WO1983002800A1

WO1983002800A1 - Fluid flow control means for internal combustion engines

Info

Publication number: WO1983002800A1
Application number: PCT/GB1983/000032
Authority: WO
Inventors: Richard Furneaux Kinnersly
Original assignee: Richard Furneaux Kinnersly
Priority date: 1982-02-05
Filing date: 1983-02-07
Publication date: 1983-08-18
Also published as: EP0101464A1

Abstract

A flow control system for an internal combustion engine comprises a flow passage (10, 12, 89) through which fluid flows towards the engine cylinder. A valve means (14, 78) driven in synchronism with the engine operates alternately to open and close the flow passage, and a control device (40, 102, 104) is provided to vary the area of the flow passage presented to the valve means. The flow control device may be movable to vary the cross-sectional area of the flow passage (10, 12, 89) which is presented to the valve means (14, 78), either in the sense of increasing or decreasing the area, or in the sense of varying the spacial relationship of the area relative to the valve means, such as varying the angular relationship of the flow passage relative to the valve means, or a combination of these two functions.

Description

FLUID FLOW CONTROL MEANS FOR INTERNAL COMBUSTION ENGINES

Description of Invention

This invention is concerned with improvements relating to internal combustion engines, and in particular relates to means for the control of flow of fluid (gas and/or li quid) in internal combustion engines. The invention has been devised primarily for the control of a fuel/air mixture to the cylinder of a crank case-scavenged two-stroke engine, but may be used to advantage in four-stroke engines.

In a conventional crank case-scavenged two-stroke engine, opening and closing of the various passages through which fluid flows is controlled by a skirt on the engine piston. Such control causes the passages to be opened and closed at specific points in the engine cycle, irrespective of engine speed, and irrespective of the state of various control devices of the engine.

It is one of the various objects of this invention to provide a valve mechanism for an internal combustion engine which permits the point at which passages are opened and/or closed to be varied in relation to the engine cycle.

According to this invention, there is provided an internal combustion engine comprising a flow passage through which fluid flows towards the engine cylinder, a valve means which is operative alternately to open and close the passage, and a flow control device movable to vary the area of the passage presented to the valve means.

The flow control device may be movable to vary the cross-sectional area of the flow passage presented to the valve means either in the sense of increasing or decreasing the area, or in the sense of varying the spacial relationship of the area relative to the valve means, such as varying the angular relationship of the flow passage relative to the valve means, without any simultaneous increase or decrease in the cross-sectional area of the flow passage itself. For example, the flow control device may be movable across the passage to vary the area of a mouth of the passage presented to the valve means. In this manner, the point at which the valve member in its movement across the mouth opens the flow passage for flow of fluid therethrough, or closes the flow passage for terminating flow of fluid therethrough, may be varied. in the application of this invention to a crank case-scavenged twostroke engine, in which the valve means moves in synchronism with the engine, for example being provided by a movable part of the engine or being driven by a movable part of the engine, the valve means may be provided by the engine piston, or may be provided by a separate member driven from the engine crank.

In this manner, the flow control device may be utilised to vary the flow of fuel and air to the engine, or to vary the point in the engine cycle at which such flow is commenced, and/or is terminated, or a combination of both of these, whereby a more desirable timed relationship between these events in accordance with the degree of throttling desired, may be obtained.

The flow passage may be that passage through which a mixture of fuel and air flows into the engine cylinder (in the case of a crank case scavenged two-stroke engine beneath the engine piston), the mouth of said passage providing the inlet port. Alternatively, the flow passage may be the transfer passage through which a mixture of fuel and air flows from the crank case beneath the piston into the cylinder above the. piston, said mouth providing the transfer port. Alternatively, in relation to a four-stroke engine, the flow passage may extend to a chamber within which (e.g.) a rotary valve member is mounted.

The valve means may be movable linearly across the mouth of the flow passage, or may be movable rotational ly across the mouth of the flow passage, conveniently being provided with one or more flow apertures through which, in the use of the engine, fuel flows to the engine cylinder.

The flow control member may similarly be mounted for linear movement across the mouth of the flow passage, or may be movable rotationally, being provided with one or more flow apertures, and being connected to, and moved by, a throttle control member of the engine. Alternatively, the flow control member may be mounted for pivotal or arcuate movement across the mouth of the flow passage. According to this invention there is also provided an internal combustion engine comprising a cylinder, a piston reciprocably mounted in the cylinder, a flow passage through which a fluid comprising a mixture of fuel and air is fed into the engine cylinder, valve means movable alternately to open and close the flow passage in timed relationship with the engine cycle, and flow control means selectively positioπable across the flow passage and which is operative

(a) to vary the restriction to flow of fluid along the flow passage; and/or (b) to vary the point in the engine cycle at which the flow passage is opened, for flow of fluid therethrough to the engine cylinder and/or to vary the point in the engine cycle at which the flow passage is closed for fluid flow therethrough, in accordance with the restriction to flow of fluid along the flow passage provided thereby.

Preferably the flow control means is operative to vary the restriction to flow of fluid along the flow passage by varying the cross-sectional area of the or part of the flow passage.

Preferably the flow control means comprises a flow control member movable generally in a plane extending at right angles . to the direction of flow of fluid through the passage to vary the cross-sectional area of the flow passage.

There will now be given detailed descriptions, to be read with reference to the accompanying drawings, of seven fluid flow control systems which are preferred embodiments of this invention and which have been selected for the purposes of illustrating the invention by way of example. In the accompanying drawings:-

FIGURE 1 is a side sectional view of the flow control system which is the first embodiment of this invention; FIGURES 2, 3 and 4 are transverse sectional views of the flow control system shown in Figure 1, showing a flow control member thereof in three different positions;

FIGURE 5 is a schematic view illustrating the timing of various events in the two-stroke engine of which the fluid control system which is the first embodiment of this invention forms part;

FIGURE 6 is a view similar to Figure 1, being a side sectional view of the flow control system which is the second embodiment of the invention; FIGURES 7 and 8 are transverse sectional views of the flow control system shown in Figure 6, showing a flow control member thereof in two different position;

FIGURES 9 to 12 are scrap views showing the fluid flow control system which is the third embodiment of this invention;

FIGURE 13 is a schematic perspective view showing the fluid flow control system which is the fourth embodiment of this invention;

FIGURE 14 is an end elevation, viewed in the direction A of Figure 13;

FIGURE 15 is a cross-sectional view taken on Figure 13; FIGURES 16 and 17 are scrap views showing the fluid flow control system which is the fifth embodiment of this invention;

FIGURE 18 is a scrap view showing the flow control system which is the sixth embodiment of this invention; and

FIGURES 19 and 20 are scrap views showing the fluid flow control system which is the seventh embodiment of this invention.

The fluid flow control system which is the first embodiment of this invention is specifically adapted for controlling the flow of a mixture of petroleum fuel and air to the crank case of a two-stroke engine.

The system comprises a housing 6 provided with a cylindrical bore 8, a flow passage 10 extending at right angles to the longitudinal axis of the bore opening into the bore, and a flow passage 12 extending from the bore and which opens into a generally lower part of the engine cylinder.

Mounted in the bore 8 is a cylindrical valve member 14, said valve member being mounted on end plates 18, 19 which are themselves journalled on bearings 20. The end plate 16 comprises a stub shaft 26 to which a drive sprocket 28 is secured. Mounted within the valve member 14 is a cylindrical control member 30, being provided with a diametral flow passage 32. The control member 30 is additionally provided with stub shafts 34, 36 which are themselves mounted in said bearings 20. The stub shaft 36 has additionally splined thereon a throttle lever 38, which may be operated to rotate the control member 30 abouts its longitudinal axis.

The diameter of the bore 8, the inner and outer diameters of the valve 14 and the outer diameter of the control member 30 are so arranged as to provide for a clearance fit one within the other. The drive sprocket 28 is driven by a pulley, chain, or gearing by the engine crank so that the valve member 14 rotates at half engine speed, the valve member moving in the direction shown in Figure 2. The valve member 14 is additionally provided with two diametrically opposite flow apertures or ports 15, which during rotation of the valve member 14, are alternately aligned with the flow passages 10 and 12.

The flow control system above described may be used in a manner in which a mixture of petroleum fuel and air is fed through the flow passage 10, and by way of the flow passage 32 to the flow passage 12, in the direction of the arrow A in Figure 2. Alternatively, air alone may be fed through the flow passage 10 and fuel may be injected directly into the flow passage 32 by an injection nozzle mounted on the centreline of the flow control member 30.

The angular positioning of the valve member 14 is so arranged that the ports 15 are in alignment with the flow passages 10 and 12 over the period in the engine cycle when fuel is required to be delivered to the engine cylinder. With the valve member 14 in its fully open position as shown in Figure 4, fuel commences to flow to the engine at the point in the cycle of the valve member 14 when the leading edges 16 of the two ports 15 move into communication with the flow passages 10 and 12 respectively, and flow of fuel to the engine is terminated when the trailing edges 17 of the apertures 15 pass beyond the flow passage 32 of the control member 30, that being the position shown in Figure 4.

In contrast to this, when the flow control member 30 is in a partially throttled position, as is shown in Figure 2, flow of fuel to the engine is terminated when the valve member 14 is at an angularly earlier position, and thus termination of flow of fuel to the engine cylinder is advanced in relation to the engine cycle compared with the condition shown in Figure 4.

Thus, by moving the flow control member to its fully throttled or idling position, fuel is delivered to the engine cylinder at a low flow rate which is terminated when the valve member reaches the angular position shown in Figure 3, which is further advanced in relation to the engine cycle as compared with the condition shown in Figure 2.

Whilst the arrangement described in Figures 1 to 4 is to effect a variation in the termination of flow of fuel through the flow passage into the engine cylinder in relation to the engine cycle in accordance with the condition of the flow control member or throttle, if desired the arrangement may readily be modified to vary the point of commencement of such flow of fuel in relation to the engine cycle, in accordance with the condition of the flow control member 30. This may be effected either by retaining the flow control member as is shown in Figures 2 to 4, being one in which movement from Its fully open to its fully throttled position is obtained by anti-clockwise movement thereof, but reversing of the direction of rotation of the valve member 14, or by retaining the direction of rotation of the valve member 14 as is shown in Figures 2 to 4, but throttling the engine by movement of the flow control member from the position shown in Figure 4 in a clockwise direction.

Dependent upon the manner in which the flow control system shown in Figures 1 to 4 Is incorporated into the internal combustion engine, and upon the direction of rotation_^ of the valve member 14, the events in the engine cycle illustrated in Figure 5 in a typical application may be varied between

10º after top dead centre in a "shut throttle" condition and 65 after top dead centre in an "open throttle" condition.

Alternatively, or in addition, the "inlet valve open" event may be varied between 6 before bottom dead centre in a "shut throttle" condition and 50º after bottom dead centre in an "open throttle" condition.

In certain circumstances, but particularly in constructions in which fuel is injected through an injection nozzle mounted on the centre line of the flow control member 30, it Is necessary to ensure that the leak rate through the valve system, when In its closed condition with respect to the valve member 14, and when in its open or closed condition with respect to the throttling means, does not pressurise the flow passage 32, which may cause variation in the rate at which fuel is injected into the flow control system, particularly at low engine speeds. To overcome this problem, a venting duct may be provided in the body 6 extending parallel to the flow passage 10, and a further duct may be provided in the flow control member 30 from the flow passage 32 generally at right angles thereto, these ducts being shown in dotted lines in Figure 3. In this manner, any excess pressure in the flow passage 32 may be relieved by the venting duct, at the point in the engine cycle when one of the ports 15 provides communication between said two ducts.

In the second embodiment of the invention, shown in Figures 6 to 8, in which similar numerals with the suffix a have been utilised to denote like parts, the central cylindrical member 30a is stationary, and throttling is effected by the provision of a cylindrical throttling sleeve 40 provided with ports 42 mounted around the valve member 14a. Thus, by manipulation of the throttle lever 38a, the throttling sleeve 40 may be moved rotationally between the position shown in Figure 7, in which the engine is fully throttled, and the position shown in Figure 8, in which the throttle is fully open. Thus, movement of the throttle control is effective to rotate said flow control member to selectively close the outlet passage 12a, and hence to vary the timing of the "inlet closed" event in accordance with the condition of the throttle, when the valve member is rotating in a clockwise direction, or the timing of the "inlet open" event in accordance with the condition of the throttle, when the valve member is rotating in an anti-clockwise direction,

Alternatively however, there may be substituted for the cylindrical flow control member 40 a flow control device which is provided by part cylindrical members which are mounted for rotation about a common axis, being moved in opposite directions by the throttle control, such that the part cylindrical members move away from one another to open the outlet passage 12a, and move towards one another to close the outlet passage 12a, conveniently meeting in abutment on or adjacent to the centreline of the outlet passage 12a when the throttle is fully closed. In this manner, not only may substantially axial flow be obtained along the outlet passage 12a throughout the full range of throttle positions, but also both the "inlet open" and the "inlet closed" events may be varied in accordance with the condition of the throttle.

Further, if desired, the part-cylindrical members may be arranged to meet in abutment when the throttle is in its fully closed condition, somewhat off-centre, and the members may be arranged to respond at differential speeds to movement of the throttle control, such that the variation which is effected to the "inlet open" event with movement of the throttle differs from the variation in the "inlet closed" event. Where, in the second embodiment, venting ducts of the type shown in dotted lines in Figure 3 are utilised, a transfer duct must be provided in the throttling member, to ensure that the venting duct provided in the body and the duct provided in the member 30a are capable of communicating throughout the range of movement of the throttling member. In the third embodiment of the invention, shown in Figures 9 to 12, in which similar numerals with the suffix b have been utilised to denote like parts, the housing 6b is provided by a generally cylindrical body through which a flow passage 10b extends along a line, spaced from the longitudinal axis. Mounted on a drive shaft 58 extending along the longitudinal axis of the housing 6b is a disc-shaped valve member 14b, shown in Figure 12. A sector of the valve member 14 b is cut away, shown in Figure 12, to provide a flow aperture or port 15b. The valve member 14 b is rotated at engine speed, and movement of the port 15b across the flow passage 10 b permits flow of fluid through the passage 10 b towards the engine cylinder. The body is provided with an annular recess 50, within which a flow control member 30b in the form of an arcuate disc Is free to move, the recess 50 having a parallel-sided path to permit entry of the member 30 b, and a dove-tail part extending over the range of operative movement of the member 30 b to retain it captive in the recess. The flow control member 30b is provided with an arcuate recess 52, one side thereof being provided with teeth 54, with which a throttle actuating pinion 56 engages. Thus by movement of the throttle lever (not shown) the throttle actuating pinion is moved to move the flow control member 30b arcuately within the groove 50, between a fully open position shown in Figure 9, and a fully throttled position in which the control member 30 b overlies the flow passage 10a.

Thus, the timing of the "valve open" or "valve closed" events will vary in dependence upon the condition of the throttle of the engine.

As with the first embodiment, the arrangement shown in Figures 9 to 12 may be utilised to advance or retard termination of flow of fluid to the engine cylinder, or to advance or retard commencement of flow of fluid to the engine cylinder, in accordance with the direction of rotation of the valve member 14b.

As an alternative, in place of the flow control member 30 b there may be used two flow control members which may be moved simultaneously by the throttle control towards the centreline of the flow passage 10b on closing of the throttle, and away from the centreline of the passage 10b on opening of the throttle. Such an arrangement similarly allows simultaneous variation of both the "inlet closed" and "inlet open" events in accordance with the condition of the throttle. Such an arrangement is conveniently mounted on the end face of a suitable ported rotary valve for a four stroke engine.

The fourth embodiment of this invention illustrated in Figures 13 to 15 is an internal combustion engine comprising a housing 66 providing a cylinder

68 within which is mounted a piston 70, and a cylinder head 72 secured to the housing. The housing 66 and head 72 are each provided with semi-circular cavities 74 and 75 respectively, which, when the head is secured to the body, provides a cylindrical chamber 76 within which a rotary valve member or rotor 78 is mounted for rotation on bearings 79 about a longitudinal axis extending at right angles to the axis of the cylinder, the rotor being provided with two inlet and two exhaust ports 80 and 82 respectively which, during rotation of the rotor, are sequentially brought into communication with the cylinder, to allow respectively a combustible fluid comprising a mixture of petroleum fuel and air to enter the cylinder, and burned gases to be ducted from the cylinder. Mounted over the chamber 76 at one end thereof is an end cap 88, a hollow stem 90 of the rotor extending therethrough, drive means being connected to said stem to cause rotation of the rotor in synchronism with movement of the engine piston 10, for example the rotor being rotated at on quarter crankshaft speed. The end cap 88 is provided with an inlet duct 89 to which combustible fluid is delivered, and with which, as the rotor rotates in the rotor chamber, the inlet port is successively aligned.

For further details of the construction and operation of this embodiment, reference may be made to my European Application 0074174A1.

Mounted in a conical space 100 between the rotor and the end cap 88 is flow control means, afforded by two flow control members 102, 104. Also extending through the end cap is throttling means, comprising two drive shafts 106, 108, each comprising a pin 107, 109 respectively which is located in a corresponding slot 103 or 105 of a respective one of the flow control members, and by rotation of which the flow control members may be moved either separately or in unison towards and away from the inlet duct 89.

Thus, the flow control members 102 and 104 are shown in Figure 14 in fully throttled positions, in which the inlet duct 89 is almost completely covered. By rotation of the drive shafts 106 and 108 in unison and in opposite directions, the flow control members may be moved away from the inlet duct, to fully open positions.

The flow control elements, whilst normally moving in opposite directions, may also be moved in unison in the same direction to change the mean angle of the "inlet open" or "inlet closed" events. Thus, the flow control elements may be the sole throttling means in the inlet system, in which case they will be capable of fully closing the inlet duct 89, or may be arranged to have a limited travel, being operative primarily to vary the effective duration of the inlet timing, whilst a separately throttled carburretor (or fuel injection system) controls the quantities of fuel flowing into the engine cylinder. The fifth embodiment of this invention, shown in Figures 16 and 17, is similar to the first embodiment above described, and similar numerals with the suffix c have been used to denote like parts. The valve member 14c is provided by a skirt of the engine piston, and the flow passage 10c is provided in the cylinder wall and opens direct into the engine cylinder at a position normally below the engine piston.

The flow control member 30c is provided by a slide member linearly movable in a direction parallel to the reciprocatory motion of the piston in a channel 60, the control member being provided with a lip which is curved to provide a circumferential surface 31c adapted for movement in close proximity with the piston periphery, but desirably without contact.

Mounted in the cylinder wall is a drive shaft 62, which is connected to the throttle lever, and which is connected to the control member 30c by an eccentric pin 64. Thus on operation of the throttle lever, the drive shaft 62

Is rotated and the flow control member 30c moves across the mouth of the flow passage 10c.

As with previous embodiments, when the flow control member is in its fully open position, as is shown in Figure 16, communication between the flow passage 10c and the engine cylinder 66 is terminated on downward movement of the piston at a time which is later in the engine cycle than when the flow control member is in a partially throttled position, such as is shown in dotted lines in Figure 16. Conversely, the point at which communication between the passage 10c and the engine cylinder 66 is opened on upward movement of the piston is advanced when the flow control member is in its fully open position, in relation to the time at which this event occurs when the flow control member is in a more throttled position.

It will of course be appreciated that if desired such advancement and retardation effects may be reversed by the mounting of the flow control member 30c in a channel above the flow passage 10c, thereby being operative in a manner such that movement of the flow control member from a fully open to a throttled position is undertaken in the direction of downward movement of the engine piston. In the sixth embodiment of this invention, shown in Figure 18, the linearly movable flow control member 30c is replaced by a pivotally mounted flow control member 30d, a control spindle 62d of which may be rotated by the throttle lever to vary the positioning of the flow control member in the flow passage 10d. Whilst in the sixth embodiment the leading edge of the control member does not retain a position for engagement with the engine piston throughout its movement, it is desirably constructed and arranged so as to co-operate with the engine piston in the fully open position, shown in full lines in Figure 18, and with the opposed wall of the flow passage 10d, when in its fully throttled position, shown in dotted lines in Figure 18.

In the seventh embodiment of this invention, shown in Figures 19 and

20, a flow control member 30e, similar to the flow control member 30d, is mounted in a flow passage 10e which is constituted by the transfer port of the engine which extends from the crank case of the two-stroke engine to an upper part of the cylinder. In this construction and arrangement, when the flow control member 30e is in its fully throttled position, shown in dotted lines in Figure 20, the transfer port 10e is effectively closed when the piston reaches the level Y in Figure 19, whilst with the flow control member 30e in its fully open position, shown in full lines in Figure 19, the transfer port is closed on upward movement of the piston when the piston reaches the level

X. In this manner, the "transfer port closing" event in the engine cycle is retarded in the engine cycle by movement of the flow control member from its throttled towards its fully open position.

However, if it were to be desired, the timing of these events could be reversed by mounting the flow control member adjacent the right hand wall of the flow passage 10e, so as to cause the flow control member to extend to the line Y in its fully open position and to the line X in its fully throttled position.

By the use of the invention above described, closer control of the volumetric efficiency of an internal combustion engine over a wide range of engine speeds may be obtained.

Thus, with conventional, fixed timing valve control systems, the highest compression ratio which can be used satisfactorily is normally determined by problems of "knock" at that speed which yields maximum volumetric efficiency, since with a fully open throttle the volumetric efficiency typically varies from 40% to 80% over the engine speed range. Whilst generally this will not exceed 50% for all but a small part of the engine speed range, the highest useful compression ratio must be determined by the brief period of high volumetric efficiency. This in turn limits the realised compression ratio and hence the realised expansion ratio, both of which (amongst other factors) determine the limits of thermal efficiency.

Conversely by the use of the present invention, the range of volumetric efficiency can be controlled more narrowly and thus the thermal efficiency increased, since the realised cycle efficiency can be moved much closer to the upper limit set by the highest useful compression ratio, and consequently the parts load efficiency (generally the worst performance region of a fourstroke spark ignition engine) can greatly be improved.

Thus, the invention may be used to maximise volumetric efficiency at all speeds, or to deliberately control it to a figure well below unity, thus allowing an intentional inbalance between the expansion and compression ratios of approximately 2 : 1.

In addition, it is to be appreciated that whilst the present invention has been described above in relation to its use in an internal combustion engine comprising spark ignition means, the invention may be utilised in a diesel internal combustion engine.

Claims

CLAIMS:

1. An internal combustion engine comprising a flow passage through which fluid flows towards the engine cylinder, a valve means which is operative alternately to open and close the passage, and a flow control device movable to vary the area of the flow passage presented to the valve means.

2. An internal combustion engine according to Claim 1 wherein the flow control device is movable across the passage to vary the area of a mouth of the passage presented to the valve means.

3. An internal combustion engine according to one of Claims 1 and 2 wherein the flow control device provides part of the flow passage.

4. An internal combustion engine according to any one of the preceding claims wherein the valve means is movable linearly across the mouth of the flow passage.

5. An internal combustion engine according to any one of Claims 1, 2 and 3 wherein the valve means is movable rotationally across the mouth of the flow passage, being provided with one or more flow apertures.

6. An internal combustion engine according to any one of the preceding claims wherein the flow control device is mounted for linear movement across the mouth of the flow passage.

7. An internal combustion engine according to any one of Claims 1 to 5 wherein the flow control device is mounted for rotational movement across the mouth of the flow passage, being provided with one or more flow apertures.

8. An internal combustion engine according to any one of Claims 1 to 5 wherein the flow control device is mounted for pivotal or arcuate movement across the mouth of the flow passage.

9. An internal combustion engine according to any one of Claims 6 to 8 wherein the flow control device comprises two flow control members mounted for relative movement of approach to reduce the area of the flow passage presented to the valve means, and for relative movement of separation to increase the area of the flow passage presented to the flow means.

10. An internal combustion engine according to any of Claims 6 to 9 wherein the flow conrol device comprises two flow control members mounted for movement in unison to vary the angular relationship of the flow passage relative to the valve member.

11. An internal combustion engine comprising a cylinder, a piston reciprocably mounted in the cylinder, a flow passage through which a fluid comprising a mixture of fuel and air is fed into the engine cylinder, valve means movable alternately to open and close the flow passage in timed relationship with the engine cycle, and flow control means selectively positϊonable across the flow passage and which is operative

(a) to vary the restriction to flow of fluid along the flow passage; and/ or

(b) to vary the point in the engine cycle at which the flow passage is opened, for flow of fluid therethrough to the engine cylinder and/or to vary the point in the engine cycle at which the flow passage is closed for fluid flow therethrough.

12. An internal combustion engine according to Claim 11 wherein the flow control means is operative simultaneously to vary the restriction to flow of fluid along the flow passage and to vary the point in the engine cycle at which the flow passage is opened or closed in accordance with the restriction to flow of fluid along the flow passage provided thereby.