GB2373823A

GB2373823A - Disc-type rotary valve for i.c. engines

Info

Publication number: GB2373823A
Application number: GB0107982A
Authority: GB
Inventors: Jack Trethowan
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-03-30
Filing date: 2001-03-30
Publication date: 2002-10-02
Anticipated expiration: 2021-03-30
Also published as: GB2373823B; GB0107982D0

Abstract

A two ported shutter valve 1 has a horizontal disk shutter 3 whose diameter exceeds the cylinder bore 14 and which is oscillated by the actuator 50 so that the sectoral shaped shutter aperture 4 sequentially opens and closes a sectoral shaped induction port 20 and a similar abutting exhaust port. The spark plug 24 functions through the said shutter aperture and the said disk shutter is pressed against the cylinder head 15 by the pressure within the cylinder to seal the ports. Alternatively the disk shutter may be continuously rotated and axially fixed to avoid contact with the cylinder head with each 90{ displaced port being sealed by a piston which has a mating exhaust or induction aperture and whose end faces are pressed against the upper face of the shutter by spring means so as to control the sealing pressure and operating torque. Four ported oscillating type and intermittently rotating type shutter valves may also be provided. The disc driveshaft may be rotated at a variable rotational rate by means of a planetary drive mechanism to increase the average port open size.

Description

VALVE FOR A FOUR STROKE ENGINE This invention relates to a valve that controls both the exhaust and induction operations of a four stroke internal combustion engine.

Four stroke internal combustion engines almost universally use separate poppet valves to control the exhaust and induction operations and modem engines commonly use four of these valves per cylinder which together with their highly developed actuating cams has resulted in complicated and expensive cylinder heads. The valve stems are located in sleeves within the exhaust and induction ducts which together with the valve heads inhibit the engine breathing.

According to the present invention there is provided a shutter valve for a four stroke engine that will control both the exhaust and induction operations and which is comprised of a horizontal disk shutter that is co-axial with the cylinder bore, a cylinder head valve body which has sectoral shaped exhaust and induction ports and which incorporates means of actuating the disk shutter so that its sectoral shaped port opening aperture or apertures sequentially opens and closes the valve ports with the spark plug and fuel injector functioning through the port opening aperture or apertures and with the diameter of the disk shutter exceeding the cylinder bore to enable the outer circumference or culminate point of the ports to coincide with the cylinder bore.

The shutter valve may be either an oscillating type valve or a rotary type valve with the ports being sized and located to satisfy the mode of operation.

Specific embodiments of the invention will now be described by way of example with reference to the following drawings in which FIG 1 shows a vertical cross sectional view through an Oscillating Shutter Valve on the line A. O. A of FIG 2.

FIG 2 shows a planwise cross sectional viewthrough an Oscillating Shutter Valve on the line A. O. A. of FIG 1.

FIG 3 shows a vertical cross sectional view through an example of an Actuator of an Oscillating Shutter Valve on the line A. A of FIG 4.

FIG 4 shows a planwise cross sectional view through an example of an Actuator of an Oscillating Shutter Valve on the line A O. A of FIG 3.

FIG 5 is a developed diagram of the cam groove of the drum cam used with the Actuator shown by FIGS 3 and 4.

FIG 6 shows a vertical cross sectional view through the pneumatic oscillator of the Actuator shown by FIGS 3 and 4. FIG 7A and 7B are planwise cross sectional views through the pneumatic oscillator on the line AA of FIG 6.

FIGS 8 shows a vertical cross sectional view through a Rotary Shutter Valve on the line A 0 A of FIG 9.

FIG 9 shows a planwise cross sectional view through a Rotary Shutter Valve on the line A 0 A of FIG 8.

FIG 10A to 10D are diagrams that illustrate the sequence of operations of a continuously rotating Rotary Shutter Valve and are based upon a planwise cross sectional view on the line A 0 A of FIG 6.

FIG 11A to 11C are diagrams that illustrate the enhanced average port open size of a Rotary Shutter Valve that is provided with a preferred variable rotational rate shutter drive mechanism.

FIG 12 shows a central vertical cross sectional view through the preferred planetary type variable rotational rate shutter drive mechanism of a Rotary Shutter Valve.

FIG 13 shows a vertical cross sectional view through the preferred planetary type variable rotational rate shutter drive mechanism on the ine A. A of FIG 12.

Referring to the drawings two examples of a Shutter Valve are shown, an Oscillating Shutter Valve 1 and a Rotary Shutter Valve 2.

FIGS 1 and 2 show that the Oscillating Shutter Valve 1 forms an integral portion of a cylinder head 15 that has differentially sized circular ring sector exhaust and induction ports 19 and 20 and integral exhaust and induction ducts 21 and 22 respectively, with the said exhaust port having an included angle of 900 and the induction port an included angle of 1200 but alternatively equi-sized ports may be provided. The said ports are positioned adjacent to each other separated by a radial interport bar 41 with the maximum included angle of the induction port being equal to half the difference between 3600 and the included angle of the exhaust port which may have a maximum included angle of 1200.

A horizontal disk shutter 3 that has a integral vertical spindle 5 is co-axially located above the cylinder 13 and oscillated by the Actuator 50 with the diameter of the said shutter exceeding the cylinder bore 14 so as to enable the circular circumference 23 of the said ports to coincide with the said cylinder bore.

The cylinder head port sealing faces 17 circumscribe the ports and are each comprised of the port radial and arcurate sealing faces together with the boss of the center column 18 with the remaining underside of the cylinder head being recessed to form a relief sector 16. A secondary seal may be provided for the said shutter spindle by means of a plurality of sealing rings 9. The means of lubricating the sealing faces of the shutter disk are shown and described hereinafter with respect to FIGS 3 and 4..

The said disk shutter has a circular ring sector shaped port opening aperture 4 that matches or exceeds the shape of the largest port with the apices of the said ports and of the said shutter aperture being set back from the cylinder axis so that the radial sides of the said ports and the said shutter aperture are parallel to each other at the end of the expansion, exhaust and induction operations.

In order to reduce the disk shutter starting torque at the beginning of the exhaust operation narrow apertures may be cut in the cylinder immediately above the top of the piston when this is in its bottom dead center position so as to relieve the pressure within the cylinder prior to the disk shutter being oscillated. These pressure relief apertures will be provided with non-return flaps so as to prevent any back flow of exhaust gases into the cylinder at the end of the induction operation, or into the crankcase if the apertures are exposed below the bottom of the piston.

The said disk shutter is oscillated via the said Actuator clockwise and anti-clockwise during the exhaust operation and anti clockwise and clockwise during the induction operation with the anti clockwise oscillating being continuous and which will hold the said shutter stationary during the compression and expansion operations. This will enable the spark plug 24 and if necessary a fuel injector 25 to be located within the said cylinder head relief sector where they can function through the said shutter aperture.

The said Actuator allows the said disk shutter to be upwardly pressed against the said port sealing faces by the pressure within the cylinder during the compression, expansion and exhaust operations and it will incorporate a retaining spring 7 to hold the said shutter in this raised position during the induction operation. The narrower the width of the radial and arcurate sealing faces around the ports then the higher will be the interface sealing pressure.

A four ported Oscillating Shutter Valve may be provided by the addition of a similar pair of diametrically opposed exhaust and induction ports that each have an included angle of 600 and with the disk shutter having two 600 included angle diametrically opposed port opening apertures. This arrangement will halve the oscillating angle but requires that an additional exhaust duct and induction duct are provided on the opposite side of the cylinder.

Various types of Actuator 50 may be used to oscillate the disk shutter with an example being shown and described hereinafter with respect to FIGS 3 and 4. This example is based upon the use of a drum cam to control the angular position of the disk shutter with a pneumatic oscillator being used to provide the necessary operating power.

FIGS 3 and 4 show an Oscillating Shutter Valve 1 that is provided with an Actuator 50 which is comprised of a drum cam 26 that revolves at half the engine crankshaft speed. The said drum cam controls the angular position of the disk shutter via the cam groove 27 by restraining the movement of the cam follower 28 that is attached to the rack 10 which is reciprocated by the pneumatic vane type Oscillator 33 via the shutter pinion 6.

The said rack is preferably cylindrical in shape and is slidably located in the bore of a circular section guide 11 that forms an integral portion of the center column 18 with the said disk shutter being coaxially mounted in center column bearings which allow it to be held up against the sealing faces of the cylinder head 15 by means of the retaining spring 7.

These Figures show that the sealing surfaces 17 are lubricated by means of radial oil feed passageways 29 that are located above the radial sealing faces of the exhaust and induction ports and are connected to these faces via a plurality of micro bore feed holes 30. The said oil feed passageways are interconnected via a circular oil channel 31 and are connected to a pressurised oil supply via the oil connector 32.

The power required to oscillate the said disk shutter is provided by the said Oscillator which enables the engine to operate at high rotational speeds and for the ports to be rapidly opened and closed with a fully open dwell period. The method of controlling the angular oscillations of the said disk shutter is further shown and described hereinafter with reference to FIGS 5,6, 7A and 7B.

FIG 5 shows the developed track of the cam groove 27 which controls the oscillations of the disk shutter as follows : - The said cam groove is comprised of a 900 Sector for each of the cyclic compression expansion exhaust and induction operations, with the track of the said cam groove for the compression and expansion being annular as the disk shutter remains stationary during these operations. The track of the said cam groove for the exhaust and induction operations respectively form loops on opposite sides of the annular track with each loop preferably being split into a 300 rapid port opening section, a 300 port fully open dwell section and a 300 rapid port closing section.

The cam follower 28 and rack 10 are actuated by the said Oscillator so as to be continuously pressed against one side of the said cam groove during the compression and expansion sectors and during the first half of the exhaust sector and the second half of the induction sector, and to be continuously pressed against the opposite side of the said cam groove during the second half of the exhaust sector and the first half of the induction sector. The angular oscillation of the said disk shutter is determined by the displacement of the respective exhaust and induction cam groove loops from the central annular position.

FIG 6 shows that the pneumatic Oscillator 33 is comprised of a vane 34 which has an integral hub 35 that is mounted onto the upper portion of the disk shutter sleeve 8 and is enclosed within a co-axial circular body 36 that allows the said vane to be rotated through an angle equal to the sum of the exhaust and induction port included angles. This operating sector is enclosed by an Integral end plate 37 the bore of which mates with the said vane hub. The said oscillator body is fastened onto the upper end of the cylinder head center column 18 with its shaft bores being provided with sealing rings 38 FIGS 7A and 7B show that the said end plate of the oscillator body is provided with a hub seal 39 and that the vane is provided with a tip seal 40 together with top and bottom edge seals which are not shown.

FIG 7A shows the said vane being rotated clockwise with this oscillation being initiated when the drum cam reaches the mid-exhaust position and will continue until it has reached the mid-induction position. FIG 7B shows the said vane being rotated anti clockwise with this oscillation being initiated when the drum cam reaches the mid-induction position and will continue until it has reached the mid-exhaust position. If the said Oscillator fails to oscillate the disk shutter at the start of the exhaust operation then the cam follower will come into contact with and be actuated by the opposite side of the cam groove to ensure that the disk shutter is oscillated.

FIGS 8 and 9 show a continuously rotating type Rotary Shutter Valve 2 that has a horizontal disk shutter 60 whose diameter is greater than the cylinder bore 65 and which has an integral spindle 61 that is coaxially located above the cylinder 64 by cylinder head bearing means and prevented from being pressed against the underside of the cylinder head 66 by the thrust bearing 76 and being retained in this position during the induction operation by the lower spindle bearing 84. The said disk shutter is continuously rotated at half the engine crankshaft speed via the driveshaft gear 82 and the shutter gear 83 and the driveshaft 63.

The said cylinder head has sectoral shaped exhaust and induction ports 67 and 68 respectively that each have an included angle of 450 and whose centres are displaced 900 apart and is provided with integral exhaust and induction ducts 69 and 70 respectively. The said disk shutter has a port opening aperture 62 that matches the shape of the said ports and which sequentially opens and closes the said ports as it rotates across them and is shown by broken lines at the end of the compression operation and by chain dot lines at the end of the expansion operation. A spark plug 24 is mounted in the 2700 position together with a fuel injector if required so that they may function through the said shutter aperture.. The provision of a disk shutter whose diameter exceeds the cylinder bore 65 enables the port culminate points 71 to coincide with the said cylinder bore.

When closed by the said disk shutter the said ports are sealed from the cylinder by means of cylindrical sealing pistons 77 that have sectoral shaped apertures 78 which match and coincide with the said port apertures. The said sealing pistons are slideably located in mating circular recesses in the said cylinder head and provided with a plurality of sealing rings 79 and are pressed down against the said disk shutter by a plurality of sealing springs 80 via thrust pins 81 that may extend above the said exhaust and induction ducts. The use of the said spring loaded sealing pistons enables a constant interface sealing pressure to be maintained which is not effected by the pressure of the combustion gases within the cylinder, but the said springs may be replaced by pneumatic cylinders that would enable the sealing pressure to be varied for each of the cyclic operations.

A four ported Rotary Shutter Valve may be provided by the addition of a similar pair of diametrically opposed 450 exhaust and induction ports with the disk shutter having a diametrically opposed pair of 450 port opening apertures. This will increase the engine breathing capacity by over 100% but requires that an additional exhaust duct and induction duct are provided on the opposite side of the cylinder.

This four ported valve must also be intermittently rotated during alternate rotation of the valve driveshaft by the provision of a one revolution device between each valve and the valve driveshaft and allowing the disk shutter to be upwardly pressed against the cylinder head to seal the ports so that the port sealing pistons 77 are eliminated.

Lubrication of the interfaces between the said disk shutter and the said sealing pistons may be effected by the supply of pressurised oil via the oil connector 73 and the peripheral oil channel 72 and a plurality of micro bore feed holes 74 with this system being extended to include the said shutter spindle seal.

The axis of the said ports and the said shutter operating aperture are set back from the cylinder axis so that a parallel sealing face remains between radial sides of the said ports and the said shutter aperture when this is in its 00, 900 and 1800 positions.

The sequence of operations of the said continuously rotating type Rotary Shutter Valve are further illustrated and described hereinafter with respect to FIGS 10A to 10D whilst the disk shutter is rotated at a uniform rate at half the speed of the engine crankshaft.

FIG 10A illustrates the exhaust operation where the port opening aperture 62 of the disk shutter 60 is rotated from its 00 position to its 900 position to open and close the exhaust port 67 that is marked by vertical hatching..

FIG 10B illustrates the induction operation where the port opening aperture 62 of the disk shutter 60 is rotated from its 900 position to its 1800 position to open and close the induction port 68 that is marked by vertical hatching..

FIG 10C illustrates the compression operation where the port opening aperture 62 of the disk shutter 60 is rotated from its 1800 position to its 2700 position with the said exhaust and induction ports remaining dosed. The spark plug 24 is located at the 2700 position which enables ignition to take place through the said port opening aperture.

FIG 10D illustrates the expansion operation where the port opening aperture 62 of the disk shutter 60 is rotated from its 2700 position to its 3600 position with the said exhaust and induction ports remaining dosed When the said disk shutter is rotated at a uniform rate the average port open size will be around 50% but this may be increased to around 90% by the provision of a variable rotational rate drive mechanism with a preferred mechanism 90 being shown and described hereinafter with respect to FIGS 12 and 13 and where the effect of the said variable rate drive mechanism upon the port open size is illustrated hereinafter with respect to FIGS 11A to 11 C.

This said variable rate drive mechanism is driven by an input gear 91 that uniformly rotates at half the engine crankshaft speed and whose output shaft forms the valve driveshaft 63 that is connected by gear means to the spindle 61 of each disk shutter 60. which causes the said disk shutter and the said valve driveshaft to be rotated at similar variable rotational rates in quadrantal increments.

FIG 11A illustrates the position soon after the start of the exhaust operation where the input gear 91 has rotated through an angle a of 150 and has caused the disk shutter spindle 61 and operating aperture 62 to be rotated through an angle p of around 400 which results in the exhaust port 67 being around 80% opened as marked by vertical hatching.

FIG 118 illustrates the mid exhaust position where the input gear 91 has rotated through an angle a of 450 and has also caused the disk shutter spindle 61 and port opening aperture 62 to be rotated through an angle, 8 of 450 which results in the exhaust port 67 becoming fully opened as marked by vertical hatching.

FIG 11 C illustrates the position towards the end of the exhaust operation where the input gear 91 has rotated through an angle a of 750 and has caused the disk shutter spindle 61 and port opening aperture 62 to be rotated through an angle p of 500 which results in the exhaust port 67 being around 80% opened as marked by vertical hatching.

After the said input gear has rotated through an angle a of 90 then the variable rotational rate drive mechanism will also have rotated the said disk shutter port opening aperture through an angle of 90 so as to fully close the said exhaust port.

This variable quadrantal sequence will be similarly repeated during the induction operation when the said input gear will be rotated from 900 to 1800 and will also be repeated during both the compression and the expansion operations when the said input gear will be rotated from 1800 to 3600 unless the disk shutter is intermittently rotated and provided with a diametrically opposed pair of port opening apertures and the said sealing pistons eliminated as required for a four ported valve as described hereinbefore..

FIGS 12 and 13 show that the preferred variable rotational rate quadrantal drive mechanism 90 is comprised of an input drive gear 91 that is rotated at the engine crankshaft speed and which may be rotatably located on the valve driveshaft 63 co-axially with the stationary ring gear 94. The said drive gear is provided with an off-center axle 92 that has a co-axial planetary pinion 93 which meshes with the said stationary ring gear with the said planetary pinion having an integral crank arm 95 and crank pin 96 that is provided with a co-axial oscillator roller 97.

The pitch circle diameter of the said planetary pinion is 25% of the pitch circle diameter of the said stationary ring gear so that it rotates through four revolutions about the said planetary axle as this is concentrically rotated once around the said stationary ring gear.

The said oscillator roller is located between the forked arms 98 of the oscillator 99 that is keyed onto the said valve drive shaft so that both the said oscillator and the said drive driveshaft are angularly oscillated by around 250 about the said planetary axle during each of its quadrantal rotations with the said crank pin following a quadrangle shaped track 100.

The disk shutter will be variably rotated in quadrantal increments at the same variable rotational rate as the said valve driveshaft but may be disconnected from it during altemate rotations so as to remain stationary during the compression and expansion operations.

Claims

1. A Shutter Valve for a four stroke engine that will control both the exhaust and induction operations and which is comprised of a horizontal disk shutter that is co-axial with the cylinder bore, a cylinder head valve body which has sectoral shaped exhaust and induction ports and which incorporates means of actuating the disk shutter so that its sectoral shaped port opening aperture sequentially opens and doses the valve ports with the spark plug and fuel injector functioning through the shutter aperture and with the diameter of the disk shutter exceeding the cylinder bore to enable the outer circumference or culminant point of the ports to coincide with the cylinder bore.

2. An Oscillating Shutter Valve as claimed in Claim 1 that is provided with an Actuator based upon a pneumatic vane type two position Oscillator to supply the operating power and determine the port opening and closing rates with a drum cam controlling the disk shutter positioning or which is based upon a three position Oscillator that will both supply the operating power and control the disk shutter positioning..

3. An Oscillating Shutter Valve as claimed in Claim 1 and Claim 2 in which the disk shutter is upwardly pressed against the cylinder head by the gas pressure within the cylinder so as to seal the exhaust and induction ports.

4. A continuously rotating Rotary Shutter Valve as claimed in Claim 1 that is provided with a disk shutter that is axially fixed to avoid contact with the cylinder head and with each port being sealed by the end face of a piston that has a mating exhaust or induction aperture and which are downwardly pressed against the upper face of the shutter disk by spring or pneumatic means so as to control the interface sealing pressure and the operating torque.

5. An intermittently rotating Rotary Shutter Valve as claimed in Claim 1 whereby the disk shutter of each valve is connected to a common drive shaft via a one revolution device so that the disk shutter is intermittently rotated and held stationary during alternate rotations of the valve driveshaft whilst the compression and expansion operations are performed and with the disk shutter being pressed against the cylinder head by the gas pressure within the cylinder so as to seal the exhaust and induction ports.

6. A Rotary Shutter Valve as claimed in Claim1, Claim 4 and Claim 5 that has 450 included angle sectoral shaped exhaust and induction ports that are displaced by 90 .

7. A Rotary Shutter Valve as claimed in Claim 1, Claim 4, Claim 5 and Claim 6 whereby the disk shutter driveshaft is rotated at a variably rotational rate by means of a variable rotational rate planetary drive mechanism so as to increase the average port open size from around 50% to around 90%

8. A valve substantially as described herein with reference to FIGS 1 to 13 of the accompanying drawings.