JPS6270608A - Valve operation apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a valve operating device for a reciprocating piston internal combustion engine, which includes a cam device rigidly fixed on a camshaft, and a valve operating device that cooperates with the cam device. and a transmission device acting on the valve against at least one valve spring acting in the valve closing direction.

BACKGROUND OF THE INVENTION The intake and exhaust valves of reciprocating piston internal combustion engines are typically operated as follows. This means that the cam of the camshaft acts via a transmission element, which is designed, for example, as a tappet, on the valve, which is loaded in the closing direction by a valve spring, the tappet being kept in constant contact with the cam by the valve spring. ing. The opening flank of the cam, which is the cam surface for opening the valve, and the Krogh-Kungzrank, the cam surface for closing the valve, define the opening and closing times of the valve, and these times are immovable in relation to the crankshaft angle. and is unchanging.

However, attempts have been made to vary at least the closing time of the intake valve as a function of the respective operating state of the internal combustion engine, in particular as a function of the rotational speed. This is done, for example, in order to obtain good torque characteristics of the engine by means of a relatively early closing time of the intake valve at low rotational speeds. On the contrary,
At high rotational speeds of the internal combustion engine, a later closing time of the intake valve is required in order to increase the output.

Devices that allow such variable control of valve opening and closing times are already known. However, this device does not avoid a complex structure and a high technical outlay, and is also prone to failures.

SUMMARY OF THE INVENTION The invention is a device for varying the opening and closing times of gas exchange valves of reciprocating piston internal combustion engines as simple as possible, which can be implemented without significant technical outlay, and which The challenge is to provide something that functions safely and reliably.

Means for Solving the Problems The present invention has solved these problems as follows. That is, the cam arrangement comprises one cam which has an opening flank that defines the opening of the valve but does not have a closing flank that guides the transmission device when the valve is closed, and the closing of the valve is effected from the cam. This occurs after the transmission has been disengaged, at a point determined primarily only by the spring force of the valve spring. With such a configuration, a valve operating system is obtained which allows at least the valve closing time to be easily adapted to the varying rotational speed of the internal combustion engine. The closing of the valve is no longer effected by a corresponding closing flank of the cam, but is instead subject to the free movement of the mass consisting primarily of the valve and transmission system and the spring force of the valve spring acting on it. In this case, the spring force of the valve spring is set as follows. This means that the valve is closed at the lowest speed of the internal combustion engine, i.e. at idling speed, within the range of the bottom dead center of the associated piston, and at the latest at the maximum permissible speed, or even earlier, when the piston is closed from the bottom dead center. It is set to close when the maximum crank angle interval is reached.

In order to avoid a strong impact of the valve against the valve seat when the valve is closed, it is advantageous if a particularly hydraulic damper device is provided for damping the closing movement of the valve.

The cam device comprises at least one second cam having an opening flank and a closing flank, and a second transmission device kept in constant contact with the second cam by a second valve spring; It is further advantageous if the transmission device is configured in such a way that it can be connected to the valve via a driving connection that acts in the valve closing direction. In such a configuration, if the second cam's claw, Kungzrank, is set to close the valve when the piston reaches a predetermined maximum crank angle spacing after bottom dead center, the valve closing delay can definitely be avoided. On the other hand, premature closing of the valve can be brought about as described above by means of the first transmission device belonging to the first cam and the first valve spring acting on it.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will now be described in more detail according to the embodiments shown in the drawings: In FIG. This valve operating device is used for operating the intake valves of conventional reciprocating piston internal combustion engines. This valve is designated by the numeral 2.

The valve 2 has a valve stem 3 that is slidably guided in a guide sleeve Φ held in a cylinder head housing 5 and is moved via a transmission device 6, 7 against the force of a valve spring 10.11. It is operated by a cam device 34 shown in FIG.

The cam device 34 includes a first cam 3 held on a cam shaft 35.
6 and a second cam 36 disposed on both sides in contact with the first cam 36.
It consists of cams 37a and 37b. As can be seen in FIG. 3, the first cam 36 only has an opening flank 38 extending over an angle α and optionally following this an open-keeping flank 39 extending over an angle β, and has a closing flank. whereas the second cams 37a, 37bfd, as shown in FIG. It has 39. The angular ranges of the opening flank 38 and the open-keeping flank 39 are the same for all cams, whereas the closing flank 0, which spans the angular range γ, is the second cam 37a,
37b.

The first cam 36 of the cam device 34 is adapted to cooperate with the first transmission device #6. The first transmission device 6 consists of a tappet acting on the free end of the valve stem 3, which tappet is connected to a disc part 13 having an annular part 13a on its outer circumference as well as to this disc part 13. The ram portion 14 has a width approximately corresponding to the width of the first cam 36. This first tappet 6 is guided in a relatively adjustable manner inside a bowl-shaped second tappet 7 which forms a second transmission device. In this case the first tappet 6
The annular part 13a slides in an internal cylinder 18 of the peripheral wall 16 of the second tappet 7, and the ram part 14 passes through a recess 15 provided in the bottom part 19 of the second tappet 7.

A first valve spring 1o is attached to the first tappet 6, and this valve spring 1o has its lower end, as seen in the figure, connected to the valve stem 3.
It is supported by a flange 23a located on the cylinder head housing 5 of a cylindrical sleeve 23 surrounding the cylinder head housing 5 at a distance. The upper end of this valve spring IQ presses against one spring receiver 9. As is well known, the spring receiver 9 is connected to the valve stem 3 through a split conical ring 8 which is engaged with and held at the end of the valve stem 3. A second transmission device consisting of a bowl-shaped tappet 7 is loaded by a spring 11 which is located outside the valve spring 10. This spring 11 also rests with its lower end in the figure on a flange 23a of a cylindrical sleeve 23 and presses with its upper end against a closing flange 12 provided at the lower end of the tappet jacket 16.

Reference numeral 22 indicates one hydraulic damper.

This hydraulic damper includes the aforementioned cylindrical sleeve 23 that surrounds the valve stem 3 at intervals, and a ring piston 24 that is fixed to the valve stem 3 and is slidably guided over the inner wall of the cylindrical sleeve 23. It consists of The ring piston 24 has one upper working chamber 25 within the cylindrical sleeve 23.
The working chamber 25 is connected to the surrounding valve spring chamber 30 via a throttle hole 26.

A chamber 27 formed under the ring piston 24 is
The valve spring chamber 30 is connected to the valve spring chamber 30 through one horizontal hole 28 formed in the flange 23a and having a cross-sectional area significantly larger than that of the throttle hole 26.
It is connected to the.

The downward opening movement seen in the valve 20 diagram is the chamber 27 and the valve spring chamber 3.
0 is generally undamped as a result of the relatively large cross-sectional area of communication with the valve 2, whereas during the closing movement of the valve 2, the hydraulic working medium contained in the working chamber 25, e.g. lubricating oil is forced out of the throttle hole 26 with a delay on the return of the valve 2, resulting in an effective damping of the valve closing movement. Since only a relatively small amount of oil reaches into the working chamber 25 during the opening movement of the valve 2 - for example via the annular groove 29 formed in the valve stem 3 - the damping action occurs in the last part of the closing stroke of the valve. In other words, it mainly occurs just before the valve hits the valve seat.

When using the valve operating device according to the invention, the opening movement of the valve 2 takes place virtually the same as in conventional valves, i.e. the cam 36
Or opening flank 38 of 37a, 37b
Operate the attached tappet 6 or 7 in the opening direction,
The cams are connected to the adjacent end faces 20.2 of both tappets 6.7.
1, whereas after the valve 2 is fully opened, a closing movement occurs, which is different from the conventional example. That is, since the first cam 36 of the cam device 34 does not have a claw, the first tappet 6 and the valve 2 are connected to each other after the cam has left the first tappet 6. A mass consisting of other structural parts is free to move under the action of the first valve spring 10. This spring mass system provides a constant absolute closing time, so that a closing of the valve 2 occurs in each case as a function of the crank angle as a function of the rotational speed of the internal combustion engine. In this case, at low rotational speeds of the internal combustion engine, the closing point is relatively early in the working stroke of the associated piston, whereas at relatively high rotational speeds, the closing point of the valve is correspondingly delayed. By correspondingly designing the valve spring 10, it is possible to ensure that at the lowest speed, i.e. at the idle speed, the closing point of the valve approximately coincides with reaching the bottom dead center of the piston at the end of the intake stroke. . It can also be provided that the valve closes at the maximum rotational speed of the internal combustion engine at the latest after the bottom dead center of the associated piston at a predetermined crank angle interval. In order to be able to simultaneously fulfill both such requirements, the moment of separation of the first cam from the first tappet 6 can be delayed, i.e. following the end of the opening flank 38 the opening can be maintained further. A flank can be provided to keep the valve fully open over a certain angular range. This open maintenance flank 3
Only when the ninth and last edge leaves the tappet 6 does free movement of this system of first tappet 6, valve 2 and first valve spring 10 occur.

As mentioned above, first, the second cams 37a, 37
b, as well as independently of the transmission device 7 cooperating with these cams, which, starting from the eye P-ring rotational speed of the internal combustion engine, control the valve movement with increasing delay within the working stroke of the associated piston with increasing rotational speed. A closure occurs, which, as is known, causes an increase in the output of the internal combustion engine. In short, the transmission device consisting of the first cam 36 and the associated first tappet 6 primarily functions here.

By the way, if we consider that the valve closes at a predetermined crank angle interval from the bottom dead center of the piston, even at a rotation speed lower than the maximum allowable rotation speed of the internal combustion engine, In order to prevent a delay in closing the valve during the actuation stroke of the piston, the second cam 37
It becomes necessary to use a system comprising a, 37b and a second transmission associated with these cams.

This second transmission device 7 consists of a bowl-shaped tappet with a peripheral wall 16 and a bottom 19, which is connected to an outer second valve spring 11 which is considerably more rigid than the first valve spring 10. is under a load of This second tappet by its end face 21 has two second cams 37a,
37b, the cams 37a, 37b conventionally also have an opening flank 38 and, if necessary, a closing flank 40 as well as an opening-keeping flank, so that the associated piston is not affected during the working stroke. The latest closing time of the valve is determined. This second transmission device, in short the second transmission #7, which is permanently moved and whose peripheral wall 16 slides into the cylinder in the bore 17 of the Radhow-Kung 5, is connected to the valve spring mass system consisting of the first transmission device 6. is not used to close the valve while causing premature closure of the valve. The limit rotational speed, i.e. the valve is connected to the first transmission device 6
The second transmission device 7 becomes effective only when the maximum permissible crank angle distance from the bottom dead center of the piston exceeds the limit rotational speed at which the valve is closed. entrainment and thus the closing of the valve 2 at a time defined by the second cam. In this case, the closing flank 40 of the second cam 37a, 37b, which regulates the closing of the valve, can be constructed in the form of a so-called output cam, so that it Closing of the valve occurs at the point at which a power increase is obtained.

According to one embodiment, the opening flank has a cam angle of 3
The closing crank is formed over a crank angle range of about 60', which corresponds to a cam angle of about 70', and includes an open-keeping flank.
It can be formed over an angular range of 80° to 80'. With this configuration, if the opening of the intake valve begins approximately at the top dead center of the associated piston, the latest closing point of the intake valve in relation to the crank angle is the piston bottom dead center reached at least 40 minutes. Time points corresponding to crank angles of ˜500° are given. The open-keeping flank 39, indicated by the numeral 39, may extend up to approximately 15 degrees of crank angle, although this is not necessarily an essential requirement for the function of the valve operating device of the present invention.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a valve operating device according to the present invention, FIG. 2 is a side view of a camshaft equipped with a cam device according to the present invention, and FIG. 3 is a cross-sectional view taken along the line ■-■ in FIG. , FIG. 4 is a cross-sectional view taken along the line IV--IV in FIG. 2. DESCRIPTION OF SYMBOLS 1... Valve operation device, 2... Valve, 3... Valve system, Cow... Guide sleeve, 5... Cylinder head housing, 6, 7... Transmission device (tappet), 8...・
・Conical ring, 9... Spring receiver, 10... Valve spring, 11... Valve spring, 12... Closing flange, 13.
... Disc part, 14... Ram part, 15... Notch part, 16... Peripheral wall, 17... Hole, 18... Internal cylinder, 19... Bottom, 20.21.・End face, 22
... Damper device, 23 ... Cylindrical bushing, 23a.
...7 lunge, 24...ring piston, 25...
Working chamber, 26... Throttle hole, 27... Chamber, 28...
Horizontal hole, 29...Ring groove, 30...Spring chamber, 34
...Cam device, 35...Camshaft, 36...First cam, 37a, 37b...Second cam, 38...
Opening flank, 39...Open maintenance flank,
Cow ○... to the closing flank hebe to the ordinary 1 to 1 hebe be he\to 1 60)”

Claims (1)

[Claims] 1. A valve operating device for a reciprocating piston type internal combustion engine, which includes a cam device rigidly fixed on a camshaft, and a cam device that cooperates with the cam device to act in the valve closing direction. and a transmission device acting on the valve against at least one valve spring, the cam device (34) having an opening flank (38) defining the opening of the valve. is equipped with one cam (36) without a closing flank that guides the transmission device (6) during the closing of the valve (2), and the closing of the valve depends primarily on the valve spring (36) after the transmission device leaves the cam. 10) Valve operating device, characterized in that it occurs at a point defined only by the spring force of item 10). 2. The spring force of the valve spring (10) is such that the valve (2) is closed within the range of the bottom dead center of the associated piston at the lowest speed of the internal combustion engine (idling) and closed at the latest at the maximum permissible speed. The valve operating device according to claim 1, wherein the valve operating device is configured to be closed when the piston reaches a predetermined maximum crank angle interval after dead center. 3. The cam (36) follows the opening flank (36) to keep the valve (2) in the fully open position for a predetermined crank angle1.
Valve operating device according to claim 1 or 2, having two open-keeping flanks (39). 4. A damper device (
22), the valve operating device according to any one of claims 1 to 3. 5. The damper device surrounds the valve stem (3) belonging to the valve (2) and the cylinder head housing (5).
) sleeve-shaped spring receiver (23, 23a) connected to
One hydraulic damper member (24, 2
5, 26), the valve operating device according to claim 4. 6. The cam device (34) is connected to the opening flank (36
) and a closing flank (40), the permanent contact with this second cam is maintained by a second valve spring (11).
A second transmission device (7) is provided, which is held in the valve closing direction via one entrainment connection (8, 9, 12). Valve operating device according to any one of claims 1 to 5, which is connectable to the valve (2). 7. The closing flank of the second cam (37a, 37b) is provided for closing the valve when the piston reaches a predetermined maximum crank angle spacing after bottom dead center. The valve operating device described in . 8. The cam device (34) is provided with second cams (37a, 37b) adjacent to both sides of the first cam (36), and the second transmission device (7) is provided with a second valve spring (36). It consists of a bowl-shaped tappet loaded by a valve stem (11), which constitutes a first transmission device (6)
one ram-shaped tappet (13, 1) acting directly on
4) for supporting movable relative to each other (1).
5, 18), the valve operating device according to claim 6 or 7. 9. According to any one of claims 6 to 8, wherein the ram-shaped tappets (13, 14) are guided concentrically within the bowl-shaped tappets (16, 19). valve operating device.