Patent Application
20070079787
1. The Technical Field
This invention relates to different aspects of reciprocating fluid devices, including those colloquially called “scotch yoke” devices.
2. The Prior Art
Known scotch yoke devices include one or more pairs of horizontally opposed pistons reciprocating in respective cylinders. Each piston of a pair is rigidly attached to the other so the pair of pistons move as a single unit. The pistons reciprocate along parallel axes which may be coaxial or which may be offset. A crank is provided centrally of the pair of pistons with an offset mounted in a slider. The slider in turn is mounted in the piston assembly between opposing sliding surfaces, which extend perpendicularly to the axes of the pistons. The slider is thus constrained to move perpendicularly to the piston axes and so, as the crank rotates, the pistons are caused to reciprocate along the piston axis, with a true sinusoidal motion. In certain circumstances the provision of a true sinusoidal motion is preferable to the quasi-sinusoidal motion provided by a crank and connecting rod arrangement found in most internal combustion engines or pumps. However such devices have certain drawbacks. Neither the slider, which reciprocates in a vertical plane, nor the pistons, can be dynamically balanced by a rotating mass. Whilst this can be partially compensated for in a multi-pair device, this still leaves rocking couples.
Further in the conventional arrangement the slider slides between a single pair of opposed surfaces which lie on either side of the big end axis. The pistons must be arranged along parallel axes and the distance between the sliding surfaces of the slider and the guide surfaces of the pistons must be larger than the diameter of the big end on the crank.
The present invention aims to at least ameliorate some of the disadvantages of the prior art and, in preferred forms, provides devices in which paired pistons are not rigidly connected together, are not necessarily coaxial and in which better dynamic balancing is achieved. The invention also allows use of uneven numbers of pistons mounted on a single big end axis.
In one broad form the invention in effect decouples the pistons from each other and provides each piston with its own pair or group of sliding surfaces and its own slider. The sliding surfaces for each piston do not lie on either side of the big end axis but are positioned remote from the big end axis. The sliding surfaces may be compound surfaces. This decoupling means that each piston is not relying on the coupling with the other piston or pistons to move in both directions and allows each piston to move along a separate axis and at a different phase to all other pistons. Whilst pistons may be interconnected via a common linkage which carries the various sliding surfaces, the pistons are not rigidly connected together. Thus a V-configuration may be achieved with a pair of pistons or a 120° layout with three pistons, for instance.
In one broad form the invention provides a fluid device, which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis;
at least two pistons, each mounted for reciprocal motion in a respective cylinder along a respective piston axis which is perpendicular to the big end axis, each piston including guide means which engages a respective engagement means on the connecting means, said guide means including a pair of guide surfaces, the guide means of the pistons all being disposed on the same side of the big end axis.
Preferably, the guide means include surfaces which extend substantially perpendicularly to the respective piston axis. However, the guide surfaces may extend at other than 90° to the respective piston axis. Even when the guide surfaces are “perpendicular” to the piston axis, the guide surfaces may deviate from the perpendicular by up to 5° either way. The engagement means may be two or more parallel linear surfaces which correspond and slide relative to the guide surfaces. Alternatively, the engagement means may include two or more roller bearings or the like.
In an alternate form of the invention, the linear parallel opposed guide surfaces may be located on the connecting means and the engagement means may be mounted on the piston. In preferred forms there are two or three pistons mounted on slider means on each big end axis. The pistons may be arranged at equal angles about the main axis if desired.
The guide means may be integral with the piston or may be located on a separate structure attached to the piston. Where a separate structure is provided, it may be pivotably mounted to the piston, preferably using a gudgeon pin arrangement. This allows one to use conventional pistons with connecting rods incorporating the guide means.
The crankshaft may be fixed relative to the cylinders or may be movable so as to alter the compression ratio and/or the timing of the pistons in the cylinders. In a V configuration, movement of the crankshaft along the bisector of the included angle between the cylinders results in a change in compression ratio without any change in phase. An alternate arrangement provides for the crankshaft axis to rotate about a distant axis, so raising or lowering the crankshaft. These arrangements may be used with a single piston engine. If desired, the crank may be moveable in a plane perpendicular to at least one piston axis. In the case of an in-line engine, the crank may be moved up or down (relative to the line of pistons) to change compression.
When two pistoris per big end axis are utilized, the pistons may be arranged in a V-configuration. The V-configuration may be at any angle, such as 90°, 60°, 72° or any other desired angle. The number of pistons per big end axis is only constrained by physical size limitations. Each big end axis may have a single connecting means upon which multiple pistons are mounted or there may be a multiple connecting means mounted on each big end axis with each connecting means having an associated piston mounted upon it.
When multiple pistons are mounted to one big end axis, they may be located the same distance from the main axis or different pistons may be at different distances from the main axis. The pistons may be disposed axially around the big end axis, or may be offset from each other in this respect.
Whilst the guide means and complementary engagement means are preferably simple planar surfaces in cross section, other configurations may be possible.
The invention, in another broad form, also provides a fluid device, which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis;
at least one piston mounted for reciprocal motion in a cylinder along a piston axis which is perpendicular to the big end axis, the at least one piston engaging an engagement means on the connecting means whereby the connecting means may have non-rotary movement relative to the at least one piston; and,
stabilizing means engaging the connecting means to limit the connecting means to a single orientation as it orbits the main axis.
The stabilizing means may include the engagement of the connecting means with the at least one piston. The stabilizing means may include a separate linkage pivotably mounted to both the connecting means and the crankcase.
The crank may be a simple crank with an offset big end axis or it may be a compound mechanism which provides for other than simple circular motion of the big end at a constant angular velocity. Examples of compound crank mechanisms are disclosed in PCT International Patent Application Nos. PCT/AU97/00030 and PCT/AU98/00287, the disclosures of which are incorporated herein.
The invention, in another broad form, also provides a fluid device, which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis;
at least one piston mounted for reciprocal motion in a respective cylinder along a piston axis which is perpendicular to the big end axis, the at least one piston engaging engagement means on the connecting means;
wherein said main axis of the crank is movable along at least one path relative to said cylinder or cylinders and said engagement means is configured such that said at least one piston is neither substantially retarded or advanced.
Where the device includes pistons arranged in a V configuration, the main axis of the crank mechanism preferably moves along a linear path which bisects the included angle of the V. Alternatively, the main axis of the crank mechanism may move along an arc.
The invention, in another broad form, also provides a fluid device, which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis; and
at least one piston mounted for reciprocal motion in a respective cylinder along a piston axis which is perpendicular to the big end axis, the at least one piston engaging engagement means on the connecting means;
wherein said connecting means has a centre of mass located on or adjacent to the big end axis.
Preferably the crank includes a counter weight which substantially and/or dynamically balances the mass of the connecting means relative to the crank axis.
The invention, in another broad form, also provides a fluid device, which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis; and
at least one piston mounted for reciprocal motion in a respective cylinder along a piston axis which is perpendicular to the big end axis, the at least one piston engaging engagement means on the connecting means;
wherein the crank has an effective centre of mass which, together with the connecting means and the at least one piston, remains stationary or substantially stationary relative to the main axis as the crank rotates.
In an alternate form of the invention, the effective centre of mass can describe an orbit, being a circle or ellipse, as the crank rotates.
The invention, in another broad form, also provides a fluid device, which includes:
a crank including a big end having a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis; and
at least one pair of non opposed pistons, each piston being mounted for reciprocal motion in a respective cylinder along a respective piston axis which is perpendicular to the big end axis, each piston engaging engagement means on the connecting means;
wherein the configuration of the connecting means and the engagement means is such that the motion of each piston is simple harmonic motion.
The invention, in another broad form, also provides a fluid device, which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis; and
at least one pair of non opposed pistons, each piston being mounted for reciprocal motion in a respective cylinder along a respective piston axis which is perpendicular to the big end axis, each piston engaging engagement means on the connecting means;
wherein each pair of pistons has a mass and motion equivalent to a single body orbiting in an orbit.
Preferably the orbit is a circle, but it may be elliptical or of another shape, such as pear-shaped.
Preferably the motion of each of the pistons is simple harmonic motion.
The invention, in another broad form, also provides a fluid device, which includes:
a crank including a big end which orbits about a main axis, the big end having a big end axis;
connecting means rotatably mounted on the big end axis; and
at least one pair of pistons, each piston being mounted for reciprocal motion in a respective cylinder along a respective piston axis which is perpendicular to the big end axis, the piston axes of each pair being at a chosen angle to each other, each piston engaging engagement means on the connecting means;
wherein each pair of pistons has a mass and motion equivalent to a single body describing an orbit;
the centre of mass of the connecting means is located on or adjacent the big end axis; and
the crank includes a counter weight located generally diametrically opposite the big end and having a centre of mass remote from the main axis, the counter weight including the equivalent of:
a first mass to statically and/or dynamically balance all or part of the mass of the big end relative to the main axis;
a second mass to statically and/or dynamically balance all or part of the mass of the connecting means relative to the main axis; and,
a respective third mass to statically and/or dynamically balance all or part of the mass of each piston relative to the main axis.
Preferably, the chosen angle is 90°, but is not limited to this. Some other preferred angles are 45°, 60°, 72° and 120°.
Preferably, the orbit is a circle and the third mass preferably statically and/or dynamically balances the mass of the pistons.
Where the orbit is not a circle, the third mass may balance the mass of the pistons in a first direction. The first direction is preferably parallel or perpendicular to a bisector of the axes of each pair of pistons.
In all forms of the invention the connecting means may have non-rotary motion relative to the piston. Preferably there is no rotary motion whatsoever, except as allowed by clearances.
The invention also provides, in one broad form, a fluid device having:
at least one piston assembly reciprocating along a piston axis;
a crank rotating about an axis and having a big end offset from the crank axis, the big end having a big end axis perpendicular to the piston axis; and
at least one intermediate member located between the big end and the piston for transferring motion of the big end to the piston assembly.
In the device, each piston assembly may have at least two surfaces with the big end bearing on one surface and an intermediate member or follower bearing on the another surface.
The device may have at least one follower which bears on both surfaces or it may have two followers each of which bears on one of the respective surfaces.
Each piston assembly may have one piston or it may have two pistons. Where two pistons per assembly are provided, preferably the at least one follower is located between the pistons.
The follower is preferably a circular cam having its centre offset from the crank axis.
The device may have one or more piston assemblies for each follower.
Where two or more pistons assemblies for each big end are provided, they may reciprocate along piston axes extending at any angle to each other. Preferably there are two piston assemblies per big end extending at 90° to each other.
Where two piston assemblies extending at 90° to each other are provided, preferably there are provided two followers, each of which engages both piston assemblies.
Preferably, the device includes constraining means which guide the respective piston assembly to limit or substantially prevent movement of the respective piston assembly transversely of its respective piston axis.
The constraining means may be mounted on or be integral with the crankcase. The constraining means may include a slot or elongate recess in the piston assembly. The slot or recess may engage a member on the crankcase or it may engage the crankshaft itself, directly or indirectly. If the slot or recess engages the crankshaft, preferably there is provided a follower intermediate the crankshaft and the slot or recess.
The device may include one or more subsidiary fluid pumps for pumping lubricating fluid or the like to specific locations of the device. Each fluid pump may be mounted on the crankcase, the crank assembly, the drive mechanism mounted on the crank or on a piston assembly. Any combination of these positions is possible. The fluid pump may be used to cause secondary movement of the piston assembly relative to the drive member and/or the crank.
The crank may include a secondary drive member which engages the at least one follower or the piston assembly. The secondary drive member may contact either continuously or intermittently as the crank rotates. The secondary drive member may drive one or more of the aforesaid secondary fluid pumps.
The invention, in another broad form, also provides a fluid device which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis;
at least one piston mounted for reciprocal motion in a cylinder along a piston axis, the piston having a cross-sectional area perpendicular to the piston axis which is perpendicular to the big end axis, the piston having guide means which engage engagement means on the connecting means; and
at least one restricting means for constraining the piston to move along the piston axis;
wherein the piston guide means bisect the piston cross-sectional area and optionally at least part of each restricting means is located within a volume defined by the piston cross-sectional area but not along the centre line of the bisection formed by the piston guide means.
In preferred embodiments, the guide means include surfaces which extend substantially perpendicularly to the respective piston axis, as already discussed.
The restricting means is intended to alleviate “jamming” of the piston in the cylinder, which can provide a problem at high temperature. It is desirable to maintain the piston so that it is aligned with the piston axis. Several preferred embodiments of the restricting means are described in connection with the drawings. It will be appreciated that when the restricting means is located within the “footprint” of the piston, metallic mass of the fluid device is minimized.
As will be seen from the drawings, in some embodiments, the restricting means is formed in pairs and a line drawn from one member to the other of the pair would be perpendicular to the centre line of the bisection of the piston formed by the piston guide means. In other embodiments, the restricting means includes members which are located on either side of the bisection formed by the first piston guide means but not along the centre line.
Each restricting means may be integral with the piston or formed separately from and attached to the piston. The restricting means may be slidably engaged in slideways which may be substantially fixed to the engine block or other suitable purchase point.
Slideways for the restricting means may be mounted to the block within the footprint of the piston, thus minimizing the size of the device of the invention. Alternatively, the slideways may project wholly or partly outside the footprint of the piston.
For a slightly less compact arrangement, the restricting means may be mounted outside, or partly inside and partly outside, the piston footprint.
Regardless of whether the restricting means is inside or outside the piston footprint, it is to be noted that the restricting means (when more than one) may be disposed symmetrically or asymmetrically of the piston axis. When there is a plurality of restricting means, they may be on one side of the line of bisection of the piston. There may be an odd number of these restricting means.
Reference is made to devices in which piston motion is achieved by sliders mounted on big ends and in which two or more pistons may be mounted on a single slider but each of which moves along a separate path to each other.
It has been found that because each piston is not directly connected to any other piston, there is a tendency for the pistons to rotate in the cylinders about an axis generally parallel the crank axis. This can lead to destructive failure of the device. We have found that providing the restricting means, extending parallel to the cylinder axis, prevents such rotation. In some versions, the restricting means lie above the swept volume of the crank shaft and big end. However, if the restricting means is configured so that at various parts of the cycle the restricting means extends into the volume swept by the crank and slider, a more compact device can result.
Consequently, in one broad form the invention provides a fluid device which includes:
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted on the big end axis;
at least one piston mounted for reciprocal motion in a cylinder along a piston axis which is perpendicular to the big end axis, the piston having guide means which engages engagement means on the connecting means; and
at least one restricting means for constraining the piston to move along the piston axis;
wherein, as the crank rotates, the at least one restricting means extends into the swept volume of the crank.
Preferably the restricting means is located within the volume defined by the axial cross-sectional area of the piston.
Preferably each piston has two restricting means and more preferably they are located symmetrically relative to the piston axis.
In conventional scotch yoke type piston fluid machines, a slider is rotatably mounted on the big end of a crank, which orbits about a main axis. The slider is constrained to move along a linear slot in the piston assembly which is generally perpendicular to the cylinder axis. Thus, as the crank rotates, the piston is caused to reciprocate along the cylinder.
In conventional single piston devices, the linear slot is positioned on the cylinder axis and so that at top dead centre the big end lies between the piston and the main axis. This invention includes various novel and inventive configurations which depart from this standard.
Thus, in a further broad form, the invention provides a reciprocating piston fluid device including
a crank including a big end axis which orbits about a main axis;
connecting means rotatably mounted-on the big end axis; and
at least one piston mounted for reciprocal motion in a cylinder and including engagement means for engaging the connecting means, whereby the piston reciprocates in the cylinder as the big end orbits the main axis, the piston having an axis perpendicular to the big end axis;
wherein, at top dead centre, the engagement means lies on one side of the big end axis and the piston lies on the other side of the big end axis.
This, in effect, is the reverse of the norm.
In another form, the invention provides a reciprocating piston fluid device including:
a crank including a big end axis which orbits about a main axis;
at least one connecting means rotatably mounted on the big end axis;
at least one piston mounted in a respective cylinder for reciprocal motion along a piston axis which is perpendicular to the big end axis; and
engagement means interconnecting the at least one piston and the at least one connecting means,
wherein the main axis is not located on the or any of the at least one cylinder axes.
Preferably, when the or one of the pistons is at top or bottom dead centre, a line joining the main and big end axes is parallel to and spaced from the respective cylinder axis of the one piston.
Preferably, the or each engagement means includes restricting means to constrain the respective piston or pistons to move along the respective cylinder axis.
Usually in scotch yoke engines or pumps, two opposed pistons are rigidly connected together about a yoke. A slider, which is rotatably mounted on a big end of a crank, slides within the yoke and causes the pistons to reciprocate.
The present invention aims to provide improved yoke constructions, which allows, in preferred forms, for two identical parts to be utilized to build up the yoke assembly. The assembly may be split generally axially or transversely relative to the cylinder axis. In preferred forms, the number of parts required is reduced whilst allowing for simple manufacture of the parts.
In one broad form the invention provides a yoke assembly for a scotch yoke type fluid device having opposed pistons reciprocating in opposed cylinders having parallel cylinder axes, the yoke assembly attached to the two pistons and including an engagement portion for receiving an engagement member rotatably mounted on a big end axis of a crank shaft and in which the engagement means reciprocates as the crank rotates, said engagement portion being split into two parts, optionally releasably engaged together.
The engagement portion may be split along a plane generally parallel to the cylinder axes or along a plane generally perpendicular to the cylinder axes.
The two parts may be identical or may be dissimilar.
Preferably the two parts may be joined together at only two locations, but more may be used if desired.
The engagement portion preferably includes two opposed channels in which the engagement means reciprocates. Each of the channels may be defined by only one of the parts of the engagement portion or both parts may define part of each channel.
Preferably, where identical parts of the engagement portion define only all or part of one channel each, each part includes legs which extend and engage the other part. These legs may be located at opposite ends of the channel but on the same lateral side, on the same end but opposite lateral sides of the channel, or on opposite ends and opposite lateral sides of the channel. Preferably, a single fastener may hold two legs, one for each part, simultaneously.
Where non-identical parts of the engagement portion are utilized, one part may have two or more spaced-apart legs located adjacent the channel and the other part may have no legs or one leg adjacent the channel.
Preferably, the legs are located at the ends of the channel, but a single leg may be positioned adjacent the channel at a mid-point. In this construction, the crank cannot pass through one side of the engagement portion.
The decoupled, paired piston/s, scotch yoke devices of this invention may be balanced perfectly in that the centre of mass of the moving parts of the engine (the crank, the pistons and their members, and any interconnecting members between the big end and the pistons) remains exactly stationary and centered on the main axis as the device members rotate, orbit and reciprocate through the cycle. A pair of pistons arranged at 90 degrees to each other and sharing the same big end axis may be perfectly balanced. A pair of pistons arranged at 90 degrees to each other and having coaxial big end axes, similarly, may be perfectly balanced (although in this embodiment a rocking couple may be set up).
An engine that is of a V configuration that is other than 90 degrees may be balanced perfectly as well. This may be achieved by splitting the big end so that there are two big end axes per pair of reciprocating masses, i.e., pistons. The two big ends axes are angularly displaced from one another about the main axis.
The adoption of a scotch yoke type connection for the pistons, wherein the sliding surfaces are perpendicular to the piston axis, can eliminate the piston motion normally observed at bottom dead centre in compound crank engines with a pinion wheel to annular gear ratio of 3/2.
While it has been stated that the piston axis is perpendicular to the big end axis, it is to be understood that it is not necessary that the piston axis passes through the big end axis.
In other broad forms, the invention includes the variations disclosed in the following patent specifications, the content of which are imported herein by reference: Australian provisional patent application No. PQ5246, Australian provisional patent specification No. PQ9567 and Australian provisional patent specifications Nos. PQ9143 and PQ9979, also International Patent Application No. PCT/AU00/00281.
Although many broad forms of the invention are disclosed in this specification, either specifically or as imported by reference, it will be appreciated by one skilled in the art that one or more aspects of each embodiment may well be applicable to other forms of the invention and this specification is to be interpreted accordingly.
Without limiting the generality of the above paragraph, specific reference is made to adaptation of the compound crank mechanisms disclosed in International Patent Application Nos. PCT/AU97/00030 and PCT/AU98/00287. In many instances, the broad forms of invention recited herein may be applied to the compound crank mechanisms disclosed in the International applications. The conventional piston arrangement in the International applications may be replaced by the engagement means referred to herein, to form a scotch yoke type engine, for example.
Again, without limiting the generality of the second last paragraph, some of the forms of the invention may be suitable for adoption in two stroke, four stroke or hybrid two stroke four stroke devices.
Manufacturers strive to increase the specific power output and the efficiency of internal combustion engines for various reasons. One technique is to use forced induction, such as by way of super charging or turbo charging.
In another broad form, present invention provides an internal combustion with in-built forced induction without the need for external devices such as supercharging or turbo charging. This is achieved by the combination of two and four stroke techniques.
Thus, in one broad form the invention provides an internal combustion engine having:
at least one piston reciprocating in a respective cylinder/crank case assembly and defining a combustion chamber and a crank volume therein;
at least on passageway linking the combustion chamber and the crank volume;
at least one first valve means for selectively closing the passageway;
at least one inlet to said crank volume;
at least one second valve means for selectively closing the inlet.
The passageway may include a secondary chamber of variable volume.
The engine may be provided with a second inlet which communicates directly with the combustion chamber via third valve means.
The crank volume may communicate with an auxiliary chamber via auxiliary valve means.
The crank volume may include vent means to selectively vent pressure. The vent means may vent to the respective combustion chamber or an a multi cylinder engine may vent to another crank volume or another combustion chamber. Preferably the vent means includes valve means to selectively vent pressure.
The at least one passageway may be external of the combustion chamber and crank volume. Alternatively the passageway may be located in the piston.
Where the passageway is external, the at least one first valve means may include a poppet valve, a reed valve, a sleeve valve, a disc valve or any other suitable valve mechanisms.
The passageway may communicate with the combustion chamber via the cylinder wall or the cylinder head.
Where a sleeve valve is used, it may rotate about the cylinder axis, either continuously or in an oscillating manner, or it may reciprocate axially relative to the cylinder, or with a combination of axial and rotatory oscillatory motion.
The first valve means may include two or more valves located in the passageway distant from each other, so as to define a secondary chamber.
In another broad form, the invention provides, in a scotch yoke fluid device, which includes a piston mounted for reciprocal motion in a cylinder, the improvement which includes a displaceable member for relieving pressure in a variable volume chamber in the cylinder during combustion.
The displaceable member may be part of an assembly for the piston, or part of the piston head, or part of the wall of the cylinder, for example.
The displaceable member may be displaced by displacing means or by variable volume chamber pressure. The displaceable member may be displaced by “inertia”, for example, if the displaceable member oscillates with the piston or if it is mounted in or on the piston or piston assembly.
Motion of the displaceable member may be controlled or modified by such means as damping springs, hydraulics, resilient members, mechanical means, tie rod/s, flexible wire/s, or friction.
The displaceable member may have more than one means influencing its movement during the piston stroke cycle. For example, pressure in the variable volume chamber may influence upward motion of the displaceable member, while downward motion may be influenced by a spring mounted between the displaceable member and the piston (or other part/s in the variable volume chamber).
In the case where the displaceable member is mounted on the piston, it is preferred that the displaceable member is connected to the piston or entrapped or captured in or on the piston and is therefore reliant on the piston for its carriage. For example, the member may be part of or may comprise the piston crown. The member may be within the circumference of the piston crown.
In various embodiments, the displaceable member or part of it may be of a compressible or deformable nature.
In one particular embodiment, the displaceable member is a free piston (i.e., able to “float”) within the piston of the scotch yoke fluid device.
The displaceable member or part of it may be provided with one or more cooling fluids or sumps. It may have sealing means and lubrication.
In a preferred embodiment, the displaceable member may be displaced once only. The purpose of this is to safeguard the engine from a pressure build up beyond a chosen critical point. After the single displacement, the member may be rendered inactive, for example by being crushed irretrievably.
In another embodiment, the member may be designed so that, after relieving excess pressure, it recovers its optimum movement potential only after one or more combustion cycles. One purpose of this is to permit the parts in the variable volume chamber to cool, for example after undesirable events such as knock, pinging or hydraulic lock.
If desired, the displaceable member may be linked or joined to a resilient modifier by suitable means.
In one embodiment, the member includes means to cause the member to move in one direction only. For example, the member may be designed to move in a direction away from the crank, or away from the pressure in the chamber. Once the member has moved in that direction, it may designed to lock at that point, unless the lock is overcome by a force causing the member to move further in the same direction as before. It will be appreciated that this design can enable the invention to be useful in recording maximum pressure or maximum inertia.
If desired, several displaceable members may be incorporated in a single variable volume chamber.
The displaceable member (or part/s of it) may be capable of projecting sound or other detectable energy, such as electromagnetic waves, for example, which can signal stressing of the member. Such emission of sound or other energy may be detectable by suitable means which can be designed to cause the control mechanism for the scotch yoke device to adjust engine settings, such as timing, to alleviate the pressure.
In yet another broad form of this invention, the invention provides a method of varying power output of a scotch yoke device having a plurality of cylinders, the method including the step of choosing the number of cylinders, the angle between cylinders, pin angles and firing order as set out in any of the rows in the Tables herein.
The invention shall be better understood from the following, non-limiting description of preferred forms of the invention, in which:
FIGS. 11 to 25 show various configurations of the guide surfaces of the invention.
FIGS. 28 to 35 are axial cross-sections through a big end and embodiments of a connecting means according to the invention.
FIGS. 36 to 44 show further variations of the connection between the connecting means and the engagement means of the piston.
FIGS. 53 to 57 show end views of further embodiments of the invention.
FIGS. 58 to 69 show end views of a slider arrangements used in embodiments of the invention.
FIGS. 85 to 126 show underside plan views of various pistons made according to the invention.
FIGS. 127 to 129 show isometric views of a further piston made according to the invention.
FIGS. 130 to 132 show isometric views of a further piston made according to the invention.
FIGS. 133 to 135 show isometric views of a further piston made according to the invention.
FIGS. 136 to 138 show isometric views of a further piston made according to the invention.
FIGS. 139 to 141 show isometric views of a further piston made according to the invention.
FIGS. 142 to 144 show isometric views of a further piston made according to the invention.
FIGS. 145 to 147 show isometric views of a further piston made according to the invention.
FIGS. 148 to 150 show isometric views of a further piston made according to the invention.
FIGS. 151 to 153 show isometric views of a further piston made according to the invention.
FIGS. 154 to 156 show isometric views of a further piston made according to the invention.
FIGS. 157 to 159 show isometric views of a further piston made according to the invention.
FIGS. 160 to 162 show isometric views of a further piston made according to the invention.
FIGS. 163 to 165 show isometric views of a further piston made according to the invention.
FIGS. 166 to 168 show isometric views of a further piston made according to the invention.
FIGS. 169 to 171 show isometric views of a further piston made according to the invention.
FIGS. 172 to 174 show isometric views of a further piston made according to the invention.
FIGS. 175 to 177 show isometric views of a further piston made according to the invention.
FIGS. 178 to 180 show isometric views of a further piston made according to the invention.
FIGS. 181 to 183 show isometric views of a further piston made according to the invention.
FIGS. 184 to 186 show isometric views of a further piston made according to the invention.
FIGS. 187 to 189 show isometric views of a further piston made according to the invention.
FIGS. 190 to 192 show isometric views of a further piston made according to the invention.
FIGS. 193 to 195 show isometric views of a further piston made according to the invention.
FIGS. 197 to 199 are end views of the embodiment of
FIGS. 204 to 207 show perspective conceptual views of various yoke constructions.
FIGS. 231 to 235 are Tables showing the choice of cylinder angle, pin angle and firing order in the method of the invention.
Referring to
Rotatably mounted on big end 16 is a connecting means, being a slider 18. The slider has two tongues 20, 22.
The slider 18 extends generally perpendicular to the axis 14. As best seen in
Each of the tongues 20, 22 engages in a T-shaped slot 30 of a respective piston 32. Each piston is mounted in a cylinder 34 for linear movement along a respective cylinder axis 36. Each slot 30 preferably extends substantially perpendicular to the cylinder axis 36 and extends diametrically across the centre of the piston. Both ends of the slot 30 are open. The slider 18 can thus move sideways relative to the piston but must move axially with the piston along axis 36. Where the slot 30 does not extend at 90° to the piston axis 36, sideways movement of the tongue 20 or 22 relative to the piston will cause axial motion of the piston 32. This enables one to control the motion of the piston 32 beyond a pure sinusoidal motion.
The piston 32 is constrained to move along its piston axis 36 and as the crank 12 rotates the slider 18 rotates about the crank axis 14. The motion of each tongue 20, 22 has a component parallel to the respective piston axis 36 and a component perpendicular to the respective piston axis 36. Thus, the pistons 32 reciprocate in their respective cylinders 34 with the tongues 20, 22 sliding sideways in their respective slots 30. The combination of the linear movement of the piston 32 and the tongue 20, 22 in the slot 30 maintains the slider 18 in a constant orientation as the crank rotates, irrespective of other pistons. In the embodiment of
In the
Optionally, the embodiments in
In this type of engine, the crank axis orbits around the main axis. In
Because each of the pistons is decoupled from any other piston, the orientation and position of the pistons may be chosen as desired. There is no need for the piston axes to extend radially from the crank axis. The piston axes may extend radially from an axis, but this axis may be remote from the crank axis. The piston axes may be parallel and spaced from each other on either side of the crank axis.
In
Slides 62 are received in engagement slots (not shown).
Planetary gear 64 at the end of the crankshaft engages annular gear 66 which drives gear 68 in a 2:3 relationship.
The engine of
Note that the engines of
Referring to FIGS. 5 to 7, there is show a reciprocating piston device 210 having two pistons 232 reciprocating in respective cylinders 234 at 90° to each other. A connecting device 218 connects the two pistons to big end pin 216 of crankshaft 212 via tongues 220 and slots 230 in the pistons 232. The connecting device 218 has two webs 240, one for each piston, which are offset axially relative to each other. This allows the pistons 232 to overlap each other and so be brought closer to the crank axis 214. Lubrication ducts 242 are provided to supply pressurized oil from the big end pin 216 to the sliding surfaces of the tongues 220 and slots 230.
The connecting device 218 includes a counter weight 244 extends downwardly on the opposite side of the big end pin 216, to tongues 220 bisecting the angle between the two webs 240. This counter weight 244 may be sized so that the centre of mass of the connecting device 218 lies on the big end axis 246. It will be appreciated that when the pistons are spaced equally about the crank axis 214, the webs 240 will balance each other and therefore a separate counter weight may not be needed.
Providing the connecting device 218 is counterweighted so that its centre of mass is centered on the big end, as the connecting device 218 orbits the crank axis 214, no rotational forces are generated relative to the centre of mass centered on big end axis 246, which would cause the connecting device 218 to attempt to rotate about the big end and which would need counter turning forces to be generated at the slot 230/tongue 220 interface.
This leaves the reciprocating mass of the pistons 232. The velocity of the pistons 232 follows a pure sinusoidal path and in combination the two pistons 232 are the equivalent of a single rotating mass in a circle. This may be balanced by adding an appropriate mass to the crankshaft 212, thereby resulting in a dynamically balanced device. For a V twin configuration, a single piston mass is added to the back of the crankshaft 212.
Referring to
Referring to
Vertical movement of the crankshaft 12 may be achieved utilizing conventional means, such as adjustable screws, hydraulic rams, a pneumatic or cam controller or the like, operating in the region of arrows 87 and 89.
It will be appreciated that a movable crank may be utilized with a single piston. It will be appreciated that the movable crank may be moved along paths other than the bisector in a V-twin engine, for example. The crank may be moved at, say, 15° to the vertical or in another desired way. This may have no effect other than to need more crank movement to achieve the same change in compression ratio.
FIGS. 11 to 25 show a number of variations of the guide surfaces of the piston and the corresponding surfaces on the engagement means. At least some of these configurations may be used for the restricting means.
The device of
The connecting rods each have a sideways extending arm 316 which engages a slider 318 which slides in guides 320 parallel to the respective cylinder axis. The connecting rod 312 may be integral with the slider 318 or it may be connected by way of a pivotable joint 322, as shown. The joint 322 may be a single axis joint or a ball type joint. In the embodiment shown, the arms 316 extend parallel to the slots 314. However they may extend at any angle.
The guides 320 aid in stabilizing the respective piston 302 because the tolerances required can result in the piston 302 rotating very slightly in the bore and cause seizing or the like. If very tight tolerances are used, the guides 320 may not be needed. The guides 320 may be integral with the crank case or may be separate items attached to the crank case by way of bolts and the like
The gudgeon pins 310 of the pistons 302 may be at 90° to the crank axis as no rotational movement of the connecting rod 312 relative to the piston 302 will occur. Use of the pistons 302 with gudgeon pins 310 allows one to use “off the shelf” pistons. However, piston 302 may be integral with connecting rod 312.
A slave crank, 338 is provided which rotates about an axis 340 parallel to the axis 331 of the primary crank. A link 342 is pivotably mounted on both the connecting means 334 at 344 and the slave crank 338 at 346. The distance of pivot point 346 from the slave axis 340 is the same as that of the big end 332 from the primary axis 331. The slave crank 338 and link 342 thus aid in maintaining the connecting means 334 in a fixed orientation as the primary crank 330 rotates. It will be appreciated that this stabilization technique may be used with any of the embodiments described herein.
FIGS. 36 to 44 show further variations possible of the connection between the connection means and the engagement means of the piston or pistons mounted thereon.
Referring specifically to FIGS. 39 to 44, it is to be understood that these are particularly suitable for use as constraining means or restricting means, as well. For convenience, the description below is in relation to connecting means.
The
In the
In connection with the embodiment in
In
The
FIGS. 48 to 50 show a four piston device 860 having pairs of pistons 862a,b arranged at 90° to each other. Each piston has an extension 864 having end walls 868 and 870 extending perpendicular to the respective piston axis. The extensions 864 extend to one side of the piston axis, as best seen in
The crank includes an offset circular cam 872 which engages the four walls 868a,b, 870a,b. As the crank rotates, the cam 872 causes both pistons 862a, b to reciprocate in their respective cylinders, not shown.
It will be appreciated that the FIGS. 48 to 50 embodiment show a device which would normally have horizontally opposed, coupled, pistons. The device of the invention, however, has decoupled the piston pairs and has achieved a configuration which is more compact than the conventional configuration. It will also be appreciated that extension 864 may be in one piece or may comprise two or more pieces joined together.
Whilst the FIGS. 48 to 50 embodiment uses a cam bearing directly on the end walls, it will be appreciated that the slider construction of the
Two sliders 880 are interposed between the cam 872 and the end walls 868a, b and 870a, b. Each slider bears on the inner face 868 of one piston and the outer face 870 of the other piston. As the crank 866 rotates this causes the sliders 880 to move both pistons. As with the
It will be appreciated that the assemblies described above may have gaps as shown filled with rubber or other elastomeric material.
Cam followers 1066 are spring loaded, being biased towards elliptical cam 1068. An oil reservoir is formed at 1069 and oil enters the reservoir through a one way valve (not shown) from the big end. At one point in its rotation, elliptical cam 1068 causes oil to be decanted from reservoir 1069. This oil is then pumped into the gap between the engagement means and the follower. Oil galley is shown at 1067. A similar configuration is found in
It is to be understood that the various forms of the slider and the engagement means on the sliders may be used with any of the other forms of the invention in any practical combination possible and the various forms are not limited to use with the components shown in the specific figures.
Referring to
Mounted on the engagement means 5024, or integral therewith, is a piston 5026, which is mounted in a cylinder 5028 for reciprocal motion along cylinder axis 5030.
The engagement means 5024 is in the form of a triangular loop and the connecting means 5020 is positioned so that the linear slot 5022 always lies with the big end axis 5018 between the slot 5022 and the piston 5026. The piston 5026 is constrained to move along the cylinder axis 5030 and so, as the crank 5012 rotates, the slot 5022 remains horizontal with the connecting means 5020 moving both vertically (and moving the piston) and side ways, relative to the engagement means 5024.
The effect of this arrangement is that the crank axis may be moved nearer the cylinder head 5032 than otherwise.
In the
In this embodiment, there is provided a common engagement means 5082 which engages the connecting means. The engagement means is effectively the same as two of the engagement means of the
Referring to
The yoke assembly includes two identical pieces 6026a and 6026b. Each piece has a centrally located mounting 6028 on which a piston 6016 mounts, a transverse section 6030 and a longitudinal section 6032.
The transverse section 6030 extends generally perpendicular to the cylinder axes whilst the longitudinal section 6032 extends generally parallel to the cylinder axes.
A channel 6034 extends in the transverse and longitudinal sections 6030, 6032 in which the slider 6032 is located. At the free end 6036 of the transverse section 6030 are bolt holes 6038 whilst at the free end 6040 the longitudinal section there are bolt holes 6042. The two identical parts are joined with the free ends 6036 of the transverse sections 6030 engaging the free ends 6040 of the longitudinal sections 6032 of the other part. The bolt holes 6038 and 6042 align and the two parts are secured together with the bolts 6044 and nuts 6046.
A tubular spacer 6048 is positioned within the channel through which the bolts 6044 pass to prevent over tightening and crushing of the slot. The longitudinal sections 6032 have closed ends 6050.
FIGS. 78 to 80 show a further variation of the yoke assembly. In this embodiment the yoke assembly 6060 is split along the cylinder axis to form two identical portions 6062a, 6062b. The portions are U-shaped, having a central body 6064 with axially extending arms 6066. Each portion is symmetrical about a centre line perpendicular to the cylinder axis.
The opposing faces of the two pairs of arms 6066 are each provided with two stud holes 6068 and studs 6070 are provided to locate the two halves together. The two halves are secured together by bolts 6074 which pass through bolt holes 6076 at each end of the arms 6066 and screw into the opposing arm 6066. The ends of the arms 6066, when joined, form a receptacle 6078 into which the piston is mounted. This receptacle allows the piston to rotate about the cylinder axis.
The assembly also includes joining members 6080. These joining members are located within the channel and have threaded studs 6082 which extend through holes 6084. The members 6080 are secured to the two halves by nuts 6086 and serve to resist bending of the two halves of the assembly out of a plane.
Referring to FIGS. 81 to 84 there is shown a V-twin fluid device 2010 (
Each of the pistons 2012 has a T-shaped slot 2018 which extends diametrically across each piston. The connecting means 2016 has corresponding T-shaped tongues 2020 which engage in the slots 2018. Each of the tongues 2020 has a two part construction—the cross arms are formed of a planar web 2024 which is attached to the vertical web 2026 by bolts 2028.
Located on either side of the slot 2018 are two axially extending restricting means, namely planar webs 2030. These webs 2030 are diametrically opposite each other and extend perpendicularly to the slot 2018 but do not extend out of the footprint of the piston. Webs 2030 extend beyond slot 2018. The webs 2030 are integral with the piston body.
The fluid device has a series of U-shaped guides 2032 which engage the webs 2030, as seen in
The guides are preferably located on the crank case by way of a locating pin 2034 and then bolted via bolt holes 2036. 384 The guides 2032 serve to limit movement of the pistons both parallel and transverse to the slot 2018 and so enable the skirt length of the piston to be reduced, if desired.
Because the webs 2030 are located to the sides of the slot, rather than at one or both of its ends, the size of the crank case need not be any greater than a conventional crank case. Further, because the webs 2030 do not extend outside the footprint of the piston, an existing crank case can be relatively easily modified to take the crank and piston assembly.
The webs and the slot 2018 may be formed integrally with the piston 2012 and so be formed of the piston material. Alternatively, separate components may be provided and the piston assembly built up from those components. Preferably, the bearing surfaces of the slot 2018 and the webs 2030 are suitably treated to provide a hard wearing surface or are provided with bearings to provide a suitable surface. It is to be understood that oil lubrication will be provided to the bearing surfaces via oil galleries or by oil splashing.
FIGS. 85 to 126 show bottom plan views of different configurations of piston webs or vertical guide means which may be used with the connecting means 2016 shown in
FIGS. 127 to 129 show a piston 20242 with a vertically extending guide bar 20244 and a horizontal slide bar 20246. The bar 20244 extends from the lower surface of the main body 20248 of the piston 20242. The horizontal bar 20246 is mounted on an inner side of the vertical bar 20244. The bar 20246 is engaged by a suitable engagement means on the connecting means whilst the vertical bar 20244 is engaged by a suitable guide surface mounted on the crank case.
FIGS. 130 to 132 show a piston 20250 with a vertical guide bar 20252 and a horizontal bar 20254. The horizontal bar 20254 has a re-entrant slot 20256 for slidably engaging a corresponding tongue on a connecting means.
FIGS. 133 to 135 show a piston 20258 having a main body 20260. Rotatably mounted to the main body by a gudgeon pin 20262 is a engagement/guide means 20264. This engagement means includes a horizontally extending portion 20266 and a vertical extending portion 20268. The horizontal portion includes a slot 20270 which slidably receives a complimentary tongue on the connecting means whilst the vertical portion 20268 is engaged by a guide mounted on the crank case. It will be noted that the vertically extending portion extends above and below the horizontally extending portion.
FIGS. 136 to 138 show a piston assembly 20272 with a Z-shaped horizontally extending member 20274 which slidably engages a complimentary surface on the connecting means. Guide webs 20275 engage guides mounted on the crank case.
FIGS. 139 to 141 show a piston assembly 20276 in which a vertical guide bar 20278 extends from the base of the main body 20280 of the piston. A horizontal bar 20282 is mounted on the main body 20280 independently of the vertical guide bar 20278.
FIGS. 142 to 144 show a piston assembly 20283 having a main body 20284 and an engagement/guide assembly 20286 mounted to the main body by pins or bolts 20288. The engagement/guide assembly 20286 has two vertical legs 20290 and a cross bar 20292. Mounted on the cross bar 20292 is a horizontally extending T-shaped engagement member 20294 which extends perpendicular to the plane of the two vertical guide bars 20290. This member 20294 is engaged by the connecting means.
FIGS. 145 to 147 show an assembly 20296 similar to that of FIGS. 142 to 144 and a similar engagement/guide assembly 20300 is mounted to the main body 20298 of the piston 20296. The assembly 20300 is mounted-to the main body 20298 by a gudgeon pin 20302 which extends in the plane of the two legs 20290. The assembly 20300 may pivot about the pins 20302.
FIGS. 148 to 150 show a piston assembly 20304 having a main body 20306 on which is mounted an H-shaped guide assembly 20308. The assembly is mounted to the main body 20306 via pins 20310. Mounted on the cross bar 20309 of the assembly 20308 is a horizontally extending engagement bar 20312. The bar 20312 is pivotably mounted to bar 20309 via pin 20314. The bar 20312 has a T-shaped slot 20316 for engaging a T-shaped tongue on the engagement means.
FIGS. 151 to 153 show a piston assembly 20318 having a guide/engagement means 20320 mounted to the main body 20322 via pin 20324. A cross bar 20326 extends between vertical members 20328 and includes a T-shaped slot 20330.
FIGS. 154 to 156 show a guide engagement assembly 20332 having a cross bar 20334, four vertical guide bars 20336 and a central connecting bar 20338. There are two vertical guide bars 20336 on either side of the cross bar 20334. The cross bar has a T-shaped slot 20339.
FIGS. 157 to 159 show an assembly similar to that of FIGS. 154 to 156 except that the cross bar 20340 is T-shaped, rather than having a T-shaped slot.
FIGS. 160 to 162 show an assembly 20342 similar to that of FIGS. 157 to 159 attached to a piston body 20344 by two pins 20346 so that pivoting is not possible.
FIGS. 163 to 165 show a piston assembly 20350 having a guide/engagement means 20352 mounted on a pin or cross bar 20354 of the piston body 20356. The pin or cross bar 20354 may be separate from or integral with the body 20356. The assembly is retained on the cross bar 20354 by bolt 20358.
FIGS. 166 to 168 show a guide/engagement assembly 20360 similar to that of FIGS. 154 to 156 but retained on the piston body 20362 by two pins 20364.
FIGS. 169 to 171 show a piston assembly 20366 functionally identical to that of FIGS. 166 to 168 but in which there is a single unitary structure and only one vertical guide bar 20368 on each side of the horizontal engagement bar as opposed to two.
FIGS. 172 to 174 show a piston assembly 20370 similar to that of FIGS. 127 to 129 but in which a horizontal slot 20372 is provided for engagement with the connecting means.
FIGS. 175 to 177 show a piston assembly 20374 having a single vertical guide bar 20376 and a T-shaped engagement bar 20378 depending from the guide bar 20376.
FIGS. 178 to 180 show a piston assembly functionally identical to the FIGS. 130 to 132 embodiment except that the re-entrant slot 20380 is much nearer to the piston body 20382.
FIGS. 181 to 183 show a piston assembly 20450 having two vertical guide bars 20452 extending from the piston body 20454. A cross bar 20456 is mounted inwardly of the bars 20452 and extends horizontally. The cross bar has a diamond shaped slot 20458 which receives a corresponding tongue mounted on the connecting means.
FIGS. 184 to 186 show a piston assembly 20460 having a piston body 20462 from which descends a guide bar/engagement assembly 20464. This assembly 20464 includes a T-shaped engagement portion 20466 having a cross bar 20468 which in turn defines an L-shaped slot 20470 to receive an L-shaped tongue mounted on a connecting means. A vertical guide bar 20472 descends from the piston body 20462. Preferably the guide bar 20472 is integral with the engagement portion 20466 but it may be separate. The guide bar 20472 preferably extends below the horizontal cross bar 20468.
FIGS. 187 to 189 show a piston assembly 20474 having a piston body 20476 and a guide/engagement assembly 20278 pivotably mounted to the body 20476 by gudgeon pin 20480. The assembly 20478 has a T-shaped portion comprising vertical leg 20482 and horizontal cross bar 20484. The cross bar has a T-shaped slot 20486 in a side wall 20488 for receiving a corresponding tongue on the connecting means.
FIGS. 190 to 192 show a piston assembly 20490 having a piston body 20492 with four vertical and parallel guide bars 20494 extending downwards. The four bars 20494 are located at the corners of a square centered on the centre of the piston's circumference.
An engagement means 20496 is pivotably mounted on the piston via gudgeon pin 20498 and is located between the vertical guide bars 20494. The engagement means includes a flat cross bar 20500 which may engage in a T-shaped slot on the connecting means.
FIGS. 193 to 195 show a piston assembly 20502 having a piston body 20504 with a guide/engagement assembly 20506 attached to the body 20504 by two pins 20508. The assembly 20506 has a vertical post 20510 and a first cross bar 20512 having four vertical guide posts 20514, each arranged at one of its corners. Mounted to the underside of the first cross bar 20512 is a second T-shaped cross bar 20516 which is engaged by a corresponding T-shaped slot on the connecting means.
Referring to FIGS. 196 to 203 there is shown a fluid device 4010 having a crank 4012 rotating about a crank axis 4013 and two pistons 4014 reciprocating in cylinders 4016 in a V configuration. The two pistons 4014 are connected to the crank 4012 via a single slider mechanism 4018, which is rotatably mounted on the big end 4020 of the crank 4012. The big end 4020 extends between webs 4022, one of which is shown. The slider 4018 has two T-shaped tongues 4024 which slidably engage in corresponding slots 4026 (see
Extending downwards from the base area of each piston are two guide bars 4028. These bars 4028 extend on either side of the slider 4018 and slot 4026. In addition, each bar extends below the slot 4026 toward the crank axis 4013. Each bar 4028 is able to dip into and out of the volume swept by big end 4020 as it orbits axis 4013. Bar 4028 fits between adjacent big ends 4020 without interfering with them. However, equivalents to bars 4028 could be located outboard of big ends 4020, instead of or in addition to the depicted configuration. This is an important improvement, since it allows the bars 4028 to support the piston 4014 all the way down to cylinder 4016, while having a very short deck height, compared to an arrangement which would have the bars 4028 extending only from the piston crown to a location short of the horizontal slide tongue 4024.
Whilst two bars 4028 per piston are shown, it will be appreciated that only one or more than two bars per piston may be used. Where two or more bars are used it is not essential that they be located symmetrically relative to the cylinder/piston axis; the bars may be positioned to one side of the slot 4026 or asymmetrically on both sides.
A corresponding number of guides 4030 (
As best seen in
As the crank 4012 rotates, the pistons 4014 reciprocate in their cylinders 4016 and, as seen in FIGS. 196 to 199, the guide bars 4028 move up and down with the pistons 4014 into and out of the volume swept by the big end 4020.
At bottom dead centre (
FIGS. 204 to 207 show conceptually components for building up yoke assemblies.
The other portion 6094 has a transverse arm 6106, piston mounting portion 6108 and two arms 6110 extending from adjacent the ends of the transverse arm 6106. The arms 6110 extend from the same side of the transverse arm 6106 and at their free ends have holes 6112. The transverse arm 6106 has a central bolt hole 6114.
When assembled the central arm 6100 is attached to transverse arm 6106 by a bolt passing through hole 6104 into hole 6114. Similarly arms 6110 are attached to transverse arm 6096 by bolts passing through holes 6112 into holes 6102. The bolt holes 6102 and 6114 may be threaded or unthreaded. Three bolts are required for assembly.
It will be appreciated that this configuration may only be used where the big end does not pass through the yoke.
Turning now to
In this embodiment, engagement means 7012 are centered on big end axis 7010. For each piston 7008a and 7008b, the engagement means 7012 are located to one side of the big end axis 7010.
It will be appreciated that it is best if the pistons reciprocate in a manner that they are one half of a sinewave out of phase from each other. Provided that the pistons are of the same mass, the engine will be perfectly balanced. It is also obvious that the crank disk and scotch yoke embodiments of the invention that are of V configuration may be balanced in the same way and that X, horizontally opposed or 180 degree configuration devices of the invention may also be balanced similarly.
It is also clear that an engine designer may wish to construct a fluid scotch yoke type device of a type depicted and described herein wherein a degree of imbalance is in some way preferred, accordingly the invention includes devices with their pistons displaced at not quite one quarter of a sine wave out from each other, say up to 10%-20% or even up to 50% of the sine wave out of true balance. This still fits broadly within the scope of the invention.
For the purpose of this discussion, the engine is a 90 degree vee twin, with the cylinders 45 degrees to the left and right of a vertical centre line. The engine is assumed to be rotating clockwise so that when the crankshaft is vertical, the left piston is going up and the right piston is at the same relative position in its cylinder but doing down.
The engine is assumed to be made up of the following components:
Crankshaft whose mass is concentrated in two positions namely the counterweight and the big-end.
Conrod whose mass is concentrated in 3 positions, the left slider, the right slider and the counterweight directly below the big-end.
The left and right pistons whose mass is assumed to be concentrated at the centre of their respective bores and some distance above the respective sliders.
The stationary parts of the engine (crank case, block, etc.) are assumed to be rigidly mounted so they can be disregarded in considering engine balance issue.
Imagine the engine is assembled, starting as follows:
Install a crankshaft which is balanced on its own. That is, its centre of mass is at its centre of rotation, the main bearing. Clearly this is perfectly balanced.
Now add the component referred to as the “con-rod”. Because the left and right slider mechanisms will be above the big-end, the conrod will require its own counterweight located directly below the big-end if we want its centre of gravity to be at the big-end. If to the crankshaft counterweight is added an amount calculated from the total mass of the conrod, the centre of gravity can be kept at the main bearing and the assembly so far will still be perfectly balanced.
Note that the conrod maintains the same orientation all the time so that it is in fact “orbiting”. Because its centre of mass is at the big end, it will have no tendency to rotate as the crankshaft rotates. If the mass of the conrod counterweight is reduced so that the conrod centre of mass was above the big-end, then the conrod would tend to rock as the crankshaft rotated. Provided it is prevented from actually rocking, its centre of mass will still describe a circle of the same radius and can still be perfectly balanced by the crankshaft counterweight.
There is thus a design choice here whether to reduce the load on the slider mechanisms by balancing the conrod or whether to reduce the mass of the conrod and the mass of the crankshaft counterweight thereby reducing inertial forces generally. An alternative would be to prevent the conrod from rotating by other means such as a second crank mechanism.
If the pistons are now added, the engine is put out of balance. However, because the piston motion is perfectly simple harmonic and the pistons are 90 degrees out of phase, the two together are exactly equivalent to one piston mass traveling in a circle. It is necessary, therefore, merely to add to the crankshaft counterweight a mass calculated from the mass of one piston (and adjusted to allow for the ratio of crankshaft throw to crankshaft counterweight distance) and the whole engine remains perfectly balanced.
This is easiest to visualize if one tilts one's head to the left so that the left piston appears to be moving vertically and the right piston moving horizontally. When the left piston is at its highest point, the crankshaft counterweight is at its lowest point. At the same instant, the “right-hand” piston is at mid-stroke and traveling to the right. As far as the horizontal motion of the crankshaft counterweight is concerned, it is at midstroke and traveling to the left. The crankshaft counterweight can therefore be adjusted to exactly balance both pistons.
The centre of mass of all moving parts of the engine remains exactly stationary. There are no higher order effects as in a conventional engine. These arise because the piston motion is not simple harmonic and the motion of a conventionally driven piston is not simple harmonic and the motion of a conventionally driven piston is not symmetrical near top and bottom dead centre.
It is also interesting to note that the internal kinetic energy of the slider engine of this invention is also constant throughout its cycle. Provided the angle of the cylinders is 90 degrees, then the combined kinetic energy of the pistons is constant. This means that there is no tendency for the mechanism to resist rotating at constant angular velocity.
The following is the theory behind the balancing of the engine with offset big ends.
A is the angle between the bores of 2 cylinders in a vee engine.
D is the angle between lines extending from the main axis to the big ends.
If D is set equal to 2*(A−90), the centre of gravity of the two pistons will be found to move in a circle so that it can easily be balanced by a counterweight on the crankshaft.
If the connecting rods are allowed to pivot relative to the pistons, it is assumed that the connecting rods are sufficiently long that the motion of the pistons is simple harmonic. Where pivoting is not allowed or limited to very small amounts the motion will inherently be simple harmonic motion to practical effect.
The mass of the connecting rods is ignored.
Angles are measured positive anticlockwise from the positive X axis.
Assume the first bore is a 0 degrees.
The second bore is at an angle A degrees.
When the big end for the first piston is at 0 degrees (so that the first piston is at TDC) the big end of the second piston is at D degrees.
Consider the general case when the big end for the first piston is at R degrees and the big end of the second piston is at D+R degrees.
The X co-ordinate of the first piston is Cos(R) measured with respect to its mean position.
The Y co-ordination of the first piston is always zero.
The radius of the crankshaft for the second piston is also unit length, but in the general case under consideration, the value of the radius projected onto the axis of the second bore is Cos(A−D−R).
Since it is of interest only to look at variations in the position of the centre of gravity of the pistons, the second piston can be taken to be at:
X=Cos(A−D−R)*Cos(A)
Y=Cos(A−D−R)*Sin(A)
The centre of gravity of the two pistons together can be taken as:
X=Cos(A−D−R)*Cos(A)+Cos(R)
Y=Cos(A−D−R)*Sin(A)+0
Note that these should both be divided by 2, but this is omitted to simplify the appearance of the algebraic expressions.
It turns out that for any value of A, if D is set at D=2*(A−90), then the centre of gravity of both pistons together moves in a circle and can be easily balanced by a counterweight attached to the crankshaft.
That this is the case can be proved by substituting 2*A−180 for D in the above expressions which become
X=Cos(A−2*A+180−R)*Cos(A)+Cos(R)
Y=Cos(A−2*A+180−R)*Sin(A)+0
which become
X=Cos(−A+180−R)*Cos(A)+Cos(R)
Y=Cos(−A+180−R)*Sin(A)+0
which equals
X=−Cos(A+R)*Cos(A)+Cos(R)
Y=−Cos(A+R)*Sin(A)
expanding Cos (A+R) in each case
X=−Cos(A)*Cos(A)*Cos(R)+Cos(A)*Sin(A)*Sin(R)+Cos(R)
Y=−Cos(A)*Cos(R)*Sin(A)+Sin(A)*Sin(R)*Sin(A)
simplifying, we get
X=Sin(A)*(Cos(R)*Sin(A)+Sin(R)*Cos(A))
Y=Sin(A)*(−cos(A)*Cos(R)+Sin(A)*(Sin(R))
or
X=Sin(A)*Sin(A+R)
Y=Sin(A)*Cos(A+R)
This is the equation of a point moving in a circle of radius Sin(A).
Thus the motion of the two pistons together can be counterbalanced by a single mass, equal in mass to one piston mass rotating on a radius of Sin(A) times the crankshaft radius. (The fact that there are actually two pistons compensates for the factor of 2 which was omitted in the expressions for X and Y above).
It will be appreciated that when A=90°, i.e. a 90° V configuration, that D=0°, i.e., the axes of the two big ends are not offset but are coaxial. Thus a 90° V configuration with a single big end is merely a special case where D=0°.
It will be apparent to those skilled in-the art that many modifications and variations may be made to the embodiments described herein without departing from the spirit or scope of the invention.
Referring now to FIGS. 214 to 216, block segment is bolted or otherwise affixed to block 516 (refer
The description of other labeled parts are the same as in the case of
Referring to
The cylinder 8022 and crankcase 8012 form a sealed unit for each piston and so the piston 8020, cylinder 8022 and crankcase 8012 together define a combustion chamber 8024 above the piston 8020 and a crank volume 8026 below the piston.
The crank volume is provided with an air inlet 8028. Communication between the crank volume 8026 and the inlet 8028 is controlled by a reed valve 8030 but a poppet valve or any other suitable valve may be used.
The crank volume 8026 communicates with the combustion chamber 8024 via passageways 8032 and 8034 and an intermediate chamber 8036. Communication between the crank volume 8026 and passageway 8032 is controlled by poppet valve 8038 whilst poppet valve 8040 controls communication between the passageway 8034 and the combustion chamber 8024.
The intermediate chamber 8036 is closed, except for the passageways 8032 and 8034. Located in the chamber 8036 to one side of both the passageways 8032 and 8034 is a movable piston 8042 which thus defines a closed volume 8044.
In operation, assuming the piston is at or near top dead centre and is just commencing a power stroke, the piston 8020 descends, reducing the volume of the crank volume 8026. Poppet valve 8040 is closed, poppet valve .8038 is open and so the pressure in the crank volume 8026 increases, closing or maintaining closed the reed valve 8030. The piston 8020 descends toward bottom dead centre, at an appropriate point in the cycle and the secondary piston 8042 moves to reduce the closed volume 8044 under the increased pressure in the crank volume 8026. At or near bottom dead centre poppet valve 8038 closes, trapping the pressurized gas in the intermediate chamber 8036.
The piston 8020 passes bottom dead centre and ascends on the exhaust stroke and so the reed valve 8030 opens as the pressure in the crank volume 8026 reduces, allowing fresh charge gas to enter the crank volume 8026. At or near top dead centre, at an appropriate point in the cycle, the upper poppet valve 8040 opens, so allowing gas from the intermediate chamber 8036 to enter into the combustion chamber 8024. The secondary piston 8042, under the effect of the closed volume 8044 aids in urging the gas in the intermediate chamber 8040 into the combustion chamber 8024. The secondary piston 8042 can be used to alter the volume of intermediate chamber 8040, it need not in some embodiments actively urge the gas out of intermediate chamber 8040.
The piston 8020 passes top dead centre and starts to descend again, on its induction stroke, increasing pressure in the crank volume 8026. When the pressure in the crank volume 8026 is greater than that in the passageway 8032, the poppet valve 8038 opens, allowing pressurized gas in the crank volume 8026 into the passageway 8032 and thence to the combustion chamber 8024. At or near bottom dead centre, at an appropriate point in the cycle, the poppet valves 8038 and 8040 close and the piston 8020 passes bottom dead centre and starts to ascend on its compression stroke. The valves 8038 and 8042 may close simultaneously or at different points in the cycle. The pressure in the crank volume 8026 decreases, causing reed valve 8030 to open and allowing another fresh charge into the crank volume 8026.
At or near top dead centre, at an appropriate point in the cycle the reed valve 8030 closes and, at an appropriate point in the cycle the poppet valve 8038 opens and the cycle commences again. The valve 8030 may close simultaneously with the opening of valve 8038 or at a different point in the cycle.
In this embodiment, the combustion chamber 8024 is provided with two independent inlets. The first inlet 8062 is a conventional inlet and feeds air and vaporized fuel directly to the combustion chamber 8024. Communication is controlled by poppet valve 8064. The crank volume 8026 is supplied with air and vaporized fuel via inlet 8028 and poppet valve 8030. The crank volume 8026 is connected to the combustion chamber 8024 via passageway 8066 and poppet valve 8068.
In use, the internal combustion engine functions as a conventional four stroke engine with air being drawn into the combustion chamber 8024 via inlet 8062 on the downward induction stoke. During this stroke, the reed valve 8030 and poppet valve 8068 are closed and the fuel air mixture in the crank volume 8026 is pressurized. At or near bottom dead centre at an appropriate point in the cycle, the poppet valve 8064 closes. At about the same point in the cycle, the poppet valve 8068 opens, allowing the pressurized fluid in the crank volume 8026 to pass into the combustion chamber 8024. Thus the amount of air and fuel in the combustion chamber 8024 is increased compared to a conventional normally aspirated internal combustion engine. The poppet valve 8068 closes whilst the piston 8020 is still near bottom dead centre, so trapping the extra fluid in the combustion chamber 8024. As the piston 20 rises on the compression stroke, a fresh charge is drawn into the crank volume 8026 via inlet 8038 and reed valve 8030. The reed valve and poppet valve remain closed until the commencement of the next induction stroke as previously described.
During a power stroke the poppet valve 8040 and reed valve 8030 are closed and the rotary valve 8074 is open, allowing the gas in the secondary chamber 8072 to be pressurized. At or near bottom dead centre the rotary valve 8074 closes, so that on the exhaust stroke a fresh charge is drawn into the crank volume 8026. At or near top dead centre, the reed valve closes and the poppet valve 8040 and rotary valve 8074 open, so allowing the pressurized gas in the crank volume 8026 to pass into the combustion chamber 8024 as the piston 8020 descends on the induction stroke. At or near bottom dead centre the poppet valve 8040 and rotary valve 8074 close and a second fresh charge is drawn in from the inlet 8028 as the piston 8020 ascends on the compression Stroke.
When operating as a 4 stroke engine, in some embodiments it may use only the cylinder wall intake port to induct working gas and the cylinder wall exhaust port to exduct spent gas, or, in another preferred embodiment, the cylinder wall exhaust port and head situated exhaust valves in conjunction with the cylinder wall intake port and/or head situated intake valves and tracts, or a combination of both sets of port and head situated valves or a combination of one or more or less of each type of respiratory means.
The engine may be run as a normally aspirated 4 stroke engine, or in the one cycle, It may have a normally aspirated intake respiration phase and a forced induction phase, or it may have a forced induction phase with no normally aspirated phase, and, furthermore these phases may overlap if desired.
This is an engine that may be used as a constant volume or constant pressure engine. The engine may be used as a 2 stroke plus steam engine, in that out of a 720 degree cycle, the first 360 respirates and operates as a 2 stroke and the second 360 as a steam engine (a compound 2 stroke steam engine, if you like).
This engine may utilize in-cylinder injection or in-cylinder air and fuel injection or stratified charge principles or pre-combustion chambers or Miller cycle associated technologies or principles. This engine may be used as a compressor or engine brake in an automobile or industrial machine or other suitable application. This engine may change its operating principles on the fly, swapping from 2 stroke to 4 stroke and vice versa, of whatever respiratory format, that is best suited to or operator chosen for a given set of performance requirement/s. This engine may utilize an external super or turbo charging means, and may be provided with separate or combined exhaust systems for different operating parameters e.g. 2 or 4 stroke and their various cross-bred versions described herein.
Volume 9032 and its valve 9053 may be used to bleed off or dump excess pressure in intake volume 9028 and/or crank case volume 9029 and/or volume 9030. Intake tract 9030 and its valve 9051 may be used to bleed off or dump excess pressure in crank case volume 9029 intake volume 9028 and/or intake volume 9032. Excess pressure in any of the intake volumes may be dumped into intake manifold 9031 or 9033 or into the earth's atmosphere. Part 9028 is an intermediate chamber. Parts 9034 and 9034a are exhaust pipes. Rotary valves 9053, 9038, 9044, 9051, 9039 have been illustrated in these drawings mainly because they are easy to portray; other valve arrangements including ones not listed herein specifically are perhaps useful and in any case a person skilled in the art would doubtless find many alternative devices and layouts that would fit the spirit of the invention herein described without departing from the intent and purposes of it.
In
If variable compression ratios are desirable and said variance is caused by lifting or lowering the crank, the exhaust ports and intake ports and/or their valves' timing may be altered to suit new piston height. This is true for engines made in accordance with the teachings of these patent applications and for 2 stroke engines of normal construction.
FIGS. 224 to 227 show arrangements for adjusting the velocity of fluid flowing into or out of a combustion chamber, whether in a conventional internal combustion engine or in an internal combustion engine of the present invention. These arrangements are applicable to all inlets where two or more separate inlets are provided, such as in the
In
For convenience, there is shown in
In the second embodiment, piston 7408 has a displaceable member 7410 and a resilient modifier 7412, such as an oil reservoir or rubber block. Movement of member 7410 beyond the crown of piston 7408 is prevented by stop 7414.
This embodiment also includes fluid delivery passageway 7416 and decant or pressure overload passageway 7418, having a pressure overload valve 7420.
With reference to
In
Turning now to the tables in
As shown in
The table in
In the table comprising
The invention has industrial applicability in relation to fluid devices in general and more specifically to internal combustion engines and pumps.
| Number | Date | Country | Kind |
|---|---|---|---|
| PR0456 | Sep 2000 | AU | national |
This application claims priority of the filing date of U.S. Ser. No. 10/381,953, presently pending, which is a US national phase application under 35 U.S.C. §371 of PCT/AU01/01214, filed Sep. 28, 2001, the complete disclosures of which are both hereby expressly incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10381953 | Aug 2003 | US |
| Child | 11526344 | Sep 2006 | US |
