DE3017813A1 - VALVE CONTROL TO START 4-STROKE DIESEL ENGINES - Google Patents

Description

; NAOHQUEREICHT [

fitel of the invention

Valve control for starting four-stroke diesel bogs

Field of application of the invention

The invention relates to a valve control for starting of quarter-cylinder diesel engines, especially supercharged ones V-type four-stroke diesel engines with lower Number of cylinders and a small V-angle.

Characteristics of the known technical solutions

It is known to provide four-stroke diesel engines with pneumatic starting devices with starter valves controlled by fluff, through which the pistons are acted upon with compressed air during the starting process in accordance with the ignition sequence. The sum of the starting torques causes the crankshaft to move until the required starting speed is reached (DE-PS 868 376).

In the case of highly charged V-type four-stroke diesel engines with a low number of cylinders and a small V angle of 45 °, however, pneumatic starting from any crank position is not possible (DE-OS 2002 982). A V engine with eight cylinders and a part symmetrical cross shaft has, at a V-angle of 45 ° firing intervals of 45 °, 90 ° and 135 ° KW and with the fully symmetrical crankshaft firing intervals of alternately 45 ° and 135 ⁰ KW .. Since at

130QU / 0941

In highly charged diesel engines, the exhaust valve already opens 50 ° to 60 KvV before the bottom dead center of the piston, only an angular range of 120 ° remains for the starting process, so that with ignition offsets of 135 ⁰ KW the engine can no longer be started from any crank position . V-motors with 6 cylinders and a V-angle of 45 ° even have ignition intervals of alternating 45 and 195 KW and thus a crank angle range of 75> in which no starting torque can be generated.

These Kofcoren must therefore with a pneumatic or electric operated starter motor so that it can be started immediately in the event of an emergency, The disadvantage here is the high air volume or dependency from a power source and that for such a drive aril KIotor au realizing great effort. Pneumatic starting is therefore particularly preferred for large diesel engines.

Object of the invention

The aim of the invention is to reduce the effort for starting particularly highly charged four-stroke diesel engines in V-design with a low number of cylinders and a small V-angle.

Explain the essence of the invention

The invention is based on the object, in particular for highly charged four-stroke diesel engines in V-design with lower Number of cylinders and a small V-angle to enable pneumatic starting from any crank position. According to the invention the object is achieved in that the starting cams and exhaust cams additionally arranged on the control shaft, each with two cam lobes for a control the starter and exhaust valves are designed according to the two-stroke process beef and only during the starting process via actuators

130014/0941

riiit these are in connection. The tliuct osition of the se-. , The drive is set to the starting position and vice versa, for example by moving the control shaft ..: -._-.--

Aubi'üiirunrebc example ■ · '-.

The invention is explained in more detail below. "- ■" ■■ 'ELn VLcx'talctdieselmoc-or in. V-3auart has two retaining valves provided with valves for controlling the gas exchange valve. The curls have an i. "Ockenerhebuhg, so that at half the speed of the expensive shafts compared to the" crankshaft, the yen; -tile are actuated after two revolutions of the crankshaft. On the control shafts cinj s; usLIL "2lich for each -Zyliaderabschnil;:.: v.vei squatting arranged only control- the starting valves and the AuGlaßvenfcile 'which have undergone working two Nockenerhebuhgen. ■ sit. The control shafts can be moved in a known manner. The internal combustion engine is started in a control shaft position. The control of the air valves and the exhaust valves is carried out according to the two-stroke process with the aid of the locks provided with two lock elevations, so that the valves are activated once with each turn of the crank. be made. In the top dead center of the piston the on opens. ^; release valve and the starting compressed air flowing into the combustion chamber moves the piston downwards. At the bottom dead center or shortly before it, the exhaust valve opens and the compressed air escapes from the cylinder. The inlet valves remain closed during the starting process. But it is also possible, for example, to use the inlet valves for the outlet of the compressed air instead of the outlet valves.

After reaching the start rotation ζ aiii, the control shaft is shifted, the control of the inlet and outlet valves now take over the crouching for the operating state and the start Fuel injections.

As a result of the changeover from the four-stroke to the two-stroke process when the internal combustion engine is started, the

1300U / 0941 BAEf ORIGINAL

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with highly charged four-stroke diesel engines in V-design with low number of cylinders and a small V-angle large ignition intervals bo reduces that pneumatic starting the internal combustion engine from any crank position can be done.

A Vicrtalct diesel engine in V-design with 6 cylinders and a V-angle of 45 ° has ignition intervals of alternately 45 and 195 KV /. ^{Since only about 120 0} KV / are available for each cylinder unit due to the valve overlap for the starting process, no starting torque can be generated in a crank angle range of 75 °. If the LIo bor remains in such a position, an immediate pneumatic start is not possible. Leg tempering after process two-clock-r be the ignition intervals 45 ° and 75 ⁰ KV / and the 3teu-jrung of the exhaust valves is such that '/ a Anl ate over a range of almost 180 IC "torque is produced. This engine kcjin according to de ;;: two-stroke process can be started with only one row, since the ignition intervals are 120 Kv /. In the case of the other row of cylinders, the injection and ignition can be initiated after the specified starting speed has been reached, so that the starting control shaft can be shifted back into the operating position without ignitions and only then does the injection begin.

130QU / 0941 BATH ORIGINAL

Claims (2)

NACHQEREi .Π " r f in d un claim Valve control ζ; To start these four-stroke engines, in particular of highly charged four-stroke diesel engines in V-design with a low number of cylinders and a small VV / angle, consisting of a control valve equipped with rjocks for controlling the inlet and outlet valves as well as the starter valves, which are operated by means of compressed air cranking the internal combustion engine cause, characterized in that the starting cam and on the control shaft additionally disposed exhaust cams cind formed with two iiockonerhebun- ^ s for controlling the starting and Auslai'3ventile by your two-stroke method and only including Anlaßvor {yes: i _t ; be in connection with these organs via oetiitii. 2. Valve control according to point 1., daharcli marked that the control shaft is displaceable. 1300U / 0941- ORIGINAL INSPECTED