US3455285A

US3455285A - Crankcase breather system

Info

Publication number: US3455285A
Authority: US
Inventors: William L Sheppard
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-11-01
Filing date: 1966-11-01
Publication date: 1969-07-15
Anticipated expiration: 1986-07-15

Description

CRANKCASE BREATHER SYSTEM Filed Nov. 1, 1966 a P2 Q My) Q 31 kg 4 Zfli'fvze! 152 4}: fldi/X/O/ E2310: I inlay/ 3. 0kg

INVENTORC E- M1, 1 5&5

United States Patent US. Cl. 123119 50 Claims ABSTRACT OF THE DISCLOSURE A crankcase ventilation valve in which a reference pressure, crankcase pressure, intake manifold pressure and rate of flow are integrated to control the rate of fume flow.

This invention relates to crankcase breather or ventilating systems for internal combustion engines and the like.

Imperfect sealing between the pistons and the cylinder walls of internal combustion engines, such as those used in vehicles, customarily results in the transfer of a fraction of the unburned fuel and the combustion byproducts from the cylinders into the crankcase, and then, in prior practice, to the atmosphere through a road tube venting the crankcase. The extent of that blow-by varies from engine to engine and with variations of the age and operating condition of the engine, but factors including the quantity of such fumes have led in recent years to the widespread adoption, particularly in automobiles, of crankcase breather or ventilating systems for re-introducing the blow-by fumes into the engine for further combustion.

It is advisable to controllably vary the rate of the flow of the fumes from the crankcase to the combustion chambers (as via the intake manifold) in an effort to correlate the flow with the extent of the blow-by under various operating conditions of the engine, and a valve is customarily inserted in the return pipe for that purpose.

The present invention relates to improvement in such valves and is directed toward avoiding interference with the proper functioning of the engine and to the accurate correlation of the rate of air flow in the breather loop with the blow-by of the engine both to insure suflicient air flow for proper ventilation and to prevent excessive air flow which can adversely affect engine performance.

The nature of the invention and its objects and features will be perceived from the following detailed description of a preferred embodiment of the invention when read with reference to the accompanying drawings in which:

FIG. 1 illustrates a valve embodying the principles of the invention together with a schematically represented internal combustion engine with which the valve is employed;

FIG. 1A is an enlargement of the portion of FIG. 1 denoted by arrow 1A; and

FIG. 2 is a graphical representation of certain relationships that can exist in the system of FIG. 1.

The schematically illustrated engine in FIG. 1 has a crankcase 12 serving as an engine oil reservoir and having a chamber 14 above the oil level which, during operation, is normally filled with air, unburned fuel vapors and combustion byproducts including incompletely burned hydrocarbons, all of which are herein generically encompassed by the term fumes. Oil can be introduced into the crankcase 12 through a capped filler pipe 16. It is not crucial to the operation of the present valve whether the cap is vented or not, and the direct admission of air to the crankcase chamber, as through an imperfectly seated dipstick will neither defeat the operation of the system nor result in excessive air flow in the fume feedback loop.

In the illustrated system, the fumes are piped from chamber 14 via line 18, through a valve 20, and then via line 22 to, in the preferred arrangement, the intake mani- "ice fold 24 of the engine. Valve 20 includes a hollow housing assembly 26 with the peripheral annulus of a flexible diaphragm, or pressure-differential responsive element 28 being sealingly clamped between the two sections thereof. A disk 33 preferably underlies the peripheral annulus of the diaphragm 28 and projects radially inwardly a selected distance to control the effective area of the diaphragm. The central portion of diaphragm 28 is clamped between two rigid clamping plates 30 and 32 which, with the diaphragm, are centrally apertured to accept an eyelet 34 which is integral with and secures a nut 36 to the clamping plates and the diaphragm. An orifice 38 is formed through the diaphragm assembly, as by an eyelet 40 extending through plates 30 and 32 and diaphragm 28.

Nut 36 threadedly accepts a downwardly projecting screw 42 carrying a dished valve 44 which is clamped between the head of screw 42 and a nut 46 thereon. Valve 44 is therefore secured in adjustably fixed relation with the central portion of diaphragm 28.

Valve 44 cooperates with a valve seat 48 formed in the hollow housing 26. Below valve seat 48, housing 26 is provided with a perforated web defining an orifice 50 adjacent the pipe 18. Orifice 50, portions of housing 26, and valve 44 bound a chamber 52 the pressure in which is applied to valve 44. Valve 44, portions of housing 26, and diaphragm 28 further define another chamber 54 which is connected to the intake manifold via pipe 22 and the pressure in which is applied to valve 44 and diaphragm 28. Valve 44 seals, or controllabl interconnects, chambers 52 and 54.

The upper portion of housing assembly 26 is exposed to the atmosphere (ambient pressure) through a filter 58 and clamps a centrally apertured washer 60 which serves as a valve seat cooperating with a thin disk valve 62. Valve 62 is free to move vertically within the upper portion of housing assembly 26 subject to pressure-differential established forces and subject to a compression spring 64 acting between valve 62 and clamping plate 30. Spring 64 exerts forces tending to seat valve 62 against its valve seat 60 and, acting through the diaphragm assembly and screw 42, tending to seat valve 44 against its seat 48. The latter effect of the spring force has significance primarily in insuring that valve 44 is closed during cranking or backfiring of the engine. Portions of housing assembly 26, valve 60, and the assembly including diaphragm 28 define a chamber 66 the pressure in which acts on valve 62 as well as upon diaphragm 28.

With the engine in operation, chamber 54 is essentially at, and is assumed in this description to be at, intake manifold pressure. While it is common to refer to and measure the intake manifold pressure in units (usually inches of mercury) of vacuum below atmosphere, for clarity and consistency in this description all pressures will be presented in absolute units and the term pressure will be understood to mean the absolute value of that pressure unless specifically stated otherwise.

Since the magnitude of the changes of the controlled pressure in the crankcase chamber 14 can be, with the practice of this invention, quite small, in discussing specific examples herein, units of inches of water are used herein and all pressures expressed in inches are understood to refer to inches of water unless otherwise noted. The pressure of the surrounding air will be referred to as the ambient pressure. While the ambient pressure at sea level is nominally approximately 407 inches of Water, in the discussed example it will be assumed that it is slightly less, or 405 inches.

With chamber 54 at intake manifold pressure and with chamber 66 in communication therewith via orifice 38, an operational pressure differential exits across valve 62 tending to move that valve from it seat 60 against the force of biasing spring 64, and air flows from filter 58, between seat 60 and valve 62, through chamber 64, orifice 38, chamber 54 and to the intake manifold. The rate of that flow can be designed to be quite low. That air flow will result in the establishment in chamber 66 of a pressure lower than ambient and higher than intake manifold. The pressure will be essentially fixed or regulated with constant ambient despite variations of the intake manifold pressure over a great range of such variations. That value may be selected as desired. In the illustrative arrangement, it is below ambient and at a value which is lower at substantially all times than the lowest pressure which will exist in the crankcase. While the crankcase pressure should not reasonably be expected to be below ambient by more than a few inches when the subject system is functioning, the designed regulated pressure may be, as an example, 383 inches, that is, 22 inches below the assumed instant ambient of 405 inches. That regulated pressure can be obtained, as an example, by using a valve 62 having a diameter (at its lip of contact) of about 0.797,inch and an effective area of about 0.5 square inch, and by using a spring 64 which exerts an upward force on valve 62 of about 0.4 pound (the equivalent of a pressure of 11 inches).

With the selected regulated pressure in chamber 66, diaphragm 28 will be subjected to two downward forces: the force resulting from the application of the regulated pressure on the effective area of its upper surface and the force of spring 64. Again, as an example, to simplify understanding, if the effective area of the upper surface of diaphragm 28 is selected to be 1.10 square inches, the downward force resulting from the above-noted 383 inch pressure in chamber 66 is equal to 421.3 inches (viewing that force in units of inches of water for convenience). The spring force, as noted is the equivalent of a pressure of 11 inches so the total downward force on diaphragm 28, from these two sources, is equal to 432.3 inches.

Diaphragm 28 is also subject to an upward force deriving from the exertion of the intake manifold, pressure, in chamber 54, on the effective area of the undersurface thereof. The net effective area of that surface is, however, small since diagram 28 is directly connected to valve 44 so that the effect of the intake manifold pressure on that portion of the diaphragm which is equal in area to the valve seat 48 is balanced or nullified by the corresponding but opposite effect of that same pressure on the corresponding area of valve 44. Thus, if the diameter of valve seat 48 at the line of valve contact is assumed to be 1.158 inches, for an effective area of 1.05 square inches, and if the area of diaphragm 28 is, as above-assumed, 1.10 square inches, the net or effective area of the undersurface of diaphragm is but 0.05 square inch. If it be assumed as an example that the instant intake manifold pressure is 201.6 inches, the noted net upward force on the diaphragm is equal to 10.08 inches. Thus, the net force on the diaphragm from these factors and with the stated assumptions, is 432.3 inches less 10.08 inches, or a net downward force of 422.22 inches. From that, it can be ascertained what pressure in chamber 52 will be required to just crack valve 44, for it will be the pressure, which, acting on the effective area of the undersurface of valve 44, will balance the above-noted net downward force on the diaphragm, that is 422.22 divided by the assumed effective area of valve 44 of 1.05 square inches or a balance pressure equal to about 402.1 inches. If the crankcase pressure, under the assumed conditions and with the assumed parameters, is such that the pressure in chamber 52 is below that value, valve 44 will remain closed; but if it is such that the pressure in that chamber would tend to exceed that value, valve 44 will open and fumes (including air) will flow from the crankcase, through pipe 18, orifice 50, past valve 44, chamber 54, line 22 and to the intake manifold.

It will be observed that if the intake manifold pressure changes, the upward force on diaphragm 28 will change correspondingly, the net force on diaphragm 28 will change, and the balance pressure will change, resulting (for any given crankcase pressure) in a change in the rate of air flow. In the preferred arrangement, this relationship is direct, that is, an increase in the absolute manifold pressure will tend to open valve 44 to increase the rate of air flow, and vice versa, over a large range of intake manifold pressures. Hence, diaphragm 28 also serves as a means to sense changes in the intake manifold pressure and to control valve 44 accordingly.

It will be observed that since an increase of absolute intake manifold pressure is viewed as a decrease of intake manifold vacuum in common trade parlance, the relationship between rate of flow and changes of intake manifold vacuum is, in that sense, inverse. It is to be understood that the statement that a certain pressure or rate varies directly or in direct relation with the variations of another is intended but to connote the sense of the change and is not intended to connote proportionality, and the same is true of any stated inverse relationships. If two factors change in the same sense, that is, if they both increase or both decrease, they are said to vary directly; if they change in opposite senses, that is, if one decreases while the other increases, or vice versa, they are said to vary inversely in both cases quite apart from the relative magnitudes or percentage of the two changes.

If the crankcase chamber 14 of the engine, under the assumed circumstances, is at, say, the instant ambient pressure of 405 inches, the pressure applied to the exposed undersurface of valve 44 will tend to exceed the abovenoted balance value and valve 44 will open to permit the fumes to flow in the noted loop from the crankcase to the intake manifold. This flow path includes orifice 50 and a pressure drop will occur across that orifice as a result of that flow, reducing the pressure in chamber 52 below that in the crankcase chamber, by the amount of that pressure drop. With the assumed parameters and conditions, the pressure drop across orifice 50 will be about 405 inches less the balance pressure of 402.1 inches or 2.9 inches. This reflects a certain rate of flow depending on the characteristics of the orifice. With the illus trated orifice having a diameter of, say, of an inch, 2. pressure drop thereacross of the noted magnitude reflects a fume-flow rate of about 1.95 cubic feet per minute. Therefore, under the assumed conditions, fumes will flow and the crankcase will be vented to the intake manifold at a rate of about 1.95 cubic feet per minute.

Since spring 64 makes up but a small fraction of the total downward force and since the force exerted by that spring will vary insignificantly with the minute corrective variations of the position of valve 44, the pressure in chamber 52, for given other conditions, will remain effectively at the balance value despite variations, over a range, of crankcase pressures, with valve 44 minorly shifting position, in response to the crankcase pressure changes, to change the rate of flow to that required to hold chamber 52 at the instant balance value. Valve 44, therefore, in effect, senses changes of crankcase pressure and adjusts the flow accordingly, the relationship again being direct, for an increase in crankcase pressure will produce an increase in flow to produce the requisite drop across orifice 50, and vice versa. Orifice 50, of course, acting in cooperation with valve 44, effectively senses, measures and controls the rate of flow of the fumes. If the rate is excessive for given ambient, crankcase and manifold pressures, the drop across the orifice will be excessive and valve 44 will restrict the flow. Conversely, if the rate is too low for the noted conditions, valve 44 will increase the rate of flow. This relationship can be viewed as inverse in that the unit tends to regulate the rate of flow to that preselected to be appropriate for each combination of conditions.

Both the intake manifold pressure and crankcase pressure are, in effect, independently sensed and measured against the reference pressure, summed (or integrated), and employed to control the rate of How, which is itself effectively sensed, measured and employed as a factor in the rate-of-fiow control. The unit can be viewed as measuring the instant rate of flow, and adjusting that sensed rate in accordance with the instant intake manifold pressure and the instant crankcase pressure, with those pressures being measured in relation to the reference pressure.

The curves of FIG. 2 present illustrative relationships between intake manifold pressure and rate of fume flow for several different crankcase pressures to illustrate the independent sensitivity of the unit to those factors and to illustrate the capability of the unit to maintain an optimum rate of flow over a large range of variation of the operational conditions. The curves of FIG. 2 are based on the assumed parameters above-discussed and it will be appreciated that the slopes may be varied, their ordinates shifted and the spacing of the family of curves changed or decreased by appropriate changes of the parameters of the unit.

Curve A in FIG. 2 illustrates the change of rate of flow of the fumes with changes of the intake manifold pressure if the crankcase pressure stops at ambient value. During cranking, the intake manifold pressure is high, spring 64 holds valve 44 closed, and there is no air flow inthe system to impede th starting of the engine. During operation of the engine over a range from high (as, 19 inches of mercury) intake manifold vacuum (a relatively low intake manifold absolute pressure), as during idling, to a very low (as, 1 /2 inches of mercury) intake manifold vacuum (an absolute pressure closely approaching ambient), the rate of flow is varied from a low value to a higher value. For example, in the illustrative example, one cubic foot of air is flowed per minute with an intake manifold vacuum of 18 inches of mercury while substantially four cubic feet of fumes are flowed per minute at an intake manifold vacuum of but two inches of mercury, both under the assumption that the crankcase is at ambient pressure. Since the extent of the blow-by is normally a function of the compression ratio which is reflected in intake manifold pressure, the rate of fiow should increase in that fashion to purge the crankcase without yet flowing excess air at any time. It is believed that the change of the rate of flow which occurs should be within the same order of percentage as the percentage change of the absolute intake manifold pressure which produced it, and the slope of the illustrative curve A is such that over the major portion of the operational range, a given percentage change of the absolute intake manifold pressure will produce but a slightly greater percentage change in the rate of flow, in the same sense. The curve may, however, be tilted by shifting the design parameters, to establish any desired relationship.

Curve B in FIG. 2 illustrates the corresponding relationships at a higher assumed crankcase pressure, as, for example, three inches above ambient pressure. The air flow is greater, throughout the range, than curve A, as it should be. Curve C in FIG. 2 illustrates the corresponding relationships at a lower assumed crankcase pressure, as, three inches below ambient, with a reduction in air flow throughout the range. Again, both curves may be tilted or shifted as desired and the spacing therebetween can be similarly varied.

The family of curves in FIG. 2 also illustrates not only the fact that the rate of flow is varied, with fixed other conditions, as a direct function of absolute crankcase pressure but also that in the preferred arrangement the magnitude of the change of the rate of How for a given change (numerical or percentage) of absolute crankcase pressure is larger than the magnitude of the change of the rate of flow for the same (numerical or percentage) change of absolute intake manifold pressure. Thus, with the assumed ambient pressure, and an assumed fixed intake manifold pressure, say, of 272 inches, a change of crankcas pressure from 402 inches to 408 inches (about 1.5% increase) will increase the flow from about 2.2 cubic feet per minute to about 3.5 cubic feet per minute or about a 58% increase in the rate of flow. In the illustrative arrangement, the same percentage change of absolute intake manifold pressure will produce a much smaller change in the rate of flow, by a factor, preferably of many times. This will be perceived from the above-discussed illustrative parameters in which the net effective area of the intake-manifoldpressure-sensing lower diaphragm surface was assumed to be 0.05 square inch while the effective area of the lower sensing surface of valve 44 was assumed to be 1.05 square inches. With those parameters, the valve assembly is about 21 times as sensitive to crankcase pressure changes as it is to intake manifold pressure changes. That ratio may of course be changed as desired, although it is important to the achievement of optimum results that the sensitivity to crankcase pressure changes be significantly greater than the responsivity to intake manifold pressure changes. It is believed that the difference should be at least two-to-one, and a minimum ratio of ten-to-one is preferred. In general, the greater the ratio of th responsivity to crankcase pressure changes to the responsivity to intake manifold pressure changes, within practical limits, the better. The limitation is primarily in the operating forces derived from the intake manifold pressure. If the ratio exceeds 40 or 50-to-1, the development of adequate forces may entail the construction of a unit which is larger in physical size than is well advised, at least for automotive use.

It will be observed, in that connection, that the sensitivity of the valve unit to crankcase pressure changes, which is controlled mainly by the size of valve seat 48 and, particularly, the above-discussed ratio between that area and the net effective area of the lower surface of diaphragm 28 can be varied to change the distance between the curves A, B and C, that the size of orifice 50 can be changed to shift the ordinate of the curves as a group, and that the points at which the knees of the curves occur can be shifted by adjusting the reference pressure established by the regulator. Other design changes can be made as desired.

What is claimed is:

1. In a crankcase breather system for venting fumes from the crankcase of an operating internal combustion engine to the intake manifold of that engine, the combination of pressure regulating means for establishing a reference pressure differing from ambient pressure, and control means including valve means responsive to said reference pressure and to the pressure in the crankcase for controlling the flow of fumes from the crankcase to the intake manifold, said reference pressure being below ambient pressure.

2. The combination of claim 1 in which said control means including valve means responds to a change of crankcase pressure in either sense to tend to change the rate of flow in the same sense.

3. The combination of claim 2 further including ratesensing means for sensing said rate of flow and in which said control means is controlled by said rate-sensing means.

4. The combination of claim 1 in which said reference pressure is under substantially all operating conditions lower than the crankcase pressure.

5. The combination of claim 1 in which said control means varies the rate of flow with variations of the difference between said reference pressure and the crankcase pressure.

6. The combination of claim 1 in which said control means is responsive to a given percentage variation of the crankcase pressure over a range of crankcase pressure variations to vary the rate of flow by a percentage which is many times greater than said given percentage.

7. The combination of claim 1 in which said control means is further responsive to the intake manifold pressure and controls the fiow of fumes in accordance with said reference pressure and in accordance both with variations of the crankcase pressure and with variations of the intake manifold pressure.

8. The combination of claim 7 further including ratesensing means for sensing said rate of flow and in which said control means is controlled by said rate-sensing means.

9. The combination of claim 7 in which said control means including valve means responds to a change of crankcase pressure in either sense to tend to change the rate of flow in the same sense.

10. The combination of claim 9 in which said control means including valve means responds to a change of intake manifold pressure in either sense to tend to change the rate of flow in the same sense.

11. The combination of claim 10 in which said control means varies the rate of flow in response to a given percentage change of the crankcase pressure by a factor many times greater than it varies the rate of flow in response to the same given percentage change of the intake manifold pressure.

12. The combination of claim 11 further including rate-sensing means for sensing said rate of flow and in which said control means is controlled by said rate-sensing means.

13. The combination of claim 7 in which said control means varies the rate of flow with variations of the difference between said reference pressure and the crankcase pressure.

14. The combination of claim 13 in which said control means varies the rate of flow with variations of the difference between said reference pressure and the intake manifold pressure.

15. The combination of claim 7 in which said control means is responsive to a given percentage variation of the crankcase pressure over a range a crankcase pressure variations to vary the rate of fiow by a percentage which is many times greater than said given percentage.

16. The combination of claim 7 in which said control means including valve means responds to a change of intake manifold pressure in either sense to tend to change the rate of flow in the same sense.

17. The combination of claim 7 in which said control means varies the rate of flow with variations of the difference between said reference pressure and the intake manifold pressure.

18. The combination of claim 7 in which said control means is responsive to a given percentage variation of the intake manifold pressure over a range of intake manifold pressure variations to vary the rate of flow by a percentage which is of the same order of magnitude as said given percentage.

19. The combination of claim 1 in which said reference pressure differs from the ambient pressure by a preselected essentially fixed amount.

21 In a crankcase breather system for venting fumes from the crankcase of an operating internal combustion engine to the intake manifold of that engine, the combination of pressure regulating means for establishing a reference pressure differing from ambient pressure, and control means including valve means responsive to said reference pressure and to the pressure in the crankcase for controlling the flow of fumes from the crankcase to the intake manifold, said means for establishing a reference pressure including a regulator having a valve.

21. The combination of claim in which said regulator controls the fiow of air in a path between atmosphere and the intake manifold including a fixed orifice and said valve.

22. The combination of of claim 21 in which said regulator includes a biasing spring biasing said valve.

23. The combination of claim 22 in which said valve means includes a pressure responsive diaphragm and in which said spring acts between said regulator and said diaphragm.

2-4. in a crankcase breather system for venting fumes from the crankcase of an operating internal combustion engine to the intake manifold of that engine, the combination of pressure regulating means for establishing a reference pressure differing from ambient pressure, and control means including valve means responsive to said reference pressure and to the intake manifold for controlling the flow of fumes from the crankcase to the intake manifold, said reference pressure being below ambient pressure.

25. The combination of claim 24 in which said control means including valve means responds to a change of intake manifold pressure in either sense to tend to change the rate of flow in the same sense.

26. The combination of claim 25 further including rate-sensing means for sensing said rate of flow and in which said control means is controlled by said ratesensing means.

27. The combination of claim 24 in which said control means varies the rate of flow with variations of the difference between said reference pressure and the intake manifold pressure.

28. The combination of claim 24 in which said control means is responsive to a given percentage variation of the intake manifold pressure over a range of intake manifold pressure variations to vary the rate of flow by a percentage which is of the same order of magnitude as said given percentage.

29. The combination of claim 24 in which said reference pressure differs from ambient pressure by a preselected essentially fixed amount.

30. In a crankcase breather system for venting fumes from the crankcase of an operating internal combustion engine to the intake manifold of that engine, the combination of pressure regulating means for establishing a reference pressure differing from ambient pressure, and control means including valve means responsive to said reference pressure and to the intake manifold for controlling the flow of fumes from the crankcase to the intake manifold, said means for establishing a reference pressure including a regulator having a valve.

31. The combination of claim 30 in which said regulator controls the flow of air in a path between atmosphere and the intake manifold including a fixed orifice and said valve.

32. The combination of claim 31 in which said regulator includes a biasing spring biasing said valve.

33. The combination of claim 32 in which said valve means includes a pressure responsive diaphragm and in which said spring acts between said regulator valve and said diaphragm.

34. A control valve assembly for a crankcase breather system for venting fumes in a fume flow path from the crankcase of an internal combustion engine to the intake manifold of that engine comprising a chamber in said path, pressure-responsive valve means responsive to the pneumatic pressure in said chamber for varying the rate of flow of fumes from the crankcase to the intake manifold, a rate-of-flow sensing pressure-droppin g orifice means connected in said path and between the crankcase and said chamber for applying a pressure to said chamber which varies in accordance with the difference between the pressure in the crankcase and the pressure drop across said orifice means, said valve means varying the rate of fiow from the crankcase to the intake manifold in direct relation to said pressure applied to said face thereof for varying said rate of flow in direct relation to changes of the crankcase pressure and in inverse relation to the sensed rate of flow.

35. The combination of claim 34 further including means responsive to changes of the intake manifold pressure for controlling said valve means for also varying said rate of flow from the crankcase to the intake manifold in direct relation to changes of the intake manifold pressure.

36. A control valve assembly for a crankcase breather system for venting fumes from the crankcase of an internal combustion engine to the intake manifold of that engine comprising means for sensing the crankcase pressure, means for sensing the rate of flow of fumes from the crankcase to the intake manifold via the breather system, and means for varying said rate of flow in direct relation to the sensed crankcase pressure and in inverse relation to the sensed rate of flow.

37. The combination of claim 36 further including means for sensing the intake-manifold pressure, and in which said means for varying said rate of flow further varies said rate of flow with variations of said intakemanifold pressure.

38. The combination of claim 37 further including means for establishing a reference pressure and in which said rate is further controlled by said reference pressure.

39. In a crankcase breather system for venting fumes from the crankcase of an operating internal combustion engine to the intake manifold of that engine, the combination of pressure regulating means for establishing a reference pressure differing from ambient pressure ratesensing means for sensing the rate of flow, and control means including valve means conjointly responsive to said reference pressure and to the pressure in the crankcase and to said rate-sensing means for controlling the flow of fumes from the crankcase to the intake manifold.

40. In a crankcase breather system for venting fumes from the crankcase of an operating internal combustion engine to the intake manifold of that engine, the combination of pressure regulating means for establishing a reference pressure differing from ambient pressure, ratesensing means for sensing the rate of flow, and control means including valve means conjointly responsive to said reference pressure and to the intake manifold and to said rate-sensing means for controlling the flow of fumes from the crankcase to the intake manifold.

41. A control valve assembly for a crankcase breather system for venting fumes from the crankcase of an operating internal combustion engine to the intake manifold of that engine comprising a housing having a port connectable to the crankcase and a second port connectable to the intake manifold, a pressure-differential-responsive element having one surface exposed to one of said ports, a valve seat at the other one of said ports, a valve element connected to said pressure-difierential-responsive element and cooperating with said valve seat to selectively block said other one of said ports, and pressure regulating means for applying a reference pressure differing from ambient pressure to the opposite surface of said pressure-differential-responsive element, said pressure regulating means including a valve separate from said valve element.

42. The combination of claim 41 in which said one port is connectable to the intake manifold and in which said other port is connected to the crankcase.

43. The combination of claim 42 further including a fixed orifice disposed between said valve and the crankcase.

44. The combination of claim 41 in which said reference pressure diifers from ambient pressure by a preselected amount.

45. A control valve assembly for a crankcase breather system for venting fumes from the crankcase of an internal combustion engine to the intake manifold of that engine comprising a valve connected in series between the crankcase and the intake manifold, and a pressure regulator controlling said valve, said pressure regulating means including a valve separate from said valve element.

46. The combination of claim 45 further including a fixed orifice connected between the crankcase and said valve.

47. A control valve assembly for a crankcase breather system for venting fumes from the crankcase of an internal combustion engine to the intake manifold of that engine comprising a housing, having a first port connectable to the crankcase and a second port connectable to the intake manifold, a pressure-differential-responsive element having one surface exposed to one of said ports, a valve seat at the other one of said ports, a valve element connected to said pressure-ditferential-responsive element and cooperating with said valve seat to selectively block said other one of said ports, said valve having one surface area exposed to said one of said ports and responsive to the pressure thereon, said valve having an opposing surface area exposed to said other one of said ports and responsive to the pressure thereon, and a pressure-dropping orifice in said first port being subjected toa pressure which varies in accordance with the difference between crankcase pressure and the pressure dro across said orifice.

48. The combination of claim 47 in which said one port is said second port and in which said other port is said first port.

49. A control valve assembly for a crankcase breather system for venting fumes in a fume-flow path from the crankcase of an internal combustion engine to the intake manifold of that engine comprising pressure-responsive valve means for controlling the rate of fume flow in said path, an orifice in said fume-flow path for developing a pressure drop thereacross which varies in accordance with the rate of fume flow in said path, and means including said orifice for applying to said pressure-responsive valve means a pressure which varies in accordance with the difference between the crankcase pressure and the pressure drop across said orifice.

50. The combination of claim 49 further including means for applying to said pressure responsive valve means a pressure which varies in accordance witht the intake manifold pressure.

References Cited UNITED STATES PATENTS 2,775,960 l/ 1957 Druzynski.

3,056,420 10/ 196 2 Dietrich.

3,108,581 10/ 1963 Humphreys.

3,144,011 8/1964 Anthes.

3,262,436 7/1966 Thompson.

3,312,207 4/ 1967 Martin et a1.

FOREIGN PATENTS 614,760 2/ 1961 Canada.

AL LAWRENCE SMITH, Primary Examiner US. Cl. X.R. 137479 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,455 ,285 July 15 1969 William L. Sheppard It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column l, line 38, "improvement" should read improvements Column 2 line 72 "it" should read its (101m 3, line 41, cancel the comma. Column 7, line 35, "a", second occurrence, should read of line 69, cancel "of", second occurrence. Column 10, line 24, after "port" insert said surface area which is exposed to said first port line 44, "witht" should read with Signed and sealed this 28th day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Ir. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents