EP2452054B1

EP2452054B1 - A control arrangement for an inlet valve in a piston engine

Info

Publication number: EP2452054B1
Application number: EP10731543.4A
Authority: EP
Inventors: Magnus Sundsten
Original assignee: Wartsila Finland Oy
Current assignee: Wartsila Finland Oy
Priority date: 2009-07-07
Filing date: 2010-06-04
Publication date: 2013-07-24
Anticipated expiration: 2030-06-04
Also published as: EP2452054A1; FI20095770A0; CN102472130B; KR101521335B1; WO2011004059A1; FI123927B; KR20120032519A; FI20095770A; CN102472130A

Description

Technical field

The invention relates to a control arrangement for an inlet valve in a piston engine according to preamble of claim 1.

Background art

There are situations in the operation of four stroke internal combustion engines in which the cylinders are not provided with enough air for self-ignition to happen during the compression stroke. This is specifically true as regards engines charged by high pressure such as two-stage turbo charged engines during engine start and during load variations. In engines of this kind higher pressures in combination with sharper or shorter cam nose forms are utilised resulting in charging action taking place in shorter time respectively. Hence, the opening times of the inlet valves under normal load of the engine are not long enough for such special situations.
One solution for providing a cylinder with enough air for compression ignition to occur is to arrange for a delay in the closing of the inlet valve for prolonging the opening time of the inlet valve when needed. Known solutions for such a variable inlet valve closure (VIC) are disclosed for instance in patent publication WO 2008/000899 .
An object of the invention is to provide a further improved control arrangement for gas exchange in a piston engine, which provides for wider possibilities for applying a delay function in the closing phase of an inlet valve. The invention is specifically aimed to be applied in turbo charged internal combustion engines referred above, so that problems of insufficient inlet air apparent in engines when operated for instance under low engine loads and during start of the engine can be tackled and solved accordingly in an optimal way.

Disclosure of the invention

The objects of the invention can be met substantially as is disclosed in claim 1 and more specifically in the other claims presenting more details of different embodiments of the invention.
The basic idea of the invention is to provide for a variable timing of the delay function in the closing phase of an inlet valve so as to better comply with the conditions in each case. According to the invention this is accomplished in practice so that the control means for controlling the releasing of pressure in the first chamber include a bevel control surface arranged for changing and variably adjusting the timing of the releasing of pressure in the first chamber.
Some level control surface is used for exemple in publication US 7137374 B1 .
The control means are with advantage arranged in a member reciprocatingly movable in the direction of the lifting movement guided by the cam device to control flow through an outlet flow duct in connection with the first chamber. In order to accomplish an adjustment the control means are arranged to be turnable around the axis of movement thereof for changing the position of the bevel control surface with regard to the outlet flow duct, and thus, timing of the releasing of pressure in the first chamber.
In one embodiment the control means comprise a turnable piston member, which is guided by the guide member, said piston member being arranged to move in crosswise direction with regard to the outlet flow duct to control the flow to be led through the piston member. In this case the guide member presses the piston member against the force of a spring when the control arrangement moves in the direction for lifting the inlet valve.
In another embodiment in which the first chamber is connected to a second chamber via the outlet flow duct, the opening of the outlet flow duct into the second chamber is selectively controlled by the guide member. In this case the control means are arranged in association with the guide member, in practice with advantage so that the control means are arranged in a sleeve member turnably attached to the guide member. The control means include a slot arranged in the sleeve member and extending in crosswise direction with regard to the opening of the outlet flow duct to control the flow therethrough. Then the relative position between the opening of the outlet flow duct and the slot can be adjusted by turning the sleeve member around its axis.
In practice the slot may with advantage be triangular and arranged such that one end in the form of an acute angle corresponds to the maximum delay in the closing of the inlet valve and another end in the form of a side of the triangle, substantially extending in the direction for lifting the inlet valve, corresponds to a situation where no delay is accomplished. Then said acute angle and said side of the triangle are connected to each other by means of the bevel control surface. Hereby full regulation from maximum delay to minimum delay can be accomplished by the control means only, whereby the minimum delay equals with no delay at all.
The control means include a slot arranged in the guide member and extending in crosswise direction with regard to the opening of the outlet flow duct to control the flow therethrough. The guide member is turnable around its axis to change the relative position between the opening of the outlet flow duct and the slot.
In a still further embodiment the control means comprise a separate piston element arranged between the piston device and the guide member. The outlet flow is led through said piston element. In this case the piston element is arranged to be turned around its axis for changing the relative position between the outlet flow duct and the piston element.
The outlet flow under pressure from the first chamber after the outlet flow duct and the control means is with advantage is led to the hydraulic medium feed line of the first chamber to be recirculated into the first chamber, and/or to be utilised in other pressure medium systems and devices in the engine.
In practice, further, regulating means, preferably a regulation shaft are provided for accomplishing the turning movement of the control means. The regulation means are movably supported on the body part and are controlled by a control unit for achieving optimum timing for the delay in the closing of the inlet valve in view of the operation of the engine in each case. One or more, or all the inlet valves of the engine, may be controlled and regulated simultaneously.

Brief Description of Drawings

In the following the invention will be described, by way of example only, with the reference to the accompanying schematic drawings, in which

Figure 1 shows a piston engine and a skeleton diagram of its valve mechanism,
Figure 2 shows a first embodiment of a control arrangement according to the invention,
Figure 3 shows a second embodiment of a control arrangement according to the invention,
Figure 3a is a partial detail view in direction D of Figure 3, and
Figure 4 shows a third embodiment of a control arrangement according to the invention,
Figure 5 shows a fourth embodiment of a control arrangement according to the invention in a situation corresponding to the maximum delay in the closing of the inlet valve of the engine,
Figure 5a shows section A-A of Figure 5,
Figure 5b shows section B-B of Figure 5,
Figure 6 shows the control arrangement of Figure 5 in a second operation position,
Figure 6a shows section C-C- of Figure 6,
Figure 7 shows the control arrangement of Figure 5 in a third operation position,
Figure 7a shows section D-D of Figure 7,
Figure 8 shows the control arrangement of Figure 5 in a fourth operation position,
Figure 8a shows section E-E of Figure 8,
Figure 9 shows the embodiment of Figure 5 in a situation corresponding to the minimum delay in the closing of the inlet valve of the engine,
Figure 9a shows section A'-A' of Figure 9,
Figure 9b shows section B'-B' of Figure 9,
Figure 10 shows the control arrangement of Figure 9 in a second operation position,
Figure 10a shows section C'-C' of Figure 10,
Figure 11 shows the control arrangement of Figure 9 in a third operation position,
Figure 11 a shows section D'-D' of Figure 11.

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 cam profiles 5' 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 2-4 showing different embodiments of the invention. 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 9 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 5' of the cam device 5. Thus, when the cam shaft 4 rotates, in Figures 2 - 4 counter-clockwise, the roller 12 follows the cam profile 5' of the cam device 5, and the changes in the cam profile 5' are transmitted 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 via an inlet duct 14 for providing a delay in the closing of the inlet valve 3. The feed line is provided with a non-return valve 15, a shut-off valve 16 and pump means 17. By means of the shut-off valve 16 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-return 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. As regards general operation of the delay function as such reference is made to the document WO 2008/000899A1 , which is hereby incorporated by reference, describing some alternative ways of implementing such an arrangement in general and the operation thereof.
The cam profile 5' includes a nose 5" extending upwards from the base circle and being arranged to move the piston device 9 upwards in the figures for providing opening of the inlet valve 3. In the versions disclosed in Figures 2 - 4 the cam profile 5' includes additionally a portion arranged under the base circle. This is utilised for defining generally the end of the delay function corresponding to the releasing of pressure in the first chamber 13, whereby by means of the present invention an additional variation of timing of the closing phase of the inlet valve can be accomplished. The role of the cam profile disclosed is explained in more detail in a Finnish patent application no. 20085756 , but since it is not directly involved with the present invention and the present invention can be applied also independently, its function is not explained more in detail in this connection.
The body part 8 is additionally provided with an outlet flow duct 18 by means of which the pressure in the first chamber 13 can be released for closing the inlet valve 3. The invention is involved with controlling more precisely the releasing of pressure in the chamber 13.
For this purpose, according to the embodiment of Figure 2, a piston member 19 including an opening with a bevel control surface 19a is provided. Thus, the hydraulic medium in chamber 13 may be led via the outlet flow duct 18 through the piston member 19 and further away via a flow duct 18a. When desired the outlet flow under pressure from the duct 18a may be availed of further in the engine. Specifically it may be led to the hydraulic pressure medium feed line of the chamber 13 to be fed back into the chamber 13 for providing the delay function of the inlet valve. In addition, or alternatively, it may be utilised in other pressure medium systems and devices in the engine. These alternatives are indicated just schematically by the arrows in broken line in Figure 2.
The piston member 19 is guided by means of the guide member 10, pressing it upwards in the figure against a spring 20 during the lifting movement relating to the opening of the inlet valve following the situation of Figure 2. The piston member 19 can be turned around its axis by means of spline means 21 arranged to cooperate with a regulating shaft 22, which is moved in the direction of its axis for turning the piston member 19. Thus, for releasing the pressure in the chamber 13, it is possible to adjust the exact moment, when the opening with the bevel control surface 19a in the piston member 19 moves to the position of the outlet flow duct 18, urged by the spring 20, during the return movement of the piston device 9 and the guide member 10 after roller 12 has passed the nose 5". The movements of the regulating shaft 22 are controlled by a control unit 34 for achieving optimum timing for the delay in the closing of the inlet valve 3 in view of the operation of the engine in each case.
In accordance with the embodiment of Figure 3 the outlet flow duct 18 connects the first chamber 13 with a second chamber 23, which is defined by the body part 8 and the guide member 10 and in which the lower end of the piston device 9 is located. Also the spring 11 is located in this second chamber 23.
In this case the control means are arranged in a sleeve member 24 turnably attached to the guide member 10 for controlling the opening of the outlet flow duct 18 into the second chamber 23. As can be best seen from Figure 3a the control means include a slot 25 arranged in the sleeve member 24 and extending in crosswise direction with regard to the opening of the outlet flow duct 18 to control the flow therethrough by means of a bevel control surface 25a. Again, the relative position between the opening of the outlet flow duct 18 and the slot 25 is adjusted by turning the sleeve member 24 around its axis by means of spline means 26 arranged in the sleeve member 24 and a regulating shaft 27. As can be seen from the drawing the second chamber 23 is provided with outlet ducts 28 for leading the hydraulic medium further away for instance to the oil sump of the engine.
In the embodiment of Figure 4 the control means comprise a separate piston element 29 arranged between the piston device 9 and the guide member 10. The hydraulic medium from the outlet flow duct 18 is led through an opening with a bevel control surface 29a in said piston element 29, and further away via the flow duct 18a. In this case the piston element 29 is arranged to be turned around its axis by means of spline means 30 arranged in the piston element 29 and the regulating shaft 31 for changing the relative position between the opening of the outlet flow duct 18 and the opening with the bevel control surface 29a in the piston element 29. In analogy with the embodiment of Figure 2 also in this case the outlet flow under pressure from the duct 18a may be recirculated to be fed into the chamber 13, and/or it may be utilised in other pressure medium systems and devices in the engine making use of pressure medium.
Figures 5-11 relate to a fourth embodiment of the invention which basically resembles the embodiment of Figure 3. In this case, however, the arrangement for providing turning movement of a sleeve member 24' is different so that a regulating shaft 33 is provided with a transversal groove 33a in which a guide pin 32 fixed to the sleeve member 24' is located. Thus, moving the regulating shaft 33 axially moves at the same time the pin 32 together with the sleeve member 24', which is hereby turnable between two end positions corresponding to the selected delay of the timing of the closing of the inlet valve. The arrangement with the transversal groove 33a allows also mutual movement of the guide pin 32 and the regulating shaft 33 during the lifting movement of the inlet valve. This is also true with the corresponding arrangements disclosed in Figures 2-4 since the spline means are dimensioned long enough in the direction of the lifting movement.
Another difference in comparison with the embodiment of Figure 3 is the shape of the slot 25', which in this case is basically triangular and arranged in the sleeve member 24' so that one end in the form of an acute angle corresponds to the maximum delay in the closing of the inlet valve 3 and another end in the form of a side of the triangle corresponds to a situation where no delay is accomplished. This slot 25' is then provided with a bevel control surface 25'a connecting the acute angle and the side of the triangle as apparent from the figures, thereby providing stepless control of the delay function.
The Figures 5-8 and 5a - 8a illustrate the operation of the arrangement in different operation phases in a situation corresponding to the maximum delay in the closing of the inlet valve of the engine. As is apparent specifically from Figures 7a and 8a the opening of the outlet flow duct 18 is located close to the acute angle in the slot 25' providing a maximum delay. In addition, as shown in Figure 7 there is a gap between the piston device 9 and the guide member 10 as long as the delay function is in operation.
On the other hand the Figures 9-11 and 9a-11a illustrate the operation of the arrangement correspondingly in different operation phases in a situation corresponding to the minimum delay in the closing of the inlet valve of the engine. After the position of Figure 11 the roller 12 will be back on the base circle of the cam device 5, whereby the positions of the different parts correspond to those in Figure 9.
As can be seen from Figure 11 representing closing phase of the inlet valve there is no gap between the piston device 9 and the guide member 10. Thus, in this case the minimum delay represents also a situation where there is no delay at all provided. Thereby it is not necessary to utilise the shut-off valve 16 (cf. Figure 2) for eliminating the delay function, but this can with advantage be accomplished by means of the suitable design of the control means.
The cam profile 5' with nose 5" of the cam device 5 is in this case conventional, which, in addition to the one shown in Figures 2 - 4, is also well suited for the operation of the control arrangement according to the invention.
The invention is not limited to the embodiments disclosed but different variations are feasible within the scope of the attached claims.

Claims

A control arrangement for an inlet valve 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 cam device (5) and the valve mechanism (6), and a guide member (10) arranged in the body part (8) between the cam device (5) and the piston device (9) to be movably responsive with the movements of the cam device (5), said body part (8) and the piston device (9) together defining a first chamber (13), into which hydraulic medium can be selectively fed, the flow of hydraulic medium out from the first chamber (13) being controlled for providing a delay in the closing of the inlet valve (3), characterised in that the control means for controlling the releasing of pressure in the first chamber (13) include a bevel control surface (19a;25a;25'a;29a) arranged for changing the timing of the releasing of pressure in the first chamber (13) to adjust the delay in the closing of the inlet valve (3).
A control arrangement according to claim 1, characterised in that the control means are arranged in a member (19;24;29) reciprocatingly movable in the direction of the lifting movement guided by the cam device (5) to control flow through an outlet flow duct (18) in connection with the first chamber (13).
A control arrangement according to claim 2, characterised in that the control means are turnable around the axis of movement thereof for changing the position of the bevel control surface (19a;25a;25'a;29a) with regard to the outlet flow duct (18), and thus, timing of the releasing of pressure in the first chamber (13).
A control arrangement according to claim 2 or 3, characterised in that the control means comprise a turnable piston member (19), which is guided by the guide member (10), said piston member (19) being arranged to move in crosswise direction with regard to the outlet flow duct (18) to control the flow to be led through the piston member (19).
A control arrangement according to claim 4, characterised in that the guide member (10) presses the piston member (19) against the force of a spring (20) when the control arrangement moves in the direction for lifting the inlet valve (3).
A control arrangement according to claim 2 or 3, characterised in that the first chamber (13) is connected to a second chamber (23) via the outlet flow duct (18), that the opening of the outlet flow duct (18) into the second chamber (23) is selectively controlled by the guide member (10), and that the control means are arranged in association with the guide member (10).
A control arrangement according to claim 6, characterised in that the control means are arranged in a sleeve member (24;24') turnably attached to the guide member (10), that the control means include a slot (25;25') arranged in the sleeve member (24;24') and extending in crosswise direction with regard to the opening of the outlet flow duct (18) to control the flow therethrough, the relative position between the opening of the outlet flow duct (18) and the slot (25;25') being adjusted by turning the sleeve member (24;24') around its axis.
A control arrangement according to claim 7, characterised in that the slot (25') is triangular and arranged such that one end in the form of an acute angle corresponds to the maximum delay in the closing of the inlet valve (3) and another end in the form of a side of the triangle, substantially extending in the direction for lifting the inlet valve (3), corresponds to a situation where no delay is accomplished, said acute angle and said side of the triangle being connected to each other by means of the bevel control surface (25'a).
A control arrangement according to claim 2 or 3, characterised in that the control means comprise a separate piston element (29) arranged between the piston device (9) and the guide member (10), the outlet flow being led through said piston element (29).
A control arrangement according to claim 9, characterised in that the piston element (29) is arranged to be turned around its axis for changing the relative position between the outlet flow duct (18) and the piston element (29).
A control arrangement according to claim 4 or 9, characterised in that the outlet flow under pressure from the first chamber (13) after the outlet flow duct (18) and the control means is led to the hydraulic medium feed line of the first chamber (13) to be recirculated into the first chamber (13), and/or to be utilised in other pressure medium systems and devices in the engine.
A control arrangement according to claim 3, characterised in that regulating means, preferably a regulation shaft (22;27;31;33), are provided for accomplishing the turning movement of the control means, said regulation means being movably supported on the body part (8) and being controlled by a control unit (34) for achieving optimum timing for the delay in the closing of the inlet valve (3) in view of the operation of the engine in each case.