EP3137743B1

EP3137743B1 - Valve timing system

Info

Publication number: EP3137743B1
Application number: EP15736065.2A
Authority: EP
Inventors: Goktan KURNAZ; Arif Caglar Pinar
Original assignee: Ford Otomotiv Sanayi AS
Current assignee: Ford Otomotiv Sanayi AS
Priority date: 2014-04-29
Filing date: 2015-04-24
Publication date: 2018-05-09
Anticipated expiration: 2035-04-24
Also published as: RU2016146472A; TR201615225T1; CN106661973B; RU2016146472A3; CN106661973A; EP3137743A1; WO2015167412A1

Description

Field of the Invention

The present invention relates to adjustable engine valves operated by a hydraulic system.

Background of the Invention

In conventional valve timing systems the rocker arm pivots around a fixed rocker shaft. These systems enable opening and closing of only one valve controlled by a profile on a cam. Recently, various systems which enable different valve actuation by varying the timing and/or the valve lift have been developed. One example of these systems is the "Multi Air" system developed by Fiat. Detailed description of the said system is given in the International patent document no. WO9834014A1 . Jacobs Manufacturing Company also has hydraulically actuated variable valve actuation and engine brake systems. Furthermore, Ostfalia University also has a similar variable valve actuation system. This system employs a piezo actuator and a stroke ratio. These systems are very expensive due to the massive, numerous and complex components they have.
International patent document no. WO9706355 , an application in the state of the art, discloses an engine valve structure actuated by a hydraulic system. The engine cylinder valve (30) and the engine cam (40) are connected to each other via an electrically controlled hydraulic system. Lost motion is permitted by deactivating the hydraulic fluid. The electrical control system optimizes engine performance by changing the amount of fluid in the hydraulic channels which helps to adjust duration and extent of valve openings. The method disclosed in the patent document no. WO9706355 is a system which determines the portion of the cam profile which is desired to be eliminated. Therefore, it is in fact a "variable lost motion" system. Its major advantage is that the amount of lost motion can be increased as much as desired. With this method, it is not possible to open the valve to an extent more than the amount determined by the cam profile or to open the valve before the time determined by the cam profile. Thus it is not a fully variable valve actuation system.
International patent document no. WO2007142724 , an application known in the art, discloses an exhaust valve actuated by a hydraulic system. This system also includes a braking control valve. This invention adjusts operation of the valve actuator according to the extent of the valve opening. There are two cam mechanisms in this invention. While one of these cam mechanisms (172) adjusts the valve opening, the other cam mechanism (126) adjusts the timing of fuel supply to the engine cylinder. By means of the patent document no. WO2007142724 , in addition to a cam profile which is always active, another cam profile (126), which is already present for adjusting the injection timing in the engine, is enabled to be actuated when desired. In this method, the cam 172 is always in interaction with the valve. Thus, the main difference of this system from the mentioned system present in this invention application is that the second cam profile does not deactivate the main cam profile when it is activated. Since this makes a two-stroke engine braking impossible, the braking power obtained in this patent will be lower than the method of the present application. In other words, since the exhaust valve is opened in the main exhaust event with the cam 172, it will not be able to allow compression of the gas in the cylinder and therefore braking power will be lower.
The international patent document no. WO200400567 , an application in the state of the art, discloses a system controlling cylinder inlet and outlet valves. The system enables actuation of the valve by using a cam mechanism. A control mechanism (21-25, 26) controls movement of the inlet and outlet valves. When the valves are coming to the closed position (when passing from the cam lobe nose to base circle), openings of the valves are adjusted independent from the cam profile. In certain cases, closing times of the valves can be delayed by a counteracting force provided by the hydraulic system by pre-adjusting this control mechanism. The system disclosed in the patent document no. WO200400567 is not a fully variable valve actuation system. It only slows down the closing of the valve or enables to fix it at a certain extent of opening when desired. This system also cannot enable the valve to be opened earlier or at a longer duration. The system presented in this application provides solutions for both problems. Since the suggested system is a fully variable valve actuation system, a new profile completely independent from the current valve opening profile can be activated.
Document US5404851 discloses a device for switching an engine from a propelling mode to a braking mode through a control slide.
The variable valve timing systems used in the above mentioned applications reach very high costs either by increasing the number of valve train components that are currently used (for example, power density engine brake system of Jacobs Vehicle Systems company requires 2 times more components) or by using high speed electrical actuators (as in the Multi Air system developed by Fiat Power Train company).
When the power density engine brake system of Jacobs Vehicle Systems is examined, since the cam designed for braking requires 2 times more valve train components, it is significantly restricted with the geometry and layout of the current system. In such systems, large design areas are required on the engine.
Additionally, another disadvantage thereof is that the alternative cam profile can only drive one of the intake or exhaust valves. On the other hand, it is known that this system makes loud noise during operation.
The system developed by Ostfalia University is excessively complex since it requires a closed loop control system and special piezo actuators for every 2 valves. Moreover, when the engine is stopped and oil leaks from the clearances, the valves will fall over the piston since no valve spring is being used. Therefore, it is understood that this system is developed only for research purposes.

Summary of the Invention

An objective of the present invention is to provide a valve timing system which does not require lost motion.
Another objective of the present invention is to make multiple independent cam designs for intake valves and similarly for exhaust valves, thereby providing a valve timing system that enables cams to be activated alternately.
A further objective of the present invention is to provide a variable valve timing system which is low cost and lightweight.
Another objective of the present invention is to provide a variable valve timing system which eliminates the requirement of valve lash adjustment.
Another objective of the present invention is to provide a variable valve timing system which eliminates use of valve train components which are subjective wear in time.

Detailed Description of the Invention

"A valve timing system" developed to fulfill the objective of the present invention is illustrated in the accompanying figures, in which:

Figure 1 is the schematic view of the active state of the second cam in the valve timing system (engine brake on).
Figure 2 is the schematic view of the active state of the first cam in the valve timing system (normal cycle).
Figure 3 is the schematic view of the hydraulic line of the first cam when the second cam is being activated in the valve timing system.
Figure 4 is the schematic view of the hydraulic line of the second cam when the second cam is being activated in the valve timing system.

The components given in the figures are assigned reference numbers as follows:

1. Valve timing system
2. Solenoid valve
3. Main oil line
4. Outlet channel
5. Upper channel
6. Inlet channel
7. First piston
8. First spring
9. Safety valve
10. Second channel
11. Second piston
12. Second spring
13. Body
14. Cavity
15. Opening
16. Third channel
17. First main piston
18. First cam
19. Fourth channel
20. Second main piston
21. Second cam
22. Fifth channel
23. Sixth channel
24. Check valve
25. Valve mechanism
26. Cylinder
27. Pushing piston
28. Valve assembly
29. Pin
30. Valve
31. Valve spring

The valve timing system (1) of the present invention used in compression brakes in internal combustion engines basically comprises

at least one solenoid valve (2),
at least one main oil line (3) through which oil is pumped,
at least one outlet channel (4),
at least one upper channel (5),
at least one inlet channel (6) to which the solenoid valve (2) is mounted and to which oil is delivered from the main oil line (3),
at least one first piston (7) located within the inlet channel (6),
at least one first spring (8) which is located within the inlet channel (6) and to which the first piston (5) exerts pressure,
at least one safety valve (9) which is located at the end of the inlet channel (6),
at least one second channel (10) to which the open end of the safety valve (9) is connected,
at least one second piston (11) which moves within the second channel (10),
at least one second spring (12) to which the second piston (11) exerts pressure,
at least one body (13) into which the second channel (10) fits and in which the second piston (11) and the second spring (12) are located,
at least one cavity (14) located on the body (13) surfaces,
an opening (15) in the structure of the second piston (11),
at least one third channel (16), by which the cavity (14) located on the body (13) surface opens outwards from the body (13),
at least one first main piston (17) to which the end of the third channel (16) that does not fit into the cavity (14) opens out,
at least one first cam (18) which operates in connection with the first main piston (17),
at least one fourth channel (19), by which the other cavity (14) located on the body (13) surface opens outwards from the body (13),
at least one second main piston (20) to which the end of the fourth channel (19) that does not fit into the cavity (14) opens out,
at least one second cam (21) which operates in connection with the second main piston (20),
at least one fifth channel (22) which opens outwards from the surface of the body (13),
at least one sixth channel (23) which branches out from the fifth channel (22),
at least one check valve (24) which is located on the sixth channel (23),
at least one valve mechanism (25) which is located after the check valve (24) and to which the sixth channel (23) opens out,
at least one cylinder (26) which is located at the end of the fifth channel (22) that is not connected to the body (13),
at least one pushing piston (27) which is located in the cylinder (26),
at least one valve assembly (28) to which the end of the pushing piston (27) opens out,
at least one pin (29) which is located between the valve assembly (28) and the valve mechanism (25),
valves constituting the valve assembly (28),
valve springs (31) which enable opening and closing of the valves (30).

In the valve timing system (1) of the present invention, upon being activated, the solenoid valve (2) enables the oil flow coming from the main oil line (3) to open out to the inlet channel (6) and push the first piston (7) located in the inlet channel (6) against the first spring (8). This allows flow of oil from the safety valve (9) to the second channel (10). The oil pressure in the second channel (10) pushes the second piston (11) against the second spring (12). At this position, the second piston (11) cannot move in the second channel (10), since flow is prohibited by the safety valve (9) and the first piston (7). In this case, the valves (30) are opened against high in-cylinder (30) pressure, thereby realizing compression release braking. The resulting hydraulic lock will prevent movement of the second piston (11) regardless of how high the pressure in the chamber is. In this (stationary) position of the first piston (11), the second cam (21) is activated, and by pushing the second main piston (20), pumps the oil from the cylinder (26) to the fifth channel (22) and pushes the pushing piston (27) thereby moving the valves (30). A valve spring (31) is provided to maintain the continuous contact between the second main piston (20) and the second cam (21) and to enable closing of the valves (30). Therefore the valve (30) opening action provided by the second cam (21) takes place against the valve spring (31). The second cam (21) is configured to perform engine brake cycle, therefore it works under higher pressures compared to the main cycle. At this position of the second piston (11), the first cam (18) will not be activated unless the third channel (16) is completely filled with oil. The movement of the first cam (18) is disabled thanks to the alignment of the cavity (14) with the opening (15) located on the second piston (11) and to the clearance between the third channel (16) and the cavity (14), which opens to the crankcase.
In order to activate the first cam (18), the solenoid valve (22) is deactivated lowering the pressure in the inlet channel (6). The first piston (7) moves downwards under the action of the first spring (8) thereby discharging the pressurized oil in the second channel (10) by aligning the upper channel (5) with the outlet channel (4). The second piston (11) starts to move upwards as the compressed spring force of the second spring (12) starts to overcome the oil pressure in the second channel (10). At this position, the third channel (16) and the fifth channel (22) are connected to each other; and the second piston (11) starts to pump the oil into the cylinder (26) with the movement it receives from the first cam (18). This way, the first cam (18) is activated. The first cam (18) performs the main cycle, and as it is also described above, valves require much lower valve opening pressures during the main cycle compared to the engine brake cycle. The oil pressure, which is created by the hydraulic lock that enables the valves (30) to open upon being combined from the third channel (16) and the fifth channel (22), exerts an equal pressure at the channels and clearances within the first piston (7) and this way there is no net force in the first piston (7) and the first piston (7) is enabled to keep its position by means of the force exerted by the first spring (8).
The sizes of the second piston (11) and the body (13), on which the second piston (11) is located, are adjusted such that the third channel (16) will start to open when the cavity (14) starts to be closed by the second piston (11) and the third channel (16) will be in interaction with the cavity (14) in order to prevent hydraulic lock within the fourth channel (19) when switching from the second cam (21) to the first cam (18) (seen in Figure 3). Likewise, the size of the cavity (14) located on the surface of the body (13) is such that it will provide interaction with the opening (15) before being closed by the second piston (11) (seen in Figure 4).
The valve mechanism (25) is utilized so as to enable renewing of the decreasing oil when the valves (30) are in closed position. When the valves (30) are in open position, the check valve (24) prevents backflow of oil in the cylinder (26) to the main oil line. When the valves (30) are close to the closed position, the pin (29) pushes the valve in the valve mechanism (25) and thus the oil within the engine main line is enabled to supply the oil within the valve timing system (1).
The valve timing system (1) of the present invention can be integrated in exactly the same way to the intake valve system side. This way, two-stroke engine braking can be achieved and an engine brake power which is much higher than those of the current engine brake systems can be achieved. In this case, the solenoid valve (2) and the valve mechanism (25) are added to the valve timing system (1) exactly the same way for the intake valve (30) systems side. Likewise, by actuating a single solenoid valve (2), two second pistons (11) provided for the intake and exhaust sides can be actuated at the same time.
Since a completely new cam profile which is independent from the other profile can be activated in the valve timing system (1), it is possible both to increase the valve (30) opening more than it is provided by the first cam (18) profile and to open it earlier.
Thanks to the valve timing system (1) of the present invention, lost motion is not required, preferably two independent cam designs separate for each intake and exhaust valve which are independent from each other can be made and arranged in the current design area, variable valve (30) timing actuators can be provided as much more inexpensive and lightweight, and the requirement of valve (30) lash adjustment is eliminated. Use of valve train components which are critical in terms of wear is eliminated. Thus the excessive wear problem in the valve (30) system is significantly reduced.
With the developed valve timing system (1), opening closing height and timing of the valves (30) can be changed by means of the cams (first cam (18) and second cam (21)) which are designed to be two or more according to need for each cylinder (26). One of the designed cams (first cam (18) and second cam (21)) has the standard opening closing profile of the valve (30) while the other cam (or cams) (first cam (18) and second cam (21)) has/have the profile necessary for the engine braking system. If the system is developed separately for the intake and exhaust valves, high engine brake powers can be attained by means of the two-stroke compression release engine brake (shown in Figure 1).

Claims

A valve timing system (1), which is used in compression release brakes in internal combustion engines, basically comprising
- at least one solenoid valve (2),

- at least one main oil line (3) through which oil is pumped,

- at least one outlet channel (4),

- at least one upper channel (5),

- at least one inlet channel (6) to which the solenoid valve (2) is mounted and to which oil is delivered from the main oil line (3),

- at least one first piston (7) located within the inlet channel (6),

- at least one first spring (8) which is located within the inlet channel (6) and to which the first piston (5) exerts pressure,

- at least one safety valve (9) which is located at the end of the inlet channel (6); and

- at least one second channel (10) to which the open end of the safety valve (9) is connected,

- at least one second piston (11) which moves within the second channel (10),

- at least one second spring (12) to which the second piston (11) exerts pressure,

- at least one body (13) into which the second channel (10) fits and in which the second piston (11) and the second spring (12) are located,

- at least one cavity (14) located on the body (13) surfaces,

- an opening (15) in the structure of the second piston (11),

- at least one third channel (16), by which the cavity (14) located on the body (13) surface opens outwards from the body (13),

- at least one first main piston (17) to which the end of the third channel (16) that does not fit into the cavity (14) opens out,

- at least one first cam (18) which operates in connection with the first main piston (17),

- at least one fourth channel (19), by which the other cavity (14) located on the body (13) surface opens outwards from the body (13),

- at least one second main piston (20) to which the end of the fourth channel (19) that does not fit into the cavity (14) opens out,

- at least one second cam (21) which operates in connection with the second main piston (20),

- at least one fifth channel (22) which opens outwards from the surface of the body (13),

- at least one sixth channel (23) which branches out from the fifth channel (22),

- at least one check valve (24) which is located on the sixth channel (23),

- at least one valve mechanism (25) which is located after the check valve (24) and to which the sixth channel (23) opens out,

- at least one cylinder (26) which is located at the end of the fifth channel (22) that is not connected to the body (13),

- at least one pushing piston (27) which is located in the cylinder (26),

- at least one valve assembly (28) to which the end of the pushing piston (27) opens out,

- at least one pin (29) which is located between the valve assembly (28) and the valve mechanism (25),

- valves constituting the valve assembly (28),

- valve springs (31) which enable opening and closing of the valves (30).
The valve timing system (1) according to Claim 1, characterized by the solenoid valve (2), which, upon being activated, enables the oil flow coming from the main oil line (3) to open out to the inlet channel (6) and push the first piston (7) located in the inlet channel (6) against the first spring (8).
The valve timing system (1) according to Claim 1 or Claim 2, characterized by the second channel (10), the oil pressure in which pushes the second piston (11) against the second spring (12).
The valve timing system (1) according to any one of the preceding claims, characterized by the valve spring (31) which is provided to maintain the continuous contact between the second main piston (20) and the second cam (21) and to enable closing of the valves (30).
The valve timing system (1) according to any one of the preceding claims, characterized by the valves (30) which enable compression release brake by being opened against high in-cylinder (30) pressure.
The valve timing system (1) according to any one of the preceding claims, characterized by the second channel (10) in which the second piston (11) cannot move since flow is prohibited by the safety valve (9) and the first piston (7).
The valve timing system (1) according to any one of the preceding claims, characterized by the second cam (21), which, when activated, pushes the second main piston (20) and thus pumps the oil from the cylinder (26) to the fifth channel (22) and pushes the pushing piston (27) thereby starting to move the valves (30).
The valve timing system (1) according to any one of the preceding claims, characterized by the first cam (18), for which, in order to be activated, the pressure in the inlet channel (6) is lowered by deactivating the solenoid valve (2).
The valve timing system (1) according to any one of the preceding claims, characterized by the first piston (7) which moves downwards under the action of the first spring (8) thereby discharging the pressurized oil in the second channel (10) by aligning the upper channel (5) with the outlet channel (4).
The valve timing system (1) according to any one of the preceding claims, characterized by the second piston (11) which starts to move upwards as the compressed spring force of the second spring (12) starts to overcome the oil pressure in the second channel (10).
The valve timing system (1) according to any one of the preceding claims, characterized by the second piston (11), which, when the third channel (16) and the fifth channel (22) are connected to each other, starts to pump the oil into the cylinder (26) with the movement it receives from the first cam (18) and thus enables to activate the first cam (18).
The valve timing system (1) according to any one of the preceding claims, characterized by the valve mechanism (25) which is utilized so as to enable renewing of the decreasing oil when the valves (30) are in closed position.
The valve timing system (1) according to any one of the preceding claims, characterized by the check valve (24), which, when the valves (30) are in open position, prevents backflow of oil in the cylinder (26) to the main oil line.
The valve timing system (1) according to any one of the preceding claims, characterized by the pin (29), which, when the valves (30) are close to the closed position, pushes the valve in the valve mechanism (25) and thus enables the oil within the engine main line to supply the oil within the valve timing system (1).
The valve timing system (1) according to any one of the preceding claims, characterized by the cams (first cam (18) and second cam (21)) which enable opening closing height and timing of the valves (30) to be changed and which are designed to be two or more for each cylinder (26) according to need.
The valve timing system (1) according to any one of the preceding claims, characterized by the second piston (11) and the body (13), on which the second piston (11) is located, whose sizes are adjusted such that the third channel (16) will start to be opened when the cavity (14) starts to be closed by the second piston (11) and the third channel (16) will be in communication with the cavity (14) in order to prevent hydraulic lock within the fourth channel (19) when switching from the second cam (21) to the first cam (18).
The valve timing system (1) according to any one of the preceding claims, characterized by the cavity (14), whose size is such that it will provide communication with the opening (15) before being closed by the second piston (11), and which is located on the surface of the body (13).