EP0695395A1 - Valve control means - Google Patents
Valve control meansInfo
- Publication number
- EP0695395A1 EP0695395A1 EP94910474A EP94910474A EP0695395A1 EP 0695395 A1 EP0695395 A1 EP 0695395A1 EP 94910474 A EP94910474 A EP 94910474A EP 94910474 A EP94910474 A EP 94910474A EP 0695395 A1 EP0695395 A1 EP 0695395A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- valve
- follower
- cam
- bore
- valve control
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- 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
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
- F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
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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
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
-
- 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
- F01L1/12—Transmitting gear between valve drive and valve
- F01L1/14—Tappets; Push rods
- F01L1/143—Tappets; Push rods for use with overhead camshafts
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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
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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
- F01L1/245—Hydraulic tappets
- F01L1/25—Hydraulic tappets between cam and valve stem
Definitions
- the present invention relates to valve control means for an internal combustion engine.
- valve control means of the present invention will be described by reference to use of the valve control means in the internal combustion engine of an automobile, but the invention should not be considered limited to such use.
- valve control means for controlling the inlet and exhaust valves of an internal combustion engine.
- a camshaft having a first cam and a second cam having a different cam profile from the first cam.
- Means are provided for relaying the camming action of the cams to an inlet or exhaust valve of the engine.
- the means for transmitting the reciprocating movement comprises a first cam follower member which engages an inlet or exhaust valve and a second cam follower member which is moveable relative to the first cam follower member and locking means which can link the two cam follower members to move together.
- the locking means of the system described in W091/12413 is operable under the control of hydraulic pressure.
- the locking means is controlled so that the lift of the controlled valve is controlled by the cam profile of one of the cams at low engine speeds and by the cam profile of the other cam at high engine speeds. This gives an advantage over the previously known engines, because the relationship between valve lift and crankshaft position can be varied at different engine speeds to optimise engine efficiency.
- the valve control means described in W091/12413 includes a hydraulic lash adjuster.
- Hydraulic lash adjusters are well known in the art and are used to compensate for wear of components in the valve drive trains.
- a hydraulic lash adjuster will expand to ensure that the components of the valve control means remain in contact with each other despite wear.
- valve control means There are tight constraints on the packaging of valve control means in modern day engines. This is particularly the case in engines which use four valve per cylinder. For this reason, valve control means used should be kept as small as possible.
- the first cam follower member of the valve control means of W091/12413 is a bucket tappet slidable in a bore provided in the second cam follower member. Bucket tappets are well known in prior art engines. In the system of W091/12413 the hydraulic lash adjuster acts between the bucket tappet and the controlled valve, with the stem of the controlled valve directly abuttin ⁇ the hydraulic lash adjuster. A more detailed description of the valve control means of W091/12413 will be given later with reference to one of the drawings of this application.
- Bucket tappets used in conventional engines are of a diameter typically in the range 19mm to 40mm.
- the tappets must be of such a size to give the reguired mechanical advantage for the cam profiles used in conventional engines.
- Mechanical advantage is gained by distancing the point of contact between the tappet and the lift portion of a cam from the central axis of the tappet.
- a minimum distance must be allowed and thus a minimum area of tappet provided. There is thus a geometrical relationship between the lift velocity of a cam profile and the area of tappet used.
- hydraulic lash adjusters are known in which one of the components which defines the expandable chamber for hydraulic fluid directly abuts a cam and the other component which defines the chamber is connected to a push rod.
- a lash adjuster has never to the applicant's knowledge been used in an overhead camshaft engine and furthermore the lash adjusters used to date in the push-rod engines have typically had an external diameter of 19mm or above since they are required to have a minimum area by the cam profiles used in the push-rod engines.
- the present invention provides valve control means for use in an internal combustion engine which has valve means, cam means comprising a rotatable camshaft having a first portion and a second portion having a different cross-section from the first portion, the valve control means comprising: first follower means engageable with the valve means and engageable with the first portion, hydraulic lash adjuster means provided in the first follower means and having a first member which defines a closed bore, a second member movable in the bore of the first member and defining with the first member a variable volume chamber for hydraulic fluid, conduit means for allowing flow of fluid to the chamber and valve means for controlling the flow of fluid to the chamber, second follower means movable relative to the first follower means and engageable with the second portion, and linking means to enable the first and second follower means to be linked together, wherein, in use of the valve control means, when the first and second follower means are not linked the motion of the valve means is controlled by the first follower means and the valve means is given in each engine cycle the lift of the first portion, when the first
- one of the follower members of the present invention is designed to be driven by a low lift cam (or no lift lobe as will be described later) designed for low speed operation, the area of the follower member engaging the cam can be reduced (minimum area being proportional to lift) .
- the bucket tappet of W091/12413 is no longer needed and the valve control means can be reduced in size.
- the valve control means of W091/12413 could be used in certain existing engines which have bucket tappets and hydraulic lash adjusters, the valve control means being simply positioned in the bores provided in the engine for the bucket tappets and the hydraulic lash adjusters.
- valve control means of W091/12413 could only be installed in a restricted range of such engines because of the overall size of the valve control means. Since the valve control means of the present invention can be made smaller than the valve control means of W091/12413, the valve control means can be installed in a greater range of engines.
- the second follower means defines a bore and the first follower means is slidably located in the bore, the cross-section of the bore matching in shape and size the cross-section of the portion of the first member of the hydraulic lash adjustment means slidable in the bore.
- first and second follower means are cylindrical and the first follower means has a diameter in the range of 3 to 18mm.
- the bucket tappets of the prior art typically have diameters in the range 19 to 4Omm.
- the first follower means is thus of a first diameter and the second follower means of a second larger diameter. Both diameters must at least be of a certain minimum to allow for the lifts of the first and second cams (if two cams are used) . However in operation, the first follower means will engage a cam of lower lift (or a lobe of no lift as will be described later) than tne second follower means and thus the first diameter can be smaller than the second diameter.
- engagement means is provided on the exterior surface of the first member of the hydraulic lash adjuster means, the engagement means enabling the linking means to link together the first and second follower means.
- linking means engages the exterior surface of the hydraulic lash adjuster means, rather than a bucket tappet (as in the prior art) .
- the present invention also provides an internal combustion engine having valve control means as previously described wherein the wear surface of the first member of the hydraulic lash adjuster means directly abuts a portion of the camshaft.
- the hydraulic lash adjuster means abuts a bucket tappet which then abuts a portion of a camshaft. This followed the accepted practice of providing bucket tappets with hydraulic lash adjusters located within. The present invention breaks away from accepted practice.
- the internal combustion engine is an overhead camshaft engine which has a poppet valve moveable to open and close a port in a cylinder of the engine then the poppet valve preferably directly abuts the second member of the hydraulic lash adjuster means.
- the present invention also has the advantage that the valve drivetrain can be made lighter since a bucket tappet is not included in the valve drivetrain.
- the push-rod is preferably connected to the second member of the hydraulic lash adjuster means.
- valve control means for use in an internal combustion engine which has valve means, cam means comprising a rotatable camshaft having a first portion and a second portion having a different cross-section from the first portion
- the valve control means comprising: first follower means engageable with the valve means and engageable with the first portion, hydraulic lash adjuster means provided in the first follower means and having a first member which defines a closed bore, a second member movable in the bore of the first member and defining with the first member a variable volume chamber for hydraulic fluid, conduit means for allowing flow of fluid to the chamber and valve means for controlling the flow of flui ⁇ to the chamber, second follower means movable relative to the first follower means and engageable with the second portion, and linking means to enable the first and second follower means to be linked together, wherein, in use of the valve control means, when the first and second follower means are not linked the motion of the valve means is controlled by the first follower means and the valve means is given the lift of the first portion
- the bore is of circular cross-section and the first member of the hydraulic lash adjuster means is of a circular exterior cross-section, the diameter of the bore being corresponding to the exterior diameter of the first member of the hydraulic lash adjuster means.
- valve control means for use in an internal combustion engine which has valve means, cam means comprising a rotatable camshaft having a first portion and a second cam having a different cross-section from the first portion
- the valve control means comprising: first follower means engageable with the valve means and engageable with the first portion, hydraulic lash adjuster means provided in the first follower means and having first member which defines a closed bore, a second member movable in the bore of the first member and defining with the first member a variable volume chamber for hydraulic fluid, conduit means for allowing flow of fluid to the chamber and valve means for controlling the flow of fluid to the chamber, second follower means movable relative to the first cam follower means and engageable with the second portion, and linking means to enable the first and second follower means to be linked together, wherein, in use of the valve control means, when the first and second follower means are not linked the motion of the valve means is controlled by the first cam follower means and the valve means is given in each engine cycle the lift of the first portion,
- the engagement means is provided on tr.e exterior surface of the first member of the hydraulic lash adjustment means.
- the engagement means comprises a recess in the exterior surface of the first member of the hydraulic lash adjuster means and the linking means comprises a locking pin in the second follower means and extendable from the second follower means to engage the recess.
- valve control means such as the valve control means described in W091/12413
- the hydraulic lash adjuster means can directly abut a portion of a camshaft (without the interposition of a bucket tappet) and therefore the valve control means can be of an overall diameter which is appreciably smaller than the diameter of the valve control means of the prior art.
- the first portion of the camshaft is a first cam having a first cam profile
- the second portion of the camshaft is a second cam having a second cam profile different to the first cam profile
- the first follower means comprises first cam follower means engageable with the first cam
- the second follower means comprises second cam follower means engageable with the second cam.
- first portion of the camshaft can be a portion of circular cross-section which imparts no lift to valve means
- second portion of the camshaft is a cam
- the second follower means comprises second cam follower means engageable with the cam.
- the present invention in a fourth aspect provides an overhead camshaft engine having a rotatable camshaft, valve means and a hydraulic lash adjuster acting between the valve means and a portion of the camshaft, the hydraulic lash adjuster comprising: a first member which defines a closed bore, a second member movable in the closed bore and defining with the first member a variable volume chamber, conduit means for allowing flow of fluid to the chamber, and valve means for controlling the flow of fluid to and from the chamber, characterised in that the cam directly engages a wear surface provided on the first member of the hydraulic lash adjuster.
- the first member preferably comprises a cavity and the conduit means comprises a first passage connecting the cavity with the exterior of the first member and a second passage connecting the cavity with the variable volume chamber, the valve means being operable to control flow of fluid from the cavity to the variable volume chamber.
- variable volume chamber For effective operation of a hydraulic lash adjuster the variable volume chamber should be lowermost so that gravity acts to encourage flow of fluid into the chamber.
- the design allows for this, whilst also allowing the lash adjuster component of greater cross-sectional area to be uppermost to engage a cam.
- a third passage is provided to connect rhe cavity with the wear surface provided on the first member, whereby the wear surface can be lubricated by fluid from the cavity.
- the third passage provides lubrication and prevents air locks in the hydraulic lash adjuster.
- Figure l shows prior art valve control means
- Figure 2 shows a cross-section of a first embodiment of valve control means according to the invention, the cross-section being taken along the line BB of Figure 3 , in the direction of the arrows shown;
- Figure 3 shows a cross-section of the valve control means of the first embodiment shown in Figure 2, the cross-section being taken along the line AA shown in Figure 2 , in the direction of the arrows shown;
- Figure 4 shows a cross-sectional view of the valve control means of the first embodiment in use in an internal combustion engine in a first operating condition
- Figure 5 shows a cross-section of valve control means according to the first embodiment of the invention in use in an internal combustion engine in a second operating condition
- Figure 6 shows a cross-section of a second embodiment of valve control means according to the present invention, the cross-section being taken along the lines DD of Figure 7, in the direction of the arrows shown;
- Figure 7 shows a cross-section of the second embodiment shown in Figure 6, the cross-section being taken along the lines CC of the Figure 6, in the direction of the arrows snown;
- Figure 3 shows a cross-section of a third embodiment of valve control means according to the invention, taken along the line FF shown in figure 9, in the direction of the arrows shown;
- Figure 9 shows a cross-section of the third embodiment shown in figure 3 taken along the line EE shown in figure 8, in the direction of the arrows shown.
- FIG. 1 a camshaft 10 having a first cam 11 of a first cam profile and two further cam members 12 and 13 each having the same cam profile, the cam profile being different to the cam profile of the cam
- the figure 1 illustrates the valve control means of the prior art in a first operating condition, in which an inlet valve 14 :s controlled by the profile of the cam 11.
- Valve control means 15 of the prior art system can be seen in figure l to comprise an outer cam follower member 16 which takes the form of a cylinder and an inner cam follower member 17 which is slidable within a bore of the outer cam follower member 16.
- the inner cam follower member 17 comprises a bucket tappet 13, well known in the prior art.
- a hydraulic lash adjuster comprising members 19 and 20 is located within the bucket tappet 13.
- the member 20 abuts the top of the inlet valve 14 and has a portion of an external diameter which corresponds to the internal diameter of the bucket ta ⁇ pet 18.
- the member 19 abuts the bucket tappet 18 and is slidable within the member 20.
- the members 19 and 20 define between them a chamber and a check valve is provided to control flow of fluid into the chamber. Fluid can be admitted into the chamber, but the check valve prevents fluid from flowing from the chamber.
- the members 20 and 19 move relative to each other to expand the. chamber defined between them to compensate for wear in the components of the valve control mechanism, eg. wear of the cam members 11, 12 and 13.
- the inner cam member thus comprises a bucket tappet 18 and a hydraulic lash adjuster located to act between the bucket tappet 13 and the valve 14.
- valve control means according to the present invention.
- the valve control means according to the present invention comprise a first cam follower member 100 which is movable in a bore provided in a second cam follower member 150.
- the first cam follower member 100 provides hydraulic lash adjustment.
- the first cam follower member 100 comprises an upper member 101 which provides a wear surface for engaging a cam.
- the upper member 101 in figure 2 is formed of two parts 101A and 101B which are attached to each other. Part 101A will typically be made of alloy cast iron and part 101B will typically be made of steel.
- the upper member 101 is generally cylindrical in form. There is an upper cavity 102 provided in the member 101 which communicates with the exterior of the member 101 via a passage 103. The cavity 102 is also in communication with the engagement surface of the member 101 via a passage 104. The cavity 102 is cylindrical and at the lower end of the cavity 102 there is provided a passage 106 leading downwardly from the cavity 102.
- the member 101 also has a lower cavity which is of greater diameter than the upper cavity 102. In the lower cavity a lower member 107 of the first cam follower member 100 is slidable relative to the member 101.
- the lower member 107 and the upper member 101 define between them a chamber 108.
- the chamber 103 can communicate with the chamber 102 via the passage 106.
- Check valve means are provided to control the flow of fluid through the passage 106.
- the check valve means comprise a valve retainer 109, a ball 110, a light spring 111 acting between the ball 110 and the valve retainer 109 and a spring 112 acting between the upper member 101 and the lower member 107.
- the lower member 107 of the first cam follower means 100 has an external diameter which corresponds to the diameter of the lower cavity of the upper member 101.
- the second cam follower means 150 comprises a first member 151 which provides a surface which is engageable by a cam.
- the member 151 is generally cylindrical in nature and will typically be made of cast iron alloy.
- Attached to the member 151 is a skirt 152 typically made of steel, again of a generally cylindrical nature.
- the outer diamater of the outer steel skirt 152 corresponds to the greatest diameter of the member 151.
- the skirt 152 has a portion of reduced diameter which defines an annular recess 154.
- the portion of reduced diameter also defines an annular seat 155 engageable by a spring.
- annular cavity 156 communicates with the annular recess 154 via passages 157.
- Locking pins 160, 161 and 162 can be seen in figure 3. Locking pin 160 can also be seen in figure 2.
- the locking pins 160, 161 and 162 are identical to each other and are mounted in the member 151 in identical fashion. Therefore, we will only discuss in detail the locking pin 160.
- the locking pin 160 is slidable in a radially extending bore in the member 151.
- a spring 163 is provided to act between an increased diameter portion of the locking pin 160 and the member 151, to bias the locking pin 160 radially outwardly.
- the locking pin 160 is biased by the spring 163 into abutment with the steel skirt 152. Since the rear portion of the locking pin 160 is flat whilst the inner surface of the skirt 152 is cylindrical, a cavity 167 is maintained between the locking pin 160 and the skirt 152 even when the locking pin 160 abuts the skirt 152.
- a passage 164 is provided in the member 151 to allow communication between the cavity 167 and the cavity 156.
- the locking pin 160 is designed to slide radially in the bore in the member 151 to engage a recess 165 defined in the exterior surface of the member 101 of the first cam follower means.
- a bore 166 is provided through the locking pin 160 to allow communication between the recess 165 and the cavity defined between the locking pin 160 and the member 151.
- a groove 168 is provided on the surface of the member 101 to allow communication of the recess 155 via a passage 170 with the bottom surface of the memaer 101.
- a pin 149 is provided to extend inwardly from the cam follower means 150 to engage a groove 148 which extends axially down the cam follower means 100.
- the pin 149 prevents relative rotation between the cam follower means 100 and 150.
- valve control means can be seen in use in an internal combustion engine in figures 4 and 5.
- FIG 4 the low speed operation of the internal combustion engine is shown.
- an inlet valve 180 of a cylinder of an internal combustion engine There can also be seen three cams 181, 182 and 133 provided on a camshaft 185 for rotation therewith.
- the cam 181 has a first low lift cam profile and the cams 182 and 183 each have the same high lift cam profile.
- the inlet valve 180 is a poppet valve provided with a spring retainer 1S6.
- a valve spring 187 acts between the spring retainer 136 and the cylinder head of the engine shown generally at 133. The spring 187 acts to bias the poppet valve ISO into its valve seat 189 .
- the valve control means of the invention is provided in a bore in the cylinder head 188, and is slidable in the bore.
- An oil gallery 190 is provided in the cylinder head 138, which communicates with the annular recess 154 of member 152 when the valve control means is located in the bore.
- a spring 192 is provided to act between the spring seat 155 of the valve control means and the cylinder head 183 and the spring 192 biases the second cam follower member 150 into abutment with the two cams 132 and 183.
- the oil pressure in oil gallery 190 is kept at a low level.
- the fluid pressure is communicated from the oil gallery 190 via the recess 154 of the valve control means to the annular cavity 156 of the valve control means.
- the fluid pressure is then relayed by the passages 164 to the cavities 167 defined behind the locking pins (locking pin 160 being shown in the figure) .
- the low oil pressure is insufficient to overcome the biasing effect of the spring 163 and therefore the locking pin 160 (and the other locking pins 161 and 162) remain retracted within the cam follower member 150 and the cam follower member 150 is not linked in any way to the cam follower member 100.
- cam follower members 100 and 150 are not linked, they move independently of each other.
- the cam follower member 100 engages the surface of the cam 181 and will transmit the camming action of the cam 181 to the inlet valve ISO. This imparts to the valve 180 a lift A shown in figure 4.
- Control means .vill be provided in the internal combustion engines to control the pressure of the fluid in the oil gallery 190.
- the control means will typically switch the oil pressure from a low pressure to a high pressure when a particular engine speed is reached.
- the pressure in the oil gallery 190 has been switched to a high pressure and the high pressure oil has been communicated to act on the locking pins 160, 161 and 162, which have engaged the inner cam follower member 100 and have linked the cam follower members 100 and 150, so that they move together.
- the inlet valve 180 is thus controlled by the profile of the cams 132 and 183, which is a higher lift profile than the profile of the cam 181.
- the increased lift of the valve is indicated at B in the figure 5.
- the hydraulic lash adjustment means of the invention is supplied with oil in both operating conditions when the cam follower members 100 and 150 engage the base circle portions of the cams 182, 181 and 183.
- the spring 112 acts to push the member 107 away from the member 101 and to draw oil into the bottom chamber 108 from the top chamber 102 via the passage 106.
- the spring 112 is of greater resilience than the light spring 111 which merely serves to locate the ball 110 adjacent to the passage 106.
- the member 107 can only move away from the member 101, since the bail 110 will act to stop fluid flowing from the chamber 108 into the chamber 102 when a compressive force is applied on the two members 101 and 107.
- the chamber 102 is supplied with hydraulic fluid via the passages 103 and passages 179 with the fluid being supplied from the cavity 156 which is in turn supplied through passage 157 and annular cavity 154 from the oil gallery 190.
- the passage 104 serves to allow a fluid to flow from the chamber 102 to the top surface of the cam follower members 100 and 150, the hydraulic fluid then lubricating the cam follower surfaces and minimising wear and preventing air being trapped in cavity 102.
- the hydraulic lash adjustment means of the invention has advantageous features not present in the hydraulic lash adjustment means of the prior art since it does not reguire a bucket tappet and therefore allows the valve control means of the present invention to be smaller than the valve control means of the prior art.
- one of the members which defines the variable volume chamber of the hydraulic lash adjuster has a wear surface which is engageable directly with a cam (or with a rocker arm positioned between the cam and the follower member, as seen in one embodiment of W091/12413) .
- the member has a recess defined on its exterior surface which can be engaged by locking pins.
- the diameter of the bore of the external cam follower means 151 can be reduced in comparison to the bores of the prior art valve control means since the bore does not have to accomodate a bucket tappet.
- the cross-sectional area of the bore can be as small as the cross-sectional area of the largest part of the largest of two members which define the expandable chamber of the hydraulic lash adjuster.
- the second cam follower member 250 has a slightly different shape, but remains generally cylindrical.
- An inner steel skirt 230 is provided in the second embodiment, which is attached to the body 251 of the cam follower member 250 and which is also attached at its lower end to the outer steel skirt 255.
- the locking pins 260, 261 and 262 are of an L-shape in cross-section.
- Springs 263 are provided to act between the lower portion of the locking pins and the inner steel skirt 230.
- Apertures such as 278 are provided in the inner steel skirt to prevent hydraulic locks by allowing the cavities defined around the springs 263 to be vented to a groove 229 running axially along the exterior of the cam follower member 200.
- the locking pin 260 can be seen to have a groove
- the groove 228 allows fluid to flow from the recess 265 provided on the exterior of the cam follower member 200 to the groove
- FIGS 8 and 9 a third preferred embodiment of the invention can be seen.
- the third preferred embodiment is very similar to the second preferred embodiment already described and only differences will be discussed.
- the first important difference between the second and third embodiments is that the third embodiment uses only two locking pins 360 and 361.
- the locking pins 360 and 361 are again of an L-shaped cross-section.
- the venting of the cavities surrounding the biasing springs 363 is provided for in a different manner in the third embodiment.
- the locking pins 360 and 361 each have a tapered portion at the front end thereof and a passage running through the locking pins which allows the cavities surrounding the springs 370 to communicate with the recesses 327 defined on the exterior of the cam follower member 300.
- the tapered portions of the locking pins 360 and 361 also allow fluid to flow from the recesses 365 through grooves such as grooves 368 defined on the exterior of the cam follower member 300. The grooves relay the oil to the top surfaces of the cam follower members 300 and 350.
- valve control means are designed to be free to rotate within a bore in a cylinder head, thereby reducing wear by allowing the cams to act on different portions of the surfaces of the cam follower members.
- the inner cam follower member comprises a hydraulic lash adjuster which engages a cam without the need for a bucket tappet.
- the inner cam follower means can be reduced in diameter from those of the prior art, with a corresponding reduction in the overall diameter of the valve control means. This is very important to meet packaging constraints within an engine.
- the low lift cam can be replaced by a lobe of circular cross-section such that at low engine speeds the valve can be deactivated (the circular lobe imparting no lift) .
- the locking pin arrangement when interlocking the inner and outer cam follower members will allow some downward movement of the outer cam follower member from its position in engagement with the base circles of the two cams engaged thereby to a position in which it starts to move the inner cam follower member downwardly.
- This can e achieved by suitable sizing of the recess in the exterior of the inner member.
- This feature allows for misalignment created by wear and ensures that the force of the valve spring is transmitted to the base circle portion of the low lift cam (or no lift lobe) at low and high engine speeds.
- the hydraulic lash adjuster thus adjusts for wear of the most worn component (the low lift cam or no lift lobe) in all conditions. This arrangement ensures that the valve is returned to its valve seat securely at low and high engine speeds, despite differences in wear between the cams of the camshaft (or the no lift lobe and the cam of the camshaft) .
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Valve Device For Special Equipments (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9306221 | 1993-03-25 | ||
GB939306221A GB9306221D0 (en) | 1993-03-25 | 1993-03-25 | Valve control means |
PCT/GB1994/000619 WO1994021899A1 (en) | 1993-03-25 | 1994-03-25 | Valve control means |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0695395A1 true EP0695395A1 (en) | 1996-02-07 |
EP0695395B1 EP0695395B1 (en) | 1997-09-10 |
Family
ID=10732735
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94910474A Expired - Lifetime EP0695395B1 (en) | 1993-03-25 | 1994-03-25 | Valve control means |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP0695395B1 (en) |
JP (1) | JP3321167B2 (en) |
KR (1) | KR100299302B1 (en) |
DE (1) | DE69405555T2 (en) |
ES (1) | ES2107819T3 (en) |
GB (1) | GB9306221D0 (en) |
WO (1) | WO1994021899A1 (en) |
Families Citing this family (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4314619A1 (en) * | 1993-05-04 | 1994-11-10 | Schaeffler Waelzlager Kg | Pestle |
US6076491A (en) * | 1994-05-03 | 2000-06-20 | Lotus Cars Limited | Valve control mechanism |
JP3865771B2 (en) * | 1994-05-03 | 2007-01-10 | ロータス カーズ リミテッド | Valve control mechanism |
US5431133A (en) * | 1994-05-31 | 1995-07-11 | General Motors Corporation | Low mass two-step valve lifter |
DE4436952A1 (en) * | 1994-10-15 | 1996-04-18 | Schaeffler Waelzlager Kg | Switchable tappet of a valve train of an internal combustion engine |
DE4440133A1 (en) * | 1994-11-10 | 1996-05-15 | Schaeffler Waelzlager Kg | Switchable cam follower |
DE4440469A1 (en) * | 1994-11-12 | 1996-05-30 | Peter Prof Dr Tenberge | Engageable tappet for valve drive in IC engine |
US5709180A (en) * | 1997-02-06 | 1998-01-20 | General Motors Corporation | Narrow cam two-step lifter |
AU2001287705A1 (en) * | 2000-09-30 | 2002-04-15 | Ina-Schaeffler Kg | Disconnectable support element |
US6739293B2 (en) | 2000-12-04 | 2004-05-25 | Sturman Industries, Inc. | Hydraulic valve actuation systems and methods |
DE10204673A1 (en) * | 2002-02-06 | 2003-08-07 | Ina Schaeffler Kg | Automotive drive switching element comprises diametrically opposed piston pair in groove mountings on inner and outer parts to run nontwistably in grooves. |
DE102006030162A1 (en) * | 2006-06-29 | 2008-01-03 | Schaeffler Kg | Locking device for a switchable valve drive member of a valve train of an internal combustion engine |
DE102007016740A1 (en) * | 2007-04-07 | 2008-10-09 | Schaeffler Kg | Switchable bucket tappets |
DE102007016739A1 (en) * | 2007-04-07 | 2008-10-09 | Schaeffler Kg | Switchable valve drive part |
KR101316459B1 (en) * | 2007-12-07 | 2013-10-08 | 현대자동차주식회사 | Variable tappet for vvl and cda |
KR100962195B1 (en) * | 2007-12-12 | 2010-06-11 | 현대자동차주식회사 | Variable valve lift apparatus |
US11187119B2 (en) | 2019-09-16 | 2021-11-30 | Eaton Intelligent Power Limited | Latch pin for use in valve lifter and valve lifter |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1958627A1 (en) * | 1969-11-21 | 1971-06-24 | Daimler Benz Ag | Adjusting device for valve lifts |
US3704696A (en) * | 1971-03-08 | 1972-12-05 | Eaton Corp | Hydraulic valve lifter |
DE3311280A1 (en) * | 1983-03-28 | 1984-10-11 | FEV Forschungsgesellschaft für Energietechnik und Verbrennungsmotoren mbH, 5100 Aachen | Hydraulic valve-clearance compensating element |
DE3347680A1 (en) * | 1983-12-31 | 1984-08-30 | Ernst 8450 Amberg Haubner | Valve timing system for internal combustion engines with two different valve timings |
CA1308977C (en) * | 1986-08-27 | 1992-10-20 | Tsuneo Konno | Valve operating device for internal combustion engine |
US5253621A (en) * | 1992-08-14 | 1993-10-19 | Group Lotus Plc | Valve control means |
US5287830A (en) * | 1990-02-16 | 1994-02-22 | Group Lotus | Valve control means |
US5193496A (en) * | 1991-02-12 | 1993-03-16 | Volkswagen Ag | Variable action arrangement for a lift valve |
US5361733A (en) * | 1993-01-28 | 1994-11-08 | General Motors Corporation | Compact valve lifters |
-
1993
- 1993-03-25 GB GB939306221A patent/GB9306221D0/en active Pending
-
1994
- 1994-03-25 EP EP94910474A patent/EP0695395B1/en not_active Expired - Lifetime
- 1994-03-25 JP JP52083894A patent/JP3321167B2/en not_active Expired - Lifetime
- 1994-03-25 DE DE69405555T patent/DE69405555T2/en not_active Expired - Lifetime
- 1994-03-25 KR KR1019950704068A patent/KR100299302B1/en not_active IP Right Cessation
- 1994-03-25 WO PCT/GB1994/000619 patent/WO1994021899A1/en active IP Right Grant
- 1994-03-25 ES ES94910474T patent/ES2107819T3/en not_active Expired - Lifetime
Non-Patent Citations (1)
Title |
---|
See references of WO9421899A1 * |
Also Published As
Publication number | Publication date |
---|---|
EP0695395B1 (en) | 1997-09-10 |
WO1994021899A1 (en) | 1994-09-29 |
DE69405555T2 (en) | 1998-02-19 |
JP3321167B2 (en) | 2002-09-03 |
KR960701282A (en) | 1996-02-24 |
GB9306221D0 (en) | 1993-05-19 |
JPH08508077A (en) | 1996-08-27 |
KR100299302B1 (en) | 2001-11-22 |
DE69405555D1 (en) | 1997-10-16 |
ES2107819T3 (en) | 1997-12-01 |
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