EP2063075A1 - Fluid actuated valve mechanism - Google Patents

Abstract

The mechanism has a control or regulating device (40) arranged such that an engine valve (2) i.e. gas exchange valve, is shiftable adjacent to a rest position in an accelerated movement phase by pressurizing one of set of fluid valve units (20, 22) with pressure of a pressure reservoir (P2) and opening of one of another set of fluid valve units (24, 26) to a base reservoir (P0). The valve is shiftable in a braking phase by opening of another unit of the former set (20, 22) to another pressure reservoir (P1) and opening another unit of the latter set (24, 26) to the base reservoir.

Description

Technical area

The invention relates to a fluid operated valve train, in particular for a gas exchange valve in a combustion cylinder of an internal combustion engine, according to the preamble of claim 1.

State of the art

Fluid operated valve trains, in particular for gas exchange valves in a combustion cylinder of an internal combustion engine, which in the context of this invention comprise hydraulically as well as pneumatically operated valve trains, have been known for a long time. First, these valve trains were used to replace a camshaft-controlled opening of a motor valve, while the closure of the valve was further provided by a spring mechanism. Such systems are for example from the German Offenlegungsschrift 1'944'177 known. But also two-sided controlled, fluid operated valve trains for valve controls are basically, for example from the CH 417'219 , already known for a long time. In this case, the principle was used that an actuating piston has two pressurized surfaces, one of which is greater than the other. In the CH 417'219 However, it is still proposed to operate the control of the fluid supply - here the oil supply - using a conventional camshaft. This principle also makes itself the suggestion after the DE 101 439 59 A1 zueigen, although a camshaft-free operation of the valve control is provided. After DE 101 439 59 A1 the area size of at least one of the two active surfaces of the actuating piston should change along its displacement path. Furthermore, it is proposed that one of two fluid pressure chambers each filled with a fluid and emptied. This proposal does not prove to be particularly advantageous because the valve control can not be set up too precisely with manageable effort.

A substantial improvement of this concept is originally from the US 5,225,641 A , improved in the proposed US 6,223,846 B1 , known, hereafter cited as Schechter. In this case, a pressurization of two oppositely arranged active surfaces is proposed, each with a fluid which is taken from a common reservoir and is controlled by supply valves. The drain valves are intended, inter alia, for pressure relief. However, this system is very complicated and can only be used to a limited extent due to the complex fluid supply control.

Fluid operated valve trains generally have the disadvantage or the problem of higher energy consumption compared to conventional mechanically driven valve drives, which then loses the power of the internal combustion engine. The known fluid operated valve train devices - especially the facilities that from the US-A-5'058'857 , from the US-A-3'844'528 , of the DE 199'31129 , of the US-A-6'170'524 of the WO-A-02/46582 and the WO-A-02 / 066'796 are common - is that the problem of excessive energy consumption is not or at least rudimentary solved. So is in the WO-A-02 / 066'796 For example, although provided that there is a buffer memory to absorb pressure fluctuations, the Hydraulikfüssigkeit from the outlet of the piston for valve control is directed into a reservoir from which it must be pumped by means of a high-pressure pump wasting energy back to the working pressure of the hydraulic system.

In Schechter is already proposed that not only the acceleration of the fluid operated valves but also the deceleration is carried out for soft placement on the valve seat by means of a fluid. It is also already indicated that the recoverable by the braking energy - there with the help of a low-pressure rail - to be used. This has already revealed a first approach to recuperation. However, at Schechter the high pressure rail still be fully loaded pressure because the low pressure rail is connected only to the reservoir. This inferior type of recuperation is also to be improved.

Presentation of the invention

The object of the invention is to provide a simplified, fluid-operated valve drive, in which the disadvantages of the prior art described above are avoided. In particular, the energy consumption by the valve control should not be excessive. Rather, the best possible form of recuperation should be used.

The object of the invention is achieved by a fluid operated valve train according to claim 1. The measures of the invention initially have the consequence that the recoverable by the deceleration of the engine valves energy is used by means of a pressure intermediate level between the valve acceleration pressure and the reservoir. This saves, e.g. Energy for charging the valve acceleration pressure and serves at the same time optimally damped braking.

In order to be able to carry out the invention, it is fundamentally possible to proceed directly from the acceleration phase into the deceleration phase. This also causes the fastest engine valve movement with minimal fluid pressure. In terms of energy, it may be advantageous to insert an unaccelerated phase between the two phases mentioned, if the valve movement speed permits (claim 2).

In principle, the recuperation of the second pressure reservoir P1 can be used not only as a pressure intermediate stage for saving energy for the high pressure stage (claim 3 and 4) but - eg when using fuel, especially diesel fuel, as a fluid - or as an alternative to providing alternative pressure for the fuel pump and / or for fuel conditioning, such as atomization, etc. (claim 5 and 6). As fuel here not only a hydraulically usable liquid in question, but also a pneumatically usable gas or similar medium, eg in gas-powered engines.

In principle, it is possible to design the second fluid valve means either as proportional valves, which can then be quantity controlled or - or additionally - simple valves only one open and one closed position and a time control. However, it seems - at least for certain applications - advantageous to make these valves for fine tuning with respect to their opening size controllable (claim 7). However, for the first fluid valve means an embodiment as fluid valves only with an optional open and a closed position to P1 or P2 seems sufficient and advantageous.

For fine tuning, it appears to be advantageous in certain cases if, during the transition phase from the first to the second phase and / or from the second to the third phase, both second fluid valve means can be connected to the base pressure reservoir P0 for a certain period of time, while one of the first Fluid valve means is open. This avoids - in particular in the case of a hydraulic design - that a phase occurs in which the pressure chambers are closed and the movement of a fluid which is only slightly compressible can lead to impacts or overpressures. It should be pointed out that corresponding problems are possible even with a pneumatic design, which can be remedied by this advantageous embodiment (claim 8). For rapid control, an embodiment with solenoid valves is advantageous. Particularly advantageous is an embodiment of the invention, in which a measuring sensor for measuring the position of the motor valve, preferably by measuring the position of the actuating piston, is provided, with which the opening and the closing of the fluid valve means is controlled or regulated (Claims 9 and 10). Further advantageous embodiments of the invention are set forth in the dependent claim 11.

The advantages of the invention, in particular within the scope of the proposed construction, can be summarized as follows: With the proposed valve control a free control of the entire movement sequence for each valve is possible without further effort, eg the lifting height from 0 to maximum, accelerations, decelerations and speeds. This is the most diverse conditions and requirements met, such as starting without starter, throttle valve free operation, optimization of the air intake in the combustion chamber at all numbers of revolutions, premature closure of the exhaust valve to reduce NOx, valve position to enhance the engine braking effect, cylinder shutdown at part load, pressure-free state of rest with mechanical Furthermore, a high energy efficiency is achieved with short and aerodynamic paths for the fluid, low and the operating condition adaptable pressure in the high pressure system, low mass and thus low energy requirements for accelerating and decelerating the moving masses , top and bottom moving parts without bending stress, slender valve stem and low frictional resistance, small piston and hydraulic or pneumatic active surfaces and low wear. Operational safety is high, as it is technically simple, without amplifying the initial acceleration (thanks to low moving mass). Also advantageous is the control of the effective movement of the motor valve with the possibilities of automatically correcting shifts in the cycle due to thermal dilation, fluid viscosity, gas bubbles, manufacturing tolerances and mechanical wear as the seal between piston and cylinder wall decreases. The system is expected to be low maintenance due to low mechanical stress on the components, the closed system with few sealing surfaces, easy replacement of the entire valve actuation, individual valves or components. The geometry is advantageous because no disruption of the routes for intake air and exhaust gases is to be expected and there is little space.

According to the embodiment according to claim 9 or 10, this aspect of the invention is characterized in that the movement sequence of the engine valve is monitored with a sensor on its route. At any time, the deviation of the effective location of the engine valve from its desired location is determined according to specification and detected by a control unit for this engine valve. It is calculated the change in the cross section of the corresponding second fluid valve means, so that the valve reaches the position according to specification again. According to this aspect of the invention, the system is self-correcting by this function, and influences which could adversely affect the movement of the engine valve need not be considered.

The above-mentioned as well as the claimed and described in the following embodiments, according to the invention to be used elements are subject to their size, shape design, material usage and their technical conception no special conditions of exception, so that the well-known in the respective field of application selection criteria can apply without restriction.

Brief description of the drawings

Figur 1

eine Darstellung eines Motorventils mit einer Ventilsteuerung gemäss einem ersten Ausführungsbeispiel der Erfindung;

Figur 2

eine Darstellung eines Motorventils mit einer Ventilsteuerung gemäss einem zweiten Ausführungsbeispiel der Erfindung.

Further details, advantages and features of the subject matter of the present invention will become apparent from the following description of the accompanying drawings, in which - exemplary - inventive devices will be explained. In the drawings shows:

FIG. 1

a representation of an engine valve with a valve control according to a first embodiment of the invention;

FIG. 2

a representation of an engine valve with a valve control according to a second embodiment of the invention.

Ways to carry out the invention

In FIG. 1 a valve assembly is shown to a first embodiment of the present invention with an engine valve 2 and a drive (actuator) for this engine valve. The valve 2 comprises - according to a conventional manner - a valve disk 3, which is fitted in a valve seat ring 7 in order to close off the engine compartment. With the valve 2 open, that is, when the valve is lowered, the combustion chamber 4 of the engine is connected to the combustion gas channel 6. This connection must be controlled or regulated with the valve train.

The engine valve 2 carries on its valve stem 5 a fixed thereto associated actuating piston 14, which has an upper, formed on the upper side of the actuating piston 14 effective area and further comprises a lower, formed on the underside of the actuating piston 14 effective area. Together with the pressure chamber housing 15, in which the actuating piston 14 is arranged to move up and down, the Stellkoben 14 forms an upper pressure chamber 10 and a lower pressure chamber 12 from. Both pressure chambers 10 and 12 each have a first fluid valve 20 or 22 and a second fluid valve 24 or 26 for a pressurized fluid, in the embodiment described here, a hydraulic oil or the fuel for the engine, preferably a diesel fuel on. These fluid valves are formed in the present embodiment as solenoid valves, wherein for the first fluid valves 20 and 22 only one open and one closed position is provided in each case via the fluid supply line 16 to the pressure reservoir P2 and the fluid drain line 18 to the pressure reservoir P1, while the second fluid valves 24th and 26 are each connectable via the fluid supply and discharge line 19 to the base reservoir P0. The second fluid valves 24 and 26 are analog or - alternatively - digitally controllable in a variety of positions. It should be noted at this point that this analog or digital modulating design of the opening of the second fluid valves 24 and 26th is only an example. Other modulation methods, such as an intermittent opening, possibly also, for example, with a pulse width modulation, assuming a suitable bandwidth of the opening, are also used.

Both first fluid valves 20 and 22 are selectively connectable to a first pressure reservoir P2 for the pressurized fluid and to a second pressure reservoir P1. It is provided that for accelerating the engine valve 2 in each case one direction of the first fluid valves 20 and 22 is opened and thus the first pressure reservoir P2 is connected to one of the two pressure chambers. To accelerate for the purpose of opening the engine valve 2, the upper first fluid valve 20 is opened. In order not to generate a back pressure, the lower second fluid valve 26, which communicates with the base reservoir P0, is simultaneously opened. To accelerate for the purpose of closing the engine valve 2 while the lower first fluid valve 22 is opened. In order not to generate a back pressure, the upper second fluid valve 24, which communicates with the base reservoir P0, is now simultaneously opened.

As already mentioned, the first fluid valves 20 and 22 can furthermore be connected to a second pressure reservoir P1. It is provided that for braking the motor valve 2 in each case one direction of the first fluid valves 20 and 22 is opened and thus the second pressure reservoir P1 is connected to one of the two pressure chambers.

For braking when opening the engine valve 2 while the lower first fluid valve 22, in conjunction with the second pressure reservoir P1, opened. In order to continue to fill the upper pressure chamber 10 with fluid, the upper second fluid valve 24, which communicates with the base reservoir P0, is simultaneously opened. In this case, the fluid flows without pressure in the upper pressure chamber 10th

To brake when closing the engine valve 2 while the upper first fluid valve 20, in conjunction with the second pressure reservoir P1, opened. In order to continue to fill the lower pressure chamber 12 with fluid, the lower second fluid valve 26, which communicates with the base reservoir P0, is simultaneously opened. In this case, the fluid flows without pressure into the lower pressure chamber 12.

In the present embodiment, it is provided and the control is also set up such that an unaccelerated movement can be carried out between acceleration and deceleration. The two first fluid valves 20 and 22 are closed and the two second fluid valves 24 and 26 open, so that the engine valve 2 performs a nearly uniform movement and each empties a pressure chamber 10 and 12 and to the same extent the other pressure chamber 10 and 12 respectively is refilled. It will be apparent to those skilled in the art that with the length of this unaccelerated phase, the movement of the engine valve may be controlled using measurement data on the current position of the engine valve 2. This is provided in the embodiment.

Furthermore, it is provided in the present embodiment that both second fluid valves 24 and 26 are open for a short time, while the first fluid valve 20 and 22 are still open. This causes no impact due to the incompressible fluid.

From this base reservoir P0 - as described below - the supply for the first fluid valves 20 and 22 fed.

In the above, individual fluid valves 20, 22, 24, 26 have been described for the fluid valve means according to the invention. In particular, the first fluid valve means 20 and 22 with the described in the exemplary embodiment optional compounds with P1 or P2 but can - without limiting the generality of Invention - but each also be designed as separate fluid valves for P1 and P2. Furthermore, it can be provided to divide the second fluid valve means 24 and 26 respectively into a fluid valve which can only be switched and additionally to a fluid valve which can be controlled with respect to its flow rate, if the special design of the hydraulic or pneumatic conditions and / or the control bandwidth necessitate this.

In the present embodiment, a two-stage pressure generation from the base reservoir P0 is first performed to the second pressure reservoir P1 and from there to the first pressure reservoir P2, in each case by a pressure stage 31 and 32, which includes a controllable high-pressure pump 33 and 35 and a check valve 38 and 39, respectively.

In this embodiment, therefore, the energy recovered by the deceleration of the engine valves 2 is used in full to maintain the pressure in the first pressure reservoir P2 by - after a start-up - the first pump from P0 to P1 hardly consumes energy and the high-pressure pump from P1 to P2 is relieved accordingly. Thus, an optimal recuperation system is proposed.

A central electronic control unit 42 determines, for each engine valve, the optimum sequence of motion due to ambient and operating conditions, and passes this instruction to the electronic valve control device 40, which gives the commands to open the fluid valves. Each engine valve 2 has its own electronic valve control device 40. The position of the engine valve 2 is detected over the entire distance by means of a measuring sensor 50 and the valve control direction 40 is transmitted, the opening of the respective outlet solenoid valve 24 or 26 to P0 in case of deviations from the target value corrected. The stroke of the engine valves 2 and the time course of the movement can be freely determined. The central, electronic Control unit 42 determines the pressure in the high-pressure system, namely in the pressure reservoirs P2 and P1.

In the fluid pressure system P2, the same pressure prevails for all engine valves 2 supplied by it. The pressure can be adjusted by means of control of the controllable high-pressure pump 33 to different operating conditions.

As parameters for control by the central controller 42, e.g. used: accelerator pedal position, brake control, gear selection, program selection automat, temperatures of engine oil or water, position of the vehicle (incline, gradient), outside air temperature.

Each engine valve 2 has a valve control device 40, which controls the movement of the engine valve as accurately as possible in accordance with the specifications of the central valve control device 42 by means of control commands to the fluid valves 20 and 22 and 24 and 26.

All valve control devices 40 of an engine report the parameters of the valve movement back to the central control device 42, which can adjust the pressure in the high-pressure system - in particular in the first pressure reservoir P2. With this system of comparing the actual position of the engine valve 2 with the target position, deviations from the specification are corrected. These can have different causes, e.g. for the fluid: temperature, viscosity, aging, with regard to wear: clearance between piston and cylinder chamber, manufacturing tolerances.

The valve stem 5 of the engine valve 2 occurs at the upper end of the upper pressure chamber 10 through the cover of the cylinder. A coil spring 62 acts in a valve spring chamber 66 on a spring plate, which is connected to the valve stem 5. In the case of errors, a limited number of engine valves concern, the cylinder in question - or more - can be partially switched off and the piston to be moved passively. Thus, an emergency program with mechanical feedback of engine valves 2 is placed in a resting state. At rest, the fluid in the high pressure system can be vented through a short opening of all fluid valves. The engine valves 2 are guided by these springs 62 in their upper position, so that maintenance and repairs can be carried out in a pressureless state. The valves are not in contact with the pistons in the engine, which are near top dead center. The cylinder head lifted from the engine block can be parked without the risk of damage in the installation position. Assembly and disassembly of the valve train are thereby considerably simplified. Fluid entering the latter through the upper valve guide 60 at the transition from the upper pressure chamber 10 to the valve spring space 66 is directed through an orifice into the non-pressurized base reservoir P0.

In a second embodiment according to FIG. 2 the motor fuel is used as the fluid, and the first pressure reservoir P2 serves as an intermediate stage for the provision of the necessary fuel pressure for fuel injection P3. A third pump is provided which provides the necessary fuel pressure. Otherwise, the operating conditions for the control and the movement of the engine valves 2 are unchanged.

It will be clear to the person skilled in the art that further modifications are possible within the scope of the patent claims without having to leave the basic idea of optimal recuperation. This includes, for example, an embodiment not shown here in the image, in which the first pressure reservoir P2 is fed directly from the base reservoir P0, while the second pressure reservoir P1 only when starting the engine, if there is no fluid pressure, either with an auxiliary pump or a Abzeigung is fed from the first pressure reservoir P2, but then its pressure solely from the deceleration of the engine valves 2 refers. In this case it can be provided that the in the second pressure reservoir P1 through the Braking energy surplus gained as an intermediate to the above-described provision of the necessary fuel pressure for the fuel

injection is used.

It is assumed in the above description that the pressures in the two pressure reservoirs P1 and P2 will be unequal, the pressure in P2 being assumed to be greater than in P1 if P1 is provided as an intermediate for P2. This is not necessary. In principle, the pressure in P1 can be the same as in the first pressure reservoir. Then, the two pressure reservoirs P1 and P2 can be connected or executed together. In this case, therefore, the deceleration force for the engine valves 2 would be approximately equal to their acceleration force. It would even be conceivable interchanging the pressure conditions, so that the deceleration force of the engine valves 2 is greater than their acceleration force, which would then be exercised longer than the deceleration force. This can be effected, for example, by interchanging P2 with P1, which are both applied to both first fluid valves 20 and 22.

LIST OF REFERENCE NUMBERS

2

engine valve

3

valve disc

4

combustion chamber

5

valve stem

6

Flue gas duct

7

Valve seat ring

8th

poetry

10

upper pressure chamber

12

lower pressure chamber

14

actuating piston

15

Pressure chamber housing

16

Fluid inflow line

17

filter

18

Fluid drain line

19

Fluid inflow and outflow line

20

upper first fluid valve, fluid valve means

22

lower first fluid valve, fluid valve means

24

upper second fluid valve, fluid valve means

26

lower second fluid valve, fluid valve means

31

pressure stage

32

pressure stage

33

high pressure pump

35

high pressure pump

38

check valve

39

check valve

40

Valve control device

42

central control / regulation device

50

measuring sensor

60

valve guide

62

valve spring

66

Valve spring chamber

P0

Base reservoir for the fluid

P1

second pressure reservoir for the fluid

P2

first pressure reservoir for the fluid

P3

additional pressure reservoir for fuel injection

Claims (11)

Fluid operated valve train, in particular for a gas exchange valve (2) in a combustion cylinder of an internal combustion engine, with - At least two fluid-filled pressure chambers (10, 12), with - One on the valve (2) acting, from a valve closing position in a valve open position and a valve open position in a valve closing position displaceable actuating piston (14) having two active surfaces, each one of the pressure chambers (10, 12) limit, wherein the pressure chambers (10, 12) are each connected to two fluid valve means, namely first and second fluid valve means (20, 22, 24, 26), each of the first fluid valve means (20, 22) can be acted upon by a first pressure reservoir (P2), each of the second fluid valve means (24, 26) is connectable to a base pressure reservoir (P0), - further comprising a control or regulating device (40, 42) for opening and closing the fluid valve means (20, 22, 24, 26), characterized in that - The first fluid valve means (20, 22) further with a second pressure reservoir (P1) are connectable so that the first fluid valve means (20, 22) closed a position, connected to the first reservoir (P2) or connected to the second reservoir (P1 ), the second fluid valve means (24, 26) can occupy a position closed or connected to the base reservoir (P0), - And the control or regulating device (40, 42) is arranged so that the valve (2), in addition to a rest position ("open" or "closed") at least in a first, accelerated movement phase is switched, which by applying a the first fluid valve means (20, 22) with the pressure of the first pressure reservoir (P2) and the opening of one of the second fluid valve means (26, 24) to the base reservoir (P0) is effected, and in a deceleration phase is switched, by opening the other the first fluid valve means (22, 20) to the second pressure reservoir (P1) and the closure of the first opened second fluid valve means (26, 24) and the opening of the other of the second fluid valve means (24, 26) to the base reservoir (P0) is effected. Valve gear according to claim 1, characterized in that the control or regulating device (40, 42) is arranged so that the valve (2) is further switchable into a substantially unaccelerated phase, by the opening of both second fluid valve means (24, 26 ) to the base reservoir (P0), the first fluid valve means (20, 22) being closed. Valve gear according to one of the preceding claims, characterized in that the second pressure reservoir (P1) is provided as a pressure intermediate stage for providing the pressure in the first pressure reservoir. Valve gear according to claim 3, characterized in that the second pressure reservoir (P1) has a lower pressure than the first pressure reservoir (P2). Valve gear according to one of the preceding claims, characterized in that a third pressure reservoir (P3) is provided which serves for fuel supply or treatment and is supplied from the first or the second pressure reservoir (P2, P1) as a pressure intermediate stage. Valve gear according to claim 5, characterized in that the fuel used in the internal combustion engine is provided as the fluid. Valve gear according to one of the preceding claims, characterized in that the second fluid valve means (24, 26) are controllable with respect to their opening size. Valve gear according to one of the preceding claims 2 to 7, characterized in that the control or regulating device is designed such that during the transition phase from the first to the second phase and / or from the second to the third phase, the two second fluid valve means (24, 26 ) are connectable to the base pressure reservoir (P0) for a certain period of time while one of the first fluid valve means (20, 22) is open. Valve gear according to one of the preceding claims, characterized in that measuring means (50) are provided for measuring the position of the valve, preferably for measuring the position of the actuating piston (14). Valve gear according to claim 9, characterized in that the movement of the valve (2) is controlled using the measured values of the measuring means (50), wherein the control in each case at least by means of the length of the acceleration phase, the length of the unaccelerated phase, with time, in the two second fluid valve means (24, 26) are opened simultaneously, and / or the opening size of the second fluid valve means (24, 26) is performed. Valve gear according to one of the preceding claims, characterized by a two-stage pressure generation for the first pressure reservoir (P2) from the second pressure reservoir (P1).

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