DE102015000369A1 - Method and device for adjusting a valve clearance - Google Patents

Abstract

Described is an internal combustion engine with a crankcase and with at least one cylinder and cylinder head, as well as arranged in the crankcase crankshaft, are driven or controlled by the cylinder head arranged in the camshaft, and with a cylinder head cover, which substantially the cylinder head over its entire width and Length completing, the cylinder head cover 1 in the installed state of the internal combustion engine has a base cover 2 with at least one opening per valve 3, which is formed by a separately formed cover 4 closable and wherein the valves are controlled by rocker arm 5.

Description

A valve control or a valve drive is a mechanism that controls the valves and thus the charge exchange by opening and closing the air inlet and exhaust gas outlet channels in a reciprocating engine. It is used in almost all four-stroke engines.

As a rule, a valve is opened by a camshaft via a tappet, drag lever or rocker arm. Valves are closed by coil springs, rarely by torsion bar springs, gas springs or positively controlled by a closing cam. The camshaft is driven by the crankshaft, in four-stroke engines with a ratio of 2: 1. The camshaft thus has half the speed of the crankshaft.

During operation, valves are opened and closed several times during each second, ie accelerated and brought to a standstill. The movements of the valves and the piston in the cylinder must be exactly matched.

Before adjusting the valves is the opening of the cylinder head. Here, there are usually covers that are held by screws or even clamping mechanisms. Valves and / or their drive can also be achieved by larger, unscrewable threaded cover. It is important which valve is to be set in which position of the motor. There are no problems if the camshaft is also exposed. Then turn with suitable means on the crankshaft until the respective cam is about 180 ° twisted to the highest valve lift.

All parts of the engine expand in operation depending on the temperature increase and depending on the material more or less. In addition, length changes due to wear occur at the transmission parts of the engine control. To allow the intake and exhaust valves to close in all operating conditions, clearance is provided between the valve and the rocker arm. The clearance is strictly prescribed by the engine manufacturer and must be adjusted at certain intervals, taking account of the wear on the valve seat caused by the constant impact of the rocker arm on the valve stem and the valve disk cone with the hot or cold engine (as required by the engine manufacturer) ,

The valve clearance must be strictly observed and controlled.

Too small valve clearance means that the valves could not close completely when the engine was warm. This causes compression loss. As a result, the hot combustion gases blow between valve and valve seat ring. This action causes the valve seat and the valve to burn. A big drop in performance is the result.

Too much valve play can cause the valves to close too early and thereby not relieve the pressurized combustion gases in time, resulting in insufficient flushing of the cylinder from the exhaust gases and poor refilling with fresh gases. This also results in very high power loss.

To ensure a safe closing of the valve under all operating conditions, a valve clearance is provided - a small distance anywhere in the valve train. This distance decreases with reaching the operating temperature, but must not be zero. Too much play in turn causes loss of power, strong noise and increased wear of the valve train.

The manufacturers therefore specify a range for the valve clearance, in the order of a few hundredths to tenths of a millimeter, usually based on the cold engine. The valve clearance should be checked at regular maintenance intervals - for example after mileage or after operating hours - and readjusted if necessary, if the engine has no automatic valve clearance compensation.

The game is usually measured with feeler gauges and then set differently depending on the design: For rocker arms that are operated by bumpers, located in the levers is often a countered screw on which the adjustment can be made. In other constructions, the pivot point of the levers is adjusted. In contrast, bucket tappets have hardened "shims" which are placed between the tappet and the cam or tappet and valve stem. These are available in fine gradations of thickness and are exchanged when necessary correction.

Just as important as the formation of the combustion chamber for the course of the combustion is the control of the fresh air column flowing into the working cylinder during the intake stroke and the burned gases flowing out of the working cylinder during the exhaust stroke.

First of all, let's look at which parts of the engine belong to the opening and closing of the intake and exhaust valves and how they are actuated.

On the crankshaft, a gear is shrunk or keyed, which drives the seated on the camshaft steering wheel. Because the Valves must be opened and closed once per cycle (suction, compression, operation, exhaust, ie two crankshaft revolutions) by the cam distributed evenly on the camshaft (1 cam for each valve), the speed of the crankshaft must match the speed of the camshaft be reduced in the ratio 2: 1, ie, diameter and number of teeth of the crankshaft and camshaft gear must be adjusted so that the cam shaft rotates only once with two revolutions of the crankshaft.

The valves are opened in engines with overhead valves by the emergence of the cam against the plunger, which in turn operates via the push rod, the rocker arm, with which the valve is opened. If the cam moves away from the tappet, the valve spring pressed between the conical half-keys and the cylinder head presses the valve onto the valve seat.

When adjusting the valve clearance, observe the manufacturer's adjustment instructions as to whether to prescribe the setting for a cold or warm engine.

• – Die Sechskantmuttern (b) an den Kipphebeleinstellschrauben der beiden einzustellenden Ventile lösen.
• – Fühlerlehre von der vorgeschriebenen Dicke zwischen Kipphebel und Ventilschaft (e) schieben.
• – Die Kipphebelleinstellschraube (a) soweit lösen/anziehen, bis sich die Fühlerlehre saugend herausziehen und wieder hineinschieben lässt.
• – Die Einstellschraube festhalten und die Sechskantmutter mit einem Schraubenschlüssel anziehen.
• – Abschließend muss das Spiel nochmals kontrolliert werden. Lässt sich die Fühlerlehre nicht saugend einschieben und herausziehen, hat sich wahrscheinlich beim Anziehen der Kontermutter die Einstellschraube verdreht. In diesem Fall muss das Einstellen nochmals vorgenommen werden.

The valve clearance is adjusted as follows on the toggle adjustment screws:

• - Loosen the hexagon nuts (b) on the toggle adjustment screws of the two valves to be adjusted.
• - Slide the feeler gauge of the specified thickness between the rocker arm and the valve stem (e).
• - Loosen / tighten the tilt lever adjustment screw (a) until the feeler gauge can be pulled out and pushed back in while it is sucking in.
• - Hold the adjusting screw and tighten the hexagon nut with a wrench.
• - Finally, the game must be checked again. If the feeler gauge can not be inserted by suction and pulled out, the adjustment screw has probably twisted when tightening the lock nut. In this case, the adjustment must be made again.

To adjust the valve clearance, both valves of the corresponding cylinder must be closed. This state is obtained by the valves when the respective cylinder is at the end of the compression stroke or at the beginning of the power stroke. To reach this valve position, turn the motor by hand until both valves move simultaneously (valve overlap). If this is the case, the engine must be further rotated 360 degrees (one crankshaft revolution). Now the valves must be closed. This can be checked by turning the push rod (c) by hand or by minimally moving the rocker arm.

For multi-cylinder engines, the clearance must be adjusted on each individual cylinder.

For a 4-cylinder in-line engine, cylinder 1 is set when cylinder 4 is in the valve overlap (VÜ) (cylinder 2 adjustable at VÜ of cylinder 3) and vice versa (cylinder 1 VÜ CylA adjustable / cylinder 2 VÜ Cyl. )

When adjusting the valve clearance, it is important that neither the responsible cam nor any existing extension of it actuates the valve. Therefore, there are usually binding rules for the position of the engine with invisible camshaft. Those who do not have these rules can simply continue to rotate the engine after the valve's largest elevation of 180 ° relative to the camshaft or 360 ° relative to the crankshaft. Once the correct position has been found, the feeler gauge shown above is needed. This is usually sufficient for a measuring range of 0.05-0.5 mm and a pitch of 0.05 mm. If you have now found the given position in the valve gear, at which the game can be measured, you pull the appropriate sheet with the set value. This can be between cam and bucket tappets or between towing / rocker arms and cams.

To assess whether the setting value has been reached exactly, some experience with the valve clearance adjustment is necessary. The blade of the feeler gauge must not be too easy or too tight to pull through.

There are hardly any major differences compared to the technical implementation of the setting option. Well known are probably Schlitzkopf- or Allen screws z. B. on rocker arms, with wrench rotatable deflection points of rocker arms and small platelets that are inserted into tappets. But also self-locking Allen screws in bucket tappets u. a. There has been in the history of valve timing. The highest demands are probably the Desmodromic valve control. Less obvious is obviously the engine of a diesel locomotive (3rd picture above). Here two valves are actuated by a cam. By only one adjusting screw, a slightly larger clearance is maintained at one of the two valves.

The setting of the valve clearance in the valve train of an internal combustion engine is among others from the DE 36 35 929 A1 known. In this invention, in a method between valve and actuator (rocker arm) a spacer is inserted whose height is equal to the sum of valve clearance and a Vorhaltebetrag, and then the valve is raised by the adjustment by the amount of reserve from the valve seat. In this method, setting errors can result from the fact that at the beginning of the adjustment, the valve to be adjusted is not seated on the valve seat.

There is a dead center mark known DE-OS 28 43 039 , in which a mark on the flywheel end face is accessible through an opening in the end face of the flywheel housing by means of stylus. Through a second opening, a distance measuring device can be set on the flat surface of the flywheel, which detects and displays the path traveled during rotation. This is a zurückgelegter angle of rotation, starting from top dead center detected. The disadvantage here is that the measured distance must be converted into a rotational angle of the crankshaft and the possible inaccuracy of Reibmitnahme the odometer through the flywheel end face; because the process can not be observed within the housing. Furthermore, these specified flywheel surfaces for attaching the Wegmessrades are not accessible in most engines, because attached clutch and gearbox housing block access. Most engines are also missing a chance to spin by hand, because accessibility is locked with coupled machine and the inertia of the coupled machine must be overcome with possible spinning at the front end of the crankshaft.

• – Antrieb von mindestens einem Ventil über eine Nockenwelle,
• – mechanische Einstellbarkeit des Ventilspieles,
• – Tassenstößel als Nockenfolger mit einem direkten Kraftschluss gegenüber dem Ventil, wobei anstelle eines Tassenstößels auch Schlepp- oder Kipphebel bei dann auf das Ventil auftretenden Seitenkräften einsetzbar sind,
• – Einstellbarkeit der Ventilfederkräfte durch eine Austauschmöglichkeit für die Ventilfedern oder einen Einsatz unterschiedlicher Unterlegscheiben bei der Abstützung einer Ventilfeder,
• – Austauschbarkeit und Positionierbarkeit gegenüber der Ventilführung der Ventilsitzringträger mit darin eingepressten Ventilsitzringen,
• – Einsatz einer Induktionsanlage als Wärmequelle zum Erwärmen des Ventiles, wobei als Wärmequelle unter anderem auch Brenner, Heißluftgebläse oder dergleichen möglich sind,
• – Messbarkeit der Ventilsitzringtemperatur über Thermoelemente,
• – Kühlbarkeit der Prüfeinrichtung durch Kühlwasser, Öl, Luft oder andere Kühlmedien.

Known, generic testing devices already have the following features:

• Drive of at least one valve via a camshaft,
• Mechanical adjustability of the valve clearance,
• - Tappets as a cam follower with a direct frictional connection with respect to the valve, wherein instead of a tappet and towing or rocker arms can be used in then occurring on the valve side forces,
• - adjustability of the valve spring forces by a possibility of replacing the valve springs or use of different washers in the support of a valve spring,
• Interchangeability and positioning relative to the valve guide of the valve seat ring carriers with valve seat rings pressed in,
• Use of an induction system as a heat source for heating the valve, wherein as a heat source, inter alia, burners, hot air blower or the like are possible,
• - measurability of the valve seat ring temperature via thermocouples,
• - Coolability of the test equipment by cooling water, oil, air or other cooling media.

The invention is concerned with the problem of improving a generic test device functionally.

This problem is solved by a generic test device with the characterizing features of patent claim 1.

Advantageous and expedient embodiments of this solution according to the invention are the subject of the dependent claims.

• – Zur Überwindung eines relativ groß eingestellten Ventilspiels und zur Erzielung geringer Stoßimpulse zwischen dem Nocken und einem das Ventil kontaktierenden Nockenfolger sowie eines geringen Verschleißes zwischen Nocken und Nockenfolger ist an einem Antriebs-Nocken – falls ein solcher eingesetzt ist – eine lange, flache Anlauframpe vorgesehen. Die Höhe dieser Rampe richtet sich nach dem maximalen Ventilspiel. Die Länge der Rampe erfasst vorzugsweise einen Nockenwinkelbereich von 50 deg. bis 130.
• – Auf den langen, flachen Anlauframpenbereich eines Nockens als Ventilantrieb folgt eine hohe Steigung der Nockenerhebung bis zu einer maximalen Höhe der Nockenerhebung, die als solche möglichst gering gewählt wird, eine lange Rastphase des Ventils bei maximalem Ventilhub ermöglicht eine hohe Verweilzeit des Ventiltellers in einer für einen bestmöglichen Wärmeaustausch gegenüber der Wärmequelle möglichst gering beabstandeten Position. Die Länge der Rastphase liegt vorzugsweise in einem Nockenwinkelbereich zwischen 20 deg. und 60, die Schließflanke des Nockens ist so ausgebildet, dass eine gewünscht hohe Aufsetzgeschwindigkeit des Ventiltellers auf den Ventilsitzring erreichbar ist. Die gewünschte Aufsetzgeschwindigkeit wird über die Drehzahl des den Nocken antreibenden Antriebsmotors eingestellt.

The invention is based on the following general considerations:

• - To overcome a relatively large set valve clearance and to achieve low shock pulses between the cam and a valve-contacting cam follower and a low wear between the cam and cam follower is on a drive cam - if one is used - a long, flat starting ramp provided. The height of this ramp depends on the maximum valve clearance. The length of the ramp preferably detects a cam angle range of 50 deg. to 130.
• - On the long, flat start ramp area of a cam as a valve drive follows a high pitch of the cam lobe up to a maximum height of the cam lobe, which is chosen as low as possible, a long detent phase of the valve at maximum valve lift allows a high residence time of the valve disk in a a best possible heat exchange with respect to the heat source as possible a little spaced position. The length of the detent phase is preferably in a cam angle range between 20 °. and 60, the closing edge of the cam is designed so that a desired high contact speed of the valve disk is reachable on the valve seat ring. The desired Aufsetzgeschwindigkeit is set via the speed of the cam driving drive motor.

The invention will be explained below with reference to the figures. The invention is not limited to the subject matter of the figures. They show schematically:

1 a top view of a cylinder head cover,

2 the top view 1 without separately formed lid,

3 a section through the cylinder head with open valve with position finder,

4 the cut out 3 with closed valve with position finder,

5 a section of the top view 2 with position finder,

6 a section through the cylinder head with separately formed lid,

7 the cut out 6 with closed valve with position finder,

8th Turning angle disc of the valve clearance adjusting tool.

In 1 is a plan view of a cylinder head 1 an internal combustion engine is shown, which is operated in particular with diesel fuel. The cylinder head 1 the internal combustion engine comprises a base cover 2 over the openings 3 in the area of the rocker arm, by a separately formed lid 4 be sealed.

2 shows the top view 1 with cylinder head 1 the internal combustion engine, which has a basic cover 2 over the openings 3 in the area of the rocker arm, that of the separately formed lid 4 be sealed without expressly reveal this separately formed lid.

In 3 becomes a cut through the cylinder head 1 with open valve with position finder 6 shown. The position finder 6 has a hexagon socket 7 on, with him on the lock nut 10 the valve clearance adjustment screw 11 of the rocker arm 5 through the opening 3 in the area of the rocker arms of the basic cover 2 is put on. The position finder is shown with the valve open.

4 shows a section through the cylinder head 1 with position finder 6 , The position finder 6 has a hexagon socket 7 on, with him on the lock nut 10 the valve clearance adjustment screw 11 of the rocker arm 5 through the opening 3 in the area of the rocker arms of the basic cover 2 is attached. The position finder is shown with valve closed with valve overlap.

In 5 is a section of the top view 2 with position finder 6 shown. The position finder 6 is with its hexagon 7 on the lock nut 10 the valve clearance adjustment screw 11 of the rocker arm 5 through the opening 3 in the area of the rocker arms of the basic cover 2 placed.

6 discloses a section through the cylinder head 1 with separately formed lid 4 , The cylinder head 1 the internal combustion engine comprises a base cover 2 over the openings 3 in the area of the rocker arm, by a separately formed lid 4 by means of O-rings 8th be sealed.

7 shows a section through the cylinder head 1 with adjustment tool 12 , The adjustment tool 12 has a hexagon socket 9 on, with him on the lock nut 10 the valve clearance adjustment screw 11 of the rocker arm 5 through the opening 3 in the area of the rocker arms of the basic cover 2 is attached. The adjustment tool 12 solves and / or closes by means of a rotary motion with its hexagon socket 9 the locknut 10 the valve clearance adjustment screw 11 of the rocker arm 5 ,

The adjustment tool 12 For example, it consists of a nut-like socket wrench with hexagon socket on the lock nut 10 the valve clearance adjustment screw 11 of the rocker arm 5 through the opening 3 in the area of the rocker arms of the basic cover 2 is attached. After the lock nut 10 the valve clearance adjustment screw 11 of the rocker arm 5 is solved, the angle of rotation disc 13 , as in 8th shown with its socket wrench 14 in the hexagon socket of the valve clearance adjusting screw 11 through the opening in the area of the rocker arms 3 inserted through it. The magnetic abutment 15 is attached to increase the positional stability of a nearby magnetic part of the internal combustion engine. Subsequently, the turntable is turned clockwise to the system, that is, the rocker arm or the valve is now free of play. The scale of the angle plate is now set to zero. Subsequently, the angle plate is rotated counterclockwise until reaching the desired degree of rotation. If the specified valve clearance is set, the angle plate is secured against rotation, then the lock nut 10 the valve clearance adjustment screw 11 of the rocker arm 5 For example, tightened with a tightening torque of 20 Nm.

This process is repeated in all valves of the internal combustion engine until the predetermined valve clearance is set to all valves of the internal combustion engine.

LIST OF REFERENCE NUMBERS

1

cylinder head

2

base cover

3

Opening in the area of the rocker arms

4

separately formed lid

5

rocker arm

6

emperata

7

Hexagon socket of position finder

8th

O-ring

9

Hexagon socket of adjusting screw

10

locknut

11

Ventilspieleinstellschraube

12

Adjusting

13

Rotation angle disc

14

Socket

15

magnetic abutment

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3635929 A1 [0024]
• DE 2843039 A [0025]

Claims (9)

Internal combustion engine with a crankcase and with at least one cylinder and cylinder head, as well as with a arranged in the crankcase crankshaft, are driven or controlled by the arranged in the cylinder head camshaft, and with a cylinder head cover, which substantially completes the cylinder head over its entire width and length, wherein the cylinder head cover ( 1 ) in the installed state of the internal combustion engine, a basic cover ( 2 ) having at least one opening per valve, which by a separately formed lid ( 4 ) is formed closable and wherein the valves by means of rocker arm ( 5 ) are driven. Internal combustion engine according to claim 1, characterized in that the opening ( 3 ) is arranged in the region of the rocker arm. Internal combustion engine according to claim 2, characterized in that for closing the opening ( 3 ) provided separately formed lid ( 4 ) Is arranged connectable to the base cover. Internal combustion engine according to one or more of the preceding claims, characterized in that it comprises at least one position finder ( 6 ) having. Internal combustion engine according to one or more of the preceding claims, characterized in that it each rocker arm a positionable or demountable position finder ( 6 ) having. Internal combustion engine according to one or more of the preceding claims, characterized in that it comprises a mountable or demountable rotating angle disc ( 13 ) having. Internal combustion engine according to one or more of the preceding claims, characterized in that each rocker arm ( 5 ) at least one valve clearance adjustment screw ( 11 ), which by means of lock nut ( 10 ) is secured. Internal combustion engine according to one or more of the preceding claims, characterized in that the valve clearance is adjustable in a range of 0.25 to 0.35 mm. Method for adjusting the valve clearance, characterized in that a device according to one or more of the preceding claims is used.

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