DE10055595A1 - The cylinder shutoff has cylinders with gas exchange valves, cam shaft, driven by crank shaft, two cams, and valve drive element - Google Patents

Abstract

The four-stroke spark ignition engine has several cylinders with gas exchange valves and at least one cam-shaft driven by a crank shaft. Each gas exchange valve is operated by a first and second cam both of which have a full stroke and are positioned so as to turn on the turning angle of an engine cycle. The first cam operates a constant stroke component of a valve drive element, and the second cam operates a no-stroke switchable component of the valve drive element.

Description

Field of the Invention

The invention relates to a method and a device for cylinder shutdown device in internal combustion engines, in particular according to the preamble of the method and the device claims 1 and 2 .

Background of the Invention

Cylinder deactivation is used in Otto engines in the partial load range. she is by switching off the fuel injection and the gas exchange valves realized the non-firing cylinders. By switching off the cylinder Medium pressure of the firing cylinders increased and their intake side unthrottled. As a result of this and by switching off the gas exchange valves, the throttle or gas exchange losses. With increasing medium pressure, the thermo also increases dynamic efficiency. All three factors lead to a decrease in strength material consumption and pollutant emissions.  

DE-30 46 402 describes a camshaft of an internal combustion engine for Zy shutdown described. This shows conventional, one-piece kig with the camshaft trained cam on those of the Noc can be uncoupled and thus freely rotated on the same. The latter can no longer drive the associated gas exchange valves, so that the be affected cylinders are switched off on the gas exchange side. This state remains received until the uncoupled cams turn again with the Noc kenwelle are connected.

In this solution, there are continuously active during cylinder deactivation fourth in addition to permanently deactivated cylinders. The latter always cool further out what when reactivating to emissions, consumption, and lei problems.

Object of the invention

The invention is based on the object of generic combustion Creating engine with cylinder deactivation, the most economical and is low in emissions and wear.

Summary of the invention

The object is achieved on the one hand by the characterizing features of procedural claim 1 . The cyclical alternation of activation and deactivation keeps all cylinders warm. This ensures optimal conditions with regard to fuel consumption, pollutant emissions and power consumption.

The object is also achieved by the characterizing features of the device claim 2 . In this way, the first cam is always assigned to the activated and the second cam to the deactivated fourth cycle during cylinder deactivation. The internal combustion engine then works as it were in 8-stroke. The usual 4 work cycles follow 4 idle cycles, which in turn are replaced by 4 work cycles, etc. By arranging and designing the two cams according to the invention in conjunction with known, switchable valve train elements, the alternating misfire operation according to the invention functions without further switching operations between the Switching the cylinder deactivation on and off. As a result, the device according to the invention operates largely without wear.

An advantageous embodiment of the invention is that the first and second cams have a rotation angle interval of 180 ° cam angle and is the rotational speed of the camshaft 1/4 of the crankshaft speed. In order to achieve a uniform sequence of the activated and deactivated cycles, the first and second cams on the camshaft must be symmetrical, ie rotated by 180 ° cam angle. The camshaft therefore only has 180 ° cam angle available for one engine cycle. However, since an engine cycle comprises 720 ° crank angle = 4 × 180 ° cam angle, the camshaft may only rotate at a quarter of the crankshaft speed.

It is advantageous that the valve drive element is preferably a switching plunger in The shape of a switchable tappet is a constant-stroke component a cylindrical inner tappet and a component that can be switched to zero stroke has annular outer plunger. This is a proven one Component that the present task by minor changes can be adjusted. Alternatively, switchable tilt, swing, and Rocker arms and roller tappets can be used.

The switchability of the switching plunger is achieved in that both plungers axially movable with respect to one another and coupled or decoupled by coupling elements are pelbar, the coupling elements against spring force hydraulically in radial Direction between the plungers are shiftable.

The fact that the inner and outer tappet contact surfaces of have approximately the same size and are sufficient for activated continuous operation,  activated continuous operation can be carried out with both plungers. It is advantageous that the first cam driving the inner tappet as an pin cam and the second cam driving the outer tappet as a double cams are formed. This makes the cam contact surfaces opti times used and the tappet stressed symmetrically.

It is also advantageous if the cam contact surface of the inner tappet is right is angular and the annular cam contact surface of the outside ram overlaps with play. In this way the first cam contact is made surface optimally adapted to the first cam in terms of shape and size. The With taking the outer tappet through the overlapping cam contact surface of the inner tappet in the case of cylinder deactivation is functionally irrelevant vant.

It has advantages that in 6-cylinder engines, the cams of each in the firing order because next cylinder compared to the previous one by 30 ° cam angle and additionally rotated by a further 180 ° cam angle. The ignition distance for the 6-cylinder engine is 720: 6 = 120 ° crank angle, which corresponds to 30 ° cam angle in the camshaft according to the invention.

When operating with cylinder deactivation, the rotation is minimized uniformity the cylinders alternately activated and deactivated in the firing order fourth. To do this, the first and the second cam must alternate in firing order be effective. This means in addition to the ignition distance of 30 ° cam angle turning the cams by a further 180 ° cam angle.

A further development of the invention is that an electronic rotation Number control to compensate for cylinder shutdown Speed fluctuations of the internal combustion engine is provided. Com here men known solutions such. B. E-gas into consideration that the Betriebskom and increase the running culture of the internal combustion engine.

Brief description of the drawings

Further features of the invention result from the following description writing, the claims and the accompanying drawing on which Embodiments of the invention are shown schematically. Show it:

Fig. 1 shows a cross section BB of Figure 3 according to the invention by a SEN switching plunger.

FIG. 2 shows a cross section AA of FIG. 3 through the switching plunger;

Fig. 3 is a partially sectioned plan view of the switching plunger;

Fig. 4 shows a part of a camshaft with first and second cams for actuating the switching plunger

Detailed description of the drawing

Figs. 1 to 3 show a switching plunger 1, which is formed as a switchable tappet cups and having an internal plunger 2 and an outer ram 3. Since the switching plunger is a component known in the technical field, only its essential components and their modifications according to the invention are explained.

The inner plunger 2 has a cylindrical inner sleeve 4 , which is guided in a cylin drical outer sleeve 5 of the outer plunger and is axially slidable ver. Inner and outer plungers 2 , 3 can be coupled to one another by coupling elements 6 , the coupling elements 6 being hydraulically displaceable in the radial direction between the inner and outer plungers 2 , 3 against spring force.

Both plungers 2 , 3 have at their cam ends cam contact surfaces 7 , 8 . The first cam contact surface 7 of the inner plunger 2 is rectangular and engages over the annular second cam contact surface 8 of the outer plunger 3rd Both cam contact surfaces 7 , 8 have the same effective area and are suitable for continuous operation with a full valve lift.

In the inner tappet 2 , a known hydraulic play compensation element 9 is provided on the valve side.

In FIG. 4, a portion of a camshaft 10 according to the invention comprising two identical cam packets 11 for the inlet or outlet valves of a 4-valve head. The cam packs 11 consist of a first and a second cam 12 , 13 , both of which have the same profile stroke and are arranged rotated relative to one another by 180 ° cam angle.

The first cam 12 is formed as a single cam for driving the inner plunger 2 , the second cam 13 as a double cam for driving the outer plunger 3 .

The camshaft 10 according to the invention rotates at 1/4 of the crankshaft speed. For a 6-cylinder engine, this results in an ignition distance on the camshaft 10 of 120 ° crank angle: 4 = 30 ° cam angle.

The device for cylinder deactivation according to the invention works as follows:
The switching plungers 1 are acted upon by the cam packs 11 . The first cam 12 drives the inner plunger 2 , which actuates an inlet or outlet valve via the hydraulic play compensation element 9 . After turning the cam shaft 10 by 180 ° cam angle (this corresponds to 4 × 180 = 720 ° crank angle = one cycle), the second cam 13 drives the outer tappet 3 . If the water applied via the oil pressure coupling elements 6 coupled to the inner plunger 2 , the inlet or outlet valves are actuated via the inner plunger 2 , so that normal 4-stroke operation is present.

If the outer tappet 3 is decoupled from the inner tappet 2 due to a lack of oil pressure, actuation of the outer tappet 3 leads to an idle stroke of the same, so that the intake and exhaust valves remain closed and thus cause a cylinder shutdown. After turning the camshaft 10 by a further 180 ° cam angle = 720 ° crank angle = one cycle, the first cam 12 is used again and opens the inlet and exhaust valves via the inner tappet 2 without switching operation. In this way, an activated fourth and a deactivated cycle follow alternately, without the need for a switching operation. The internal combustion engine works as it were in 8-stroke, the last 4 strokes acting as empty strokes. Since the coupling elements do not have to be changed every cycle, but only when the cylinder deactivation is switched on and off, there is no risk of wear for the same. Due to the alternating cylinders between activated and deactivated operation, they cannot cool down. This avoids the disadvantages caused by cooling with regard to fuel consumption, pollutant emissions and performance behavior.

In the 6-cylinder engine, the ignition interval is 120 ° crank angle, which corresponds to 30 ° cam angle on the camshaft according to the invention. Since Zylin derabschaltungen in the firing order an activated a deactivated cylinder follows, must to the corresponding actuation or non-actuation of the gas Wech selventile a first cam 12, a second cam 13 to follow. However, this means that the cam packs 11 of the next cylinder in firing order must be rotated by a further 180 ° cam angle in addition to the 30 ° cam angle in addition to those of its predecessor.

LIST OF REFERENCE NUMBERS

1

switching plunger

2

interior follower

3

outer slide

4

inner liner

5

outer sleeve

6

coupling element

7

first cam contact surface

8th

second cam interface

9

hydraulic lash adjuster

10

camshaft

11

cam package

12

first cam

13

second cam

Claims (10)

1. A method for cylinder deactivation in internal combustion engines, in particular in a 4-stroke gasoline engine, which has several cylinders with gas exchange valves and at least one camshaft ( 10 ) which is driven by a crankshaft, characterized in that when operating with cylinder deactivation each cylinder is alternately activated and deactivated in successive cycles. 2. Device for cylinder deactivation in internal combustion engines, in particular in particular in a 4-stroke gasoline engine which has a plurality of cylinders with gas exchange valves and at least one camshaft ( 10 ) which is driven by a crankshaft, characterized in that for actuating each Gas exchange valve a first and a second cam ( 12 , 13 ) are provided, both of which have full stroke height and are arranged rotated by the angle of rotation of an engine cycle, and that the first cam ( 12 ) a constant stroke, the second cam ( 13 ) to zero stroke switchable component of a valve train element be actuated. 3. Device according to claim 2, characterized in that the first and second cams ( 12 , 13 ) have a rotation angle distance of 180 ° Noc kenwinkel and the speed of the camshaft ( 10 ) is 1/4 of the crankshaft speed. 4. The device according to claim 3, characterized in that the Ven tiltriebselement is preferably a switching plunger ( 1 ) in the form of a switchable bucket tappet, which as a constant-stroke component of a cylindrical inner plunger ( 2 ) and as a switchable to zero stroke component egg NEN annular outer plunger ( 3rd ) having. 5. The device according to claim 4, characterized in that the two plungers ( 2 , 3 ) are axially movable relative to one another and can be coupled or uncoupled by coupling elements ( 6 ), the coupling elements ( 6 ) being hydraulically counter to spring force in the radial direction between the plungers ( 2 , 3 ) are relocatable. 6. The device according to claim 5, characterized in that the inner and the outer plunger ( 2 , 3 ) have cam contact surfaces ( 7 , 8 ) of approximately the same size and sufficient for activated continuous operation. 7. The device according to claim 6, characterized in that the inner tappet ( 2 ) driving first cam ( 12 ) as a single cam and the outer tappet ( 3 ) driving second cam ( 13 ) are designed as double cams. 8. The device according to claim 7, characterized in that the cam contact surface ( 7 ) of the inner plunger ( 2 ) is rectangular and the annular cam contact surface ( 8 ) of the outer plunger ( 3 ) engages with play. 9. The device according to claim 8, characterized in that in the case of 6-cylinder engines, the cams ( 12 , 13 ) of the next cylinder in firing order are arranged rotated by 30 ° cam angle and additionally by a further 180 ° cam angle. 10. The device according to claim 9, characterized in that a electronic speed control to compensate for by cylinder circuit caused fluctuations in the speed of the combustion engine tors is provided.