Valve Shut-Off Arrangement for a Multicylinder Internal Combustion Engine

The present invention relates to a multicylinder internal combustion engine and, more particularly, to a six or eight cylinder internal combustion engine provided with a valve shut-off means and with a cam shaft having non-rotatably supported thereon a hollow shaft with cams, which hollow shaft is connected with transmitting elements operating the valves effecting a shut-off action of the engine.

In order to lower a power consumption of high power internal combustion engines with six or eight cylinders under certain operating conditions it has been proposed in, for example, German Patent Application P 29 30 967.9 to interrupt the fuel feed to several cylinders and simultaneously deactivate inlet and outlet valves associated with the cylinders. A disadvantage of this proposed construction resides in the fact that the valve shut-off mechanism employs an expensive planetary transmission arrangement with a brake means, with the planetary transmission and brake means providing a non-rotational or rotational connection between the cams associated with the valves adapted to be shut-off and the cam shaft.

In German Offenlegungsschrift 2,621,794, another valve shut-off arrangement is proposed which is accommodated in a rocker arm bearing, with the rocker arms being actuated by a bottom positioned cam shaft through a push rod. A disadvantage of this proposed construction resides in the fact that because the moving masses are relatively large, such a control arrangement only permits a limited number of revolutions.

In German Patent Application P 28 14 087.6, another valve shut off arrangement is proposed for connecting or disconnecting the valve, with the arrangement being disposed between a swing arm and an end of a valve stem.

A disadvantage of this proposed arrangement resides in the fact that such construction perforce results in an unfavorable structural height of the internal combustion engine.

The aim underlying the present invention essentially resides in providing a valve shut-off arrangement for a multicylinder internal combustion engine by which it is possible to incorporate or retain the existing cam shaft bearing as well as valve operating parts of the engine in an extensively unchanged or unaltered condition.

In accordance with advantageous features of the present invention, the valve shut off arrangement is provided which includes a cam shaft on which a hollow shaft with cams is non-rotatably supported, with the hollow shaft being connected with transmitting elements operating the valves which are to be shut-off. A connection to the transmitting elements is eliminated for the cams by an axial displacement of the hollow shaft.

By virtue of the above-noted features of the present invention, a very simple construction of a mechanical arrangement is arranged and, to effect a valve shut off, the cams arranged on the hollow shaft are merely moved away from the transmitting elements such as, for example, rocker arms, swing arms, or the like, so that they can freely rotate beside the transmitting elements.

In accordance with further features of the present invention, a connection between the cams and the transmitting elements may be eliminated by a hydraulic means connected with the hollow shaft and controllable in dependence upon a load and number of revolutions or rotational speed of the internal combustion engine.

Advantageously, the parts of the hollow shaft arranged beside the cams have a diameter corresponding to that of a cam base circle.

In accordance with further features of the present invention, the hollow shaft is provided with a collar connected with a switching lever of the hydraulic unit.

Accordingly, it is an object of the present invention to provide a valve shut-off arrangement for a multicylinder internal combustion engine which avoids, by simple means, shortcomings and disadvantages encountered in the prior art.

Another object of the present invention resides in providing a valve shut-off arrangement for a multicylinder internal combustion engine which may be installed with a minimum modification of existing valve operating parts of the engine.

A further object of the present invention resides in providing a valve shut-off arrangement for a multicylinder internal combustion engine which functions realiably under all load conditions of the engine.

A still further object of the present invention resides in providing a valve shut-off arrangement for a multicylinder internal combustion engine which is simple in construction and therefore relatively inexpensive to manufacture.

Another object of the present invention resides in providing a valve shut-off arrangement for a multicylinder internal combustion engine which does not adversely effect the structural height of the engine.

These and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawing which shows, for the purpose of illustration only, one embodiment in accordance with the present invention, and wherein:

FIG. 1 is a partially schematic longitudinal cross sectional view of a cam shaft arrangement for a multicylinder internal combustion engine with partially illustrated swing arms, for a valve shut-off arrangement of the present invention; and

FIG. 2 is a switching control diagram of a valve shut-off arrangement constructed in accordance with the present invention for an eight cylinder internal combustion engine.

Referring now to the drawings wherein like reference numerals are used in both views to designate like parts and, more particularly, to FIG. 1, according to this figure, a cam shaft arrangement includes an inner cam shaft 1 and a quill shaft generally designated by the reference numeral 2 concentrically supported thereon. The hollow shaft 2 is nonrotatably connected with the cam shaft 1 by a suitable fitting key or adapter spring 3 but is guided on the cam shaft 1 for a longitudinal displacement. The hollow shaft 2 includes a cylindrical hollow shaft part 4 and two cams 5 on which are supported transmitting elements 6 constructed as swing levers and associated with the inlet and outlet valves of the respective cylinders, which inlet and outlet valves are adapted to be selectively shut-off.

A collar 7 is provided on the hollow shaft 2, with the collar 7 being adapted to provide an engagement portion for a suitable actuating unit such as, for example, a hydraulic unit 8 which is controllable in dependence upon the rotational speed of the engine and/or the load. The hydraulic unit 8 includes a spring-loaded piston 9 connected to a switching lever 10 having a bifurcated end section 11 extending over the collar 7. In FIG. 1, the hollow shaft 2, displaceable between two cam shaft bearings 12, 13 is illustrated in a position wherein the valves are connected.

In order to shut off the deactivatable valves, the hollow shaft 2 is shifted by the hydraulic unit 8 toward the left of FIG. 1 to such an extent that the cams may fully rotate adjacent the swing arms 6. In the displaced position, the swing arms 6 rest on the cylindrical hollow shaft part 4 and the deactivatable valves are shut off, i.e., they are in a closed position. The activation of the respective valves takes place at a point in time at which the cams 5 contact the swing arms 6 with the base circle.

FIG. 2 provides an example of a switching control arrangement for an eight-cylinder V-type internal combustion engine provided with two cam shafts 1a and 1b driven by a timing chain 14. Each cam shaft 1a, 1b is provided with two hollow shafts, with each hollow shaft having two cams respectively associated with one cylinder designated I-VIII. Based on identical ignition interval or spacing, hollow shafts 2 of the cam shaft 1a are located interior and the hollow shafts 2 of the cam shaft 1b are located exteriorly. The hydraulic unit 8 is provided for controlling a positioning of each of the hollow shafts 2, with appropriate pressure medium lines or conduits 15, 16 being connected to the respective hydraulic devices 8.

As shown in FIG. 2, a control unit, of conventional construction, is provided for controlling the shutting off and reconnecting of the respective cylinders. Engine load and rotational speed sensors (not shown) in addition to possibly further signal transmitters or sensors are provided for supplying input variables to the control device 17. The control device 17 actuates four solenoid-operated valves 18 in a speed and load range of the engine suitable for valve connection or activation. The solenoid operated valves 18 are arranged in fuel lines 20 leading to injection nozzles 19 and are adapted to re-instate or restart a previously interrupted fuel feed for the disconnectible cylinders I, IV, VI, VII.

A second control device 21 is provided for the valve shut-off arrangement, with the second control device 21 receiving a readiness signal for a control device 17. The control device 21, which is in the readiness position, then acts on four solenoid-operated valves 23 after receipt of a further signal from a signal generator responding to a specific cam position. The spring loaded pistons 9 arranged in the hydraulic cylinders of the respective hydraulic units 8 are placed under pressure and the hollow shafts 2 are brought, by way of the bifurcate switching levers 10, into a position wherein the swing arms 6 are again supported on the cams 5 associated with the valves which can be shut off.

Accordingly, the previously disconnected cylinders I, IV, VI, VII, are once again reconnected or activated and an eight cylinder operation of the internal combustion engine is resumed.

While we have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to one having ordinary skill in the art and we therefore do not wish to be limited to the details shown and described herein, but intend to cover all such modifications as are encompassed by the scope of the appended claims.