CN111075531A - Fully variable electro-hydraulic valve system - Google Patents
Fully variable electro-hydraulic valve system Download PDFInfo
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- CN111075531A CN111075531A CN202010026697.5A CN202010026697A CN111075531A CN 111075531 A CN111075531 A CN 111075531A CN 202010026697 A CN202010026697 A CN 202010026697A CN 111075531 A CN111075531 A CN 111075531A
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- 230000000903 blocking effect Effects 0.000 claims abstract description 9
- 230000007246 mechanism Effects 0.000 claims description 27
- 238000007789 sealing Methods 0.000 claims description 17
- 230000002093 peripheral effect Effects 0.000 claims description 7
- 230000005540 biological transmission Effects 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims 1
- 239000003921 oil Substances 0.000 abstract description 78
- 239000010705 motor oil Substances 0.000 abstract description 15
- 238000000034 method Methods 0.000 abstract description 11
- 230000008569 process Effects 0.000 abstract description 10
- 230000002000 scavenging effect Effects 0.000 abstract description 4
- 230000009471 action Effects 0.000 description 11
- 230000033001 locomotion Effects 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000010720 hydraulic oil Substances 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 230000009849 deactivation Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004200 deflagration Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
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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
- 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
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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
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- General Engineering & Computer Science (AREA)
- Valve Device For Special Equipments (AREA)
Abstract
The invention discloses a fully variable electro-hydraulic valve system, which comprises: the sliding sleeve is fixed relative to the engine, the piston abuts against the valve assembly, and the spiral shaft is axially controlled by a cam surface of the camshaft; the spiral shaft is provided with a spiral groove and a blocking part, and when the spiral groove is communicated with the limiting oil hole, the sliding sleeve cavity is communicated with a low-pressure oil path of the engine to release pressure; the first end of the screw shaft is provided with a screw shaft axial protruding part, the screw shaft axial protruding part is provided with a screw shaft abutting plane, one end of the piston, which is opposite to the screw shaft, is provided with a piston axial protruding part, and the head of the piston axial protruding part is provided with a piston abutting plane. The invention solves the problem that the normal operation of the system is influenced due to the loss of the engine oil in the sliding sleeve cavity, keeps the crank angle corresponding to the opening time of the air valve unchanged, and is particularly suitable for the variable stroke control of the air inlet valve of the engine with a scavenging process.
Description
Technical Field
The invention relates to the technical field of engine valve mechanisms, in particular to a fully-variable electro-hydraulic valve system.
Background
The Fully Variable Valve System (FVVS) can realize continuous variation of the maximum lift of the Valve, the opening continuous angle of the Valve and the Valve timing, and has important significance for energy conservation and emission reduction of the engine. The FVVS can adopt the mode of early closing of the inlet valve (EIVC) to control the working medium quantity entering the cylinder, thereby canceling the throttle valve, the gasoline engine without the throttle valve can greatly reduce the pumping loss, and the fuel consumption in medium and small loads is reduced by 10-15%. The fully variable valve mechanism is matched with supercharging intercooling, so that the problems of deflagration and high heat load of an engine after supercharging can be solved, low-temperature combustion is realized on the premise of greatly improving the average effective pressure, the heat efficiency of the engine is improved, and the emission of harmful gas is reduced; therefore, the FVVS technology has become one of the important development directions of new internal combustion engine technology.
At present, a more advanced fully variable valve mechanism is a MultiAir (also known as UniAir) system developed by combining Schaeffler and Feiyat, the system adopts a camshaft-driven electro-hydraulic valve mechanism, and the valve motion law is controlled by combining a camshaft and an electromagnetic valve. The working principle of the system is as follows: the hydraulic piston is driven by the cam and is connected with the driving piston through a sliding sleeve cavity, and the sliding sleeve cavity is controlled by a switch type electromagnetic valve. When the electromagnetic valve is in a completely closed state, the hydraulic piston pushes the driving piston through the hydraulic pressure to transmit the hydraulic pressure generated by the rotation of the cam to the air valve; the intake valve is now fully cam controlled and in an open state. When the electromagnetic valve is in a fully open state, the liquid pressure can not transmit the driving force, the hydraulic piston can not push the driving piston, and the intake valve is no longer controlled by the cam and is in a fall-back or closed state. By controlling the opening and closing time of the electromagnetic valve, various different valve motion laws can be realized, and the function of the fully variable valve mechanism is realized. However, the electromagnetic valve has a complex structure and high price, and the popularization and application of the technology are limited.
In order to replace an expensive high-speed solenoid valve, chinese patent CN109339896A discloses a fully variable electro-hydraulic valve device with a buffer function, comprising: a camshaft and a valve assembly; the air valve assembly comprises a spiral shaft, a sliding sleeve, a piston and a return spring, wherein the spiral shaft and the piston are respectively connected with the sliding sleeve in a sliding and sealing mode, the piston abuts against the air valve assembly, a sealed sliding sleeve cavity is formed in the sliding sleeve by a space between the spiral shaft and the piston, and the return spring is clamped between the spiral shaft and the piston; the screw shaft is controlled by the cam surface of the camshaft in the axial direction; the peripheral wall of the spiral shaft, which is connected with the sliding sleeve in a sliding and sealing manner, is a spiral peripheral wall, the end part of the spiral shaft is provided with a control gear meshed with a rack, and the rack is driven by a linear actuating mechanism controlled by an engine electric control unit; the oil inlet hole and the limiting oil hole are formed in the sliding sleeve, the oil inlet hole is close to the spiral shaft, the limiting oil hole is close to the piston, the oil inlet hole and the limiting oil hole are respectively communicated with a low-pressure oil way of the engine, and a one-way valve is arranged on a connecting pipeline between the limiting oil hole and the low-pressure oil way of the engine. The invention adopts the screw shaft and the camshaft to jointly control the valve motion, changes the opening and closing time of the oil inlet hole by rotating the screw shaft, can realize the function of a fully variable valve mechanism, has high response speed and convenient control, replaces a high-speed electromagnetic valve with high price, and is suitable for a multi-cylinder engine.
However, in application it is found that: first, if the device is applied to the variable stroke control of the intake valve, since the engine is mostly designed with a scavenging process, the crank angle (relative to the top dead center) corresponding to the opening time of the intake valve is required to be constant, but the device can block the limit oil hole only at a certain time of the rising section of the cam surface, fig. 9 shows a set of crank angle/valve lift curve of the device, and shows that the crank angle corresponding to the opening time of the valve changes with the change of the blocking time of the limit oil hole, so the application of the device is limited. Secondly, in the stopping process of the engine, hydraulic oil in the sliding sleeve cavity can slowly leak, and when the engine is started, the sliding sleeve cavity can have an oil-free phenomenon, so that the system fails to work. Thirdly, the mechanism has the problem of too high seating speed in the process of seating the electro-hydraulic control valve, so that the sealing surfaces of the valve and the valve seat are damaged by impact, and the service life is influenced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a fully-variable electro-hydraulic valve system, which aims to solve the problem that the normal operation of the system is influenced due to the loss of engine oil in a sliding sleeve cavity and keep the crank angle corresponding to the valve opening time constant.
In order to solve the technical problems, the invention adopts the following technical scheme:
a fully variable electro-hydraulic valve system, comprising: a camshaft and a valve assembly; the sliding sleeve is fixed relative to an engine, the screw shaft and the piston are respectively connected with the sliding sleeve in a sliding and sealing mode, an inner cavity between the screw shaft and the piston is called a sliding sleeve cavity, the return spring is clamped between the screw shaft and the piston, the piston abuts against the valve assembly, and the screw shaft is controlled by a cam surface of the camshaft in the axial direction; the screw shaft is provided with a first end and a second end which are oppositely arranged, the screw shaft is provided with a screw structure, the second end of the screw shaft is in transmission connection with a gear rack mechanism, the gear rack mechanism comprises a control gear and a rack, the control gear is arranged at the second end of the screw shaft, and the rack is driven by a linear actuating mechanism controlled by an engine electric control unit;
the sliding sleeve is provided with an oil inlet hole and a limiting oil hole, the oil inlet hole and the limiting oil hole are respectively communicated with a low-pressure oil way of the engine, and a one-way valve is arranged on a connecting pipeline between the oil inlet hole and the low-pressure oil way of the engine; the spiral structure comprises a spiral groove arranged on the circumferential surface of the spiral shaft, the groove surface of the spiral groove close to the first end of the spiral shaft is a spiral surface, the part between the spiral surface and the first end of the spiral shaft is a plugging part capable of plugging the limiting oil hole, the spiral groove is provided with an oil through hole, the oil through hole is communicated with the spiral groove and the sliding sleeve cavity, and when the spiral groove is communicated with the limiting oil hole, the sliding sleeve cavity is communicated with a low-pressure oil path of the engine for pressure relief; a screw shaft axial protruding part is arranged at the first end of the screw shaft, a screw shaft abutting plane is arranged on the screw shaft axial protruding part, a piston axial protruding part is arranged at one end, opposite to the screw shaft, of the piston, and a piston abutting plane is arranged at the head of the piston axial protruding part; the sliding sleeve is provided with a positioning pin, the piston is provided with a guide groove extending along the axial direction, and the positioning pin extends into the guide groove; the gear rack mechanism is further provided with a limiting device and a return spring, when the return spring enables the rack to move to a limit position limited by the limiting device, the piston abutting plane abuts against the spiral shaft abutting plane, the limiting oil hole is blocked by the blocking part of the spiral shaft, and the valve lift of the valve assembly is controlled by the camshaft.
When the screw shaft is controlled by the base circle section of the cam surface and the rack moves to the other limit position in the opposite direction of the limit device, the spiral groove is communicated with the limit oil hole.
The first end of the screw shaft is provided with two screw shaft axial protruding parts, and the heads of the two screw shaft axial protruding parts are respectively provided with a screw shaft abutting plane; the number of the piston axial protruding parts is two, the heads of the two piston axial protruding parts are respectively provided with a piston abutting plane, and the piston abutting planes correspond to the screw shaft abutting planes one by one.
The two pistons are abutted against the same plane, and the two screw shafts are abutted against the same plane.
The two piston abutting planes are symmetrically arranged relative to the center of the piston, and the two screw shaft abutting planes are symmetrically arranged relative to the center of the screw shaft.
And a thrust bearing is arranged at the second end of the spiral shaft, and a wear-resistant gasket is arranged between the thrust bearing and the cam surface of the cam shaft.
Wherein the control gear is connected with the screw shaft in a torque transmission manner.
Wherein the rack is simultaneously meshed with the control gears of the plurality of screw shafts.
The linear actuating mechanism is a linear motor or an actuating electromagnet or an air cylinder or a hydraulic cylinder.
The end part of the piston of the sliding sleeve is provided with a stepped hole structure, the stepped hole structure comprises a large hole and a small hole, the small hole is matched with a sliding sealing surface of the piston, a buffer ring is arranged in the large hole, the buffer ring is sleeved on the sliding sealing surface of the piston and is in sliding sealing fit with the inner peripheral surface of the large hole, and the buffer ring and the piston form a buffer cavity in the stepped hole; the peripheral surface of the outer end of the piston is provided with a flange which is used for colliding the buffer ring when a valve of the valve assembly is seated, the end part of the piston of the sliding sleeve is provided with a baffle, and when the valve of the valve assembly is closed, a buffer distance is reserved between the buffer ring and the baffle; the sliding sleeve is provided with a buffer oil hole communicated with the buffer cavity, and the buffer oil hole is communicated with a low-pressure oil way of the engine through a throttling device.
After the technical scheme is adopted, the invention has the technical effects that:
1) according to the invention, as the spiral shaft is provided with the spiral groove and the plugging part, before the spiral shaft is pushed by the cam surface to move downwards, the plugging part plugs the limiting oil hole, the piston is in rigid connection with the spiral shaft, and when the spiral shaft moves downwards, the valve is opened along with the spiral shaft, and the opening time is always unchanged; and the spiral shaft continuously moves downwards, when the spiral groove is communicated with the limiting oil hole, the sliding sleeve cavity is communicated with a low-pressure oil way of the engine to release pressure, so that the valve is separated from the control of the cam surface, and the valve falls down to the seat to be closed under the action of the valve spring force. The communication time of the spiral groove and the limiting oil hole can be changed by rotating the spiral shaft, and the closing time of the valve is further changed, so that the function of the fully variable valve mechanism can be realized, but the crank angle corresponding to the opening time of the valve is kept unchanged, and the fully variable valve mechanism is particularly suitable for being applied to the control of variable stroke of the intake valve of an engine with a scavenging process. When the valve returns, hydraulic oil enters the sliding sleeve cavity from the oil inlet hole, and rapidly resets the screw shaft together with the reset spring, the linear actuating mechanism controlled by the engine electric control unit drives the screw shaft to rotate, the response speed is high, the control is convenient, and the high-speed electromagnetic valve with high price is replaced, so that the valve is suitable for a multi-cylinder engine.
2) After the ECU of the engine is shut down and the power is off, the rack moves to the limit position of the limiting device under the action of the return spring, at the moment, the piston abutting plane abuts against the spiral shaft abutting plane, engine oil does not work, the camshaft and the valve are in a rigid connection state, and the valve lift of the valve assembly is completely controlled by the camshaft, so that the influence of the engine oil loss on the normal operation of the system is avoided.
3) When the valve is about to be seated, the piston firstly collides with the buffer ring, and because of the action of the throttling device, engine oil in the buffer cavity plays a damping role in the movement of the buffer ring, and the buffer ring moves slowly, so that the valve is slowly seated, the impact damage to the sealing surface of the valve and the valve seat is reduced, and the service life of the valve mechanism is effectively prolonged. When the valve descends again, the buffer ring moves downwards under the action of the pressure of the oil, and the buffer ring has enough time to move to the position of the baffle plate before the valve is seated again due to the short buffer distance; the valve buffering effect can be adjusted by adjusting the throttling effect and the buffering distance of the throttling device.
4) When the spiral shaft is controlled by the base circle section of the cam surface and the rack moves to the other limit position in the opposite direction of the limit device, the spiral groove is communicated with the limit oil hole, at the moment, the camshaft does not start to work, the spiral groove is communicated with the limit oil hole to release pressure, the piston stops moving, the valve is closed, and the cylinder stopping process of the engine can be realized.
Drawings
FIG. 1 is a cross-sectional view of an embodiment of a fully variable electro-hydraulic valve system of the present invention;
FIG. 2 is a schematic perspective view of the screw shaft of FIG. 1;
FIG. 3 is a schematic perspective view of the piston of FIG. 1;
FIG. 4 is a schematic view of a rack and pinion mechanism for driving the screw shaft in the embodiment shown in FIG. 1;
FIG. 5 is a schematic perspective view of the rack gear shown in FIG. 4 moving to the right to the extreme position of the limiting device, with the screw shaft and the corresponding abutment surface of the piston abutting against each other;
FIG. 6 is a cross-sectional view of a portion of the rack shown in FIG. 4 moved to the right to the limit of the stop and with the system in the starting position;
FIG. 7 is a cross-sectional view of a portion of the components of the system shown in FIG. 4 with the rack moved to the left to another extreme position and with the system in a cylinder deactivation state;
FIG. 8 is a crank angle/valve lift graph of the embodiment shown in FIG. 1;
FIG. 9 is a crank angle/valve lift graph of the disclosed technology referred to in the background;
in the figure, 101-camshaft, 102-helical shaft, 102A-control gear, 102B-helical shaft abutting plane, 102C-helical shaft axial projection, 102D-helical groove, 102E-helical surface, 102F-oil through hole, 102G-blocking part, 103-sliding sleeve, 104-return spring, 105-piston, 105A-piston axial projection, 105B-piston abutting plane, 105C-guide groove, 105D-flange, 106-valve component, 107-oil inlet hole, 108-one-way valve, 109-oil sump, 110-pressure retaining valve, 111-wear-resistant gasket, 112-thrust bearing, 113-rack, 114-pressure reducing valve, 115-return spring, 116-limiting device, 117-linear actuator, 118-a limiting oil hole, 119-a positioning pin, 121-a buffer ring, 122-a baffle, 123-a buffer oil hole, 124-a throttling device, a Q-sliding sleeve cavity, an R-buffer cavity and an S-buffer distance.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
As shown in FIG. 1, in the fully variable electro-hydraulic valve system, a sliding sleeve 103 is fixed relative to an engine, a screw shaft 102 and a piston 105 are respectively connected with the sliding sleeve 103 in a sliding and sealing mode, the screw shaft 102 is controlled by a cam surface of a camshaft 101 in the axial direction, and the piston 105 abuts against a valve assembly 106.
In the sliding sleeve 103, a space between the screw shaft 102 and the piston 105 is a sliding sleeve cavity Q, the return spring 104 is clamped between the screw shaft 102 and the piston 105, and the common acting force of the return spring 104 and the oil pressure to the piston 105 is far smaller than the acting force of the valve spring to the piston 105. The sliding sleeve 103 is provided with an oil inlet 107 and a limiting oil hole 118; the oil inlet 107 is connected with a one-way valve 108, is communicated with an engine oil circuit through a pressure reducing valve 114 and is communicated with an oil pan 109 through a pressure retaining valve 110; the stopper oil hole 118 communicates with the engine oil passage through the pressure reducing valve 114, and communicates with the oil pan 109 through the pressure retaining valve 110.
A stepped hole structure is arranged at the end part of the piston of the sliding sleeve 103, the stepped hole structure comprises a large hole and a small hole, the small hole is matched with the sliding sealing surface of the piston 105, a buffer ring 121 is arranged in the large hole, the buffer ring 121 is sleeved on the sliding sealing surface of the piston 105 and is in sliding sealing fit with the inner peripheral surface of the large hole, and a buffer cavity R is formed in the stepped hole by the buffer ring 121 and the piston 105; the outer end peripheral surface of the piston 105 is provided with a flange 105D for hitting the cushion ring 121 when the valve of the valve assembly 106 is seated, a stopper plate 122 is attached to the piston end of the slide sleeve 103, and a cushion distance S is provided between the cushion ring 121 and the stopper plate 122 when the valve of the valve assembly 106 is closed.
The sliding sleeve 103 is further provided with a buffer oil hole 123 communicated with the buffer cavity R, the buffer oil hole 123 is connected with a throttling device 124, is communicated with an engine oil circuit through a pressure reducing valve 114 and is communicated with the oil pan 109 through a pressure retaining valve 110; the engine oil line and the associated pressure reducing valve 114, pressure retaining valve 110, oil pan 109, etc. constitute a low-pressure oil line of the engine, and the throttle device may be a throttle valve or an orifice, etc.
The structure has a buffering function. When the valve is about to be seated, the piston 105 firstly collides with the buffer ring 121, and due to the action of the throttling device 124, the engine oil in the buffer cavity R plays a role in damping the motion of the buffer ring 121, and the buffer ring 121 slowly moves to make the valve be seated slowly, so that the impact damage to the sealing surfaces of the valve and a valve seat is reduced, and the service life of the valve mechanism is effectively prolonged. When the valve descends again, the buffer ring 121 moves downwards under the action of the oil pressure, and the buffer ring 121 has enough time to move to the position of the baffle 122 before the valve is seated again because the buffer distance S is short; the valve cushioning effect can be adjusted by adjusting the throttling effect and the cushioning distance of the throttling device 124.
As shown in fig. 1, 2 and 4, the screw shaft 102 has a first end and a second end which are oppositely arranged, the second end is in transmission connection with a rack-and-pinion mechanism, the rack-and-pinion mechanism comprises a control gear 102A and a rack 113, the control gear 102A is arranged at the second end of the screw shaft 102, and the rack 103 is driven by a linear actuator 117 controlled by an Electronic Control Unit (ECU) of an engine. The control gear 102A is connected to the screw shaft 102 in two ways, one is a fixed connection, and the other is a control gear 102A which is axially slidable relative to the screw shaft 102 but not rotatable relative thereto, such as a spline connection, which must be capable of transmitting torque regardless of the connection. The linear actuator 117 is a mature technology, and may be a linear motor, an actuating electromagnet, an air cylinder, a hydraulic cylinder, or the like, and the connection relationship between the linear actuator and the rack 113 is well known to those skilled in the art, and will not be described herein.
As shown in fig. 2, the screw shaft 102 is provided with a spiral structure, the spiral structure includes a spiral groove 102D opened on the circumferential surface of the screw shaft 102, a groove surface of the spiral groove 102D near the first end of the screw shaft 102 is a spiral surface 102E, a portion between the spiral surface 102E and the first end of the screw shaft 102 is a blocking portion 102G capable of blocking the limit oil hole 118, the spiral groove 102D is provided with an oil through hole 102F, the oil through hole 102F communicates with the spiral groove 102D and the sliding sleeve cavity Q, and when the spiral groove 102D communicates with the limit oil hole 118, the sliding sleeve cavity Q communicates with the low-pressure oil path of the engine to release pressure.
As shown in fig. 2, a first end of the screw shaft 102 is provided with a screw shaft axial protrusion 102C, the screw shaft axial protrusion 102C is provided with a screw shaft abutting plane 102B, and in order to make the force more uniform when abutting, the first end of the screw shaft 102 is provided with two screw shaft axial protrusions 102C, and the two screw shaft axial protrusions 102C are respectively provided with one screw shaft abutting plane 102B. The two screw axes abut against the plane 102B in the same plane and are symmetrically arranged relative to the center of the screw axis 102.
As shown in fig. 1 and 3, the sliding sleeve 103 is provided with a positioning pin 119, the piston 105 is provided with a guide groove 105C extending in the axial direction, the positioning pin 119 extends into the guide groove 105C, and the rotational degree of freedom of the piston 105 relative to the sliding sleeve 103 is restricted by the positioning pin 119, that is, the piston 105 can only move in the axial direction of the guide groove 105C but cannot rotate.
One end of the piston 105 opposite to the screw shaft 102 is provided with a piston axial direction protrusion 105A, and a head of the piston axial direction protrusion 105A is provided with a piston abutting plane 105B. In the same principle, in order to make the stress more balanced during the abutting, the number of the piston axial convex parts 105A is two, the heads of the two piston axial convex parts 105A are respectively provided with a piston abutting plane 105B, and the piston abutting planes 105B are in one-to-one correspondence with the screw shaft abutting planes 102B. The two piston abutment planes 105B are coplanar and symmetrically arranged with respect to the center of the piston 105.
The working principle of the invention for controlling the valve motion by combining the screw shaft and the camshaft is as follows:
the engine oil in the engine oil path (low-pressure oil path) of the engine can flow to the sliding sleeve cavity Q through the oil inlet 107 and the limiting oil hole 118. Under the action of the camshaft 101, the screw shaft 102 moves downwards, when the blocking part 102G of the screw shaft 102 blocks the limiting oil hole 118 (at this time, the engine oil cannot flow out from the oil inlet hole 107 due to the action of the one-way valve 108), the sliding sleeve cavity Q becomes a closed cavity, the pressure of the hydraulic oil is increased, the piston 105 is pushed to move downwards, and the piston 105 pushes the valve to move downwards.
When the screw shaft 102 is pushed to move downwards by the cam surface after the screw shaft abutting plane 102B is separated from the piston abutting plane 105B, because the screw shaft 102 is provided with the spiral groove 102D and the blocking part 102G, the blocking part 102G firstly blocks the limiting oil hole 118, so that the piston 105 and the screw shaft 102 become rigid connection, the valve is opened along with the piston, and the opening time is not changed all the time. The spiral shaft 102 continues to move downwards, when the spiral groove 102D is communicated with the limiting oil hole 118, the sliding sleeve cavity Q is communicated with a low-pressure oil path of the engine to release pressure, so that the valve is separated from the control of the cam surface, and the valve pushes the piston to move upwards under the action of the valve spring force. If the screw shaft 102 does not block the limiting oil hole 118 any more in the process of closing the valve, the motion process of closing the valve is not affected by the cam surface and moves under the combined action of the spring force of the valve and the oil pressure. If the valve is closed, the screw shaft 102 returns upward along with the cam surface to block the limiting oil hole 118 again, at this time, the sliding sleeve cavity Q becomes a sealed cavity, and the valve motion rule is controlled by the cam surface along with the screw shaft 102. Because the cam surface, the spiral surface, the limiting oil hole and the like are all of mechanical structures and are fixed and unchangeable, the motion rule of the valve is fixed no matter the valve is closed in the mode, the valve is in a gradually increasing or decreasing relationship along with the rotation of the spiral shaft, and the change of the valve stroke is in a linear relationship with the rotation angle of the spiral shaft.
The function of the fully variable valve mechanism can be realized by changing the communication time of the spiral groove 102D and the limiting oil hole 118 by rotating the spiral shaft 102 and further changing the closing time of the valve, but the crank angle corresponding to the opening time of the valve is always kept unchanged, so the fully variable valve mechanism is particularly suitable for controlling the variable stroke of the intake valve of an engine with a scavenging process, as shown in FIG. 8.
In the return stroke, the hydraulic oil enters the sleeve chamber Q from the oil inlet 107 through the check valve 108, and rapidly returns the screw shaft 102 together with the return spring 104.
In the invention, after the ECU is powered off when the engine is stopped, the rack 113 moves to the limit position limited by the limiting device 116 under the action of the return spring 115, at this time, the position relation between the piston 105 and the screw shaft 102 is in the state shown in figures 5 and 6, namely, the piston abutting plane 105B abuts against the screw shaft abutting plane 102B, the engine oil in the sliding sleeve cavity Q does not work, the camshaft and the valve are in a rigid connection state, and the valve lift is completely controlled by the camshaft 1, thereby avoiding the influence of the engine oil loss on the normal operation of the system.
In the present invention, as shown in fig. 7, when the screw shaft 102 is controlled by the base circle section of the cam surface and the rack 113 moves to another limit position in the opposite direction of the limit device 116, the spiral groove 102D communicates with the limit oil hole 118, at this time, the camshaft 1 does not start to work, the spiral groove 102D already communicates with the limit oil hole 118 for pressure relief, and thereafter, no matter whether the screw shaft 102 is controlled by the base circle section or the non-base circle section of the cam surface, the piston 105 stops moving, the valve is in a closed state, and the cylinder deactivation process of the engine can be realized.
In the present invention, fig. 4 shows an example in which one rack 113 is simultaneously engaged with 6 control gears 102A, and each control gear 102A corresponds to one valve assembly, i.e., it is applied to a six-cylinder engine, and the concept of the present invention can be extended to a 4-cylinder engine or an 8-cylinder engine, etc., and the number of cylinders is not limited.
In the present invention, a thrust bearing 112 is provided on the end face of the control gear 102A, a wear pad 111 is provided between the thrust bearing 112 and the cam surface of the camshaft 101 to reduce wear, and the distance between the piston abutting plane 105B and the screw axis abutting plane 102B can be adjusted by the thickness of the wear pad 111, and when the non-cam surface of the camshaft 101 abuts against the screw axis 102 (or abuts against the wear pad 111 and the thrust bearing 112), the distance between the two is zero or nearly zero.
The present invention is not limited to the embodiments described above, and all modifications that can be made based on the concept, principle, structure and method of the present invention will fall within the scope of the present invention.
Claims (10)
1. A fully variable electro-hydraulic valve system, comprising:
a camshaft and a valve assembly;
the sliding sleeve is fixed relative to an engine, the screw shaft and the piston are respectively connected with the sliding sleeve in a sliding and sealing mode, an inner cavity between the screw shaft and the piston is called a sliding sleeve cavity, the return spring is clamped between the screw shaft and the piston, the piston abuts against the valve assembly, and the screw shaft is controlled by a cam surface of the camshaft in the axial direction;
the screw shaft is provided with a first end and a second end which are oppositely arranged, the screw shaft is provided with a screw structure, the second end of the screw shaft is in transmission connection with a gear rack mechanism, the gear rack mechanism comprises a control gear and a rack, the control gear is arranged at the second end of the screw shaft, and the rack is driven by a linear actuating mechanism controlled by an engine electric control unit;
the sliding sleeve is provided with an oil inlet hole and a limiting oil hole, the oil inlet hole and the limiting oil hole are respectively communicated with a low-pressure oil way of the engine, and a one-way valve is arranged on a connecting pipeline between the oil inlet hole and the low-pressure oil way of the engine; it is characterized in that the preparation method is characterized in that,
the spiral structure comprises a spiral groove arranged on the circumferential surface of the spiral shaft, the groove surface of the spiral groove close to the first end of the spiral shaft is a spiral surface, the part between the spiral surface and the first end of the spiral shaft is a plugging part capable of plugging the limiting oil hole, the spiral groove is provided with an oil through hole, the oil through hole is communicated with the spiral groove and the sliding sleeve cavity, and when the spiral groove is communicated with the limiting oil hole, the sliding sleeve cavity is communicated with a low-pressure oil path of the engine for pressure relief;
a screw shaft axial protruding part is arranged at the first end of the screw shaft, a screw shaft abutting plane is arranged on the screw shaft axial protruding part, a piston axial protruding part is arranged at one end, opposite to the screw shaft, of the piston, and a piston abutting plane is arranged at the head of the piston axial protruding part;
the sliding sleeve is provided with a positioning pin, the piston is provided with a guide groove extending along the axial direction, and the positioning pin extends into the guide groove;
the gear rack mechanism is further provided with a limiting device and a return spring, when the return spring enables the rack to move to a limit position limited by the limiting device, the piston abutting plane abuts against the spiral shaft abutting plane, the limiting oil hole is blocked by the blocking part of the spiral shaft, and the valve lift of the valve assembly is controlled by the camshaft.
2. The fully variable electro-hydraulic valve system according to claim 1, wherein the spiral groove communicates with the stopper oil hole when the spiral shaft is controlled by the base circle section of the cam surface and the rack moves to another limit position in the opposite direction of the stopper.
3. The fully variable electro-hydraulic valve system according to claim 1, wherein the first end of the screw shaft is provided with two screw shaft axial protrusions, and the heads of the two screw shaft axial protrusions are respectively provided with one screw shaft abutting plane; the number of the piston axial protruding parts is two, the heads of the two piston axial protruding parts are respectively provided with a piston abutting plane, and the piston abutting planes correspond to the screw shaft abutting planes one by one.
4. The fully variable electro-hydraulic valve system of claim 3, wherein the two pistons abut against a plane and the two screw spindles abut against a plane.
5. The fully variable electro-hydraulic valve system of claim 4, wherein two of the piston abutment planes are symmetrically disposed with respect to a center of the piston, and two of the screw axis abutment planes are symmetrically disposed with respect to a center of the screw axis.
6. The fully variable electro-hydraulic valve system according to claim 1, wherein a thrust bearing is provided at the second end of the screw shaft, and a wear pad is provided between the thrust bearing and the cam surface of the camshaft.
7. The fully variable electro-hydraulic valve system of claim 1, wherein the control gear is torque-transmitting connected with the helical shaft.
8. The fully variable electro-hydraulic valve system of claim 1, wherein the rack gear is simultaneously engaged with the control gears of a plurality of the screw spindles.
9. The fully variable electro-hydraulic valve system of claim 1, wherein the linear actuator is a linear motor or an actuator electromagnet or a pneumatic or hydraulic cylinder.
10. The fully variable electro-hydraulic valve system according to claim 1, wherein a stepped hole structure is provided at a piston end of the sliding sleeve, the stepped hole structure comprises a large hole and a small hole, the small hole is matched with the sliding sealing surface of the piston, a buffer ring is arranged in the large hole, the buffer ring is sleeved on the sliding sealing surface of the piston and is in sliding sealing fit with the inner circumferential surface of the large hole, and the buffer ring and the piston form a buffer cavity in the stepped hole; the peripheral surface of the outer end of the piston is provided with a flange which is used for colliding the buffer ring when a valve of the valve assembly is seated, the end part of the piston of the sliding sleeve is provided with a baffle, and when the valve of the valve assembly is closed, a buffer distance is reserved between the buffer ring and the baffle;
the sliding sleeve is provided with a buffer oil hole communicated with the buffer cavity, and the buffer oil hole is communicated with a low-pressure oil way of the engine through a throttling device.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010026697.5A CN111075531A (en) | 2020-01-10 | 2020-01-10 | Fully variable electro-hydraulic valve system |
| US17/791,170 US20230031051A1 (en) | 2020-01-10 | 2020-12-29 | Fully variable electro-hydraulic valve system |
| PCT/CN2020/140614 WO2021139564A1 (en) | 2020-01-10 | 2020-12-29 | Fully variable electro-hydraulic valve system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010026697.5A CN111075531A (en) | 2020-01-10 | 2020-01-10 | Fully variable electro-hydraulic valve system |
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| Publication Number | Publication Date |
|---|---|
| CN111075531A true CN111075531A (en) | 2020-04-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010026697.5A Pending CN111075531A (en) | 2020-01-10 | 2020-01-10 | Fully variable electro-hydraulic valve system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021136225A1 (en) * | 2020-01-04 | 2021-07-08 | 潍坊力创电子科技有限公司 | Fully variable electro-hydraulic valve system having buffering function |
| WO2021139564A1 (en) * | 2020-01-10 | 2021-07-15 | 潍坊力创电子科技有限公司 | Fully variable electro-hydraulic valve system |
-
2020
- 2020-01-10 CN CN202010026697.5A patent/CN111075531A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021136225A1 (en) * | 2020-01-04 | 2021-07-08 | 潍坊力创电子科技有限公司 | Fully variable electro-hydraulic valve system having buffering function |
| US11788441B2 (en) | 2020-01-04 | 2023-10-17 | Weifang Lichuang Electronic Technology Co., Ltd | Fully variable electro-hydraulic valve system having buffering function |
| WO2021139564A1 (en) * | 2020-01-10 | 2021-07-15 | 潍坊力创电子科技有限公司 | Fully variable electro-hydraulic valve system |
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