WO2012160401A1

WO2012160401A1 - Common rail electro-hydraulic valve operation system

Info

Publication number: WO2012160401A1
Application number: PCT/HU2012/000038
Authority: WO
Inventors: Nandor Vestroci; Fatemeh Hajibagher
Original assignee: Nandor Vestroci; Fatemeh Hajibagher
Priority date: 2011-05-20
Filing date: 2012-05-14
Publication date: 2012-11-29
Also published as: HUP1100259A2

Abstract

Electro-hydraulic valve-control system for internal combustion piston-engines, which utilizes the main components of the already known Common Rail fuel injection system for its operation, that is its pressurized hydraulic working fluid originates from the pressure chamber or feeder pump of the Common Rail fuel system, therefore its working fluid is the engine fuel itself, thereby resulting a drastically simplified hydraulic valve-operation system. The control of the engine valves is effected by electronic solenoid valves, which makes possible computerized valve-control.

Description

Common Rail Electro-Hydraulic Valve Operation System

Technical field:

0001 The invention relates to the field of internal combustion engines of the piston type, specifically to the intake and exhaust valve-operation system of such engines.

Background of the Invention:

0002 The above type engines in wide-scale use today utilize mostly the generally known mechanical valve-operation system for the operation of the intake and exhaust valves, in which a timing chain turns a camshaft, which in turn moves the return-spring engaged valves through the cams and rocker arms. The disadvantage of this system is that the valve-opening time and movement-profile cannot, or just in a limited manner, through somewhat cumbersome mechanical devices, be regulated, therefore the operation of the valves cannot adjust always optimally to the momentary motor operation requirements.

0003 The problem could be addressed by the use of hydraulic valve operation systems, which could regulate the interval and the length, also the movement of valve opening according to momentary need, the present generally accepted such systems however did not gain general acceptance, one reason being their relative complicatedness, also their proneness to failure and damage to the engine, and for various other difficulties with such systems.

Accordingly, the purpose of the Invention is to result a hydraulic valve- operation system for the above type engines with substantial structural

0004 simplicity and elimination of the disadvantages of the present systems, thereby making possible the practical application of a hydraulic valve- opening system. In the Invention the activation of the valves is hydraulic, and their control is electronic. Summary of the Invention:

0005 The invention is based on the recognition that the main components of the already known Common Rail fuel injection system are essentially the same is that of a hydraulic system, since it uses a fluid (which is the fuel) fed and pressurized by a pump, whose flow is controlled by suitable means (solenoid valves) at the required time in the required quantity, which system therefore can be well adopted for the purpose of hydraulic operation of the intake and exhaust valves. In this way substantial structural simplicity can be achieved, since by utilizing the components of the Common Rail fuel injection system a separate hydraulic pump including its mechanical pump-drive, and a separate hydraulic working fluid including its reservoir will become needless, further, a separate pressure chamber may also be un-necessitated, only electronic control valves and pressure tubes have to be added to the already existing fuel system to replace the presently mostly used full mechanical valve-drive systems. The

0006 working of the Invention is based on the principles of the Common Rail system, that is all of its working units receive the pressurized hydraulic fluid from one common pressurized chamber.

Summarizing the novelty of the Invention its most defining aspect is that the hydraulic pressure required for its operation originates from the already existing Common Rail fuel injection system, and its hydraulic working fluid is the engine fuel itself.

As a result of the above, since Diesel fuel is also a lubricant, in case of Diesel engines it ensures the lubrication of the valve-stem and guide, therefore, as a main advantage, the Invention makes possible a dry cylinder-head, since it excludes mechanical components requiring

0007 lubrication. For other types of engines lubrication of such parts has to be provided, which is possible through already known means, thus it does not constitute part of the Invention. Further it is mentioned that Diesel oil may be more ready for use as working fluid for hydraulic operation than 0008 gasoline.

In the Invention the (2) common pressure chamber storing the hydraulic fluid (fuel) may be undivided, as the simplest layout, in which the hydraulic valve-operation system works directly from the pressure chamber of the Common Rail fuel injection system. However, since the precision of the pressure required for the proper operation of the fuel injectors is critical, which might be disturbed by possible pressure fluctuations related to the operation of the (6) valves, the (2) pressure chamber may be divided, in which there is a physical divider between the (2) pressure chamber of the Invention and that belonging to the fuel injectors, or it may be a completely separate (2) pressure chamber fed by the pump of the Common Rail system. The alternative solution to the above detrimental pressure fluctuation may be a precision pressure-sensor inside the Common Rail fuel injection pressure chamber, which feeds continuous pressure readings

0009 to the CPU controlling the injection, which in turn continuously recalculates the precise required time-intervals for the injectors so that the exact amount of fuel could be injected at the momentary pressure inside the pressure chamber, which un-necessitates the division of the Common Rail pressure chamber. In the case if divided pressure chambers are used, separate pressure regulators and intake flow- and pressure control valves may become necessary to maintain proper pressure in the respective pressure chambers.

In the Common Rail fuel systems the operation of the injectors (which are essentially electric valves) is controlled by the Central Processing Unit (CPU). The amount of the injected fuel is determined by the fluid pressure and the opening-time interval of these valves, with which, assuming constant pressure inside the common pressure chamber, very precise fuel- quantity regulation may be achieved. Such devices are excellently suited

0010 for the Invention for the operation of the intake and exhaust valves, with which their opening time and movement-profile may be precisely regulated. Accordingly, in the Invention there is a CPU- (or other suitable electronic 0011 impulse-generator device) controlled (3) solenoid valve (flow-control valve) attached to (2) pressure chamber for each valve separately, which guides the hydraulic fluid through (4) pressure tube to or from (5) valve guide to (6) valve. It seems logical to utilize the stem of (6) valve as the hydraulic piston, in which case (5) valve guide will be the hydraulic cylinder, but (6) valve may also be a separate unit operated by a separate hydraulic actuator unit connected to (4) pressure tube (followingly the Invention is explained in association with a (6) valve incorporating the actuator). In the Invention (6) valve is engaged by a suitable spring-means (conventional or pneumatic spring, etc.) in order to return (6) valve into its valve-seat, when needed, or alternatively, (6) valve may be closed hydraulically similar to its opening by the introduction of pressurized hydraulic fluid from (2) pressure chamber at the opposite end of (5) hydraulic cylinder, controlled by (3)

0012 solenoid valve. It is being remarked here in relation to the electronic controlling of (3) solenoid valves that the control unit is not a part of the Invention, also that the most suitable device for the purpose appears to be the CPU used on most engines of the type to which the Invention relates, but it may also be any other suitable device capable of generating electric impulses which are suitable to properly control (3) solenoid valves.

The 3 solenoid valve directs and controls the flow of the hydraulic fluid by already known flow-control methods pertinent to such solenoid flow-control valves, and through this the opening time and movement of (6) valve, the Invention does not include any stipulation in this respect, only that (3) solenoid valve, as a part of the hydraulic system and by electronic control, must be suitable to regulate at least the length of the opening period of (6)

0013 valve, but as a further advantage, or if needed, to also regulate its stroke, its movement within the stroke, and any other necessary modes working of (6) valve. The Invention does not aim to provide an exact working order of the operating of (6) valve, which is a function of the individual application and may include many different variations, thus in the present description only several most basic working methods are mentioned as examples, as follows: Regulation of only the opening period of (6) valve, as the simplest operation method: in this case the electronic control device sends an impulse to (3) solenoid valve at the required moment to command it to open the relevant outlet of (2) pressure chamber, which allows the pressurized hydraulic fluid to flow from (2) pressure chamber into (4) pressure tube and trough it into (5) hydraulic cylinder, which opens (6) valve at its full length. The closing of (6) valve happens by a subsequent electric impulse, which commands (3) solenoid valve to close off the outlet of (2) pressure chamber, and depressurize (4) pressure tube through a separate bleed-off passage, thereby allowing (6) valve to return into its valve-seat. Regulating the stroke-length of (6) valve by regulating the opening period of (3) solenoid valve together with the regulation of the opening period of (6) valve: this method required the maintenance of very precise pressure inside (2) pressure chamber, similar to the fuel injection. In this case at the moment of opening of (6) valve (3) solenoid valve opens only until (6) valve travels to the required portion of its full stroke-length, at which point (3) solenoid valve closes until the end of the opening period of (6) valve, at which moment (3) solenoid valve depressurizes (4) pressure tube. It is remarked here, that the operation of the Invention may involve constant pressure fluctuations, which may be detrimental to this type of valve-control. The remedy might be the same as already mentioned hereinbefore, that is a pressure sensor placed in (2) pressure chamber sending continuous readings to the electronic control device, which exactly calculates for each valve stroke the exact time-interval of the opening of (3) solenoid valve at the momentary hydraulic pressure to effect the exact required movement of 6 valve. Servo-piston valve-movement control: here (6) valve is connected with a movement-sensor / signaling device (such as a linear potentiometer) which gives feedback to the electronic control device with respect to the movement and position of (6) valve for the precise regulation of its movement.

4. Valve-movement profile control in order to stagnate, speed up, or stop-and-start (6) valve within its stroke, as required by optimal engine-performance: this, by the concurrent application of the above methods, can be accomplished by the precise regulation (reduction and enlargement) of the flow-crossection of (3) solenoid valve within the stroke, which will slow or speed up the in- or outflow of the hydraulic fluid in (4) pressure tube and thus the movement of (6) valve, and by the momentary closure of (3) solenoid valve to

0018 momentarily stop (6) valve during its in- or outward movement, if such is required.

5. Closing of (6) valves hydraulically to exclude the difficulties of valve- closure arising in some applications, when conventional springs are used: an optional method of returning (6) valve into its seat. In this case there is a hydraulic fluid-introduction in (5) hydraulic cylinder at the valve-end, which is pressurized by (3) solenoid valve at the moment in which (6) valve must close, subsequent to which (3) solenoid valve depressurizes this passage. The (6) valve has to be provided by a spring means to keep it in place in the closed state, such spring means fastened to the valve stem so it would not lag behind the valve when it is closed hydraulically.

With respect to (3) solenoid valve it is remarked herein that in the explanation it is treated as one integrated unit, which is however not a

0019 requirement in the Invention, it may consist of multiple, harmonized- operation units located at the most suitable points of the system.

In practice, at the closing of (6) valve it may be necessary to reduce the 0020 intensity of its movement in order to avoid its slamming into the valve-seat when (4) pressure tube gets depressurized, which can cause damage or the braking off of the valve-plate after a certain period of time. This may be accomplished by the proper reduction of the outflow-crossection of the hydraulic fluid passage leading out of (4) pressure tube.

As a summary of main advantages of the Invention, the electro-hydraulic system comprised in it, by its simplified structure, can make possible the practical implementation of such system for general use in order to substantially enhance engine performance by the optimal regulation of the working of the intake and exhaust valves, also resulting an environmentally cleaner engine; its further novelty being that it makes possible engine revolution-independent valve-control allowing entirely new engine operation possibilities. As examples of such, at freezing cold starts the system can keep the" engine-valves open while shutting off injection until

0021 the starter breaks the frozen oil in the engine and reaches the proper starting engine rpm. in order to aid the battery, which may be particularly useful in heavy-duty engines, or oppositely, in road-vehicle engines in downhill drive all the valves can be closed together with the shutting off of the injection as a retarder in order to slow the vehicle as much as possible on the down-slope. Another substantial advantage of the Invention is that in the absence of the mechanical components it makes possible a drastic noise-reduction. In this respect it is mentioned herein, that in road vehicles a silent engine may actually be considered a hazard, especially in case of large vehicles, such as trucks, however, if engine-noise reduction can be accomplished, this hazard may be eliminated by replacing the brute engine noise with a "smart", environment-friendly noise generator to safely announce the arrival of the vehicle to others.

0022 Further, engine fuels, for being lighter than generally used hydraulic oils, may be less susceptible for viscosity change due to change in temperature. Of course fuel, if it is used in average hydraulic systems, may be very hazardous, and very problematic to handle. However, in the Invention the operation takes place in one unit with the Common Rail fuel injection system, which is already in the engine-top, from which the fuel has to travel only a very short distance to the valves, thereby eliminating

0023 the problems relating to its handling, and excluding a noticeable increase in fire hazard. The invention, by replacing the generally used mechanical valve-systems with their inherent mechanical friction, results a substantial reduction in the engine-energy required for its operation.

With respect to some concern that in hydraulic valve-systems, because of the lack of mechanical parts, in case of any malfunction a contact between the valve and piston easier can take place resulting substantial damage to the engine, the Invention easily makes possible the employing of electronic control-circuits monitoring the other electronic and hydraulic components of the system, and in case of the slightest problem they immediately depressurize the pressure tube leading to the problem-valve returning it

0024 into the valve-seat and cut off concurrently the fuel-flow, thereby preventing engine damage. Computerization of the system makes also possible immediate self-diagnosis and remedial action, which can be the immediate shutting off of the engine, or only the isolation of a valve and compensation with the other same valve (in four valve per cylinder engines), or isolating and shutting off the whole cylinder, in order to permit restricted engine operation temporarily until a remedy to the situation is effected.

Description of the Drawing:

The attached illustration shows the basic configuration of the Invention. In the illustration 1 marks the pump of the already known and available Common Rail fuel injection system with arrows representing the possible

0025 routes of the hydraulic fluid, and 2 marks the pressure chamber of the

Invention, which can be the pressure chamber of the Common Rail fuel injection system, shown with continuous contour. In the middle of 2 pressure chamber the wide-spaced dashed line refers to an alternative arrangement, in which the 2 pressure chamber is the same unit as the pressure chamber of the Common Rail system but is physically separated from it, and the tightly dashed lines show the contour of two separate pressure chambers in the case in which the 2 pressure chamber is completely separated from the pressure chamber of the Common Rail system. The illustration shows the pressure regulator - overflow valve applied on the pressure chambers of Common Rail systems. The arrows pointing from 2 pressure chamber refer on one side to the valves of the

0026 cylinders, and on the opposite side to the fuel injectors, the illustration using a four-cylinder engine as an example. Following 2 pressure chamber only the details of one valve are shown, which are naturally the same for each valve. In the illustration 3 marks a hydraulic fluid-flow regulator solenoid valve, 4 is a pressure tube, 5 is the hydraulic cylinder, which is, in the drawing, the valve-guide itself, and 6 is the valve to be operated by the Invention.

Description of the Embodiment:

In the Invention the pressurized hydraulic working fluid, which is the engine fuel, is contained in the pressure chamber of the already known Common Rail fuel injection system, which is therefore also the common rail pressure chamber (2) of the Invention, or alternatively by a separate common rail pressure chamber (2) provided with pressure regulation means and connected with the feeder pump (1) of the Common Rail fuel injection system, which supplies the working fluid of fuel and maintains pressure inside the pressure chamber (2). In the pressure chamber (2), for each

0027 intake and exhaust engine-valve (6) of the engine, there is one electronically controlled solenoid valve (3) suitable for the regulation of the flow of the pressurized hydraulic fluid, which is connected by a pressure tube (4) with a hydraulic cylinder (5) pertaining to the actuator of the valve (6), which cylinder (5) may be the valve-guide of the engine-valve (6) itself, and through it with the hydraulic piston of the actuator, which may be the stem of said engine-valve (6). The engine-valve (6) is engaged by a spring- type or hydraulic return means. The solenoid valve (3) is suitable for the 0028 directing of the hydraulic fluid stored in the pressure chamber (2) into and out of the pressure tube (4) by electronic control, as required for the proper operation of the engine-valve (6).

Citation literature:

1. Development of a Piezoelectric Controlled Hydraulic Actuator for a

Camless Engine by John Steven Brader

Department of Mechanical Engineering

College of Engineering and Information Technology

University of South Carolina, 2001

http://www.me.sc.edu/research/AARG/Thesis%20Final.pdf

2. Electro-hydraulic valve control system for internal combustion engine valves

Patent number: US4466390

3. Electrohydraulic valve control device for internal combustion engines Patent number: US5154143

Claims

Claims:

1. Common Rail electro-hydraulic valve-operation system for the intake and exhaust valves (6) of internal combustion piston-engines utilizing the main components of the already known Common Rail fuel injection system for reason of structural simplicity, wherein its application assumes the existence of such Common Rail fuel injection system on the engine.

2. Common Rail electro-hydraulic valve-operation system according to Claim 1 , wherein the hydraulic operation of the valves (6) is based on the Common Rail system, therefore the hydraulic pressure required for its operation is stored in a common pressure chamber (2).

3. Common Rail electro-hydraulic valve-operation system according to Claim 1 , wherein said pressure chamber (2) may be a shared one with the pressure chamber of the Common Rail fuel injection system, or it may be separated from it.

4. Common Rail electro-hydraulic valve-operation system according to Claim 1 , wherein said pressure chamber (2) is fed by a fuel pump (1) pertaining to the Common Rail fuel injection system, therefore its hydraulic working fluid is the engine fuel itself.

5. Common Rail electro-hydraulic valve-operation system according to Claim 1 , wherein the actuation of said valves (6) happens hydraulically.

6. Common Rail electro-hydraulic valve-operation system according to Claim 1 , wherein said pressure chamber (2) is equipped with one solenoid valve (3) for each said valve (6), and a pressure tube (4) connecting said solenoid valve (3) with a valve-guide (5) pertaining to said valve (6), said valve-guide (5) also acting as a hydraulic cylinder, and the stem of said valve (6) also acting as a hydraulic piston, said pressure tube (4) provided with a bleed-off passage controlled by said solenoid valve (3) to let the hydraulic fuel out of the system, as required.

7. Common Rail electro-hydraulic valve-operation system according to Claim 6, wherein alternatively there may be a separate hydraulic cylinder and piston to act as actuator for said valve (6) in the place of said valve-guide (5) and said stem of valve (6).

8. Common Rail electro-hydraulic valve-operation system according to Claim 1 , wherein said solenoid valve (3) is suitable for the high precision regulation of the movement of said valve (6) as required, even independently from the engine revolution.

9. Common Rail electro-hydraulic valve-operation system according to Claim 1 , wherein said solenoid valve (3) is controllable by the Central Processing Unit of the engine, or by a similar electronic control device.