US2797674A

US2797674A - Crankcase ventilation system

Info

Publication number: US2797674A
Application number: US465915A
Authority: US
Inventors: Dolza John
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1954-11-01
Filing date: 1954-11-01
Publication date: 1957-07-02
Anticipated expiration: 1974-07-02

Description

July 2, 1957 J. DOLZ'A 2,797,674

CRANKCASE VENTILATION SYSTEM Filed Nov. 1, 1954 4 Sheets-Sheet 1 INVENTOR (foil? P0820 ATTORNEY July 2, 1957 J. DOLZA 2,797,674

CRANKCASE VENTILATION SYSTEM I Filed NOV. 1, 1954 4 Sheets-Sheet 2 INVENTOR BY (52,? @0220 069M ATTORNEY J. DOLZA CRANKCASE VENTILATION SYSTEM July 2, 1957 4 Sheets-Sheet 3 Filed Nov. 1, 1 54 INVENTOR ATTORNE):

July 2,- 1957 J. DOLZA CRANKCASE VENTILATION SYSTEM 4 Sheets-Sheet 4 Filed Nov. 1, 1954 INVENTOR cfofiypafza W M U$ATTORNEY United States Patent Ofiice 2,797,674 Patented July 2 I957 rant CRANKCASE VENTILATION SYSTEM John Dolza, Davisburg, Mich., assiguor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 1, 1954, Serial No. 4 5,915

' 19 Claims. l. 123-119 The present inventionrelates to internal combustion engines and more particularly to means'for ventilating the crankcase of an engine so as to remove any deleterious fumes contained therein.

During normal operation of an internal combustion engine, the burning of the fuels and heating of the lubricating oils produces a considerable volume of by-products which appear in the engine crankcase in the form of vapors, gases, etc. These by-products :are frequently of a corrosive nature and unless removedfrom the crankcase, they may accumulate in suflicient quantities to cause harmful effects on the interior of the engine. In addition these vapors may eventually condense in the crankcase in sufficient quantities to dilute the lubricants and impair their effectiveness. Accordingly, numerous systems have been devised to ventilate engine crankcases with fresh air in an effort to continuously remove the vapors and gases as they are formed. In order to insure an adequate flow of air through the crankcase, these systems have employed some means for creating a forced draft. Although these means may be effective to produce a draft, the volume of the draft usually varies as the load on theengine or the speed of the vehicle varies. Thus the systems employed heretofore, although producing adequate ventilation under some operating conditions, produce excessive or inadequate ventilation under other conditions. 7 It an effort to correct this difliculty, additional means may be provided for maintaining a uniform flow of air through the crankcase. However, they are normally of doubtful effectiveness as Well as being complex and expensive.

It is now proposed to provide means for positively in ducing a draft of constant volume through the crankcase during all engine operating conditions. This is .to be accomplished by interconnecting the crankcaseventilating system with the induction system of the engine. This will permit use of the intake manifold vacuum to induce a flow of air through the crankcase. By placing the inletand the outlet for the crankcase ventilation system on. theopposite sides of the throttle valve, the pressure drop across the throttle valve or substantially the entire intake rnanifold vacuum, will be effective to produce a dijaft of air through the crankcase. However, the amount of the manifold vacuum will vary over a considerable range during operation of the engine. This .variationis approximately a function of the position of the throttle valve.

Accordingly, it is proposed to provide, suitable means for insuring the correct amount of ventilating air flowing through the crankcase in relation to engine speed and manifold pressure. This isto be accomplished by providing a control valve in the ventilation system which ,is responsive to movement of the throttle valve. The control valve is especially calibrated so, that the throttle valve will position the control valve to allow a predetermined amount of :air to flow. as a result of themanifold vacuum normally produced by that throttlesetting. As can be seen by a propercalibration of the valve, the optimum volume of fresh air will flow through the crankcase for all engine loads. 7

In the past the air flowing through the crankcase ventilating system has been drawn through some form of air cleaner. However, due to the low volume of air-flowing through the crankcase, these filters normally are notvery effective. In addition, such filters are normally not considered as being of sufficient importance to warrant the expense of a filter which would be effective enough to removefine grit and dust particles. Moreover, these air filters are frequently ignored and do not receive the adequate servicing to insure their operating effectively. As a result :an excessive amount of harmful dust is allowed to enter the crankcase ventilation system thus resulting in abrading .of the fine bearing surfaces and also the dirty filter will reduce the flow of air to such a small volume that serious condensation will occur. 7

It is now proposed to provide a crankcase ventilating system which will eliminate the necessity for using aspecial or separate air cleanerforthe air drawn into the crankcase. This is to be accomplished by drawing the air for the ventilating system from the induction systemafter it has passed through the air cleaner for/the induction system. This may be done by placing the intake for the ventilating system in communication with the induction system posterior to the air cleaner. Thus it can be seen that the necessity fora separate air cleaner for the crankcase ventilation system has been eliminated. It should .be noted that the volume of air required for the crankcase is relatively small compared to that required by the induction system. Thus the relatively small increasein load will not necessitate an increase in the capacity of the induction air cleaner. Due to the large volume of air handled by this air cleaner and the fact that theair flowing therethrough is drawn into the engine, this air cleaner is normally very effective in removing any forcing. matter from the air flowing therethrough. In :additiomair clean- .ers of. this nature normally receive adequate servicing to insure their operating effectively at all times. Thus it can be seen that in addition to eliminating the expense of a separateair cleaner, all of the air entering the crankcase will be cleaner than before as it must pass through the more larger and moreeflicient aircleaner normally provided for the intake of the induction system.

I leretofore, the air flowing through the crankcase ventilatingsystem has been drawn from the atmosphere into the crankcase withoutany satisfactory means for preheating the airbefore it enters the crankcase. This frequently results in excessively cold air entering the-crankcase and frequently causes the aforementioned harmful vapors, etc., to condense in the crankcase. This condensate may dilute the lubricants and/ or form sludges that interfere with the flow of the lubricants. This is particularly true during normal winter driving conditions, i. e., the average ambient temperature is very low. and the majority of the time the engine is not run long enough to result in the engine reaching optimum operating temperatures.

It is now proposed to employ means for preheating the airdrawn into the crankcase and, more particularly, only when the engine is below normal operating temperatures.

This may be accomplished by passing the air for the crankcase ventilating system in heat exchanging relation with the engine exhaust means before the air enters. the .crankcase. The exhaust gases will become very hot even though the engine is still cold, thus the air drawn into the crankcasewill be heated practically assoon asthe engine is started. Since present day engines are normally provided with an exhaust stove for preheating the air in the induction system, the intake for the ventilating system may be placed in heat exchanging relation with thestove. Moreover, since the flow of exhaust gases through the. stove is controlled by a thermostat responsive to engine temperatures, the air in the crankcase will not be preheated after the engine has attained normal operating temperatures thereby preventing overheating of the engine. It is thus apparent that an economical means for preheating the ventilating air has been provided by thermostatically controlled means as such thermostatic means are normally already provided in the induction system.

In the drawings:

Fig. 1 is a cross sectional view of an engine having a crankcase ventilating system embodying the present inv ention. V

Fig. 2 is a cross sectional view taken substantially along the plane of line 2-2 in Fig. 1.

Fig. 3 is a cross sectional view taken substantially along the plane of line 3-3 in Fig. 2.

Fig. 4 is a cross sectional view taken substantially along the plane of line 44 in Fig. 2.

Fig. 5 is a side elevational view of a modification of the present invention.

Fig. 6 is a plan view taken substantially along the plane I of line 66 in Fig. 5. r

Fig. 7 is a cross sectional view taken substantially along the plane of line 7-7 in Fig. 5.

Referring to the drawings in more detail, this invention may be embodied in any suitable engine 10. In the present instance, the engine 10 is of the so-called V-type in which a cylinder block 12 is provided with two angularly disposed banks of cylinders. Although these banks may contain any desired number of cylinders 14, in this instance, they are provided with three cylinders each as disclosed in United States Patent No. 2,632,340, V-6

engine by Dolza et al. The lower end of each of the cylinders 14 intersects the bottom wall 16 of the cylinder block 12 to form openings 18 that communicate with a space formed below the banks of cylinders. This space may be bounded by the bottom wall 16, front end wall 20 and rear end wall 22 and the side walls of the cylinder block 12. An oil pan 24 may be secured to the block 12 for enclosing this space and forming a crankcase 26 for the crankshaft 28. In the present instance the crankcase 26 is divided into three separate compartments 30, 32, and 34 by a pair of transverse bulkheads 36 and 38.

The crankshaft 28 may be supported at

journals

40, 42, 44 and 46 by main bearing inserts in

bulkheads

20, 22, 36 and 38. A piston rod (not shown) maybe provided for each cylinder for connecting the pistons to the throws of the crankshaft.

The space between the banks of cylinders may form a gallery 62 for receiving a camshaft 64. The camshaft 64 may be provided with a plurality of journals 66, 68, 70 and 72 that ride in bearing inserts in the

bulkheads

20, 22, 36 and 38 for permitting rotation of the camshaft 64. A plurality of cams 74 may be spaced axially along the shaft 64 for slidably engaging tappets (not shown) on the lower ends of the push rods (not shown), for actuating the intake and exhaust valves for the various cylinders 14 of the engine 10. Timing gear means 76 such as a gear 80 on the crankshaft 28 and a gear 82 on the camshaft 64 may be provided inside of the timing gear cover 78'so that they may be drivingly connected together by a driving chain 84 for rotating the camshaft 64 from the crankshaft 28. If it is desired to balance out secondary vibrations, a secondary balance shaft 85 may be disposed 'below the camshaft 64 in the bottom of the camshaft gallery 62 so as to be driven by the timing gear means '76 as disclosed in co-pending application Serial No.

cember 15, 1954. The fuel supply system 88 includes a fuel pump 92 connected to the fuel tank and preferably that is mounted on the intake manifold 110.

mounted on or within the induction system so as to be seated in a recess 94. A substantially vertical push rod 96 may be slidably disposed in a guide 98 through the induction system 90 with the lower end of the rod 96 riding on an eccentric 100. The upper end of the rod may project into the recess 94 and engage the fuel pump rocker arm 102. Thus rotation of the eccentric 100 will drive the fuel pump 92 by means of the reciprocating push rod 96.

The induction system 90 may include a heating chamber 104, an air cleaner 106, a carburetor 108 and an intake manifold 110. In the present instance the heating chamber 104 comprises a sheet metal structure that forms a shroud 112 around an exhaust crossover pipe 114. When the engine 10 is cold, the air for the induction system 90 may be drawn in through the openings 116 in the ends of the shroud 112 so as to pass in heat exchanging relation with the exhaust pipe 114. However, when the engine 10 reaches normal operating temperatures, a thermostat 117 will move the intake valve 118 and cause the air to be drawn through the opening 120 directly into the induction system 90 without preheating it.

The intake manifold 110 may be secured on the top of the cylinder block 12 so as to form a cover for the camshaft gallery 62. The manifold 110 may include a central chamber 122 and an opening 124 in the top there- .of. A plurality of distribution passages 126 may communicate between the chamber 122 and the intake valves of the various cylinders 14.

The carburetor 108 may include a throttle body 130 In the present instance the throttle body extends over the opening 124 and the recess 94 to form a support for the fuel pump 92 and the carburetor 108. The carburetor 108 which is of the so-called down draft type is positioned on the throttle body so that a vertical passage 132 forms an outlet that discharges the air-fuel mixture through the opening 124 into the central chamber 122. The upper end of the passage 132 forms an air inlet 134. A venturi may be provided intermediate the ends of the passage to facilitate the aspiration of atomized fuel into the air flowing therethrough while a throttle valve 133 may be provided in the throttle body 130 adjacent the lower end of the passage 132 to control the volume of the charge flowing therethrough.

The air cleaner 106 may include a housing 136 which is mounted on top of the manifold 110 concentrically about the carburetor 108. The housing 136 may extend forwardly to interconnect the heating chamber 104 with the carburetor intake 134. In the present instance the air cleaner 106 has a porous filter element 138 which is positioned inside of the housing 136 to divide it into an outer and

inner compartment

140 and 142, respectively. Thus any air which is drawn through the induction system 90 into the cylinders 14 will first pass through the heating chamber 104, when the engine is cold, or inlet 120 when the engine is hot. Then through the air cleaner 106, the carburetor 108 and the distribution passages 126 in the intake manifold 110.

A ventilation system 144 may be provided for the crankcase 26 and the camshaft gallery 62. The ventilating system 144 may employ a circulation through the inside of the engine 10 which will effectively remove any fumes that are created during operation of the engine 10. The intake 146 for the present ventilating system 144 may communicate with a portion of the induction system 90 posterior to the filter element 138. In the present instance this intake 146 comprises a passage that extends through the carburetor to form an opening 148 that communicates with the inner chamber 142 of the air cleaner 106 between the venturi and the filter element 138. Thus all of the air which enters the crankcase 26 must first pass through the filter element 138 and the heating chamber 104 if the engine is cold. The lower end of the passage 150 may communicate with the recess 94 for the .fuel pump 92. A duct 152 may be formed in- ,the mani may flow downwardly through the passage 150 and duct 152 into the timing gear case 78.

After the air enters the timing gear case 78 it may flow downwardly below the front end wall 20 and into the front of the crankcase 26. One or more suitably spaced openings 154 may be provided in the floor 16 of the camshaft gallery 62 so that the air in the crankcase 26 may flow upwardly into the camshaft gallery 62. It is desirable that the openings 154 be disposed about the crankcase 26 to insure the air flowing to all parts thereof. It is thus apparent that an endless supply of filtered fresh air may flow through the timing gear case 78 and the crankcase 26 so as to sweepany noxious fumes therefrom.

The outlet 158 for the ventilation system144mayinterconnect the camshaft gallery with the induction system posterior to the throttle valve 133. In the present instance the outlet includes an oil separator 159 and an enlarged duct 160. The oil separator 159 may. include a perforated cup member 161 that fitsover the opening 163 and inside of the housing 165. Thus the air may flow up through the member 161 and down-through the housing 165 into the space 165a. When the air turns to pass through the perforations, the oil particles will be centrifugally thrown from the air flow and drain back through the opening 163. In the event any oil does pass through the perforations, it will collect on the inside of the housing 165 and drain down behind the dam 167 from whence it may flow to the opening 163.

The duct 160 may be disposed in'the throttle body 130 so as to communicate with the space 165a. The upper end of the duct 160 may form a valve chamber 162. A short passage 164 may extend horizontally through the throttle body 130 to intersect the vertical passage 132 in the carburetor 108 posterior to the throttle valve133.

The other end of the short passage 164 forms an opening 158 for the ventilation system 144 on opposite sides of the throttle valve 133, the pressure at the opposite ends of the ventilation system 144 will be a function of the intake manifold vacuum. Thus whenever the engine 10 is in operation, there will be a pressure that will tend to cause a positive draft for ventilating the crankcase 26 with fresh air.

It should be noted that during oper ation of the engine 10, as the position of the throttle valve 133 varies between open and closed, there will be wide fluctuations in the pressure differential across the throttle valve 133. When the throttle 133 is fully opened for full throttle operation, there will be little resistance to air flow and the drop across the throttle valve will be a minimum. However, when the throttle valve. 133 is closed for idling, there will be a very large resistance to the flow ofair and accordingly, a very large pressure differential. Since the intake and outlet 146 and 158, respectively, for the ventilation system 144 are on opposite sides of the throttle valve 133, the large vacuum during idle conditions will tend to produce a considerably larger draft through the crankcase than the small vacuum occurring during full throttle operation. Therefore unless some suitable means are provided for controlling the volume of this draft, it will be either excessive or inadequate under some conditions. In

the Present instance a control valve 170 is provided in the valve chamber. 162 for controlling theflow of air through the crankcase 26.

Since these variations in the manifold vacuum are a function of the position of the throttle valve 133, it has .more of-the opening 166. Therefore, in spite of the increasedvacuum the optimum flow of air will circulate .tlrroughthe, crankcaser26 at all times.

.beenfound advantageous to make the control valve 170 responsive to movement of the throttle valve 133. Ac-

. cordingly, the present control valve 170includes a plate :172 which is mounted on the throttle valve shaft 174 so as to rotatewith thethrottle valve 133. Theplate; 172 is preferably a planular disc positioned to cover at least aiportion ofthe opening 166 formed in the wall of the valve chamber-162 by the horizontal passage 164. The

periphery of the plate 172 may be provided with a substantially spiral cam surface 176 that extends across the opening 166 so that as the plate 172 rotates the amount of the op ening 166 covered by the plate 172 will vary. This cam surface 176 is preferably shaped so that for any given positionof the throttle valve 133, the plate 172 will cover enough of the opening 166 to result in a predetermined amount of air flowing therethrough for the amount of manifold vacuum normally producedat that throttle setting. Thus as the throttle valve 133 closes and the pressure drop. between the inlet 146 and outlet 158 increases, the plate 172 will progressively cover more and It can be seen that a ventilation system 144 has been provided in which the intake manifold vacuum produces adraft of substantially uniform volume. In addition, the

.air is very effectively filtered and preheated when the engine is cold by thermostatically controlled means.

The modification shown in Figs. 5 through 7, inclusive, is particularly adapted for use on a conventional V-8 engine. 200 employing a so-called double H intake manifold 202. However, it should be understood that this .form .of the invention is equally applicable to any type of engine.

The intake manifold 202 comprises a body which is adapted to be secured to the engine 200 so as extend over the space between the two banks of cylinders. The manifold 202 may include distribution passages that form ports 204 adapted to communicate with the intake valves for the cylinders in the engine 200. In the present instance these passages are in the form of two separate Hs which have

parallel center passages

206 and 208. A water passage 210 may be provided in the front of the manifold 202. The ends of the passage may form ports a 212 that communicate with the water jacket in the head.

A flange 214 may be provided above the center of the passage 2l 0for receiving a water hose suitable for cona pair of

openings

223 and 225 in the flange 217.

The carburetor 218 may be of any desired design such as the carburetor 108 employed in the preferred embodiment. The present carburetor 218 is of the downdraft type in which a substantially vertical intake pasage 221 extends downwardly from the top of the carburetor 218 to form a single opening 222a in the top of the carburetor that communicates with an air cleaner 224 while the lower portion divides into two separte branch passages 226 and 228 that form a pair of outlet openings that register with the

openings

223 and 225 in the mounting flange 217. Each branch passage 226 and 228 may be provided with a venturi to facilitate atomizing the fuel into the air and a throttle valve 230 for controlling the rate of flow therethrough. The throttle valves 230 are preferably mounted on a common throttle shaft 232. A choke 233 may be provided for varying the air-fuel mixture. It may be seen that air entering the engine 200 will flow from the air 7 buretor riser 216, and then through the distribution passages in the intake manifold 202.

If the engine 200 is started when the temperature thereof is considerably below normal operating temperatures,

the particles of atomized fuel may precipitate out of the air-fuel mixture onto the walls of the distribution passages. Accordingly, means may be provided for heating the walls of the distribution passages to cause re-evaporation of any fuel particles that condense thereon. In the present

instance exhaust ducts

234 and 236 are provided in the manifold 202 in heat exchanging relation with the walls of the distribution passages. One duct 234 may be connected to one end of an exhaust crossover pipe 238 that extends around the end of the engine 200 from one bank of cylinders. The other duct 236 may be connected to another exhaust crossover pipe 248 that extends around the end of the engine from the other bank of cylinders.

The

ducts

234 and 236 which may communicate with each other to form a U shape extend under the distribution'passages in heat exchanging relation with the walls thereof. In order to increase the heat transfer, a plurality of heat absorbing fins 242 may be provided on the walls separating the exhaust ducts from center portions of the distribution passages. A by-pass valve 244 may be disposed in the manifold 202 to deflect exhaust gases through the

ducts

234 and 236 and when the engine 200 is cold. A suitable thermostat similar to thermostat 117 may be provided for moving the valve 244 to a position which will deflect the exhaust gases from one pipe to the other without the gases passing through the duct.

' In order to remove any noxious fumes from the crankcase, a ventilating system 246 may be employed. This system 246 may employ any desired circulation such as in the preferred embodiment wherein the air flows through the timing gear case into the crankcase and out through the camshaft gallery. However, in the modification,

the air flows into one end 248 of the camshaft gallery 250, into the crankcase, and then into the other end 252 of the gallery. The inlet means for the modification may comprise a passage 254 that extends vertically through the carburetor housing 218. The upper end of the passage may include an intake 256 that projects into the mixture supply passage 220 through the carburetor 218 anterior to the choke valve 233 and throttle valves 230. The lower end of the passage 254 communicates with the bottom of the intake manifold to form an opening 258 adjacent the

exhaust ducts

234 and 236. A set of flanges 260 may project from the manifold 202 around the opening 258 so as to compress a gasket 262 against a raised center portion 264 on the camshaft gallery cover 266. Thus a chamber 268 will be formed between the manifold 202 and the cover 266 with the lower end of the passage 254 communicating with the chamber 268 adjacent one side thereof. An opening 270 may be provided in the chamber 268 that communicates with the inlet end 248 of the ventilation system 246. In the present instance this comprises the end 248 of the camshaft gallery 250 in front of the baffle 272. Thus the air flowing into the chamber 268 will have passed through the air cleaner 224 and in heat exchanging relation with the

exhaust ducts

234 and 236. In order to increase the amount of heat transfer to the air in the ventilation system, fins 274 may be formed in the cover 266 to divide the chamber 268 into a tortuous path.

After the air in the ventilation system 246 has passed through the crankcase, camshaft gallery 250, etc. and

swept all of the noxious fumes therefrom, it may be drawn through the passage 276, into the induction system. A control valve 280 similar to that in the preferred embodimen may be provided for controlling th flow of air therethrough. The plate 282 of valve 280 is mounted on the throttle valve shaft 232 so that the periphery registers with a portion of the opening 284. Thus as the throttle valves 230 move and the vacuum changes, the plate 282 will open and close the opening 284 so as to maintain a substantially uniform flow at all times.

It is to be understood that, although the invention has been described with specific reference to particular embodiments thereof, it is not to be so limited since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the ap pended claims.

What is claimed is:

1. A crankcase ventilation system for an engine having a crankcase and an induction system with a throttle valve therein, said ventilation system comprising an intake duct having one end thereof communicating with said induction system on one side of said throttle valve, the other end thereof communicating with said crankcase for discharging fresh air from said induction system into said crankcase, and an outlet duct having one end thereof communicating with said crankcase, the other end of said outlet duct communicating with said induction system on the opposite side of said throttle valve for exhausting air from said crankcase into said induction system and means in one of said ducts actuated by movement of said throttle valve for controlling the flow of air through said duct.

2. A crankcase ventilation system for ventilating the interior of an engine having an induction system with a filtered intake, said ventilation system comprising an intake duct having one end thereof communicating with said induction system posterior to said filtered intake forming an inlet for drawing filtered fresh ventilating air from said induction system into said duct, the other end of said duct communicating with said interior for discharging said filtered fresh air into said interior, an outlet duct having'one end thereof communicating with said interior and the other end thereof communicating with said induction system and forming an outlet for discharging exhaust gases from said interior, and heating means in heat exchanging relation with said intake duct for heating said fresh air before it is discharged into said crankcase.

3. A crankcase ventilation system for ventilating the interior of an engine having an induction system with a filtered intake, said ventilating system comprising an intake duct having one end thereof communicating with said interior of said engine, an outlet duct having one end thereof communicating with said interior, the other end of said intake duct communicating with said induction system posterior to said filtered intake for drawing fresh filtered air from said induction system into said interior, and heating means disposed in heat exchanging relation with said intake duct.

4. In an engine having a crankcase and an induction system which includes an air cleaner adjacent the inlet therefor and a throttle valve, a crankcase ventilation system comprising an inlet duct having one end thereof communicating with said induction system between said throttle valve and said air cleaner, the other end of said duct communicating with said crankcase for discharging air from said induction system into said crankcase, heating means for heating said air before it is discharged into said crankcase, an outlet duct having one end thereof communicating with said crankcase, the other end of said outlet duct communicating with said induction system on the other side of said throttle valve for discharging said air from said crankcase into said induction system.

5. A crankcase ventilation system for ventilating the interior of an engine having a crankcase and an induction system with a throttle valve for controlling the air flow and a filtered intake, said ventilation system comprising an intake duct having one end thereof communicating with said induction system to form an inlet therein between said throttle valve and said filtered intake and the other end thereof communicating with said crankcase for discharging air from said induction system into said crankcase, an outlet duct having one end thereof communicating with said crankcase and the other end thereof communicating with said induction system to form an outlet therein posterior to said throttle valve, an oil separator disposed in said outlet duct and being effective to separate any oil particles from the air flowing into saidinduction system, and valve means in one of said ductsflopejrativly 6. A crankcase ventilation system for ventilating the 1 interior of an engine having an induction system with a throttle valve therein, said ventilation System comprising the combination of an intake duct having one end thereof communicating with said interior for discharging fresh air into said interior and the other end thereof communicating with said induction system anteriorto said throttle valve, an outlet ducthaving one end thereof communicatingwith said interior for exhausting said airjfrfom said interior and the 'other end thereof communicating with said induction system posterior to said throttle valve,'and valve means in one of said ducts, said valve means being responsive to movement of said throttle valve for controlling the volume of air flowing through said ventilation system.

7. In an engine having crankcase means and an induction system which includes fuel mixing means, a throttle valve and an air cleaner forming an inlet for said induction system, a crankcase ventilation system comprising an inlet duct having one end thereof communicating with said induction system between said throttlevalve and said air cleaner, the other end of said duct communicating with said crankcase means for discharging fresh'air from said induction system into said means, an outlet duct having one end thereof communicating with said crankcase means and the other end thereof communicating with said induction system on the opposite side of said throttle valve for exhausting the air from said crankcase into said induction system, and valve means in one of said ducts,

said valve means being actuated by movement of said throttle valve for controlling the flow of gases therethrough.

8. In an engine having a crankcase, a camshaft gallery communicating with said crankcase, a timing gear housing communicating with said crankcase and an induction system which includes an air cleaner and a throttle valve, a crankcase ventilation system comprising inlet duct means having one end thereof communicating With the induction system between said throttle valve and said air cleaner, the other end of said inlet duct means'cornmunicating with said timing gear housing for discharging fresh air from said induction system into said timing gear housing, outlet duct means havinggne end thereof communica hlsa sam ha t a le y andj he other. en he c mmun a n w thn eidti tiu t pn sy on theoth side of said throttle valve, and valve means disposed in said outlet duct for controlling the volume of fiow of air therethrough, said valve means being actuated by movement of said throttle valve.

9. In an engine having a crankcase, a camshaft gallery communicating with said crankcase, a timing gear housing communicating with said crankcase and an induction system which includes an air cieaner and a throttle valve, a ventilation system comprising inlet duct means having one end thereof communicating with the induction system between said throttle valve and said air cleaner, the other end of said duct means communicating with said timing gear housing for discharging fresh air from said induction system into said timing gear housing, outlet duct means having one end thereof communicating with said camshaft gallery and the other end thereof communicating with said induction system on the other side of said throttle valve, and valve means disposed in said outlet duct for controlling the rate of air flow there through, said valve means being actuated by movement of said throttle valve, heating means for preheating said fresh air before it is discharged into said timing gear housing.

10. In an engine having an exhaust system, a crankcase, a camshaft gallery communicating with said crankcase, a timing gear housing communicating with said ra kcase. an an. 'cle Y induction. system which includes an air and'ajfth ottle,;yalve','a' ventilation system comr smg inletgdu'ct (means disposed in, heat exchanging jrelation' with' saidjexhaust system, one end of said inlet duct means communicating with the ,indu'ctionisystem bet weenfsaidfthrottleiiialve and said air, cleaner, the other e "d of' s'aid inlet dncf meanslc'ommunicating with said ring g ar housingforf discharging fre'sh' from 'said u et,di1 t:'ti for controlling thevolume of flow of fresh a r therethrough, saidfyalvemeans being responsive to movement ofsaid throttle valve.

11. In an enginefhaying antexhaust system, a crankcase, a camsfhaft'gallery ,commnnicating with said crankcase, a timing g'e'ar housing communicating with said crankcase and an induction system having a portion fthejreof disposed in heat exchanging relation with said exhaust system and including an air cleaner and a throttle valve, a ventilation system comprising inlet duct means having onege'ndfthereof communicating with said induction system posteriorjto said portion and said air cleaner Qandanterior to saidthrottle valve, the other end of said duct means communicating with said timing gear housing for discharging'fresh air. from said induction system into said timing gear housing, outlet duct means having one end thereof communicating with said camshaft gallery and theother end thereof communicating with said inanother side of said housing, a throttle valve in said passage, a duct communicating with said passage between said throttle valve and said inlet, said duct being adapted to form an intake for a crankcase ventilation system, a second duct communicating with said passage between said throttle valve and said outlet, said second, duct being adapted to form discharge means for said crankcase'ventilation system.

13. Carburetor means comprising a housing, a passage extending through said housing, said passage forming an inlet in one side of said housing and an outlet in another side 'of said housing, a throttle valve in said passage, a duct communicating with said passage between said throttle valveand said-inlet, said duct being adapted to form an intake for a crankcase ventilation system, a second duct communicating with said passage between said throttle valve and said outlet, said second duct being adapted to form discharge means for said crankcase ventilation system, valve means in one of said ducts actuated by movement of said throttle valve for controlling the flow of gases through said ducts and said crankcase ventilation system.

14. A carburetor comprising a housing, a passage extending through said housing to form an inlet on one side of said housing and an outlet on the other side of said housing, a throttle valve disposed in said passage between said inlet and said outlet and being mounted on a throttle shaft for rotation therewith, a first duct communicating with said passage between said throttle valve and said inlet, said first duct being adapted to form an intake for a crankcase ventilation system, a second duct communicating with said passage between said throttle valve and said outlet, said second duct being adapted to form discharge means for said crankcase ventilation system, a control valve disposed in one of said ducts and connected to said shaft for rotation therewith,

15. A carburetor comprising a housing, a passage extending through said housing, said passage forming an inlet in one side of said housing and an outlet in another side of said housing, said inlet being adapted to be connected to an air cleaner for receiving filtered air therefrom, a throttle valve disposed in said passage between said inlet and said outlet and being mounted on a throttle shaft for rotation therewith, a first duct communicating with said passage between said throttle valve and said inlet, said first duct being adapted to form an intake for a crankcase ventilation system, a second duct communicating with said passage between said throttle valve and said outlet, said second duct being adapted to form discharge means for said crankcase ventilation system, and a control valve in said second duct for controlling the flow of air through said ducts and said crankcase ventilation system, said control valve comprising a plate mounted on said shaft for rotation therewith, said plate being positioned to register with at least a portion of said second duct.

16. Control means adapted to be actuated by movement of a throttle valve disposed in an induction system for insuring substantially uniform flow of ventilating air flowing through a crankcase ventilation system at all times, said control means comprising passage means having one end thereof communicating with said induction system, the other end of said passage being adapted to communicate with said ventilation system, said passage means including a wall having an orifice therein for the flow of air therethrough, a plate mounted on said throttle shaft for movement therewith, said plate having the periphery thereof positioned to register with at least a portion of said orifice.

17. Crankcase ventilation control means adapted to be actuated by movement of a throttle valve mounted on a throttle shaft that is disposed in an induction system to insure a substantially uniform volume of ventilating air flowing through said crankcase ventilation system at all times, said control means comprising passage means for the flow of said ventilating, air, one end of said passage means being adapted to communicate with said induction system, the other end of said passage being adapted to communicate with said ventilation system, a wall disposed in said passage means and having an opening therein for the flow of air therethrough, a plate mounted on said throttle shaft with the periphery thereof 'registering with at least a portion of said opening, said 12 lease ventilation system land an induction system including a carburetor with a throttle valve therein, said intake manifold comprising a plurality of distribution passages adapted to form a portion of said induction system, an exhaust passage extending through said manifold in heat exchanging relation with at least a portion of said distribution passages, inlet means in said manifold for said crankcase ventilating system, said inlet means including a chamber disposed in heat exchanging relation with said exhaust passage and 'a pair of ducts, one of said ducts having one end thereof communicating with said chamher and the other end thereof adapted to communicate with said carburetor anterior to said throttle v alve, said first duct being adapted to carry air from said carburetor to said dhamber, the other of said ducts having one end communicating with said chamber and the other end adapted to communicate with said crankcase ventilating system for discharging heated air from said chamber into said ventilation system.

19. An intake manifold adapted for installation on an 7 engine having a crankcase ventilation system and an induction system including a carburetor with a throttle valve therein, said intake manifold comprising a plurality of distribution passages adapted to form a portion of said induction system, an exhaust passage extending through said manifold in heat exchanging relation with at least a portion of said distribution passages, inlet means in said manifold for said crankcase ventilation system, said inlet means including a pair of ducts and a chamber formed in heat exchanging relation with said exhaust passage by engagement between said manifold and said engine, one of said ducts having one end thereof communicating with said chamber and the other end thereof adapted to communicate with said carburetor anterior to said throttle valve, said first duct being adapted to carry air from said carburetor to said chamber, the other of said ducts having one end communicating with said chamber and the other end adapted to communicate with said crankcase ventilating system for discharging heated air from said chamber into said ventilation system.

References Cited in the file of this patent UNITED STATES PATENTS 1,654,147 Shannon Dec. 27, 1927 1,792,560 Worbois Feb. 17, 1931 1,954,198 Cochrane Apr. 10, 1934 2,056,762 Barr et al. Oct. 6, 1936 FOREIGN PATENTS 115,638 Switzerland July 1, 1926