the select fit plunger-to-body clearance and separate check valve. In the type of hydraulic lash adjuster described in U.S. Pat. No. 2,956,557, since the plunger-to-body clearance is essentially sealed, instead of shortening from its operating length over the entire duration of the valve event, it shortens from its operating length only at the beginning of the valve event. It does so when the plunger is moved through the distance necessary to abut the seal against the seal gland, e.g., 0.13 mm (0.005 in.). A hydraulic lash adjuster of that kind is difficult, if not impossible, to install in an engine valve train because the plunger must typically be depressed up to 2 mm (0.080 in.) to attain the appropriate installed length.
- This invention accordingly has the objective of providing an improvement over prior art hydraulic lash adjusters of the type described in U.S. Pat. No. 2,956,557 and U.S. Pat. No. 6,598,572 by the addition of an auxiliary check valve which permits the plunger to be freely depressed to the limit of its travel and by this action, to be semi-permanently closed until resetting is necessary to facilitate reinstallation such as during engine service. Other objects and advantages of the invention will be apparent from the following description when considered in connection with the accompanying drawings.
- The invention in essence provides a hydraulic lash adjuster assembly for an internal combustion engine having a lash adjuster body with a bore formed therein, a plunger assembly, a fluid chamber containing said plunger assembly; the chamber being equipped to contain therein a supply of hydraulic fluid. The pressure chamber is formed between the bottom of said first bore and said plunger assembly. The plunger assembly has a valve opening to permit the fluid communication between the fluid chamber and said pressure chamber. A check valve is provided for selectively opening and closing said plunger assembly valve opening. The check valve is arranged such that the check valve opening remains open until closed by concurrent engagement of the check valve element and the plunger assembly with the bottom of the bore body in response to movement of the plunger assembly in an inward direction with respect to the bore body, and such that the check valve opening then remains closed until opened by outside intervention. A biasing means urges the plunger assembly in an outward direction with respect to the bore, thus enlarging the pressure chamber to take up slack in the valve drive train. A sealing means engaged with the bore body is activated to move in sealing engagement with the plunger assembly in response to movement of the plunger assembly in an inward direction with respect to the bore for restricting fluid flow from the pressure chamber and to inhibit further movement of the plunger assembly in an inward direction. The lash adjuster being arranged such that the plunger assembly is disengaged from said sealing means and pressure in said pressure chamber is relieved upon movement of the plunger assembly in an outward direction, so that a limit of inward movement can take place each time a load is applied to the plunger assembly before the pressure chamber is again closed.
-
FIG. 1 is a cross-sectional view of a prior art hydraulic lash adjuster. -
FIG. 2 is an elevational view of the hydraulic lash adjuster of the present invention. -
FIG. 3A is a cross-sectional view taken along line 3-3 ofFIG. 2 showing the auxiliary check valve in the closed position ready for engine operation. -
FIG. 3B is a cross-sectional view taken along line 3-3 ofFIG. 2 showing the auxiliary check valve in the open position, ready for installation into an engine valve train. -
FIG. 3C is a cross-sectional view taken along line 3-3 ofFIG. 2 showing an alternative construction of the auxiliary check valve in the closed position ready for engine operation. -
FIG. 3D is a cross-sectional view taken along line 3-3 ofFIG. 2 showing the alternative construction of the auxiliary check valve illustrated inFIG. 3C , in the open position ready for installation into an engine valve train. -
FIG. 4 is a detail, fragmented, enlarged sectional view of the lower encircled portion ofFIG. 3A to better illustrate the combination seal-check valve and auxilary check valve. -
FIG. 5 is a detail, fragmented, enlarged sectional view of the lower encircled portion ofFIG. 3B to better illustrate the combination seal-check valve and auxiliary check valve. -
FIG. 6 is a perspective view of the auxiliary check valve pin. -
FIG. 7 is a perspective view of an alternative construction auxiliary check valve pin. - This present invention provides the means to facilitate hydraulic lash adjuster installation by providing an auxiliary check valve which remains open until the lash adjuster plunger has been moved to the limit of its travel. By this means the hydraulic lash adjuster relatively easily assumes its proper installed length. A final step in hydraulic lash adjuster installation is the rotation of the camshaft through one full revolution. During the rotation the valve closing force of each engine valve spring is in turn transmitted to each hydraulic lash adjuster. This force is sufficient to overcome the opposing force of the plunger return spring and allow the hydraulic lash adjuster to shorten to the limit of its available travel.
- As the hydraulic lash adjuster is shortened in length, the plunger assembly displaces fluid through the auxiliary check valve from the high pressure chamber to the reservoir chamber. Viscous drag forces acting on the check valve pin element of the auxiliary check valve are insufficient to move it since it is held in place within the check valve body, for example, by means of an interference fit or a spring. As the hydraulic lash adjuster continues to shorten in length, the end of the check valve pin extending from the check valve body contacts the lash adjuster body and stops such that the check valve body element of the plunger assembly continues to move until the tapered surfaces of the check valve pin and check valve body are mated, halting the flow of fluid through the auxiliary check valve and halting as well the movement of the plunger assembly. As the camshaft continues to rotate, the plunger return spring extends the plunger assembly, and as it does so, the combination seal-check valve opens and fluid is drawn from the reservoir chamber to the high pressure chamber until the hydraulic lash adjuster installed length is achieved.
- Throughout this and subsequent valve events, the auxiliary check valve remains closed due to the action of a self-locking taper between the check valve pin and the check valve body and/or the hydraulic pressure sustained in the high pressure chamber. The auxiliary check valve is able to be reset to the open position, for example during engine valve train service, by depressing the check valve pin through the rocker arm lubrication port of the ball plunger while holding the ball plunger fixed.
- As shown in
FIG. 1 , a prior art hydraulic lash adjuster 1 is illustrated comprising abody 3, aplunger assembly 5 defined by aball plunger element 7 and aleakdown plunger element 9 which are received within thebody 3 in close fitting relationship and which define areservoir chamber 11 between them. The bottom of theleakdown plunger element 9 forms, in cooperation with the end of a reduceddiameter portion 13 of the body bore, ahigh pressure chamber 15. Aseparate check valve 17 is provided in the end of apassage 19 which connects thereservoir chamber 11 and thehigh pressure chamber 15. Thecheck valve 17, which is shown as a ball, but which can be a flat disk or the like, is retained by acheck valve retainer 19 which is in interference fit with a counter bore 21 formed in the leakdown plunger element and which provides a seat for theplunger return spring 23. - In general in most prevalent prior art designs a
compression spring 25 acting between the bottom of thecheck valve retainer 19 and thecheck valve 17 biases thecheck valve 17 into a normally closed position. Anoil feed hole 27 opens into the body bore and intersects anoil feed groove 29 which in turn intersects anoil feed hole 31 in theball plunger element 7 to supply hydraulic fluid to thereservoir chamber 11. Anaxial port 33 at the top supplies lubricant to a rocker arm (not shown) which engages thesemi-spherical end 35 formed at the upper end of theball plunger element 7. Theplunger assembly 5 is retained within thebody 3 by means of acap retainer 37. - In the prior art embodiments of the kind illustrated in
FIG. 1 , the amount of plunger deflection or “leak down” which occurs during an engine valve event is controlled by the fit between the body bore and the outside diameter of theleakdown plunger element 9, requiring the clearance between these members to be held very precisely, e.g., to the range of about 5.1-5.8 μm (0.000200-0.000230 in.), which can only be achieved by machining the individual parts to extremely close tolerances and selectively pairing the leakdown plunger elements and the bodies to obtain the desired clearance. This is an extremely demanding requirement; a requirement alleviated by the present invention. - Referring to
FIG. 3A , a cross-sectional view of thehydraulic lash adjuster 41 configured in accordance with a preferred embodiment of the invention is shown, comprising abody 43 and aplunger assembly 45 slideably fitted within the bore ofbody 43. Theplunger assembly 45 is provided with acap element 47 and avalve seat element 49 which is received within the base of thebody 43 with thecap 47 and top of thevalve seal 49 defining areservoir chamber 51 between the interior ofcap 47 and the top of thevalve seat 49. The bottom of thevalve seat element 49 forms, in cooperation with thebottom portion 53 of the interior ofbody 43, ahigh pressure chamber 55. - It is seen in accordance with the invention that a combination seal-
check valve 57 is provided between passageways and component clearances which connect thereservoir chamber 51 and thehigh pressure chamber 55. The combination seal-check valve 57 shown comprises a ring with a locational transition or locational interference fit with the interior bore of thebody 43. The combination seal-check valve 57 is free to move within the axial space created between thevalve seat 49 and aring seal retainer 59 which is in interference fit on the end portion ofvalve seat 49. The bottom face of thevalve seat 49 provides a seat for theplunger return spring 61. - An
oil feed hole 63 opens into thebody 43 and intersects anoil feed groove 65 in thecap element 47 which intersects anoil feed hole 67 in thecap element 47 to supply hydraulic fluid to thereservoir chamber 51. Anaxial port 69 in the top of the semi-sphericaltop end 71 supplies lubricant to a rocker arm (not shown) which engages thesemi-spherical end 71 formed at the top of thecap 47. Theplunger assembly 45 is retained within thebody 43 by means of aretainer 73. - With reference to
FIG. 3A and, in particular, to the enlarged fragmentary depiction ofFIG. 4 , it is seen that the auxiliary check valve is comprised of avalve pin element 75 which is slideably fitted through thebore 77 invalve seat 49. - The amount of plunger deflection which occurs during an engine valve event is controlled not by “leak down” as in prior art hydraulic lash adjusters of the kind illustrated, for example, by
FIG. 1 , but by the axial clearance 79 (FIG. 4 ) between the combination seal-check valve 57 and thevalve seat 49 as shown inFIGS. 3A and 4 . Because the combination seal-check valve 57 of the invention is interference fitted to the bore of thebody 43, when theplunger assembly 45 shown inFIG. 3A is depressed relative to thebody 43 during the initial portion of the engine valve event, the combination seal-check valve 57 remains stationary until the plunger assembly has moved through a distance equal to theaxial clearance 79. - It is to be noted that, as the
plunger assembly 45 is depressed, fluid within thehigh pressure chamber 55 is displaced to thereservoir chamber 51 by first flowing through a multiplicity ofopenings 81 provided in thering seal retainer 59, through theradial clearance 83 andaxial clearance 79, then through theradial clearance 85, and finally, respectively through the multiplicity of connecting valve seat radial andaxial passages 87 as shown more clearly inFIG. 4 . When fluid passage through theaxial clearance 79 is interrupted by the abutment of the combination seal-check valve 57 against the bottom surface 89 (FIG. 4 ) of thevalve seat 49, the pathway for fluid flow between thehigh pressure chamber 55 and thereservoir chamber 51 is closed as shown inFIG. 5 and further plunger deflection is resisted by the resulting hydraulic pressure forces within thehigh pressure chamber 55. - The hydraulic pressure forces act on the combination seal-
check valve 57 to enforce respectively axial and radial seals where its surfaces abut thevalve seat 49 and the bore of thebody 43 as shown inFIG. 5 . At the conclusion of the valve event, theplunger return spring 61 extends theplunger assembly 45 relative to thebody 43 to compensate for any lash in the engine valve train (not shown) and as it does so, theaxial clearance 79 is restored as shown inFIG. 4 and fluid is transferred from thereservoir chamber 51 to thehigh pressure chamber 55 in the manner previously described. - Those skilled in the art of hydraulic lash adjuster design recognize that prior art hydraulic lash adjusters incorporating a combination seal-check valve present difficulties when the adjuster is being installed in an engine valve train because the installed length of the hydraulic lash adjuster within the valve train requires that the
plunger assembly 45 be depressed into thebody 43 through a distance greater than theaxial clearance 79. However, as seen by reference toFIG. 3B andFIG. 5 , and for the reasons which follow the auxiliary check valve of the present invention resolves this prior art difficulty by the novel arrangement provided. - Referring in particular to
FIG. 3B andFIG. 5 it is seen that the hydraulic lash adjuster of the invention comprises avalve pin 75 that is positioned relative to thevalve seat 49 by utilizing an interference fit between the mating cylindrical surfaces ofvalve pin 75 and the bore 77 (FIG. 5 ) ofvalve seat 49. It will be apparent that an alternative embodiment (not shown) may utilize alternatives, such as a conventional spring or a frangible element to position thevalve pin 75 relative to thevalve seat 49. With thevalve pin 75 positioned as shown inFIG. 5 , there exists a radial clearance 91 (FIG. 5 ) between mating taperedsurfaces valve seat 49 andvalve pin 75. - As the engine valve train (not shown) is initially rotated to install the
hydraulic lash adjuster 41, depressing theplunger assembly 45 into thebody 43, after the combination seal-check valve has been closed as shown inFIG. 5 by the mechanism previously described, fluid continues to be displaced from thehigh pressure chamber 55 to thereservoir chamber 51 through theclearance 91 and through one ormore passageways 97 formed in thevalve pin 75 shown inFIG. 6 or alternatively through ahelical passageway arrangement 103 formed in thevalve pin 75 shown inFIG. 7 . As theplunger assembly 45 is further deflected, theend bottom portion 99 of thevalve pin 75 contacts theinterior bottom 101 of thebody 43 and ceases movement. In this position, thevalve seat 49 then slides down over theend portion 95 ofvalve pin 75, and as it does so diminishes theclearance 91 to zero, thereby closing the valve to fluid flow and halting further deflection of the plunger assembly. - At the conclusion of the valve event, the
plunger return spring 61 extends theplunger assembly 45 relative to thebody 43 to compensate for any lash in the engine valve train (not shown) and as it does so, theaxial clearance 79 is restored and fluid is transferred from thereservoir chamber 51 to thehigh pressure chamber 55 in the manner previously described and is position ready as shown inFIG. 3B for engine operation. In a preferred embodiment the matinglower portion 95 of valve pin 75 (FIG. 6 ) andvalve seat 49 surfaces comprise a self-locking taper which semi-permanently maintains the valve in the closed position as shown inFIG. 4 . Thebottom end portion 99 of thevalve pin 75 which extends below theplunger assembly 45 limits plunger travel in the bore at the bottom 101 (FIG. 5 ) of thebody 43 of the hydraulic lash adjuster assembly. Thevalve pin 75 may be reset as shown inFIG. 5 , for example during engine valve train service, by depressing thepin 75 relative to theplunger assembly 45 through theport 69. -
FIGS. 3C and 3D illustrate an alternate auxiliary check valve wherein the auxiliary check valve mechanism comprises aspherical configuration 105 positioned on the bottom of thebody 43 and a suitably configuredopening 77 in the bottom of the - Various alterations and modifications will become apparent to those skilled in the art from a reading of the detailed disclosure presented herein and it is intended that such apparent alterations and modifications from the disclosure herein provided are encompassed within the contemplations of the invention to the extent that such are within the scope of the appended claims.
Claims (8)
1. A hydraulic lash adjuster assembly for an internal combustion engine, the lash adjuster comprising:
a) a lash adjuster body having a body bore formed therein;
b) a plunger assembly that includes a reservoir chamber equipped to contain therein a supply of hydraulic fluid positioned within said body bore;
c) a fluid pressure chamber formed between the bottom of said bore and the bottom of said plunger assembly;
d) a valve opening in said plunger assembly to permit fluid communication between said reservoir chamber and said pressure chamber;
e) a plunger check valve for selectively opening and closing said check valve arranged such that the check valve opening remains open until closed by concurrent engagement of the check valve element and the plunger assembly with the bottom of the body bore in response to a linear movement of the plunger assembly thereby retaining the check valve opening in a closed position until opened by outside intervention;
f) a biasing means for urging the plunger assembly in a direction that increases the volume of the pressure chamber to take up slack of a valve drive train;
g) a sealing means engaging the plunger assembly in response to movement of the plunger for restricting fluid flow from the pressure chamber and to inhibit further movement of the plunger assembly; and
h) said lash adjuster being arranged such that the plunger assembly is disengaged from said sealing means and pressure in said pressure chamber is relieved upon movement of the plunger assembly as the volume of the pressure chamber increases so as to limit inward movement of the plunger assembly when a load is applied to the plunger assembly and before the pressure chamber is again closed.
2. The lash adjuster of claim 1 wherein the fluid chamber contains a supply of hydraulic fluid.
3. The hydraulic lash adjuster of claim 1 where said valve opening in said plunger assembly comprises a cylindrical coaxial portion and where said plunger check valve comprises a complementary cylindrical coaxial portion.
4. The hydraulic lash adjuster of claim 1 wherein said valve opening in said plunger assembly comprises a cylindrical coaxial tapered portion and where said check valve element comprises a spherical configuration coupled with a mating sealable complemental opening.
5. The hydraulic lash adjuster of claim 3 wherein the check valve element is provided with at least one groove providing fluid communication between said fluid chamber and said pressure chamber such that when said check valve is open, said groove communicates with fluid between said reservoir chamber and said pressure chamber.
6. The hydraulic lash adjuster of claim 3 where said groove is longitudinal.
7. The hydraulic lash adjuster of claim 3 where said groove is helical.
8. In a hydraulic lash adjuster system for an internal combustion engine, comprising an outer cylindrical body, a plunger assembly slideably positioned within said body and a valve pin movably positioned within said plunger assembly, the improvement comprising:
a) a moveable plunger equipped with an auxiliary check valve in combination with said lash adjuster;
b) said check valve devised to be maintained in an open position until the plunger has been moved to a level of its movement range;
c) said combination upon installation in association with an engine valve with valve spring and with rotatable camshaft enables the check valve to be maintained in a closed position by means of a locking contacting engagement by a self-locking auxiliary check valve.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US11/968,713 US20090173303A1 (en) | 2008-01-03 | 2008-01-03 | Hydraulic lash adjuster equipped with auxiliary check valve |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US11/968,713 US20090173303A1 (en) | 2008-01-03 | 2008-01-03 | Hydraulic lash adjuster equipped with auxiliary check valve |
Publications (1)
Publication Number | Publication Date |
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US20090173303A1 true US20090173303A1 (en) | 2009-07-09 |
Family
ID=40843577
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Application Number | Title | Priority Date | Filing Date |
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US11/968,713 Abandoned US20090173303A1 (en) | 2008-01-03 | 2008-01-03 | Hydraulic lash adjuster equipped with auxiliary check valve |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100282194A1 (en) * | 2008-08-28 | 2010-11-11 | Toyota Jidosha Kabushiki Kaisha | Sealed-type lash adjuster |
US8695551B2 (en) | 2011-06-23 | 2014-04-15 | Caterpillar Inc. | Hydraulic lash adjuster including band of radial recirculation openings |
WO2016019953A1 (en) * | 2014-08-05 | 2016-02-11 | Schaeffler Technologies AG & Co. KG | Hydraulic play compensation device for a valve train of a combustion engine |
USD785047S1 (en) * | 2014-07-26 | 2017-04-25 | Eaton Corporation | Pivot plunger |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2956557A (en) * | 1958-12-11 | 1960-10-18 | Morris V Dadd | Hydraulic tappets |
US6598572B2 (en) * | 2001-06-15 | 2003-07-29 | Eaton Corporation | Hydraulic lash adjuster |
US20050224030A1 (en) * | 2004-02-26 | 2005-10-13 | Jose Masello & Majo Cecur | Hydraulic lash adjuster and improved method of assembly thereof |
-
2008
- 2008-01-03 US US11/968,713 patent/US20090173303A1/en not_active Abandoned
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2956557A (en) * | 1958-12-11 | 1960-10-18 | Morris V Dadd | Hydraulic tappets |
US6598572B2 (en) * | 2001-06-15 | 2003-07-29 | Eaton Corporation | Hydraulic lash adjuster |
US20050224030A1 (en) * | 2004-02-26 | 2005-10-13 | Jose Masello & Majo Cecur | Hydraulic lash adjuster and improved method of assembly thereof |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100282194A1 (en) * | 2008-08-28 | 2010-11-11 | Toyota Jidosha Kabushiki Kaisha | Sealed-type lash adjuster |
US8695551B2 (en) | 2011-06-23 | 2014-04-15 | Caterpillar Inc. | Hydraulic lash adjuster including band of radial recirculation openings |
USD785047S1 (en) * | 2014-07-26 | 2017-04-25 | Eaton Corporation | Pivot plunger |
WO2016019953A1 (en) * | 2014-08-05 | 2016-02-11 | Schaeffler Technologies AG & Co. KG | Hydraulic play compensation device for a valve train of a combustion engine |
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