EP2834482B1

EP2834482B1 - Gas exchange valve arrangement and valve

Info

Publication number: EP2834482B1
Application number: EP13715721.0A
Authority: EP
Inventors: Sören HÖSTMAN; Magnus Sundsten; Ulf Granlund
Original assignee: Wartsila Finland Oy
Current assignee: Wartsila Finland Oy
Priority date: 2012-03-09
Filing date: 2013-03-04
Publication date: 2016-05-04
Anticipated expiration: 2033-03-04
Also published as: CN104185722A; WO2013132153A1; EP2834482A1; KR102029518B1; BR112014020534A2; BR112014020534B1; CN104185722B; FI20125250L; KR20140140022A

Description

Technical field of the invention

The present invention relates to a gas exchange valve arrangement for an internal combustion engine in accordance with the preamble of claim 1. The invention also concerns a gas exchange valve according to the other independent claim.

Background of the invention

Gas exchange valves of internal combustion engines are most often operated by rotating camshafts, but also hydraulically operated systems are known. Hydraulic valve opening systems are used especially in large internal combustion engines, where they can provide the benefits of variable gas exchange valve opening and closing times. Both mechanical and hydraulic valve opening mechanisms are often bulky and require a lot of space above the cylinder heads. Large valve springs are needed to enable fast closing of the gas exchange valves.

Summary of the invention

An object of the present invention is to provide an improved gas exchange valve arrangement for an internal combustion engine. The characterizing features of the arrangement according to the present invention are given in the characterizing part of claim 1. Another object of the invention is to provide an improved gas exchange valve for an internal combustion engine. The characterizing features of the gas exchange valve according to the present invention are given in the characterizing part of the other independent claim.
The gas exchange valve arrangement according to the invention comprises at least one gas exchange valve for opening and closing flow communication between a gas exchange duct and a cylinder of the engine, the gas exchange valve comprising a valve head and a valve stem, a pressurizing chamber for pressurizing hydraulic fluid, a reciprocating piston that protrudes into the pressurizing chamber, a receiving chamber that is arranged around the valve stem of the gas exchange valve, and a hydraulic fluid duct for connecting the pressurizing chamber to the receiving chamber. A piston surface is arranged in the receiving chamber in connection with the valve stem for opening the gas exchange valve. The arrangement further comprises a second piston surface that is arranged in connection with the valve stem and exposed to the pressure in the gas exchange duct for facilitating closing of the gas exchange valve.
The construction according to the invention is very compact, since the means for opening the gas exchange valves are arranged around the valve stems. The hydraulic fluid also lubricates the valve guides and valve stems. Because of the second piston surface that is exposed to the pressure in the gas exchange duct, smaller valve springs can be used.
The gas exchange valve according to the invention comprises a valve head and a valve stem, and a piston surface that is in connection with the valve stem and on which hydraulic pressure can be applied for opening the gas exchange valve. The gas exchange valve further comprises a second piston surface that is arranged in connection with the valve stem and exposable to the pressure in a gas exchange duct for facilitating closing of the gas exchange valve. The piston surfaces can be at the ends of a projection that is arranged around the valve stem. The projection can be an integral part of the valve stem, or a sleeve that is arranged around the valve stem. If the projection is a sleeve, it can be made of a different material than the rest of the gas exchange valve.
According to an embodiment of the invention, in the gas exchange valve arrangement the second piston surface is arranged in the gas exchange duct.
According to an embodiment of the invention, the arrangement comprises a spring that is arranged around the valve stem for closing the gas exchange valve and the receiving chamber is arranged below the spring.
According to an embodiment of the invention, the pressurizing chamber comprises a first portion with a first diameter and a second portion with a second diameter, and the arrangement comprises a first hydraulic fluid duct for connecting the first portion of the pressurizing chamber to a receiving chamber of a first gas exchange valve and a second hydraulic fluid duct for connecting the second portion to a receiving chamber of a second gas exchange valve, and the piston comprises a first pressure surface for pressurizing hydraulic fluid in the first portion of the pressurizing chamber and a second pressure surface for pressurizing hydraulic fluid in the second portion of the pressurizing chamber. According to another embodiment of the invention, the first pressure surface is arranged at the end of the piston and the second pressure surface is an elbow that is arranged at a distance from the end of the piston. According to another embodiment of the invention, the arrangement comprises one pressurizing chamber and one piston for each gas exchange valve.
When the gas exchange arrangement is provided with separate means for pressurizing the hydraulic fluid for each of the gas exchange valves, the same amount of hydraulic fluid can be supplied at the same time to each of the valves. The valves open thus at the same time and the valve lift is equal for each valve.
The pressurizing chamber can be arranged, for instance, in the cylinder head. The invention can be applied both to intake valves and exhaust valves. The reciprocating piston can be moved by a rotating cam, but also other means can be used for driving the piston.

Brief description of the drawings

Fig. 1 shows a gas exchange valve arrangement according to an embodiment of the invention.
Fig. 2 shows the gas exchange valve arrangement of figure 1 with closed gas exchange valves.

Detailed description of the invention

Embodiments of the invention are now described in more detail with reference to the accompanying drawings.
In figures 1 and 2 is shown a gas exchange valve arrangement for an internal combustion engine according to an embodiment of the invention. The engine is a large internal combustion engine that can be used, for instance, as a main or an auxiliary engine of a ship or at a power plant for producing electricity. The engine can comprise any reasonable number of cylinders, and each cylinder is provided with an own cylinder head 3.
The gas exchange valve arrangement comprises a first gas exchange valve 1 and a second gas exchange valve 1', which are used for opening and closing flow communication between a gas exchange duct 2 and a cylinder of the engine. The gas exchange valves 1, 1' are arranged in the cylinder head 3. In figure 1 the gas exchange valves 1, 1' are open, and in figure 2 the valves 1, 1' are closed. In the embodiment of the figures, the gas exchange duct 2 is an intake duct and the gas exchange valves 1, 1' are intake valves. However, the engine can be provided with an identical or similar arrangement for the exhaust duct and exhaust valves. In the embodiment of the figures, the number of the intake valves 1, 1' in each cylinder is two, but also a different number of intake valves 1, 1' could be used. Each of the first intake valve 1 and the second intake valve 1' comprises a valve stem 1b, 1b' and a valve head 1a, 1a' that is in co-operation with a valve seat 4, 4'. The intake valves 1, 1' are closed and kept closed by springs 12, 12' in a conventional manner. However, instead of conventional coil springs, for instance air springs could be used. In the embodiment of the figures, the springs 12, 12' are arranged around the valve stems 1b, 1b' partly inside the cylinder head 3 and partly above the cylinder head 3. The movement of the intake valves 1, 1' is guided by valve guides 15, 15', which are sleeves that are arranged around the valve stems 1b, 1b'.
The intake valves 1, 1' are opened hydraulically. For pressurizing hydraulic fluid that is used for opening the intake valves 1, 1', the valve arrangement is provided with a pressurizing chamber 9. In the embodiment of the figures, the pressurizing chamber 9 is arranged inside the cylinder head 3. However, the pressurizing chamber 9 could also be arranged in some other part of the engine. A reciprocating piston 7 is arranged to protrude into the pressurizing chamber 9. The piston 7 is connected to a cam follower unit 11 that comprises a cam follower wheel 11a. The cam follower wheel 11a follows the surface of a rotating cam 10, and when the cam follower wheel 11a becomes engaged with the lobe 10a of the cam 10, the piston 7 is moved towards the upper end of the pressurizing chamber 9, i.e. away from the rotation axis of the cam 10. Instead of the rotating cam 10, the arrangement could be provided with some other means for driving the piston 7. A receiving chamber 5, 5' is arranged around the valve stem 1b, 1b' of the intake valve 1, 1'. The receiving chamber 5, 5' is below the spring 12, 12'.
The middle part of the valve stem 1b, 1b' of the intake valve 1, 1' is provided with a projection 1c, 1c'. The projection 1c, 1c' has a first end that is arranged in the receiving chamber 5, 5' and a second end that is located closer to the cylinder, i.e. between the first end of the projection 1c, 1c' and the valve head 1a, 1a' of the intake valve 1, 1'. In the embodiment of the figures, the projection 1c, 1c' is an integral part of the valve stem 1b, 1b', but the projection 1c, 1c' could also be a sleeve that is arranged around the valve stem 1b, 1b'. A benefit of a separate sleeve is that different material can be used than in the valve 1, 1'. Different valve and sleeve combinations can be used according to the requirements of each application where the invention is used. First end of the projection 1c, 1c' forms a first piston surface 1d, 1d', which delimits the receiving chamber 5, 5'. The receiving chamber 5, 5' is connected to the pressurizing chamber 9 through a hydraulic fluid duct 6, 6'. When the hydraulic fluid in the pressurizing chamber 9 is pressurized by the piston 7, the fluid flows in the hydraulic fluid duct 6, 6' into the receiving chamber 5, 5' above the projection 1c, 1c'. The pressure in the receiving chamber 5, 5' acts on the first piston surface 1d, 1d' and pushes the intake valve 1, 1' downwards and opens the valve 1, 1'. The construction according to the invention is very compact, since the means for opening the gas exchange valves are arranged around the valve stems. The hydraulic fluid also lubricates the valve guides 15, 15' and valve stems 1b, 1b'. Second end of the projection 1c, 1c' forms a second piston surface 1e, 1e'. The second piston surface 1e, 1e' is located in the intake duct 2, and is thus exposed to the pressure in the intake duct 2. The pressure facilitates closing of the intake valve 1, 1' and a smaller valve spring 12, 12' can thus be used.
For ensuring that both the first intake valve 1 and the second intake valve 1' open simultaneously and the valve lift is equal in both valves 1, 1', the gas exchange valve arrangement is provided with an own pressure surface 8, 8' and hydraulic fluid duct 6, 6' for each of the valves 1, 1'. Also the pressurizing chamber 9 comprises a first portion and a second portion. A first hydraulic fluid duct 6 connects the first portion of the pressurizing chamber 9 to the receiving chamber 5 of the first intake valve 1. A second hydraulic fluid duct 6' connects the second portion of the pressurizing chamber 9 to the receiving chamber 5' of the second intake valve 1'. The piston 7 is provided with a first pressure surface 8 for pressurizing hydraulic fluid in the first portion of the pressurizing chamber 9, and with a second pressure surface 8' for pressurizing hydraulic fluid in the second portion of the pressurizing chamber 9. The first portion of the pressurizing chamber 9 is arranged at the end of the pressurizing chamber 9 and has a first diameter. The second portion of the pressurizing chamber 9 is concentric with the first portion and has a second diameter that is greater than the first diameter. The first pressure surface 8 of the piston 7 is arranged at the end of the piston 7 and pressurizes thus the hydraulic fluid in the first portion of the pressurizing chamber 9. The second pressure surface 8' is an elbow of the piston 7 and pressurizes the hydraulic fluid in the second portion of the pressurizing chamber 9. The areas of the first and the second pressure surfaces 8, 8' are equal, and the same amount of hydraulic fluid is thus delivered into the receiving chambers 5, 5' of the first and the second intake valves 1, 1'. Instead of a pressure chamber 9 with different portions for the first intake valve 1 and the second intake valve 1', the arrangement can be provided with separate pressure chambers 9 for each of the valves 1, 1'.
When the cam follower wheel 11a enters the descending slope of the lobe 10a of the cam 10, the piston 7 is allowed to move downwards in the pressurizing chamber 9. The force of the spring 12, 12' pushes the intake valve 1, 1' upwards, and consequently the hydraulic fluid is pushed through the hydraulic fluid duct 6, 6' back into the pressurizing chamber 9. The pressurizing chamber 9 is provided with hydraulic fluid inlets 13, 13' for introducing additional hydraulic fluid into the pressurizing chamber 9 to compensate leakages from the system. The hydraulic fluid inlets 13, 13' are provided with check valves 14, 14' for allowing flow into the pressurizing chamber 9 but preventing flow in the opposite direction.
It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may vary within the scope of the appended claims. For instance, the arrangement can be provided with a system for variable valve closing timing between the cam follower unit and the piston. Also, the construction of the piston surfaces can be different from the construction shown in the figures.

Claims

A gas exchange valve arrangement for an internal combustion engine, which arrangement comprises
- at least one gas exchange valve (1, 1') for opening and closing flow communication between a gas exchange duet (2) and a cylinder of the engine, the gas exchange valve (1, 1') comprising a valve head (1a, 1a') and a valve stem (1b, 1b'),

- a pressurizing chamber (9) for pressurizing hydraulic fluid,

- a reciprocating piston (7) that protrudes into the pressurizing chamber (9),

- a receiving chamher (5, that is arranged around the valve stem (1b, 1b') of the gas exchange valve (1, 1'),

- a hydraulic fluid duel (6, 6') for connecting the pressurizing chamber (9) to the receiving chamber (5, 5'),

- a piston surfaces (1d, 1d') that is arranged in the receiving chamber (5, 5') in connection with the valve stem (1b, 1b') for opening the gas exchange valve (1, 1'), and

- a second piston surface (1e, 1e') that is arranged in connection with the valve stem (1b, 1b') and exposed to the pressure in the gas exchange duet (2) for facilitating closing of the gas exchange valve (I. 1'),
characterized in that the arrangement comprises a spring (12, 12') that is arranged around the valve, stem (1b, 1b') and the receiving chamber (5,5') is arranged below the spring (12, 12').
An arrangement according to claim 1, characterized in that the second piston surface (1c, 1c') is in the gas exchange duet (2).
An arrangement according to claim 1 or 2, characterized in that the piston surfaces (1d, 1d', 1e, 1e') are at the ends of a projection (1c, 1c') that is arranged around the valve stem (1b, 1b').
An arrangement according to claim 3, characterized in that the a projection (1c, 1c^-) is a sleeve that is arranged around the valve stem (1b, 1b').
An arrangement according to claim 4, characterized in that the sleeve is made of a different material than the gas exchange valve (1, 1').
An arrangement according to claim 3, characterized in that the a projection (1c, 1c') is an integral part of the valve stem (1b, 1b').
An arrangement according to any of the preceding claims, characterized in that the pressurizing chamber (9) comprises a first portion with a first diameter and a second portion with a second diameter, and the arrangement comprises a first hydraulic fluid duct (6) for connecting the first portion of the pressurizing chamber (9) to a receiving chamber (5) of a first gas exchange valve (1) and a second hydraulic fluid duct (6') for connecting the second portion to a receiving chamber (5') of a second gas exchange valve (1'), and the piston (7) comprises a first pressure surface (8) for pressurizing hydraulic fluid in the first portion of the pressurizing chamber (9) and a second pressure surface (8') for pressurizing hydraulic fluid in the second portion of the pressurizing chamber (9).
An arrangement according to claim 7, characterized in that the first pressure surface (8) is arranged at the end of the piston (7) and the second pressure surface (8') is an elbow that is arranged at at distance from the end of the piston (7).
An arrangement according to any of claims 1-6, characterized in that the arrangement comprises one pressurizing chamber (9) and one piston (7) for each gas exchange valve (1, 1').
An arrangement according to any of the preceding claims, characterized in that the pressurizing chamber (9) is arranged in the cylinder head (3).
An arrangement according to any of the preceding claims, characterized in that the arrangement comprises a rotating cam (10) for moving the reciprocating piston (7).
An arrangement according to any of the preceding claims, characterized in that the gas exchange valve (1, 1') is an intake valve.
An arrangement according to any of claims 1-11, characterized in that the gas exchange valve (1, 1') is an exhaust valve.