EP2340362B1

EP2340362B1 - Control arrangement for a valve operating assembly and a method for controlling the closing movement of a valve operating assembly

Info

Publication number: EP2340362B1
Application number: EP09744424A
Authority: EP
Inventors: Magnus Sundsten
Original assignee: Wartsila Finland Oy
Current assignee: Wartsila Finland Oy
Priority date: 2008-10-29
Filing date: 2009-10-09
Publication date: 2012-09-05
Anticipated expiration: 2029-10-09
Also published as: FI20086021A; FI121245B; EP2340362A1; CN102197200A; CN102197200B; FI20086021A0; WO2010049583A1

Description

Technical field

The invention relates to a control arrangement for a valve operating assembly in a piston engine according to preamble of claim 1 as well as to a method for controlling the closing movement of a valve operating assembly in a piston engine according to preamble of claim 6.

Background art

There are situations in the operation of a four stroke internal combustion engine in which the cylinders are not provided with enough air for self-ignition to happen during the compression stroke. Such situations may appear especially during engine start and during load variations. One solution is to provide for a delay in the closing of the inlet valve for prolonging the opening time of the inlet valve when needed. An example for an arrangement of this kind of a variable inlet valve closure (VIC) is disclosed in patent publication WO 2008/000899 .
When a delay function is in use at the closing phase of the inlet valve the valve tappet member is for a while not directly in mechanical force transmission connection with the cam shaft. At a later phase this connection is however reestablished, but this must occur slowly enough to ensure smooth operation and prevent breaking of the parts in question. Therefore an efficient and reliable control arrangement is needed for the operation of the valve operating assembly and specifically for providing efficient braking of the movement of the valve tappet and other valve moving members included in the valve operating assembly.
An object of the invention is to provide a control arrangement for a valve operating assembly and a method for controlling the closing movement of a valve operating assembly, which solve the above mentioned problems of the prior art. A specific object of the invention is further to provide an efficient, straightforward and reliable braking method and arrangement to be adapted for the closing phase of a valve operating assembly in connection with the delay function of the inlet valve.

Disclosure of the invention

The objects of the invention can be met substantially as is disclosed in claims 1 and 6 and in the other claims. According to the first aspect of invention the guide member includes a third chamber, which is arranged to be in communication with the first duct for releasing of pressure in the first chamber, and a control piston located in said third chamber and movably arranged with regard to the guide member for controlling pressure medium flow through said third chamber.
The guide member is provided with a second duct for communication between the first duct and the third chamber and a third duct for releasing of pressure in said third chamber. The control piston is then arranged to control the opening and closing of said third duct.
Efficient operation of the arrangement can be achieved if the diameter of the third duct is smaller that the diameter of the second duct.
The control piston is arranged to partly extend out from the guide member after releasing of pressure in the first chamber for engaging with the piston device and braking its movement toward the guide member.
The outward extending movement of the control piston is with advantage accomplished by means of the hydraulic medium entering from the first chamber into the third chamber.
By means of the invention the braking function takes place in the upper part as well as in the lower part of the piston device included in the control arrangement of the valve operating assembly making the operation efficient and smooth. The braking function is available always when also the delay function for delaying the closing of the inlet valve is in use, and it is practically independent on the operating speed on the engine. Since the operation of the control piston can be accomplished by making use of the hydraulic medium normally utilised for the inlet valve delay function, an uncomplicated construction and reliable operation can be achieved.
The invention is further defined by a method for controlling the closing movement of a valve operating assembly in accordance with claims 6 and 7.

Brief Description of Drawings

In the following the invention is described in more detail, by way of example only, with reference to the accompanying drawings, in which

Figure 1 shows a piston engine and a skeleton diagram of its valve mechanism,
Figures 2 - 6 show an embodiment of a control arrangement according to the invention in separate consecutive stages of operation with the delay function for the delayed closing of the inlet valve being on, and
Figure 7 shows the embodiment of figures 2 - 6 in a certain stage of operation with the delay function for the delayed closing of the inlet valve being off.

Detailed Description of Drawings

Figure 1 shows a schematic view of a piston engine 1 as far as it is relevant to the understanding of the invention. The gas exchange of the cylinders (not shown) in the piston engine 1 is carried out under the control of gas exchange valves, i.e. inlet valves and exhaust valves, located on a cylinder head 2. Only inlet valves 3 are shown and they are operated by means of valve mechanisms 6 which are typically guided by the cam profiles of cam devices 5 arranged on a camshaft 4 of the engine. The force transmission connection between each valve mechanism 6 and the corresponding cam device 5 is realised by a control arrangement 7.
The control arrangement 7 is shown in more detail in Figures 2 - 6. The control arrangement 7 comprises a body part 8, which is typically attached to the engine body. A piston device 9 is movably arranged within the body part 8. The upper end of the piston device 9 is arranged in force transmission connection with the valve mechanism 6 (not shown closer). This connection may be mechanical or hydraulic. The movements of the piston device 9 are controlled by a guide member 10 arranged at the lower end of the piston device within the body part 8. The guide member 10 is in engagement with and urged by a spring 11 towards a roller 12, which receives its guidance from the cam profile of the cam device 5. Thus, when the cam shaft 4 rotates, in figures 2 - 6 counter-clockwise, the roller 12 follows the cam profile of the cam device 5, and the changes in the cam profile are transmitted via the control arrangement 7 and the valve mechanism 6 to the inlet valve 3 so as to affect the opening and closing of the inlet valve 3.
The body part 8 and the piston device 9 together define a first chamber 13, into which hydraulic medium can be selectively fed for providing a delay in the closing of the inlet valve 3. The feed line is provided with a shut-off valve 14 and a non-retum valve 15. By means of the shut-off valve 14 the feed line to the first chamber 13 may be connected or disconnected, depending on whether or not the aim is to use the delay function for the delayed closing of the inlet valve 3. Due to the non-retum valve 15 the control arrangement cannot cause any pulsations in the source of hydraulic medium. This is of importance when lubricating oil is used as a hydraulic medium.
The body part 8 is additionally provided with a duct 16 for releasing of pressure in the first chamber 13 and with a second chamber 17, which encloses the guide member 10, the spring 11 as well as the lower end of the piston device 9.
The guide member 10 includes a groove 10a in its mantle surface and is additionally provided with a third chamber 18. A duct 19 connects the groove 10a to the third chamber 18. A control piston 20 is movably arranged in the third chamber 18 and said chamber is further connected with ducts 21 and 22 to an oil sump providing lubrication for the camshaft and the parts connected therewith.
The function of the arrangement is as follows. In figure 2 the control arrangement 7 is inoperative and the roller 12 is located on the base circle of the cam profile of the cam device 5. In this phase the inlet valve 3 is closed (not shown). In figure 3 the cam device 5 has rotated counter-clockwise so that the cam part of the cam device 5 has lifted the roller 12 upwards in the figure. Thus, also the guide member 12 and the piston device 9 have moved upwards and as a consequence the corresponding inlet valve 3 has opened. Simultaneously the first chamber 13 is filled with hydraulic medium fed through the feed line 14 and 15.
In figure 4 the roller 12 has returned on the base circle of the cam device 5. As a consequence the guide element 10 has moved downwards in the figure as well, pressed by the spring 11, so that the groove 10a in the mantle surface of the guiding member 10 has moved at the position of the duct 16 connecting the first and the third chambers 13 resp. 18. Hereby also the pressure in the first chamber 13 is released so that the piston device 9 starts to move downwards in the figure thereby allowing also the inlet valve to start dosing. The movement of the piston device 9 is braked by the hydraulic medium still remaining in the chamber 13. Since the pressure in chamber 18 below the control piston 20 is at the same time increased and acts on the first end 20a of the control piston 20, the control piston 20 is forced upwards so that its second end 20b extends out from the guide member 10, as is disclosed in figure 4. As a consequence the connection between the chamber 18 and the duct 21 is opened. Since the diameter of the duct 21 is, however, smaller than that of the duct 19, the control piston 20 remains in the outward position of figure 4. Further, due to the continued movement of the guide member 10 the engagement between the piston device 9 and the guide member 10 is hereby cut off and the guide member 10 reaches is lowermost position under the pressure of the spring 11 and defined by the base circle of the cam device 5.
In figure 5 the piston device 9 has moved further downwards and engages the second end 20b of the control piston 20 starting to press the control piston 20 downwards in the figure. As a consequence the first end 20a of the control piston 20 starts to close the duct 21. Due to the increasing of pressure in chamber 18 also the control piston 20 starts to brake the downward movement of the piston device 9. Finally, as apparent from figure 5, the duct 21 is entirely closed by the control piston 20 whereby full braking effect is achieved both by the hydraulic pressure affecting the control piston 20 and the hydraulic pressure in the upper chamber 13 effecting directly on the piston device 9. Due to this combined braking operation providing increased braking area efficient braking is achieved.
In figure 6 the piston device 9 has moved again into contact with the guide member 10 and the cycle can restart.
Since the delay function for the delayed closing of the inlet valve is an option to be availed of in certain special situations, figure 7 illustrates the operation of the arrangement according to the invention under normal load situations of the engine. The situation of figure 7 corresponds to the one disclosed in figure 4, but in this case the feed line 14 and 15 is closed. As a consequence no hydraulic medium is fed into the chamber 13. The guide member 10 and the piston device 9 remain in direct contact through the whole operation cycle and the control piston is inoperative, since the chambers and ducts are mainly filled with air.

Claims

A control arrangement for a valve operating assembly in a piston engine adapted between a cam device (5) of a camshaft (4) of the engine (1) and an inlet valve mechanism (6) arranged to open and close the inlet valve (3) in association with a cylinder of the engine, which control arrangement (7) comprises a body part (8), in which a piston device (9) is movably arranged to be in force transmission connection with the camshaft (4) and the valve mechanism (6), the body part (8) and the piston device (9) together defining a first chamber (13), into which hydraulic medium can be selectively fed for providing a delay in the closing of the inlet valve (3), the body part (8) further being provided with a first duct (16) for releasing of pressure in the first chamber (13) under control of a guide member (10) movably arranged in the body part (8) between the cam device (5) and the piston device (9), characterised in that the guide member (10) includes a third chamber (18), which is arranged to be in communication with the first duct (16) and a control piston (20) located in said third chamber (18) and movably arranged with regard to the guide member (10) for controlling pressure medium flow through said third chamber (18).
Control arrangement according to claim 1, characterised in that the guide member (10) is provided with a second duct (19) for communication between the first duct (16) and the third chamber (18) and a third duct (21) for releasing of pressure in said third chamber (18), and that the control piston (20) is arranged to control the opening and closing of said third duct (21).
Control arrangement according to claim 2, characterised in that the diameter of the third duct (21) is smaller that the diameter of the second duct (19).
Control arrangement according to any one of the preceding claims, characterised in that the control piston (20) is arranged to partly extend out from the guide member (10) after releasing of pressure in the first chamber (13) for engaging with the piston device (9) and braking its movement toward the guide member (10).
Control arrangement according to claim 4, characterised in that the outward extending movement of the control piston (20) is accomplished by means of the hydraulic medium entering from the first chamber (13) into the third chamber (18).
A method for controlling the closing movement of a valve operating assembly in a piston engine by means of a control arrangement (7) adapted between a cam device (5) of a camshaft (4) of the engine (1) and an inlet valve mechanism (6) arranged to open and close the inlet valve (3) in association with a cylinder of the engine, which control arrangement (7) comprises a body part (8), in which a piston device (9) is movably arranged to be in force transmission connection with the camshaft (4) and the valve mechanism (6), the body part (8) and the piston device (9) together defining a first chamber (13), into which hydraulic medium is fed for providing a delay in the closing of the inlet valve (3), the body part (8) further being provided with a first duct (16) for releasing of pressure in the first chamber (13) under control of a guide member (10) movably arranged in the body part (8) between the cam device (5) and the piston device (9), char- - acterised in that the guide member (10) is provided with a third chamber (18) arranged to be in communication with the first duct (16) for leading hydraulic medium from the first chamber (13) into and through the third chamber (18), and that a control piston (20) movable with regard to the guide member (10) is located in said third chamber (18) for controlling the pressure in said third chamber (18) in order to break the closing movement of the valve operating assembly.
A method according to claim 6, characterised in that the releasing of pressure in the first chamber (13) is arranged to increase the pressure in the third chamber (18) such that the control piston (20) is moved with regard to the guide member (10) to extend partly out from the guide member (10) for engaging with the piston device (9) and braking its movement toward the guide member (10).