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
  • 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
• • 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

• the invention relates to a hydraulic actuator for a gas exchange valve for internal combustion engines.
• the gas exchange valve should be opened and closed as quickly as possible in order to minimize the flow losses of the gas exchange valve when the combustion air is drawn in or when the exhaust gases are pushed out of the combustion chamber.
• the invention has for its object to provide a hydraulic actuator for a gas exchange valve that can exert a large force at the beginning of the opening movement on the gas exchange valve, which enables quick control movements of the gas exchange valve and in which
• Gas exchange valve hits the valve seat at low speed.
• a large hydraulic force is transmitted from the actuator to the gas exchange valve at the start of the opening movement of the gas exchange valve, so that the gas exchange valve can be lifted safely and quickly from the valve seat despite the back pressure from the combustion chamber onto the valve plate of the gas exchange valve.
• the annular piston is no longer moved and, as a result, only a smaller hydraulic force acts on the piston of the actuator, which in turn transmits it to the gas exchange valve becomes.
• the energy required to adjust the actuator piston is reduced, so that the overall energy requirement for the valve control of the internal combustion engine drops.
• the actuating speed of the gas exchange valve also changes.
• the gas exchange valve when the gas exchange valve is closed with the hydraulic actuator according to the invention, the gas exchange valve can be braked before the gas exchange valve hits the valve seat of the internal combustion engine. This reduces the wear on the valve seat and gas exchange valve as well as the noise development of the valve control of the internal combustion engine.
• the beginning of the braking process of the gas exchange valve when it is closed is independent of the manufacturing tolerances of the gas exchange valve and the temperature-related conditions which are always present in internal combustion engines Changes in length due to thermal expansion.
• a very stable operating behavior of the internal combustion engine can therefore be realized with the actuator according to the invention, which is not influenced by temperature expansions or by manufacturing tolerances.
• the piston has a recess, that the ring piston has an outer surface and a stepped center hole with a larger diameter and a smaller diameter, and that the ring piston with the larger diameter of the center hole can be pushed onto the piston, so that the ratio of the actuating forces of the actuator when opening the gas exchange valve and during the rest of the actuating movement can be adjusted in a simple manner.
• This effect can be further increased by the fact that the diameter of the piston is different on both sides of the recess and that the ring piston can be pushed onto the larger diameter.
• the device for limiting the volume decrease of the second chamber is a pressure accumulator with a piston which is hydraulically connected to the second chamber and that the path of the piston can be limited, so that the hydraulic means can be used in a simple manner Ring piston can be locked. Since the pressure accumulator does not reach the high temperatures of the gas exchange valve and the cylinder head of the internal combustion engine, the position in which the ring piston is after the gas exchange valve has been opened is is locked, regardless of the thermal expansion of the gas exchange valve and the cylinder head.
• the pressure accumulator is a spring accumulator or a gas accumulator and / or that the path of the piston can be limited by a stop, in particular an adjustable stop, so that the actuator according to the invention can be easily adjusted.
• first chamber can be connected to a pump via a first switching valve
• second chamber can be connected to an oil sump via a second switching valve
• delivery chamber pressure is applied to the third chamber, so that through the actuation of two switching valves, the gas exchange valve with the hydraulic according to the invention
• Actuator can either be opened or closed, the increased force when the gas exchange valve is lifted from the valve seat and the deceleration of the gas exchange valve before it hits the valve seat are automatically realized by the hydraulic actuator according to the invention.
• the effect of the actuator according to the invention is further supported by the fact that the first chamber and the second chamber are hydraulically connected to one another via a throttle, in particular an adjustable throttle, and / or that a check valve between the second chamber and the first chamber is provided, which blocks the hydraulic connection from the first chamber to the second chamber.
• the throttle has a significant influence on the braking of the gas exchange valve before it hits the valve seat.
• the device for limiting the volume decrease in the second chamber has a shut-off valve which is connected to an opening in the second chamber and closes the opening in its one switching position and releases it in its other switching position for fluid outflow.
• the shut-off valve closes, the ring piston is fixed, so that the closing time of the shut-off valve determines the stroke of the ring piston.
• the point in time at which the braking action is applied when the gas exchange valve closes is dependent on the stroke of the ring piston, which starts earlier with a larger stroke of the ring piston and later with a smaller stroke.
• the shut-off valve can thus be used to set the start of braking regardless of manufacturing tolerances or material expansion due to temperature fluctuations.
• the shut-off valve is not used as an additional structural unit, but rather its function is assigned to the second switching valve, which is required anyway for initiating the closing process of the gas exchange valve.
• a flow-controlled valve is arranged between the first chamber and the throttle arranged between the two chambers to influence the braking behavior of the actuator piston and thus the gas exchange valve, which valve is designed such that it can be closed by the fluid flowing into the first chamber ,
• This has the advantage that in the initial phase of the stroke of the actuator piston, in which both switching valves are open, fluid cannot flow directly from the first switching valve via the throttle into the hydraulic relief chamber or oil sump.
• this flow-controlled valve can be dispensed with, since only small amounts of fluid flow through the throttle, but with a larger throttle opening, only a small one is achieved
• the braking effect on the gas exchange valve is essential for the flow-controlled valve to shut off the throttle to avoid major leaks.
• FIG. 1 shows a longitudinal section of a hydraulic actuator according to the invention with its hydraulic connection
• 2 shows a longitudinal section of the actuator according to FIG. 1 in three different positions
• FIG. 5 each shows a longitudinal section of a and 6 flow-controlled valve in FIG. 4 in the open (FIG. 5) and closed (FIG. 6)
• the housing 1 shows a hydraulic actuator with a housing 1 in longitudinal section.
• the housing 1 has a stepped cylinder bore 3.
• a sleeve 5 is pressed into the housing 1, the inner bore of which is part of the stepped cylinder bore 3. In the area of the sleeve 5 is in the
• Cylinder bore 3 an annular piston 7 and a piston 9 out.
• the gas exchange valve (not shown) is closed.
• the cylinder bore 3, the piston 9 and the annular piston 7 delimit a first chamber 13 in the direction of a longitudinal axis 11 of the piston 9. So that no liquid or fluid can escape between the cylinder bore 3 and the piston 9, a first sealing ring 15 is on the left in FIG. 1 End of the first chamber 13 arranged.
• the piston 9 has a recess 17.
• the diameter of the piston 9 on both sides of the recess 17 are of different sizes.
• the piston 9 On the side facing the sealing ring 15, the piston 9 has a smaller diameter di, and at the other end of the recess 17, the piston 9 has a larger diameter d 2 .
• the annular piston 7 is arranged between the sleeve 5 and the piston 9.
• the annular piston 7 is fitted into the cylinder bore 3 in such a way that on the one hand it can be displaced in the axial direction and on the other hand that a good sealing effect is achieved between the cylinder bore 3 and the annular piston 7.
• the annular piston 7 has a stepped center bore 19 with a smaller diameter d 3 and a larger diameter which is as large as d 2 .
• the fit between the annular piston 7 and the larger diameter d 2 of the piston 9 is also selected so that the annular piston 7 and piston 9 can be moved relative to one another in the axial direction and a good sealing effect is nevertheless achieved.
• the cylinder bore 3 and the annular piston 7 delimit a second chamber 27.
• the cylinder bore 3 has a diameter d 4 in this area, which corresponds to the outer diameter of the annular piston 7.
• this has a shoulder with the diameter ds.
• the first chamber 13 can be hydraulically connected to a pump 31 via a first switching valve 29.
• the first switching valve 29 can be designed, for example, as an electrically operated solenoid valve.
• the pump 31 acts permanently on the third chamber 25 with the delivery pressure generated by it.
• a hydraulic switching connection between the second chamber 27 and a relief chamber or oil sump 35 can be established by means of a second switching valve 33, for example an electrically operated solenoid valve.
• a check valve 39 is arranged in a line 37, which connects the second chamber 27 and the second switching valve 33.
• a hydraulic accumulator 41 is connected between check valve 39 and second chamber 27.
• the hydraulic accumulator 41 has a piston 43 which moves against the force of a spring 45 when the pressure acting on the end face of the piston 43 facing away from the spring 45 is sufficiently high. This pressure is the same as the pressure in the line 37.
• the path of the piston 43 against the force of the spring 45 is limited by a stop 47, which can also be made adjustable.
• Between the first chamber 13 and the second chamber 27 is one hydraulic connection is provided, in which an adjustable throttle 49 is arranged.
• the diameter d 4 of the cylinder bore 3, the annular piston 7 and the right side of the recess 17 in FIG. 1 form a first annular surface Ai with an outside diameter d 4 and an inside diameter d 6 , which corresponds to the inside diameter of the recess 17.
• the pressure of the hydraulic fluid in the first chamber 13 acting on the first annular surface Ai tries to move the piston 9 to the right.
• the resulting force is responsible for opening the gas exchange valve, not shown.
• the hydraulic force acting on the first ring surface i is reduced by the hydraulic forces acting on a third ring surface A 3 and a fourth ring surface A 4 .
• the third annular surface A 3 is limited by the shoulder in the piston 9, which is formed by the diameter di of the piston 9 and the diameter d 6 of the recess 17. This applies to the third annular surface A 3 in the first chamber 13 hydraulic fluid from a force acting to the left in FIG. 1.
• the fourth annular surface A. is delimited by a shoulder 51 of the piston 9 in the region of the third chamber 25.
• the shoulder 51 is formed by the diameter d 2 and the diameter d 5 of the piston 9.
• the fourth ring surface A. always exerts a force acting against the opening direction on the piston 9, since, as already mentioned, the pre-pressure of the pump 31 is always applied to the third chamber 25.
• the piston 9 moves to the right when the delivery pressure of the pump 31 is applied to the first chamber 13.
• the annular piston 7 transmits the hydraulic force acting on it via the shoulder of its stepped center bore 19 to the piston 9.
• the movement of the piston 9 in FIG. 1 to the right results in the opening of the gas exchange valve, not shown.
• FIGS. 2a, 2b and 2c show different stages of the opening movement and the closing movement, by means of which the above is to be clarified.
• the actuator is shown in a position in which the gas exchange valve is closed and the full opening force is available.
• the piston 9 m To close the gas exchange valve, the piston 9 m must be moved to the left in FIGS. 1 and 2. This is done by closing the first switching valve 29 and opening the second switching valve 33. This position of the switching valves 29 and 33 is shown in FIG. 1.
• the hydraulic force exerted on the shoulder 49 of the piston 9 by the fluid in the third chamber 25 and under the supply pressure of the pump 31 moves the piston 9 to the left. Hydraulic fluid from the first chamber 13 and the second chamber 27 via the check valve 39 and the second switching valve 33 m the oil sump 35 is required.
• the spring 45 of the hydraulic accumulator 41 can lift the piston 43 from the stop 47 and move the piston 43 again in its starting position.
• the ratio of the opening force when lifting the gas exchange valve from the valve seat, the reduced opening force when opening the gas exchange valve and the closing force when closing the gas exchange valve can be matched to one another by means of a suitable choice of the diameters di to de, in order to achieve optimal operating behavior of the hydraulic actuator ,
• FIG. 3 shows a section of the actuator according to FIG. 1 only to the extent of interest below with housing 1, first chamber 13, second chamber 27 and third chamber 25 and its hydraulic connection to hydraulic pump 31 with the example as 2/2 -Way solenoid valve trained first switching valve 29 and the hydraulic connection between the first chamber 13 and second chamber 27 shown via the throttle 49.
• the hydraulic relief chamber or oil sump is still designated as 35 and the line connecting the second chamber 27 with the second switching valve 33, for example a 2/2-way solenoid valve, is designated by 37.
• the hydraulic actuator is modified insofar as the device for limiting the volume decrease of the second chamber 27, which is designed as a hydraulic spring accumulator 41 in FIG.
• shut-off valve 50 which is connected to an opening in the second chamber 27, for example is connected to the line 37 and closes the opening in the second chamber 27 or the line connection on the line 37 in its one switching position and in its other switching position releases the fluid to the oil sump 35.
• the function of this shut-off valve 50 which is only symbolically shown in FIG. 3, is assigned to the second switching valve 33, which stands for releasing the fluid outflow from the second chamber 27 in the basic position shown in FIG. 3 and for shutting off the second chamber 27 in its other switching position is switched.
• the changeover valve 33 retains its function for closing the gas exchange valve already described with respect to FIG. 1.
• the first switching valve 29 are opened. Fluid now flows into the chamber 13 under the delivery pressure, so that the piston 9 of the actuator is displaced together with the annular piston 7 as shown in FIG. 2b. If the second switching valve 33 is switched into its blocking position at any time during the displacement of the annular piston 7, no fluid can flow out of the second chamber 27 and the annular piston 7 is blocked. The stroke of the annular piston 7 is thus determined by the time of the changeover of the second changeover valve 33 which is open at the start of the opening movement of the actuator. As described above, to close the gas exchange valve, the annular piston 7 is pushed back by the pressure in the third valve chamber 25 as soon as the first switching valve 29 is blocked again and the second switching valve 33 is opened again.
• the pressure in the first chamber 13 decreases via the throttle 49. After a stroke, the piston 9 abuts the annular piston 7 and takes it along on its further stroke. As a result, a high volume flow and a strong pressure increase in the first chamber 13 are triggered, so that the piston 9 is braked strongly.
• the braking action starts from the point in time at which the annular piston 7 moves with the piston 9, so that the point in time at which the braking operation is started is determined by the stroke length of the annular piston 7 set when the gas exchange valve is opened. So that by
• the point in time when the braking process is started when the gas exchange valve is closed can be determined.
• a flow-controlled valve 51 which is designed in this way, is switched on between the first chamber 13 in the housing 1 and the throttle 49 in the connecting line to the second chamber 27 in the housing 1 that it can be closed by the fluid flowing into the first chamber 13.
• This flow controlled valve 51 prevents fluid in the initial phase for opening the gas exchange valve, in which both the first switching valve 29 and the second switching valve 33 are open, directly from the first switching valve 29 via the second Switching valve 33 flows to the oil sump 35; because the leakage current flowing through the throttle 49 increases the energy requirement for the valve control if it increases unacceptably. This is particularly the case if the braking effect during the closing process of the gas exchange valve is increased
• Control of the throttle 49 should be reduced moderately. If the first switching valve 29 is open, the valve 51 is closed by the fluid flow flowing from the hydraulic pump 31 into the first chamber 13, and thus the connection to the throttle 49 is shut off. If the first switching valve 29 is closed, that is to say returned to the switching position shown in FIG. 4, the valve 51 opens and the connection necessary for pushing the fluid out of the first chamber 13 via the throttle 49 during the closing process of the gas exchange valve is restored.
• the structure of the flow-controlled valve 51 is shown schematically in FIGS. 5 and 6, FIG. 5 showing the open valve and FIG. 6 the closed valve.
• the flow-controlled valve 51 has a housing 52 with a first valve connection 53 connected to the chamber 13 of the actuator, with a second valve connection 54 connected to the throttle 49 and a third valve connection 55 connected with the outlet of the first switching valve 29.
• the first valve connection 53 communicates with a lower valve chamber 56, the third valve connection 55 with an upper valve chamber 57 and the second valve connection 54 with an annular chamber 58 located between the lower and upper valve chambers 56, 57.
• a valve opening 60 surrounded by a valve seat 59 is formed in the housing 52 between the lower valve chamber 56 and the annular chamber 58.
• a guide sleeve 61 is in the upper valve chamber 57 used, in which a valve member 62 designed as a sliding piston is slidably guided.
• the valve member 62 cooperates with the valve seat 59 for closing and releasing the valve opening 60, so that the annular space 58 is blocked off by the lower valve chamber 56 when the valve member 59 is seated on the valve seat 59 and when the valve member 59 is lifted off the valve seat 59 62 (FIG. 5) is connected to the lower valve chamber 56.
• a valve opening spring 63 is inserted, which is designed as a compression spring and is on the one hand in the lower
• Valve space 56 trained shoulder 64 and on the other hand supported on the valve member 62.
• the valve opening spring 63 rests the valve member 62 against a stop 65 formed in the guide sleeve 61.
• the valve member 62 is provided with a central through opening 66 which permanently connects the upper valve chamber 57 to the lower valve chamber 56.
• the through opening 66 is designed as a throttle, for which purpose the inner contour 67 has such a configuration that that of the upper
• Valve space 57 flowing to the lower valve space 56 causes a pressure drop in the passage opening 66.
• the through opening 66 has the shape of a double truncated cone, in which two truncated cones with their smaller base areas are placed one on top of the other.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Valve Device For Special Equipments (AREA)
• Fluid-Driven Valves (AREA)
• Valve-Gear Or Valve Arrangements (AREA)

Applications Claiming Priority (5)

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• 2002
  • 2002-07-30 AT AT02762231T patent/ATE301239T1/de not_active IP Right Cessation
  • 2002-07-30 US US10/450,824 patent/US6776129B2/en not_active Expired - Fee Related
  • 2002-07-30 WO PCT/DE2002/002791 patent/WO2003038246A2/fr active IP Right Grant
  • 2002-07-30 EP EP02762231A patent/EP1440225B1/fr not_active Expired - Lifetime
  • 2002-07-30 JP JP2003540495A patent/JP4314115B2/ja not_active Expired - Fee Related

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