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
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/12—Transmitting gear between valve drive and valve
  • F01L1/18—Rocking arms or levers
  • F01L1/185—Overhead end-pivot rocking arms
• • 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
  • F01L1/28—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of coaxial valves; characterised by the provision of valves co-operating with both intake and exhaust ports
• • 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
  • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
  • F01L9/10—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic
  • F01L9/11—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column
  • F01L9/12—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column with a liquid chamber between a piston actuated by a cam and a piston acting on a valve stem
  • F01L9/14—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column with a liquid chamber between a piston actuated by a cam and a piston acting on a valve stem the volume of the chamber being variable, e.g. for varying the lift or the timing of a valve
• • 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
  • F01L1/02—Valve drive
  • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
  • F01L1/08—Shape of cams
• • 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
  • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
  • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
  • F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
  • F01L2001/34423—Details relating to the hydraulic feeding circuit
  • F01L2001/34446—Fluid accumulators for the feeding circuit

Definitions

• This invention relates to the art of variable valve control system for internal combustion engines and more particularly, to a fully flexible valve timing system enabling control of load and improvement in effective valve area. Description of the prior art
• a fully flexible valve control system offers the optimal solution by eliminating pumping losses through the provision of the load control function.
• the above systems have not demonstrated the required flexibility to fulfill this objective except over a very narrow load range.
• most of the current electro-hydraulic systems suffer from degradation at higher rpm.
• the objective is to design a variable valve actuation (WA) mechanism with the capability to control load over the entire operating range.
• WA variable valve actuation
• valves It is also desired to enable the valves to function as the optimal load control device.
• the present invention provides an improved valve opening and duration control arrangement. It is yet another objective to improve valve actuation and sequencing flexibility to enhance performance and economy and reduce emissions.
• the above and other objectives of the present invention are achieved, according to a preferred embodiment thereof, by providing an improved control of valve open duration by progressively advancing the intake valve closing phase angle.
• the closing phase angle is shifted in a stepless manner.
• the arrangement functions without effecting the opening phase angle and overlap period and is equally adaptable for partial or full phasing of any of the valve events.
• the charge admitted to the cylinders can be a function of the valve duration in terms of the angular rotation of the crankshaft.
• a high-speed hydraulic actuator is positioned to interact with a first (main) camshaft to impart a periodic displacement stroke to the valve via the actuator to open and close the valve according to a cam profile.
• a second (control) camshaft is positioned to interact with a pressure relief mechanism (valve) on the actuator to discharge hydraulic fluid from within, thereby collapsing the actuator and allowing the valve to return to a closed position regardless of the present orientation of the first camshaft.
• a full range phasing mechanism is mounted at the driven end of the control camshaft. This allows the control camshaft to be phased in relation to the first camshaft to modulate the width of the control profile and thus valve duration.
• a significant increase in the effective valve area is realized by having the main camshaft incorporate "wide" cam lobes. These function to operate the valve during two consecutive strokes, viz. exhaust followed by intake.
• a further modification is made to the intake system by having a "merged" intake/exhaust manifold wherein the intake and exhaust passages are joined together to form a straight through passage. Forced air means maintain airflow through the passage so that exhaust gases expelled from the valve orifice are diverted in the discharge direction and fresh air is admitted from the upstream direction. This is a particularly useful feature with variable compression ratio engines wherein a large portion of the combustion chamber surface may be occupied by the sub-piston adversely effecting valve area.
• Figure 1 is a cross sectional view of the arrangement.
• Figure 2 is a cross sectional view of another embodiment of the arrangement.
• Figure 3 is a cross sectional view of the wide lobe cam.
• Figure 4 is a sectional view of the merged intake-exhaust manifold.
• Figure 5 is detailed drawing of a high-speed actuator.
• Fig 1. shows a sectional view of the arrangement 10 constructed according to the invention as illustrated for one valve 101 in an internal combustion engine.
• valve 101 is shown to be mounted in a partial view of the cylinder head 103.
• the detail of the valve spring, clips, valve seat etc., are not shown as they are well known in the art and are not taught by the invention.
• Lubrication channels 104 which provide a conduit for the engine lubricating oil system are illustrated as formed within the cylinder head 103
• a hydraulic actuator 140 is mounted on the cylinder head 103, connected with the lubrication channel 104 and positioned adjacent the valve 101.
• a camshaft 110 is mounted in the cylinder head above the actuator.
• a cam 111 is mounted on the camshaft 110. The camshaft will rotate to move the cam lift surface 111 into contact with the actuator top piston 142. The downward movement of the top piston will be transmitted via the pressurized fluid medium 141 to the lower plunger 143 causing it to move valve 101 to the open position.
• the timing of the valve opening is set by the rotation of the camshaft 110.
• the arrangement 10 provides an additional control element, a pressure relief valve 144 formed in the body of the actuator. It is this control element which allows the adjustment of the open duration of the valve 101.
• a control camshaft 120 is mounted adjacent the relief valve 144.
• a control cam with control surface 121 is mounted on the control camshaft and positioned to engage the pin 148 of relief valve 144 for a preselected portion of the rotation of the control camshaft.
• the control camshaft may be driven by an arrangement taught in U.S. Patent 4,747,375, C375) granted to John K. Williams.
• the '375 arrangement allows a crankshaft to drive a camshaft with variable phasing over the entire load range.
• the present invention utilizes this variable phasing unit to adjust the engagement of the control surface 121 with the pin 148 of the relief valve 144.
• control camshaft can be made much lighter and at less cost than the main camshaft since it interacts only with the pressure relief mechanism. Accordingly the phasing unit is also very light allowing it to be directly connected to an accelerator pedal.
• FIG 2 shows another embodiment of the present invention wherein the actuator 140 interacts with the valve 101 via a rocker arm.
• a rocker arm 102 is hingedly mounted to the top portion of the actuator.
• a camshaft 110 is mounted over a plurality of rocker arms (one for each valve).
• a cam 112 is mounted on camshaft 110 and is in sliding contact with rocker 102.
• the cam 112 shown in this case is the wide lobed cam mentioned above.
• camshaft 110 will rotate to move the cam lift- surface 112 into contact with the rocker arm 102.
• the rocker arm 102 will pivot from the hinged mounting to begin to push the valve 101 to an open position.
• the timing of this event coincides with the beginning of the exhaust stroke of the particular cylinder.
• the valve remains open during the exhaust stroke and into the intake stroke.
• the control camshaft 120 is mounted adjacent actuator 140, where control cam surface 121 is engageable by relief pin 148 as before.
• control cam surface 121 When upon further rotation of control cam 121, the control surface causes the relief pin to be pushed inward to release the hydraulic fluid the actuator 140 will contract to move pivot point 140 downwards as viewed in the drawing. This causes a corresponding upward movement of the opposite end of rocker 102 to bring valve 101 to a closed position under the influence of the valve closing spring.
• the top surface of the rocker 102 is so shaped as to facilitate the rocker to pivot about a second pivoting point formed by the sliding contact point of cam 112 and rocker 102.
• a further advantage of this embodiment is that actuator wear is reduced and the actuator can be made simpler since it executes a single function stroke per cycle rather than the double stroke of the first embodiment. Thus in this mode the actuator can function with only a single movable plunger.
• the wide cam lobe 112 may also be employed in the first embodiment shown in Fig. 1. If needed, the lobe 112 may incorporate a slight depression or valley approximately in the middle to enable the valve to retract slightly while the piston 160 is near the top of its stroke.
• FIG. 4 shows an embodiment of the merged intake-exhaust system employed in conjunction with a dual function valve.
• the manifold 150 comprises an upstream portion 151 and a downstream portion 152 respectively to valve 101.
• An integral roots or scroll type blower 153 driven by the crankshaft is shown attached to the manifold forcing air through conduits 151 and 152.
• TDC top dead center
• the fuel injection pulse begins approximately when the valve is near TDC (soon after the gas equilibrium point is reached), and stops before the valve 101 is closed.
• the fuel injection pulse width may be synchronized with the valve duration pulse, or injection may be through a separate valve port in the cylinder operated in the conventional manner.
• a separate smaller valve may be positioned across from the main valve(s) in the combustion chamber to open momentarily near the TDC point to flush out trapped gasses.
• the passage 150 is shown to turn sharply at an acute angle at the point of communication with the cylinder. This creates a ramming effect by the airstream facilitating cylinder charging at high revolutions.
• Figure 5 shows the detailed design of a high speed actuator.
• most actuator designs are plagued by slow response times which result in serious degradation of the of the operational profile at high rpm.
• Many designs, to enhance response time store the expelled hydraulic fluid in a pressure reservoir. Since the reservoir is connected via conduit, delay arises due to path restriction. Also, transfer of fluid between actuator and reservoir is effected by solenoids, adding to the cost of the units.
• the actuator shown in Fig. 5 has an integral pressure reservoir to store the expelled fluid and return it in the shortest possible time during the neutral interval.
• the actuator 140 encloses an internal volume space 141 formed by the casing and movable plungers 142 and 143.
• Plungers 142 and 143 are formed with a second smaller diameter to slidably fit into a smaller cylindrical bore formed within the body of the actuator. This reduces the volume of fluid displaced for a proportional relative movement of the plungers improving response time.
• the first volume chamber 141 communicates with a second volume chamber 145 by way of a check valve 144.
• Check valve 144 has a large bore diameter respective to the volume chamber to facilitate rapid transfer of fluid.
• the second volume chamber 145 has a movable piston 146 biased by spring 147 in the direction of the check valve 144.
• a pin 148 slidably passes through a bore in the actuator body and a second bore in the slidable piston 146 to communicate with the check valve 144. Inward motion of the pin 148 opens check valve 144 allowing hydraulic fluid to enter volume 145 forcing piston 146 against biasing spring 147.
• the pin is flanged at two points to limit travel.
• Another check valve 149 admits hydraulic fluid from the engine lubrication system to prime the actuator initially.
• the spring coefficient 147 can be matched to the coefficient of valve spring 105 to determine the valve return rate in order to avoid excessively high valve seating velocities.
• damping can also be achieved by having fluid occupy the back space of piston 146 and by spilling this fluid through calibrated spill bores.
• chamber 145 incorporates a small bore at a preselected volume to bleed off excess fluid.
• the base of the actuator is flanged for mounting on the cylinderhead.
• An oil inlet passage is shown which mates with a corresponding oil supply channel 104 from the engine lubrication system.
• Another spring is mounted between the outer peripheral flange of plunger 142 and housing 140 to urge the plunger against the cam face and improve response.
• relief pin 148 may be operated by small two- position solenoids attached to the actuator. Signals from an ECU can then be employed to operate the actuators. In some modes of operation a number of valves in each cylinder may be disabled to increase the flow velocity into the cylinders. This can also be done by having split lobes for the control cam 121 and engaging pin 148 before intake begins for some of the valves.
• the actuators may be used in conjunction with a conventional throttle valve in which the actuators are altogether disabled (in the fully extended position) at high rpm and charge flow is controlled in the usual manner for the upper load ranges.
• the above invention demonstrates a vastly improved and efficient valve control system for an engine's valves. Furthermore, the system overcomes many of the disadvantages of the prior art in a very cost effective manner. System reliability is improved, while at the same time energy drain and stress on moving components is reduced.

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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)

Applications Claiming Priority (3)

Publications (2)

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ID=22068937

Family Applications (1)

Country Status (5)

Families Citing this family (9)

Family Cites Families (7)

• 1994
  • 1994-05-23 WO PCT/US1994/005635 patent/WO1994028288A2/en not_active Ceased
  • 1994-05-23 DE DE69432362T patent/DE69432362T2/de not_active Expired - Fee Related
  • 1994-05-23 EP EP94918052A patent/EP0775252B1/de not_active Expired - Lifetime
  • 1994-05-23 AU AU69538/94A patent/AU6953894A/en not_active Abandoned
  • 1994-05-23 JP JP50080195A patent/JP3597532B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

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