Cylinder valve assembly with valve spring venting arrangement

Abstract

The invention relates to a cylinder valve assembly (19) comprising a pneumatic valve spring arrangement (25) including a first (29) and a second (31) valve spring member defining a valve spring cavity (33), and a valve spring venting arrangement (27) comprising a first venting cavity portion (37) in fluid flow connection with the valve spring cavity (33); a second venting cavity portion (39); a movable sealing member (41) arranged to allow a pressure difference between the first venting cavity portion (37) and the second venting cavity portion (39); a feedback channel fluid flow connecting the first venting cavity portion (37) and the second venting cavity portion (39); and a venting channel (53). The sealing member (41) is configured to be movable between a first sealing member position where the sealing member (41) prevents fluid flow from the first venting cavity portion (37) through the venting channel (53); and a second sealing member position where the sealing member (41) allows fluid flow from the first venting cavity portion (37) through the venting channel (53). The valve spring venting arrangement (27) further comprises an elastic member (55) urging the sealing member (41) towards the first sealing member position.

Claims

1. A cylinder valve assembly for an internal combustion engine, comprising: a valve; a valve actuator for moving said valve; and a pneumatic valve spring arrangement including a first valve spring member and a second valve spring member defining a valve spring cavity, said second valve spring member being arranged to move in relation to said first valve spring member to compress gas in said valve spring cavity when said valve actuator moves said valve, wherein said cylinder valve assembly further comprises a valve spring venting arrangement comprising: a first venting cavity portion in fluid flow connection with said valve spring cavity to receive gas from said valve spring cavity; a second venting cavity portion; a movable sealing member arranged to allow a pressure difference between a first gas pressure in said first venting cavity portion and a second gas pressure in said second venting cavity portion; a feedback channel allowing fluid flow through the feedback channel from said first venting cavity portion to said second venting cavity portion; and a venting channel for gas exhaust from said valve spring venting arrangement, wherein said sealing member is configured to be movable between: a first sealing member position in which said sealing member is arranged in such a way that said sealing member prevents fluid flow from said first venting cavity portion through said venting channel; and a second sealing member position in which said sealing member is arranged in such a way that said sealing member allows fluid flow from said first venting cavity portion through said venting channel, wherein said valve spring venting arrangement further comprises an elastic member urging said sealing member to move from said second sealing member position towards said first sealing member position.

2. The cylinder valve assembly according to claim 1, wherein: said sealing member is configured to receive a first force resulting from the first gas pressure in said first venting cavity portion, and a second force resulting from the second gas pressure in said second venting cavity portion; said first force is directed to urge said sealing member to move towards said second sealing member position, and said second force is directed to urge said sealing member to move towards said first sealing member position; and said feedback channel, said sealing member, and said elastic member are dimensioned in such a way that said sealing member is moved from said first sealing member position to said second sealing member position during a portion of a time when said valve actuator moves said valve.

3. The cylinder valve assembly according to claim 1, further comprising a gas inlet for providing gas to said pneumatic valve spring arrangement.

4. The cylinder valve assembly according to claim 3, further comprising an inlet channel allowing fluid flow between said gas inlet and the first venting cavity portion of said valve spring venting arrangement.

5. The cylinder valve assembly according to claim 4, further comprising a counter-pressure channel that allows fluid flow to said second venting cavity portion.

6. The cylinder valve assembly according to claim 5, wherein said feedback channel comprises said inlet channel, said counter-pressure channel, and a pressure-levelling channel connected to allow fluid flow between said inlet channel and said counter-pressure channel.

7. The cylinder valve assembly according to claim 6, wherein a cross-sectional area of said pressure-levelling channel is smaller than a cross-sectional area of said inlet channel and a cross-sectional area of said counter-pressure channel.

8. The cylinder valve assembly according to claim 6, wherein a first end of said pressure levelling channel that is connected to said inlet channel is at a lower vertical level than a second end of said pressure levelling channel that is connected to said counter-pressure channel.

9. The cylinder valve assembly according to claim 1, wherein said valve actuator is a pneumatic actuator.

10. An internal combustion engine arrangement, comprising: a cylinder having an inlet and an outlet; and the cylinder valve assembly according to claim 1 arranged to allow control of fluid flow through at least one of the inlet and the outlet of said cylinder.

11. A vehicle comprising the internal combustion engine arrangement according to claim 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

(2) In the drawings:

(3) FIG. 1 is a side view of a vehicle according to an example embodiment of the present invention, in the form of a truck.

(4) FIG. 2 is a schematic illustration of a part of an ICE arrangement according to an example embodiment of the present invention.

(5) FIG. 3A schematically illustrates an example embodiment of a cylinder valve assembly according to the present invention.

(6) FIG. 3B is an enlargement of a portion of the cylinder valve assembly in FIG. 3A.

(7) FIG. 4 is a diagram illustrating an example venting sequence of the cylinder valve assembly in FIGS. 3A-B.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

(8) FIG. 1 schematically shows a vehicle, here in the form of a truck 1, including an ICE arrangement 3 according to an example embodiment of the present invention. The ICE arrangement 3 comprises a control unit 5 for controlling operation of the ICE arrangement 3.

(9) Referring to FIG. 2, the ICE arrangement 3 comprises a cylinder 7 having an inlet 9 and an outlet 11, a piston 13, a fuel supply member 15, a tank for holding fuel 17, a first cylinder valve assembly 19 for controlling flow through the inlet 9 using valve 20, and a second cylinder valve assembly 21 for controlling flow through the outlet 11 using valve 22. As is schematically illustrated in FIG. 2, the first cylinder valve assembly 19 comprises valve 20, valve actuator 23, pneumatic valve spring arrangement 25, and valve spring venting arrangement 27. The second cylinder valve assembly 21 has the same general configuration. As is also schematically shown in FIG. 2, the control unit 5 is connected to, and configured to control operation of, the fuel supply member 15, the first cylinder valve assembly 19, and the second cylinder valve assembly 21.

(10) An example embodiment of the cylinder valve assembly 19 will now be described with reference to FIGS. 3A-B.

(11) As was mentioned above in connection with FIG. 2, the cylinder valve assembly 19 comprises a valve 20, a valve actuator (not shown in FIG. 3A), a pneumatic valve spring arrangement 25, and a spring venting arrangement 27.

(12) Referring to FIG. 3A, the pneumatic valve spring arrangement includes a first valve spring member 29 and a second valve spring member 31, defining a valve spring cavity 33, and a coil spring 35. The coil spring 35 can be dimensioned to be relatively weak, and the main return force acting on the valve 20 when it is opened by the valve actuator may result from compression of the gas inside the valve spring cavity 33.

(13) With continued reference to FIG. 3A and FIG. 3B, the valve spring venting arrangement 27 comprises a first venting cavity portion 37 fluid flow connected with the valve spring cavity 33, a second venting cavity portion 39, a movable sealing member 41 arranged to allow a pressure difference between a first gas pressure P.sub.1 in the first venting cavity portion 37 and a second gas pressure P.sub.2 in the second venting cavity portion 39, a gas inlet 43, an inlet channel 45, a check valve 47, a counter-pressure channel 49, a pressure-levelling channel 51, a venting channel 53, and an elastic member 55.

(14) In the example embodiment of FIG. 3A and FIG. 3B, the inlet channel 45, the counter-pressure channel 49, and the pressure-levelling channel 51 together form a feedback channel fluid flow connecting the first venting cavity portion 37 and the second venting cavity portion 39.

(15) As is also indicated in FIG. 3A, a first end 52a of the pressure levelling channel 51 fluid flow connected to the inlet channel 45 is at a lower vertical level than a second end 52b of the pressure levelling channel 51 fluid flow connected to the counter-pressure channel 51.

(16) Furthermore, a cross-sectional area of the pressure-levelling channel 51 is smaller than a cross-sectional area of the inlet channel 45 and a cross-sectional area of the counter-pressure channel 49. It should be noted that the first venting cavity portion 37 is in fluid flow connection with the valve spring cavity 33 through a flow channel having a first minimum cross-sectional area, and that the feedback channel has a second minimum cross-section area smaller than the first minimum channel cross-sectional area. In the example embodiment of FIGS. 3A-B, the second minimum cross-sectional area is the cross-sectional area of the pressure-levelling channel 51.

(17) A valve lift sequence, including valve spring venting, using the cylinder valve assembly 19 in FIGS. 3A-B will now be described with reference to the timing diagram 57 in FIG. 4. The timing diagram 57 in FIG. 4, which is based on a simulation of the cylinder valve assembly 19 in FIGS. 3A-B, includes a first curve 59 representing displacement of the valve 20 during an opening sequence of the valve 20, a second curve 61 representing the first gas pressure P.sub.1 in the first venting cavity portion 37, a third curve 63 representing the second gas pressure P.sub.2 in the second venting cavity portion 39, a fourth curve 65 representing displacement of the sealing member 41, and a fifth curve 67 representing flow through the venting channel 53.

(18) As can be seen in FIG. 4, the variation of the first pressure P.sub.1 (curve 61) follows the displacement of the valve 20 (curve 59) (and the corresponding pressure increase inside the valve spring cavity 33) with practically no delay. The variation of the second pressure P.sub.2 (curve 63) is, however, delayed in relation to the first pressure P.sub.1 (curve 61), due to the passage of gas through the feedback channel, which comprises the input channel 45, the counter-pressure channel 49, and the pressure-levelling channel 51 in the example configuration of FIGS. 3A-B. Due to the initial pressure difference between the first pressure P.sub.1 (curve 61) and the second pressure P.sub.2 (curve 63), the sealing member 41 moves away from the first sealing member position (the position shown in FIG. 3B) to the second sealing member position, where a fluid passage between the first venting cavity portion 37 and the venting channel 53 is opened (towards the left in FIG. 3B). As was mentioned above, this movement of the sealing member is represented by the fourth curve 65 in FIG. 4. When the second pressure P.sub.2 (curve 63) again “catches up” with the first pressure P.sub.1 (curve 61) so that the combined force from the left in FIG. 3B resulting from the second pressure P.sub.2 and the elastic member 55 acting on the sealing member 41 surpasses the force from the right resulting from the first pressure P.sub.1 acting on the sealing member 41, the sealing member 41 moves back to close the venting channel 53. This movement back and forth of the sealing member 41 results in the flow of gas (which may advantageously include oil mist) represented by the fifth curve 67 in FIG. 4 through the venting channel 53.

(19) It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.