Porsche patent for the 1987 S4 crankcase breather system

Crankcase ventilation system for motor vehicles

US 4753214 A
ABSTRACT

A crankcase ventilation system for motor vehicles comprises a main ventilation system and a safety ventilation system, in which at an air guiding housing of the intake system, connecting pieces are arranged to which the lines of the two systems are connected. So that the connection between the lines of the two systems and the air guiding housing is simplified with respect to construction and also requires little space, a joint connecting piece having connecting pipe sections for the lines of both systems is provided at the air guiding housing. Separate ducts lead away from the connecting pipe sections and extend to remotely arranged outlet openings. The outlet openings of both ducts--seen in flow direction--extend at a distance from one another.


CLAIMS(15)
What is claimed:
1. A crankcase ventilation system for motor vehicles, in which the crankcase gases are returned from the cylinder block and crankcase into an air guiding housing of an intake system of an internal-combustion engine via a main ventilation system or a safety ventilation system for accommodating blockage of the main ventilation system, comprising
a main intake line connected to the main ventilation system and the crankcase,
a safety intake line connected to the safety ventilation system and the crankcase in by passing relation to the main intake line, and
a common connecting piece for connecting the air guiding housing with both the main intake line and the safety intake line.
2. A crankcase ventilation system according to claim 1, wherein said common connecting piece includes respective separate ducts which lead away from connecting pipe sections for the main intake line and the safety intake line, said separate ducts extending to remotely arranged outlet openings, and wherein outlet openings of the ducts, seen in flow direction, extend at a distance to one another and lead into the air guiding housing.
3. A crankcase ventilation system according to claim 2, wherein the connecting piece is developed to be approximately Y-shaped.
4. A crankcase ventilation system according to claim 2, wherein a duct of the safety ventilation system extends as a continuation of a pertaining connecting pipe section and has a straight shape.
5. A crankcase ventilation system according to claim 2, wherein a duct of the main ventilation system surrounds a duct of the safety ventilation system.
6. A crankcase ventilation system according to claim 5, wherein the two ducts of the main ventilation system and the safety ventilation system are arranged eccentrically with respect to one another.
7. A crankcase ventilation system according to claim 5, wherein wall sections of the ducts of the main ventilation system and the safety ventilation system rest against one another along portions thereof.
8. A crankcase ventilation system according to claim 2, wherein a outlet opening of the main ventilation system, seen in flow direction, is arranged in front of an outlet opening of the safety ventilation system.
9. A crankcase ventilation system according to claim 1, wherein a duct of the main ventilation system and an assigned connecting pipe section are placed against one another at an angle.
10. A crankcase ventilation system according to claim 2, wherein a duct of the main ventilation system is developed to be closed at the side that is opposite its outlet opening.
11. A crankcase ventilation system according to claim 2, wherein the connecting piece is inserted into a pipe section of the air guiding housing and is connected with it via a locking connection.
12. A crankcase ventilation system according to claim 2, wherein a duct of the safety ventilation system, with its free end containing an outlet opening, projects with portions thereof into the interior of the air guiding housing.
13. A crankcase ventilation system according to claim 2, wherein an end of the duct containing an outlet opening is arranged outside an interior limiting wall in the area of the pipe section.
14. A crankcase ventilation system according to claim 2, wherein the air guiding housing is formed by an air guiding scoop arranged between an air mass meter and a throttle valve pipe section.
15. A crankcase ventilation system according to claim 1, wherein said common connecting piece is a unitary one-piece molded part that includes respective main intake and safety intake ducts connecting the main intake line and the safety intake line to different outlet openings in the air guiding housing.



DESCRIPTION
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to a crankcase ventilation system for motor vehicles, in which the crankcase gases are returned from the cylinder block and crankcase into an intake system of an internal-combustion engine via a main ventilation system or a safety ventilation system. Connecting pieces are arranged at an air guiding housing of the intake system for connecting lines of the main ventilation system and of the safety ventilation system.

In the case of a known crankcase ventilation system (Service Information 1985, Porsche 928 S, USA, Pages 30 and 31) of the initially mentioned type, two connecting pieces arranged at a spacing from one another are provided at the air guiding housing of the intake system, one connecting piece being connected with the line of the main ventilation system and the other connecting piece being connected with the line of the safety ventilation system. This crankcase ventilation system functions well, but the construction of the air guiding housing with the two connecting pieces is costly. In addition, the two connecting pieces require considerable space at the air guiding housing so that the narrow space conditions that anyhow are present particularly in the area of the intake system of a four-valve engine are limited even more.

It is an objective of the invention to take such measures at a crankcase ventilation system that the connection between the lines of the two systems and the air guiding housing is simplified with respect to construction and also requires little space.

According to the invention, this objective is achieved by providing a common connecting piece that connects both crankcase ventilation systems with the air guide housing. In certain preferred embodiments, the common connecting piece has outlet openings to the air guide housing that are spaced from one another in the vented gas flow direction. The preferred embodiments of the invention have a unitary connecting piece with a Y-shape, the arms of the y connecting respectively to the two ventilation systems.

The main advantages achieved by means of the invention are that by the arrangement of only one connecting piece for the lines of both systems, a simple and space-saving connection is established between the lines and the air guiding housing. By means of the separate ducts inside the connecting piece for the two systems and the outlet openings that are offset with respect to one another, a good functioning of the crankcase ventilation system is achieved. When the outlet opening of the main ventilation system is, for example, closed by ice, the safety ventilation system with the outlet opening that in sections projects into the inside of the air guiding housing will take over the crankcase ventilation until the closed connection of the main ventilation system in the air guiding housing has become penetrable again after the engine operating temperature or a sufficient engine compartment temperature has been reached. The connecting piece can be constructed in an easy and cost-effective way. Because of the locking connection between the connecting piece and the short pipe section of the air guiding housing in certain preferred embodiments, a rapid and easy mounting of the connecting piece is ensured.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a frontal schematic view of an internal-combustion engine having a crankcase ventilation system constructed in accordance with a preferred embodiment of the invention;

FIG. 2 is a diagrammatic view from above onto the crankcase ventilation system of FIG. 1;

FIG. 3 is a sectional view taken along the Line III--III of FIG. 2; and

FIG. 4 is a sectional view taken along the Line IV--IV of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS
A multicylinder internal-combustion engine 1 for a motor vehicle comprises a cylinder head 2 and a cylinder block and crankcase 3. For the return of the crankcase gases from the cylinder block and crankcase 3 into an intake system 4 of the internal-combustion engine 1, a crankcase ventilation system is provided that is composed of a main ventilation system 6 and a safety ventilation system 7.

In the case of the main ventilation system 6, the crankcase gases (blow-by gases) move from the cylinder block and crankcase 3 into an oil filler neck 8. Subsequently, they pass through a line 9 that is connected via an angle connection 10 with a cylinder head cover 11 that penetrates it. Inside the cylinder head cover 11, between the two central cylinders, an oil separator is arranged that is not shown in detail. After flowing through the oil separator, the crankcase gases, via another angle connection 12 and a line 13 arranged outside the cylinder head cover, reach a connecting piece 14 that is arranged at an air guiding housing 15 of the intake system 4. Inside the angle connection 12, a throttle is inserted that is not shown.

When the main ventilation system 6 fails, for example, caused by icing (=closing of the throttle bore and/or of the outlet opening of the connecting piece), the excessive pressure in the cylinder block and crankcase 3 will rise because of lacking pressure balance and the safety ventilation system 7 will be actuated. In the case of the safety ventilation system 7, the crankcase gases, via an opening of the cylinder block and crankcase 3 that is not shown, will reach the oil filler neck 8. At 16, a safety valve is inserted into a connection of the oil filler neck 8 that opens at an excessive pressure of 80 to 100 mbar. When the safety valve is open, the crankcase gases, via a line 17, flow directly to the air guiding housing 15 (FIG. 2).

According to FIGS. 2 and 3, a joint connecting piece 14 having respective connecting pipe sections 18, 19 for the lines 13, 17 of the two systems 6, 7 (main ventilation system and safety ventilation system) is provided at the air guiding housing 15, in which case separate ducts 20, 21 lead away from the two connecting pipe sections 18, 19 and extend to remotely arranged outlet openings 22, 23. The two connecting pipe sections 18, 19 extend at an angle to one another. The outlet openings 22, 23 of the two ducts 20, 21, seen in flow direction B, extend at a distance A to one another and lead into the air guiding housing 15. Duct 21 of the safety ventilation system 7 that is shaped in a straight line extends as a continuation of the connecting pipe section 19 and with its free end containing the opening 23, in sections, projects into the interior space 24 of the air guiding housing 15. The cross-section of the duct 21, seen over its whole longitudinal course, is constant. The duct 20 of the main ventilation system 6 surrounds the duct 21 of the safety ventilation system 7 in sections, in which case the two ducts 20, 21 are arranged eccentrically with respect to one another. Wall sections of the interior duct 21 and of the exterior duct 20 are merged together at 25. The exterior duct 20 has an approximately crescent-shaped cross-section (FIG. 4).

The connecting pipe section 18 of the main ventilation system 6 extends at an angle to the connecting duct 20, the side 26 of the duct 20 that is opposite the outlet opening 22 being developed to be closed. The outlet opening 22 of the main ventilation system 6, seen in flow direction B, is arranged in front of the outlet opening 23 of the safety ventilation system 7, in such a way that the outlet opening 22 of the main ventilation system 6 extends in the area of a connecting pipe section 27 of the air guiding housing 15. The outlet opening 23 of the safety ventilation system 7 extends approximately in parallel to an interior limiting wall 28 of the air guiding housing 15.

The approximately Y-shaped connecting piece 14 is inserted into the molded-on connecting pipe section 27 of the air guiding housing 15 and connected with it via a locking connection 29. The locking connection 29 comprises groove-shaped molded-on parts 30 at the connecting piece 14 that engage in corresponding recesses 31 of the connecting pipe section 27. The air guiding housing 15 is formed by an air guiding scoop 32 developed in the shape of a pipe section connection that is arranged between an air mass meter and a throttle valve connection piece, namely below a throttle valve that is not shown.

Although the present invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only, and is not to be taken by way of limitation. The spirit and scope of the present invention are to be limited only by the terms of the appended claims.

PATENT CITATIONS
Cited Patent Filing date Publication date Applicant Title
US2311036 * 27 May 1940 16 Feb 1943 Dick Wills Engine breather and ventilating system
US3059628 * 13 Dec 1960 23 Oct 1962 William J Linn Gas and fume disposal system for internal combustion engines
US3372685 * 5 Dec 1966 12 Mar 1968 Ardell T. Bestland Excessive crankcase pressure warning system and relief valve
US4011846 * 24 Mar 1975 15 Mar 1977 Did-Mor Engineering And Manufacturing Co. Anti-pollution device
DE3627376A1 * 12 Aug 1986 18 Feb 1988 Unilever Nv Bundle of a plurality of individual packs, and method for its manufacture
* Cited by examiner
NON-PATENT CITATIONS
Reference
1 * Porsche, Information Service 1985, 928S USA, Jun. 1985, pp. 30 & 31.
* Cited by examiner
REFERENCED BY
Citing Patent Filing date Publication date Applicant Title
US5140968 * 14 Feb 1992 25 Aug 1992 Navistar International Transportation Corp. Closed loop breather system for engine crankcase
US8151777 29 Oct 2008 10 Apr 2012 Toyota Jidosha Kabushiki Kaisha Intake pipe structure of internal combustion engine
CN1298968C * 15 Apr 2004 7 Feb 2007 日产自动车株式会社 Internal-combustion engine with cylinder mixing air recycle system
CN101230792B 22 Jan 2008 29 Dec 2010 通用汽车环球科技运作公司 Engine PCV system with venturi nozzle for flow regulation
CN101539044B 18 Mar 2009 30 Nov 2011 丰田自动车株式会社 用于内燃发动机的电控窜缸混合气返回装置
EP0874141A1 * 9 Apr 1998 28 Oct 1998 Daimler-Benz Aktiengesellschaft Venting device for the pipe connected to the intake manifold of a combustion engine
EP1469171A2 * 14 Apr 2004 20 Oct 2004 Nissan Motor Company, Limited Internal combustion engine with blow-by gas recirculation system
WO2009084144A1 * 29 Oct 2008 9 Jul 2009 Toyota Motor Co Ltd Intake pipe structure of internal combustion engine
* Cited by examiner
CLASSIFICATIONS
U.S. Classification 123/572
International Classification F02F7/00, F01M13/00, F02B75/22, F01M13/02
Cooperative Classification F02F7/006, F01M13/00, F02B75/22, F01M13/025
European Classification F01M13/00
LEGAL EVENTS
Date Code Event Description
10 Sep 1996 FP Expired due to failure to pay maintenance fee
Effective date: 19960703
30 Jun 1996 LAPS Lapse for failure to pay maintenance fees
6 Feb 1996 REMI Maintenance fee reminder mailed
30 Sep 1991 FPAY Fee payment
Year of fee payment: 4
12 Jun 1987 AS Assignment
Owner name: DR. ING. H.C.F. PORSCHE AKTIENGESELLSCHAFT, PORSCH
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:LANGLOIS, KARL;BATZILL, MANFRED;REEL/FRAME:004725/0879
Effective date: 19870604

=====

There are a number of important features in this original concept. The rear passenger valve cover breather (patent figure 12) has a volume separator inside the valve cover (not displayed in the drawing) and approximately 6mm metering orifice in the elbow. The connection (patent figure 16, 7, 17) has a check valve with approximately 1-1.5 psi cracking pressure. The from passenger valve cover breather (patent figure 10, 9, 6, 5) has no separator and no metering orifice. The connection from the oil filler neck to the intake manifold plenum has an approximately 2mm metering orifice.

Subsequently, multiple different variations of this system were produced. The two later ones are describes in the below figure from the workshop manual:

While the implementation in the early GTS engines on the left is more faithful to the original concept, the implementation on the righ

t for the later GTS engines deviated significantly from the original concept. A connection between valve covers is added, a check valve is eliminated, etc. The GTS engine breather system is broadly considered a failure, but it is not clear whether this is because of the external breather system per se or some other, more fundamental problems with the engine design.

The early S4 crankcase breather system that closely corresponds to the system originally described in the patent documents works somewhat adequately if the engine, including the engine redline, is stock and if the car is run on stock tires at moderate lateral accelerations. If the engine rpm is increased or other changes made, problems often appear. Subsequent GT models had more serious problems in even their stock form.

The lateral accelerations are relevant for the following reasons. In a 90-degree V8 engine, the oil drains from the cylinder heads are in approximately 45-degree angle relative to the vertical plane. In a 1g lateral acceleration, from the oil drain perspective the engine is effectively turned sideways with the oil drains horizontal on the outside turn bank of the engine. In this situation, there is no gravity drain, and the pressure differential between the crankcase and the head mostly determines in which direction the oil flows. If the crankcase pressurizes and the heads are relieved, it is logical to assume that the oil will flow into the heads instead of the sump.

In addition, the piston pumping pulses create havoc in the oil drains. It is possible that if blow by gasses increase the pressure and density of the crankcase and high rpms then increase the energy delivered by the piston pumping pulses, the oil may be ejected from the oil drains into the heads. The combination of high blow by rates, high engine speeds, and relatively low pressure in the heads compared to the crankcase may lead to oil drain problems so significant that the oil pump pickup in the sump will be starved of oil, resulting in engine failure.

I believe that the GT and S4 models’ crankcase breathing problems can be mostly resolved by redesigning the external crankcase breather system. Higher the operating rpms and higher the lateral accelerations, more extensive the required internal engine modifications. However, the engine internals of GT and S4 models are adequate for most uses, while improvement are of course possible.

The GTS engine has many issues relating to oil consumption and crankcase breathing, and I believe those aren't caused mainly by the breather system and in any case can't be cured with minor tweaks of the stock breather system. I believe that one problem in the GTS engine is the crankshaft. First, the increased stroke increases the pumping pulse energy by about 18.5% based on a crude back of the envelope formula. Second, the GTS crankshaft counterweights are very poorly designed. They not only cause high bearing loads but also block the crankcase gas flow with the addition of the center counterweights and the large fan angles of the counterweights. Finally, at least some GTS pistons do not have sensible oil drain provisions, leading to poor oil control on the bore walls and significant blow by that may be impossible to resolve with an external breather system. This combination leads to a situation in which crankcase is pressurized by blow by, oil is ejected to the intake manifold, the ejected oil will cause detonation, detonation will cause increased blow by, etc.

===

Reading the patent is illuminating. What they described in the patent was implemented in the '87 S4.

The factory intent was to primarily vent from the filler neck to the valve cover and then from the valve cover to the MAF elbow. For this to work, they must have assumed that the oil filler neck always has a higher pressure than the valve cover. We should verify that assumption. If the assumption is not true, then there is trouble with the air flowing the wrong way in oil drain channels.

The connection from the oil filler neck to the MAF elbow Y was thought of as a secondary, backup, "safety" venting channel. For that to work, all that was needed the static pressure at the MAF elbow being lower than at oil filler neck. It is not necessary for the valve covers to have a lower pressure than the oil filler neck.

Inexplicably, in the GTS model they eliminated the path that was described as the main breather channel in the patent. They connected the passenger valve cover to the driver valve cover. I can only think of one logical explanation of why they did this. They intended the crankcase to vent to the valve covers thru the head oil drains. The two valve covers were connected, because under lateral g-forces one side of oil drains, but not both, could be blocked by oil. They counted on at least some of the eight large oil drains to flow enough blowby gas to the valve covers that they could then be routed to the passenger side and then to the MAF elbow. The safety vent directly from the oil filler neck to the MAF elbow remains there.

What could have motivated the change? The components aren't any cheaper in the GTS version, in fact there's one more metal valve cover elbow fitting needed which is expensive. They must have thought that the connection that they eliminated, from the oil filler neck to the passenger side valve cover was counterproductive. The only way that I can think of it being counterproductive is if they came to the conclusion that air was flowing in the wrong direction from the front of the passenger side valve cover to the oil filler neck and that air being replaced by air flowing up the drain channel. Why else would they eliminated that connection?

This leads to the interesting question why would air flow from the valve cover to the oil filler neck? The only reasons I can come up with are the following: either it's the piston pumping pulses doing something unexpected, or the crankshaft rotation pulling a low pressure to the oil filler neck at high rpms.

Anyone else with any hypotheses why they moved away from the scheme of the patent?

Also, what's up with the check valve in the y? Here's Mike Schmidt writing about the system:  Mike Schmidt has figured out how the 928 S4 crankcase breather is supposed to perform it's functions and offers this explanation

Quote:
The air can't go through the smaller diameter angle cut section of the plastic "Y" piece because of the check valve.
Mike mentions that there' a check valve in the y-piece. The patent doesn't mention it and neither of the two y-pieces I have have a check valve. Unless the check valve is the 100 millibar valve they mention. That's it I am guessing. 100 millibars is a lot, though, like 1.5 psi. It really is only a safety valve then if calibrated as the patent prescribes, and the filler neck to will only vent directly to the filler neck when the situation is pretty dire in terms of excessive crankcase pressure.

Edit: mystery solved, my spare 87 engine has a check valve in the oil filler neck. Haven't measured the cracking pressure, though.

Ok, so the mystery deepens. The factory seems to have eliminated the check valve from the GTS oil filler neck when they moved the port higher. Is this true? If it is true then, isn't the throttle closed breather flush function simply going to draw the air from MAF elbow and the crankcase doesn't get flushed with fresh air? I think I understand the factory's intent with the S4 breather system, but now the GTS system doesn't look very well though out to me. Maybe they thought that by connecting the valve covers they would get enough crank rotation induced flow in the heads and crankcase, and wanted to eliminate the check valve simply to increase the flow capacity of the system?

taken from updates by "ptuomov"

===

If there is no check valve in the oil filler neck, like with the GTS, what's to prevent the closed throttle circuit from drawing the air directly from the hose that connects the oil filler neck and the MAF elbow? As far as I see nothing. If so, there's not fresh air circulating in the crankcase, removing water and fuel vapors.

The early GTS, based on hearsay, has a 6mm restrictor in the valve cover elbow and a 5mm restrictor in the oil filler neck. That arrangement flows about the same as the S4 system at high crankcase pressures, assuming that the 5mm orifice and the safety check valve flow about the same.
  
According to hearsay, some GTS engines have no 6mm restrictor in the valve cover elbow. This will increase the flow capacity of the system, but now the gas velocity in the air-oil separator tube in the valve cover may become too high and the elbow will spew out oil. It would in my opinion be a preferable solution to increasing flow capacity to add an additional breather to the other side and retain the 6 mm restrictor on both sides.

ptumov

=====Interesting discussion about this:  https://rennlist.com/forums/928-forum/776080-how-to-do-the-boosted-car-crankcase-breathing-right-7.html

and more here:  https://rennlist.com/forums/928-forum/560928-twin-turbo-928-fixed-and-back-out-there-terrorizing-the-streets-77.html#post13127650